This evening started with the Moon high in the sky and waxing its way to half. Next to it Saturn sat, close in fact, so close I pointed the scope at it, around 22:30 and both the Moon and Saturn fit in the same field of view 🙂
So I took a few exposures, worried that either the Moon would be overexposed or Saturn underexposed. I settled on 0.001s and took a bunch of shots. Below is my setup by the light of my rather bright head torch, turned on only for this photo I might add.
Esprit 120 and MyT
Next it was back to trying to resolve the guiding issues that had troubled me the night before. The good news was Tom from the Software Bisque website (not the Tom Bisque, another Tom) had come back with a few suggestions and questions that made me think. I had a good set of guide stars to choose from.
Hw many guide stars!
The autoguide Setup window is where I would spend most of my time I was sure, changing parameters.
Guider settings
I recalibrated the mount, this time using 100arcsec as the parameter. The previous calibration run produced a rather short cross.
Poor calibration ?
This gave me a better ‘cross’ and I think should improve the guiding, although I am still skeptical about just how quick it calibrates, some 4-5 seconds.
Better calibration
Back to guiding the mount was still all over the place, I am convinced it is overcorrecting, on the basis if I don’t guide I get better stars up to 45s or so. I added in a much longer settle period and this seemed to help, but still the graph is a long way from the sort of guiding I was getting before they updated the software.
Poor guiding
The wind was a bit gusty tonight as last night and for sure this was not helping, you can tell from a few exposures it was wind related jumps and drifting
I sat back after a while of changing different settings feeling that it was not improving, so I took a whole bunch of images, only 90s of the Sharpless object Trevor had mentioned, SH2-101 which is called the Tulip nebula. Trevor had produced a lovely image from his 14″ in the UK so I thought I would have a quick go, knowing most of the frames would be lost.
Final set of guider settings
So by 00:30 I decided to start to pack up, the wind had picked up, I was cold, the guiding was still a problem, so by just gone 1am I was heading down the mountain, some 1 hour and 20min drive! The final view from the bridge as it were was this.
View from TSX
The next day I processed the data for the Sharpless object and it was ok, given the short amount of data. One for the 12″ I think.
SH2-101 Tulip Nebula
Meanwhile I processed a single image of the Moon and Saturn and was pleased with the result as seen above. Here is a version with Saturn as an insert.
So I have arrived in Tenerife and for a few nights only I am up at the MONS observatory, using the plateau (concrete platform with power) outside the dome.
It was dark when I arrived at 20:15 so I am setting up by head torch and given the tripod and mount and scope are all in bits it has taken some time to put it back together.
I setup in the corner where Bob normally sits as thee were a bunch of students using the scopes normally kept in the sheds outside. After setting up I panicked as I had forgot my UK to EU plug ! I asked the lady leading the student outreach and she let me in the MONS and I searched for a plug and found one, despite everything being emptied out due to the MONS having work done to it. However on testing the plug it did not work 🙁
A call to the operator did not produced anything. So I tore down the scope and packed in the car, very disheartened. As I was just about to head off the operator arrived with another plug ! I took my laptop and tried it, but it did not work either. It took a while to work out but of course the power had been turned off from the fuse box and flicking the RCD produced power and so reluctantly I emptied the car and went about setting back up 🙁
By this time it was approaching midnight and I had been at this for some 4 hours. I started the laptop, found I was pointing almost spot on to Polaris, so using my Polemaster it took a few minutes to adjust. I then set about slewing to a nearby object, syncing and then finding a guide star, at this point my troubles where just about to begin. It was now 1am.
So after setting the temperature of the camera to -25℃ and the gain to 7 and offset to 20 I found the scope would not guide. It was bouncing all over the place, some of it was the wind, but some of it was erratic behaviour of the mount, so it seemed like it was overcorrecting. I started to change some of the settings but t no avail. All I could do was to shortened the exposure to around 90 seconds and try and get some data, even if the stars were slightly trailed. I would try to take a longer look at the guiding tomorrow night.
Not so great guiding
So I slewed to one of the objects I was to target, a galaxy called NGC 891 in Andromeda and started collecting data. All in all I grabbed 44 images before the guider was causing so much of an issue even 90 seconds was too long (processed image below)
I then slewed to M45 in Taurus but still the guiding problems persisted. I took 4 x 90 second images and then decided to call it a night at around 3:30am.
Now for packing up the scope and the 1 hour 20 minute drive back down the mountain. How I miss observing from Hacienda on La Palma!
So the main approach here was to start testing the ZWO ASI1600mm on 5min images and decide which is the best Gain and Offset to use. As the object is a planetary nebula I have used my Astrodon 5nm OIII filter to bring out the faintest parts of the nebula. To be thorough, and this will take time, I plan on running the tests for all 7 filters I have.
I have done extensive reading on the topic of image analysis and hope to apply here what I have learnt. Given then camera is running 12 bit, I have a maximum pixel value of 4096 which represents saturation and then any further response is non-linear. Once I have completed 5min testing I will try for 10, 15 and 20 mins. I will then perform further testing by taking a sample set of 10 images to stack and see how that compares with similar total exposure times across the frames.
Amp glow is a particular problem with CMOS. Despite the ZWO site suggesting that amp glow is virtually removed in the Pro Cooled camera, it is clearly not, as can be seen in single 5 min subs. The good thing is a dark will remove it effectively. What I need to make sure is that the amount glow does not swamp the image so much that it overpowers the signal from the faint nebula.
Increasing the gain and offset value from left to right you can see a marked increase in the amp glow. The image slices below are taken from the far right of each frame.
The offset figures in relation to the gain figures have been taken from my reading of various material. The median values are that of the background and the maximum values that of the stars. You can see on this 5min exposure that by the time I reached a gain of 300 one or more of the stars are saturated. In fact the brightest star in this slice is SAO 22510 which is mag 9.53.
Another way to visualise the saturation effect is looking at the raw unstretched image, whilst a star is visible in the image using gain 139 and 200, on close inspection within PI and looking at the values of the pixels of the star they are not saturated. However gain 300 is. The purpose of this is that an unstretched image is not the defect for telling if parts of the image are saturated as some texts describe, but one can see the increased brightening of the star by gain 300 to know it is a problem.
So whilst I have seen the clipping a a few stars at the highest gain I have tested, what about the planetary nebula itself? From the below stretched image one could assume that the brightest part of the nebula was fairly bright and heading towards saturation, but don’t be fooled! Also there is a noticeable increase in the background brightness as the gain increases.
Again as for the amp glow, the aim is to balance the ability to amplify the faintest parts of the nebula without swamping them with the background brightness.
Again here are the values of the settings for gain and offset against the central section of the image.
So how bright did the background get? The graph below shows a section of the background free from stars and charts the increase of brightness from a mean figure of 9 ADU with the gain set to 0 and a mean figure of 104 with the gain set to 300. So a large increase but but at least up until gain 200 not a problem, as we will see when we look at the faintest part of the nebula later.
This graph looks at the bright star SAO 22551 (HIP 8063) which is mag 6.66 and the brightest star in the image. Again as previously seen in the right hand slice of the image the star is saturated by gain 300. All figures are the maximum pixel values.
Now let’s focus on the nebula itself and go back to using the mean ADU figures. The picture below shows the section of the nebula I will use for analysis. In particular I focused in on the brightest lobe of the central portion of the planetary nebula and the faintest portion of the left arc.
So looking at the faintest nebula within the left arc we can see that it is not very bright at all and the brightest it gets at gain 300 and offset 65 has a mean figure of 96 ADU. Each and every image at the different gain setting and offset setting is seemingly just below that of the background, which in itself is interesting as the nebula seems to be fainter than the background. So more analysis was needed.
However I then went back and looked at a selection of areas of the background across the image to find that the original background selection to the bottom left of the image was brighter than other areas. Below you can see the image of gain 200 and offset 50, this time with 5 selection boxes. Preview 6 is the nebula as recorded before is mean 56 ADU. Preview 5, so the sky right next door to it has a mean figure of 55, so just below the nebula, hence it is only barely visible. Preview 1 is 54 ADU and Preview 4 is also 54 ADU. So there is brightening on that bottom left corner of the image, so had the nebula fallen at that spot then it would be swapped by the background.
There is only 1 ADU between the nebula and the background adjacent to it at gain 200 offset 50. If we looked at the same to regions in the image of gain 300 and offset 50 then you get a 2 ADU difference. The image with gain 300 and offset 65 gives a 3 ADU difference. So the results show that both gain and offset both help increase the contrast between the background sky and the faintest part of the nebula.
Various previews can be seen to analyse the background vs nebula brightness
The final image below shows the brightest part of the nebula. At gain 300 and offset 65 you see a mean value of 544 ADU which compares to 96 ADU for the faintest part of the nebula and an adjacent background of 93 ADU.
The final piece of information pertains to the camera/chip specification and performance. The graphs below are from the ZWO website and clearly show as expected the more you increase the gain the read noise is lowered but unfortunately so is the full well maximum (the amount of electrons you can store in a pixel) and the lower the dynamic range, which for deep sky objects is a required.
So from this first piece of testing what have we learnt? Whilst there seems to be a good sense for increasing the gain and offset to help with the SNR especially between the background and the faintest part of the nebula, the increase in amp glow, decrease in dynamic range and reduction in the well count are all factors. Stacking as we will see, will undoubtably help the situation without necessarily setting a high gain. You can see why people say use Unity Gain, so the setting where 1 electron on the sensor = 1 ADU potentially gives the best result from a tradeoff point of view.
I have spend over 4 hours today reading about the Gain and Offset settings for the ZWO ASI1600mm Pro Cooled mono CMOS camera I have on the back of the 12″ Officina Stellare 305 RiDK f/7/9 telescope.
ZWO ASI1600mm Pro Cooled on Officina Stellare 305 RiDK
In particular the posts by Jon Rista and the images with a similar setup from Glen Newell have led me to a handful of setting I will now try from my location and on M76, the Little Dumbbell planetary nebula that I had started to image recently. I must also comment that Kayron Mercieca also had some useful information pertaining to testing your camera and OTA imaging train for exposure times. See link here
Discussion on exposure times and setting – Cloud Nights
So I have already taken a set of images on the 8th October, 14 of them and they were at a Gain and Offset of 10 (I believe these settings are less than perfect) and an exposure of 1200s, so 20mins through an Astrodon OIII narrowband filter. My location is on a good night in the Orange Zone as per the charts borrowed from the forum discussions and when referring to broadband imaging. For narrow band as per my test here I am between the purple and blue zones.
Inspecting the original frames I took you can see slight amp glow from the right of the image, the background has a median of 10 ADU at 12bits. None of the stars are saturated or clipped. The brightest star is 1,854 ADU our of a dynamic range of 0-4,095 ADU. The faintest nebula I can see is 11 ADU so just above the background and the brightest part of the nebula is 77 ADU.
M76 – 1 x 20min OIII Gain 10 Offset 10 – ASI1600mm Pro Cooled
So I will attempt to take a set of images at the following settings across 4 exposure times of 300s, 600s, 900s and 1200s at or after astronomical night at 20:56 onwards if the clouds hold off.
Gain 0 – Offset 10
Gain 75 – Offset 12
Gain 139 – Offset 21
Gain 200 – Offset 50
Gain 300 – Offset 50
Gain 300 – Offset 65
So after several false starts of broken cloud disrupting my ability to keep the dome open, I managed to grab the first 6 frames of 300s as above. Here is an animated GIF of all the images in order of Gain lowest to highest. (Click the image to animate or right mouse click and download)
In my next blog I will look at the analysis of the first 6 frames whilst I take the other frames to compare.
Tonight Bob and myself had a couple of things to achieve on the dome so that it would be ready for Autumn. As the Moon was out in full force, Bob decided to have a go at ironing out some more configuration bugs with guiding whilst I later in the night would test out the automated TPoint run.
Something I had not appreciated about an automated run was that instead of selecting bright stars, slewing and manually centering as you would when doing a non-automated Tpoint run, the automated run takes images of random or selected areas in the sky rather than centering on a star and then determine how far off it is from where it thought. Unlike a Closed Loop Slew that would take 2 images, one when it completes the initial slew and another when it has shifted to account for the error and plate solving to make sure it is now in the right place, the automated Tpoint just takes that single image then moves on, registering the error as it goes, building the model and applying the correcting to make the pointing better.
So at 23:27 Bob had finished attempting to setup guiding in PHD2 on for the QHY5 guide camera on the Talk 102. There wee still some problems, especially around a little trailing in 2-3 minute images. I suspect that the guider was being over aggressive in correcting in RA and possibly DEC causing the issue. Bob started to play with the parameters but decided to try again another night after reading the PHD2 manual.
Now for the automated TPointing run. We had to go in and setup The SkyX (TSX) so that it could control not only the dome and mount but also the camera on the back of the OS12″. Once that was done we setup the automated calibration run settings to find 10 targets evenly spread around the sky and avoiding the North Celestial Pole.
Target setup
What we did have a challenge with was the Moon, which being very bright does not lend itself well to being able to plate solve next to it with a large telescope, mainly due to light scatter within the tube and an ever increasing brightness in the background.
So the first major obstacle when we clicked start, was once it slewed to the first star field, plate solving there. This proved rather difficult to get working, about 1.5 hours of rather difficult! It kept failing to plate solve. So after reading the manual (RTFM) I realised that there was really only 1 parameter that needed to be changed to get this working and that was increasing the exposure.
TPoint in action
After changing this for 30s to 60s and then again to 120s the solving worked. Why? Well because the Signal to Noise Ration (SNR) was simply not high enough due to the background glow caused by a full Moon.
Target 5 acquired
Now the first target was solved the mount went on slewing, the dome turning and the camera imaging until I reached target 6 of 10 and then it failed again. However looking at the downloaded image it was not hard to see why, clearly the Moon was just off to one side.
Nearby Moon….cannot plat solve this!
So I skipped this target and carried on to complete the set. So with an initial 7 targets solved (a few others were near the Moon) that was enough for the mount to land on the target every time and each time the solving got quicker to the point of being sub second.
With the understanding of how to do an automated Tpoint firmly in the bag we decided to shut down the IMT3 for the night and await a cold dark evening after the clocks go back on 21st September to perform a large Tpoint run of around or possibly over 300 targets.
I find I notice some interesting things on the All Sky Camera, which is a USB 3 ZWO ASI120MC-S CMOS camera inside a purpose built casing and clear dome. Firstly I land up with beautiful clouds rolling past. I also noticed the light pollution as I mentioned in a previous post from the bathroom window upstairs. This image is when I had the camera on the ground by the observatory as I was testing the maximum length of powered USB I could get away with before data loss caused issues.
Bathroom light on
When the light is turned off it is noticeably darker.
Bathroom light off
Sometimes I get visitors to the camera.
Daytime visitor
and sometimes I unexpectedly capture a meteor 🙂
Raindrop, Clouds and Meteor
So it transpires I can use a single 3m powered USB cable to the USB hub, I cannot use 2 x 3m powered USB as that causes data loss and hangs and I cannot use a single unpowered cable either.
So I managed to go out and quickly bag a few images of M13 to test the travel scope on the night of the 1st to the 2nd September. It was relatively cool and clear. The main aim was could I take images that were not overexposed on stars whilst capturing the fainter stars at the same time. Also I wanted to make sure I could process an image too.
So all in I took 10 x 5 minute exposures but unfortunately I had not read the Skywatcher manual and had not locked up the focus tube. This meant that the first 3 frames were out of focus so I tightened the locking latch and then took the other 7.
On processing the image I noted the black (white) band to the top and right of the image where I had not switched off the setting for Overscan. I could not PixInsight to recognise it properly so I simply pre-processed the image and then cropped it out before processing.
Overscan area present
I managed to get Photometric Colour Calibration working which helped get the colour just right. I then processed in my usual way using the following workflow.
Apart from the various benefits of darker nights such as better sleeping patterns for humans alongside a bat friendly environment then the benefits for astronomers cannot be understated.
We use a Sky Quality Meter from Unihedron in order to measure the seeing conditions and record it in the long exposure deep sky objects we try to image.
Below is the graph for the entire night of 8/9th September 2019 and the effect of bathroom light close by can be observed at around 21:20. This clearly demonstrates how bad local light pollution can be. By 4:30am the astronomical darkness window had passed and the SQM was dropping.
The effect of the new street light policy at 1am is obvious as an increase from a SQM reading from 20.4 to a maximum of 20.59 is observed until 4am when the street light came back on again and the sky quality immediately drops.
This places the local area as bortle class 4 ( 21.69–20.49) and a long way from a rural setting (21.69-21.89) or even Kielder Water (21.88) which can only get worse with more housing developments and unnecessary outdoor lighting.
So although we are grateful for improvement in the local dark skies it would be great to see the lights staying off for longer in winter so we can attempt to get better images. Hopefully we can start to come close to appreciate what people saw before the intrusion of unnecessary artificial lights in our life bloated out the wonders of the night sky without having to resort to traveling to the top of La Palma.
First thing to say is this is a very long blog, much went wrong tonight before it went right and thus I selected to record as much of the problems here as evidence later if I have the same problem or others indeed do. Tonight I am imaging M76 a planetary nebula in Perseus known as the Little Dumbbell. This is my first real object to image through the IMT3’s 12″ scope. The weather looked good and a quick look through the All Sky Camera showed a clear sky with Vega shining bright overhead and a slight glow with the Sun still setting to the West.
View through ASC
The first thing I needed to do was to slew to a bright mag +2 star, in this instance Caph in nearby Cassiopeia and centre and sync the scope which I did through TheSkyX (TSX). I then slewed to a magnitude +9 star (SAO 21164) nearby so that I could perform an autofocus through the OIII filter using SGPro. The best fit was 73,914.
Auto Focus Achieved
I then took a single 60s exposure just to make sure the focus was right, the stars coming in at around Half Flux Radius (HFR) 4. Meanwhile the camera cooler was running at -20℃ and 28% so I lowered to -28℃ at 60%. It should be noted that every time I perform a closed loop slew in TSX and the camera connects, the camera then looses the information of its status in SGPro and the only way to resolve to disconnect and reconnect. I again will note this is the TOSA User Guide.
Focus image on Mag +9 star
Then I slewed to M76, which on first inspection was still being my neighbours house. So I waited for a while longer and around 21:10 it appeared above the roof for its polar orbit around Polaris. I took a quick image with SGPro of 60 seconds through the OIII filer to see where I was pointing, given I only have a 60 point TPoint model (I need 300 for the best pointing accuracy).
M76 slightly off target
So given I was slightly out I selected the Luminance filter, went back to TSX and performed another Closed Loop Slew and then synced the scope for good measure. The resulting image through TSX and then through SGPro showed a perfect improvement.
On Target
Before imaging I went back to look at the PEC as Bob had mentioned not being able to image for very long on the Tak FS102 after we had taken it off, added the adjuster plate, reattached and added some weights. Not surprisingly the TPoint model will need redoing, however I noted the PEC was turned off, maybe I had not saved the last time I enabled. So I reenabled and saved.
PEC Now Re-enabled
I then went looking for a guide star with PHD2, however even with 10 seconds I could not see one. I looked at TSX and indeed the Field of View (FoV) indicator for the guider showed a fairly barren piece of sky with barely a magnitude +11 star visible.
Guider FoV – bottom right square is fairly limited in stars
Blank guider image …..
I performed a quick check of the SQM and it was reading 19.37 and the Hitec Weather station had a reading of around 25 meaning between Haze and Clear. Another quick check of the ASC and that was showing clear. So either I had to move the scope to find a guide star or I could image without guiding……so the only way to tell was take a quick 5min image and see what it looked like.
SQM reading
Hitec Astro Weather Station
Trailing stars
As suspected the resulting 5min image showed trailing, not surprising given the TPoint model is out so I decided to guide. I slewed around trying to find a decent guide star but nothing came up, literally nothing, which then got me thinking this was not right. So I checked a bright star in the FoV for the guider, still nothing. So I then disconnected the camera and checked the settings and there it was, the setting was for the SX814 which was not powered on (aka GingerGeeks main camera on the Epsrit 120) so I changed this to the Lodestar and took another image, this came into view! Not sure the problem of why it keeps reverting to the SX814 but I will need to check each time and will add to the TOSA User Guide.
Wrong guide camera selected 🙁
So I moved back to M76 entering with TSX again and took an image for guiding through PHD2 and full of stars, well a handful at any rate, plus a load of hot pixels (I need to apply some darks).
I see guide stars and hot pixels 🙂
The resulting guider graph was smooth, too smooth, and the resulting 5 min image was trailed! Ok so something else not right, so after taking a look it turned out I had selected a hot pixel to guide on, so I exposed a little longer from 5s to 10s and selected what looked more like a star and this time tried to guide. The guiding went off the chart which proved this was a star and that I needed to calibrate the guider (seemingly every night I go out, I will need to see if that is right). So off I went to calibrate the guider.
Guiding too flat…
Hot pixel not a star!
Finally a star but guiding off the chart!
In calibrating I realised the Darks were going to be needed, the first calibration run failed. I then went out to cover the scope using my trusty chair to help with the lift I needed to reach the end of the 12″ as it was point upwards. I then went back inside and took a set of darks ( I thought I had done this before), anyway with a new dark library in hand I recalibrated the guider.
Makeshift ladder…do not try this at home 🙂
Cover on scope for guider darks
Cover off scope
Now suffice to say the problems did not stop there, I had guider calibration failed, star did not move enough and after 4 attempts I managed to calibrate the guider and the guiding then started at last! the main thing was to change the number of steps required to 6 and the pulse time changed then to 1500ms from 200ms. This was enough to resolve the problem.
Guider RA and Dec are Questionable!!!
Guider calibration stars did not move enough
Guider calibration not enough points
Finally guider calibration successful 🙂
For completeness here are the settings I am now using that work in PHD2
Correct guider settings
So after much time spent and it now being precisely 22:33 I realigned M76 in the centre as it had moved with all the calibration challenges (remembering to change the filter to Luminance during the Closed Loop Slew in TSX and then back to OIII to start my imaging run.
I tested at 2 minutes first, then 5 minutes, then 20 minutes before starting the final run to decide on the subs I would use. By 23:14 I had the 20 minutes sub and settled on 20 minute subs for the rest of the night.
Guider graph looking very smooth
First 20min sub image down and fairly tight stars for my focal length and OIII
Quick stretch of M27 single sub in PixInsight
M27 zoomed section single 20min OIII Sub
Meanwhile the Summer Triangle of Deneb, Vega and Altair could be seen through the ASC and I noted that the star Tarazed in Aquila next to Altair at magnitude +2.7 could be seen also.
Summer Triangle through the ASC
I noticed the trellis lit up and had a quick word with my daughter to close the blind in the bathroom 🙁
Bathroom light on without blind down 🙁
Here is the temperature and pressure information from the dome internal sensors at around midnight.
Internal sensor readings around midnight
At 03:49 I decided to do a quick autofocus to see if the focus had changed during the night and given the temperature outside was now around 5℃. I paused the current sequence which gave me the option of cancelling or pausing at the end of the current image. I then ran autofocus but no stars were found. I went into the setting for autofocus within SGPro and changed the exposure time for the OIII filter from 1 to 20 seconds. This allowed the autofocus to see stars but the auto focus would not complete successfully and just kept creeping out. So instead I gave up, especially since astronomical darkness was finishing soon. Instead I slewed to my Flat position at Az 359, 21′ and Alt 00, 00′ to take the flats.
Co-ordinates for Flat Panel
I went out to the dome to manually turn on the light sheet which we need to automate and then turned it off after I took 10 flats through the OIII filter at 10 seconds each to get a good illumination. It would be 0.5 seconds through Luminance filter. I then packed up set the darks running and went to bed.
In this part we’ll look at the Node-RED flow that controls the Arduino with a 4-Relay Shield attached. As previously mentioned, these relays are used to allow us to remotely reset the All Sky Camera and HiTechAstro Wx STn, which we found had a tendency to hang and wouldn’t reset unless the USB connection was broken and remade. As we would not be in a position to unplug and re-plug the USB connections I came up with a solution. By modified some short USB extension cables and breaking into the +5v line I could then connect to the ‘Normally Closed’ contacts of one of the relays, picking the relay effectively turns off the USB device connected to that cable.
Relay Shield that attaches directly to an Arduino UNO
Modified USB extension cableSnapshot of the flow to control the relays to reset ASC and Wx Stn
For this solution, we don’t write any code for the Arduino but do load it with Standard Firmata code that comes with the Arduino IDE.
Just open a new sketch, select the StandardFirmata from the Examples and upload to the Arduino.
Firmata is a generic protocol for communicating with microcontrollers from software on a host computer. It is intended to work with any host computer software package.
If not done already we need to go to npm and install the node-red-node-arduino nodes.
Originally I used a Dashboard Switch to select each relay, but it can get confusing when turning on the relay turns off the device attached, so I replaced the Switch with a Button node, pass the message to a Trigger node that will activate for 7 seconds (give the OS time to recognize the USB device has been disconnected), debounce the signal before passing onto the Arduino Output node which connects to the local Arduino and writes to the selected digital pin turning the relevant Relay On.
As there are only a few basic nodes in this flow, here are some snapshots of how each is set-up:
This button will appear on the Dashboard under the Reset Controls group
7 seconds seems long enough but can easily be changed.
Off Button
On Button
debounce the signaldebug options Pin 7 drives the appropriate relay
So the above covers the two relays that are used to reset the All Sky Camera and HiTechAsto Wx Stn. The same building blocks are used to control a pair of battery power LED worklights to provide illumination for the Web Cameras we have dotted around the dome and on the mount. After inadvertently leaving the lights on, on one occasion, the batteries needed to be replaced after a single use. So now in addition to having switches control the lights, we also have Buttons to push for preset times on of 1, 3, 7 or 10 minutes, with an option to turn them off early.
LED lighting control
Unlit dome
Picture-in-Picture Flip-Flat ClosedJust a couple of counter-weightsWill the last one out please turn off the lights
Wrapping up for today
Here’s the Node-RED flow for the Relay Shield
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I chose to run Node-RED locally on my Windows 10 laptop so my first step was to download and install a supported prerequisite version of Node.js which will also include npm (Node Package Manager).
npm is the worlds largest Software Registry containing over 800,000 code packages. It is free to use and Open-source developers use npm to share their software.
npm includes a CLI (Command Line Client) that we will use to download and install software.
Having installed Node.js open Windows PowerShell to execute the npm cli command to install Node-RED
npm install -g --unsafe-perm node-red
The command installs Node-RED as a global module along with its dependencies.
Once installed as a global module we can use the node-red command to start Node-RED in a terminal. Ctrl-C or closing the terminal window will stop Node-RED.
You can then access the Node-RED editor by pointing your browser at http://localhost:1880/
To access the Node-RED Dashboard point your browser at http://localhost:1881/
By default, Projects are disabled 🙁 , so brush up on your Vi skills* as we need to go and edit settings.js file located in the .node-red directory. *other editors are available.
Just remember to press escape key, colon, w q bang when done! … now where did I drag that up from, I hadn’t used Vi in years!
After an initial foray into Node-RED, I realised I would need to use Projects within Node-RED. A pre-req for this is Git. With that installed I was good to create my first Project.
I was surprised how quickly I was able get some meaningful results and was soon using npm to add nodes from the Node-RED library for the Dashboard, Arduino and much more. It wasn’t long before I had my first Dashboard displaying the output of the BME280 sensor which looked like the following:
My first Node-RED Dashboard display
An early comment from our dear friend Mil Dave asked “What’s the Dew Point“? … thanks Dave !
Google to the rescue, however the Dewpoint calculation formulae found on the web look pretty scary. Fortunately a search of the Node-RED library found a flow with a dewpoint function defined that I was able to adapt to my flow. A snapshot of the flow follows as it is now beginning to take shape and looks like this:
Node-RED Flow
The green debug nodes are useful to follow the message as they progress through the flow, the debug output can be displayed in the debug window, the system console or as node status appearing just below the debug node
The data from the Arduino arrives on the Serial node which is configured for the com port the Arduino is connected to. I’ve found it easier to determine the relevant com port from the Arduino IDE rather than via control panel and device manager. Also the ‘Get board info’ from the IDE has prove very useful when running Node-RED on MAC OS.
Double clicking any node will open up an Edit window to let you configure each node
Connected to the Serial node is a Split Node. This splits the incoming message into a sequence of messages and is setup to split the message when it finds a comma.
The message is passed to the next node which is a function node which contains some Javascript to give a variable name to each of the values received from the Arduino.
The next Function node Splits these seven values and presents them on a separate output of the node which can then be connected to individual Dashboard Gauges.
var msgS1C = {payload: (msg.payload.S1C).toFixed(2)};
var msgS1F = {payload: (msg.payload.S1F).toFixed(2)};
var msgS2C = {payload: (msg.payload.S2C).toFixed(2)};
var msgS2F = {payload: (msg.payload.S2F).toFixed(2)};
var msgBT = {payload: (msg.payload.BT-1.4).toFixed(1)};
var msgBH = {payload: (msg.payload.BH).toFixed(1)};
var msgBP = {payload: (msg.payload.BP).toFixed(0)};
return [msgS1C, msgS1F, msgS2C, msgS2F, msgBT, msgBH, msgBP];
Having split these values out, the Temperature and Humidity values need to be recombined by the Join node so they can be passed to the Dew Point function node.
var newMsg = {};
var parts = msg.payload.split(",");
var Th = parseFloat(parts[0]);
var Hu = parseFloat(parts[1]);
var temp = -1.0*Th; es = 6.112*Math.exp(-1.0*17.67*temp/(243.5 - temp)); ed = Hu/100.0*es; eln = Math.log(ed/6.112); td = -243.5*eln/(eln -17.67);
var Dp = td.toFixed(1);
newMsg = {payload: Dp,
topic: "DewPoint"};
return newMsg;
The DewPoint is now passed to a Dashboard Gauge node and displayed. The Dashboard currently looks like this:
IMT3 Environmental Dashboard
In Pt.3 we’ll take a look at the flow that controls the Arduino with the 4-Relay Shield that allows us to remotely reset the All Sky Camera, HiTechAstro Wx Stn and control a pair of LED lights to illuminate the rig so we can use ManyCam to monitor the web cams installed in the observatory.
The following is the current Node-RED flow running on the IMT3 MAC Mini
IMT3 Environmental Monitoring Pt.1 Bob Trevan – Aug2019
When Dave, Mark and I first started planning what equipment we were going to install in IMT3 we started with a block diagram of what we thought we were going to install so we could determine the number of USB ports we would need and the power requirements. This soon morphed into much more as we started adding kit to the project.
Although the Observatory is install in the UK and not Spain as was originally planned, we decided we would still need a fair bit of monitoring to allow remote sensing of the local conditions. In particular making sure it was safe to open the shutter for a remote observing session
During AstroFest in Feb 2019 we bought a HiTechAstro Deluxe Weather Station which can be used as an ASCOM safety device to autonomously close the Dome Shutter if rain or cloud is detected. Although we were lead to believe it would directly interface with the Pulsar Dome Controller, this was not the case and required a simple interface consisting of a SPST Relay to control the shutter. Once the Relay is picked the shutter closes and will stay closed until the operator manually resets the state of the relay via the weather station software. The software has a number of options to configure to determine when to close the shutter
Although the Shutter itself has a battery pack that has sufficient capacity to close the shutter in the event of a power outage we decided to add an APC UPS with PowerChute software so provide AC power resilience to critical components. The shutter battery is wirelessly charged when the dome is parked at the end of each observing session.
In addition to the Cloud and Rain sensor, we also have a Sky Quality Meter and All Sky camera mounted on the same pole. The cable run to the pole from the panel inside the dome to which we were mounting various components … MAC Mini, 10-port USB HUB, Power Bricks, etc … is about 10m. The cabling provided with the Weather Station was somewhat shorter than this which meant having to extend it with the challenges of making the external connections water tight.
The HiTechAstro Wx Stn is also a Cloud Sensor utilizing an IR sensor to measure the Sky Temperature and a Dallas DS18B20 to measure Ambient Temperature. The waterproof probe is attached to the underside of the mounting bracket.
For monitoring the Dome Internal conditions I started looking at what we could achieve using an Arduino (*1) with various sensors. Currently we have two Arduinos installed, the first utilizes an Arduino UNO R3 with a Bosch BME280 (*2) Temperature, Humidity and Pressure Sensor and a pair of Dallas DS18B20 (*3) temperature probes for monitoring the internal temperatures of the enclosures housing the MAC Mini and Intel NUC (*4) (more on the NUC later). The current version of code running on this Arduino is provided at the end of this part of the blog.
A second Arduino has a 4-relay shield attached. The relays are used to control two 380 lumens LED lights inside the dome and after modifying a couple of short USB extension leads, breaking into the +5v line, the remaining 2 relays are used to reset the All Sky Camera and HiTechAstro Deluxe Wx Stn, when the need arises (which is all too frequently). This Arduino is programmed to run Standard Firmata code allowing Node-RED to communicate via the serial port and control the relays.
*1 Arduino is an open-source electronics platform based on easy-to-use hardware and software. Arduino boards are able to read inputs – light on a sensor, a finger on a button, or a Twitter message – and turn it into an output – activating a motor, turning on an LED, publishing something online.
The Arduino integrated development environment (IDE) is a cross-platform application (for Windows, macOS, Linux) that is written in the programming language Java, C, C++. It is used to write and upload programs to Arduino compatible boards. User-written code only requires two basic functions, for starting the sketch and the main program loop. For more info see https://en.wikipedia.org/wiki/Arduino_IDE
*2 Bosch BME280 The BME280 is an integrated environmental sensor developed specifically for mobile applications where size and low power consumption are key design constraints. The unit combines individual high linearity, high accuracy sensors for pressure, humidity and temperature in an 8-pin metal-lid 2.5 x 2.5 x 0.93 mm³ LGA package, designed for low current consumption (3.6 μA @1Hz), long term stability and high EMC robustness.
*3 Dallas DS18B20 The DS18B20-PAR digital thermometer provides 9 to 12–bit centigrade temperature measurements and has an alarm function with nonvolatile user-programmable upper and lower trigger points. The DS18B20-PAR communicates over a 1-Wire bus, which by definition requires only one data line (and ground) for communication with a central microprocessor. It has an operating temperature range of –55°C to +100°C and is accurate to ±0.5°C over a range of –10°C to +85°C.
*4 Next Unit of Computing (NUC) is a line of small-form-factor barebone computer kits designed by Intel. The NUC motherboard measures 4 × 4 inches (10.16 × 10.16 cm)
The Bosch BME280 Sensor uses the I2C bus and the Dallas DS18B20 probes use a One-Wire interface. Each of the DS18B20 has a unique internal 64-bit address created during the manufacturing process, so you can just keep adding as many as you need with relative ease.
Currently, every 20 seconds, the Arduino spits out 7 values separated by commas and terminated with a line feed, these are:
DS18B20 Ext sensor Temperatue in °C
DS18B20 Ext sensor Temperature in °F
DS18B20 Int sensor Temperature in °C
DS18B20 Int sensor Temperature in °F
BME280 sensor Temperature in °C
BME280 sensor Humidity in %
BME280 sensor Pressure in mPa
e.g. 27.0000,80.6000,26.0000,78.8000,28.53,43.53,1008.28
Mark also donated a HiTechAstro Hub to the project which is used to control DC power to the Cameras, Focuser, Filter Wheels and potentially Dew Heaters, but with three rigs mounted on the SB Paramount ME-II we were quickly using all available USB Ports and Switched DC power ports available.
After several ‘Hangs’ of the NUC due the to the software packages tested with the All Sky Camera, we added a MAC mini to run the environment applications, leaving the Intel NUC to run the Main Applications to control the mount and Cameras. The Sky X, Sequence Generator Pro etc…
So we now have a number of PC / MAC applications, controlling and displaying various functions of IMT3. But how do we display the Arduino data ?
Working for IBM, Dave had been exposed to Node-RED. Originally developed by IBM, Node-RED is a flow based development tool for visual programming for wiring together hardware devices, APIs and online services as part of the Internet of Things.
Node-RED provides a web browser-based flow editor, which can be used to create Javascript fuctions. The runtime is built on Node.js. The flows created in Node-RED are stored using JSON. Since version 0.14 MQTT nodes can make properly configured TLS connections.
In 2016, IBM contributed Node-RED as an open source JS Foundation project.
One of the Node-RED projects is a dashboard UI for Node-RED, and this is how the Arduino sensor data is displayed, along with the flow that controls the 4 relays on the Arduino Relay Shield.
We have a new vocabulary to learn; IoT, MQTT, node.js, Node-RED, JSON, Arduino, Sketch, Flow and new languages to learn C, C++, Javascript and we haven’t even mentioned the BBC MicroBit or Raspbery Pi and Python 🙂
I’ll describe the Node-RED flows I currently have working and the Dashboard in Pt. 2.
Arduino Code:
/********************************************************************
* Arduino code used for monitoring the Internal Ambient Temperature,
* Humidity and Air Pressure of IMT3 Observatory using a Bosch BME280 sensor
* and two Dallas DS18B20 temperature probes to measure the temperatures of
* the MAC Mini and Intel NUC enclosures.
*
* I have commented out alot of the lines used during development, but left
* them in to help comment the code.
*
* Currently, every 20 seconds, the Arduino spits out 7 values separated by
* commas and terminated with a line feed, these are:
*
* DS18B20 Ext sensor Temperatue in °C
* DS18B20 Ext sensor Temperature in °F
* DS18B20 Int sensor Temperature in °C
* DS18B20 Int sensor Temperature in °F
*
* BME280 sensor Temperature in °C
* BME280 sensor Humidity in %
* BME280 sensor Pressure in mPa
*
* e.g. 27.0000,80.6000,26.0000,78.8000,28.53,43.53,1008.28
*
* The above will be displayed as Gauges on a Node-RED Dashboard.
*
* Bob Trevan August 2019
*******************************************************************/
/******************************************************************
This is a library for the BME280 humidity, temperature & pressure sensor
Designed specifically to work with the Adafruit BME280 Breakout
----> http://www.adafruit.com/products/2650
These sensors use I2C or SPI to communicate, 2 or 4 pins are required
to interface. The device's I2C address is either 0x76 or 0x77.
Adafruit invests time and resources providing this open source code,
please support Adafruit and open-source hardware by purchasing products from Adafruit!
Written by Limor Fried & Kevin Townsend for Adafruit Industries.
BSD license, all text above must be included in any redistribution
*******************************************************************/
#include <Wire.h>
#include <SPI.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>
#include <OneWire.h>
#include <DallasTemperature.h>
#define BME_SCK 13
#define BME_MISO 12
#define BME_MOSI 11
#define BME_CS 10
Adafruit_BME280 bme; // I2C
char buffer[60];
// Onewire Reference and assign it to pin 5 on the Arduino
OneWire oneWire(5);
// declare as sensor reference by passing oneWire reference to Dallas Temperature.
DallasTemperature sensors(&oneWire);
// declare the device addresses
//Device 1: 0x28, 0x41, 0x0F, 0x84, 0x1F, 0x13, 0x01, 0x16
//Device 2: 0x28, 0x89, 0x25, 0x6E, 0x1F, 0x13, 0x01, 0x3F
//Device 3: 0x28, 0xAD, 0x43, 0xE2, 0x1B, 0x13, 0x01, 0x8D
//Device 4: 0x28, 0x0B, 0xA9, 0x63, 0x1F, 0x13, 0x01, 0xCC
//Device 5: 0x28, 0x52, 0xDA, 0x71, 0x1F, 0x13, 0x01, 0x68
//Device 6: 0x28, 0xAA, 0xBD, 0x68, 0x3C, 0x14, 0x01, 0x4E
// Select the pair of sensor used with this Arduino, these addresses have previously been read with a separate piece of Arduino code.
DeviceAddress ExtSensor = {0x28, 0xAA, 0xBD, 0x68, 0x3C, 0x14, 0x01, 0x4E};
DeviceAddress IntSensor = {0x28, 0x52, 0xDA, 0x71, 0x1F, 0x13, 0x01, 0x68};
// Variables to hold the temperatures
float ExtC; // originally had one sensor hanging out of my study window
float IntC; // and a second sensor by my desk.
void setup() {
Serial.begin(9600);
// Serial.println(F("BME280 test"));
bool status;
status = bme.begin(0x76); // I2C Address
if (!status) {
Serial.println("Could not find a valid BME280 sensor, check wiring!");
while (1);
}
// Serial.println("-- Default Test --");
Serial.println();
// set the resolution to 9 bit - Valid values are 9, 10, or 11 bit.
sensors.setResolution(ExtSensor, 9);
// confirm that we set that resolution by asking the DS18B20 to repeat it back
//Serial.print("Exterior Sensor Resolution: ");
//Serial.println(sensors.getResolution(ExtSensor), DEC);
//Serial.println();
// set the resolution to 9 bit - Valid values are 9, 10, or 11 bit.
sensors.setResolution(IntSensor, 9);
// confirm that we set that resolution by asking the DS18B20 to repeat it back
//Serial.print("Interior Sensor Resolution: ");
//Serial.println(sensors.getResolution(IntSensor), DEC);
//Serial.println();
}
void loop() {
// Tell the Ext sensor to Measure and Remember the Temperature it Measured
sensors.requestTemperaturesByAddress(ExtSensor); // Send the command to get temperatures
// Get the temperature that you told the sensor to measure
ExtC = sensors.getTempC(ExtSensor);
//Serial.print("Exterior Sensor: ");
//Serial.print("Temp C: ");
Serial.print(ExtC,4); // The four just increases the resolution that is printed
Serial.print(",");
//Serial.print(" Temp F: ");
// The Dallas Temperature Control Libray has a conversion function... we'll use it
Serial.print(DallasTemperature::toFahrenheit(ExtC),4);
Serial.print(",");
// Tell the INT sensor to Measure and Remember the Temperature it Measured sensors.requestTemperaturesByAddress(IntSensor); // Send the command to get temperatures
// Get the temperature that you told the sensor to measure
IntC = sensors.getTempC(IntSensor);
//Serial.print("Interior Sensor: ");
//Serial.print("Temp C: ");
Serial.print(IntC,4); // The four just increases the resolution that is printed
Serial.print(",");
//Serial.print(" Temp F: ");
// The Dallas Temperature Control Libray has a conversion function... we'll use it
Serial.print(DallasTemperature::toFahrenheit(IntC),4);
Serial.print(",");
//Serial.println("\n");
printTemp();
printHum();
printPa();
delay(20000);
}
void printTemp() {
dtostrf(getTemp(),1,2,buffer);
// Serial.print("Temperature = ");
Serial.print(buffer);
Serial.print(",");
// Serial.println(" *C");
}
void printHum() {
dtostrf(getHum(),1,2,buffer);
// Serial.print("Humidity = ");
Serial.print(buffer);
Serial.print(",");
// Serial.println(" %");
}
void printPa() {
dtostrf(getPa(),1,2,buffer);
// Serial.print("Pressure = ");
Serial.println(buffer);
// Serial.println(" hPa");
}
double getTemp(void) {
double t;
t = bme.readTemperature();
return (t);
}
double getHum(void) {
double h;
h = bme.readHumidity();
return (h);
}
double getPa(void) {
double p;
p = (bme.readPressure() / 100.0F);
return (p);
}
After a full day of all three geeks making more changes to the observatory, I setup my travel scope, Esprit 120 to get some more time logged before taking it on any serious holiday.
Before starting I thought I would record, compute and apply a Periodic Error Correction (PEC) model to the MyT mount similar to doing the one on the MEII earlier. Recording it was fairly straightforward using TheSkyX (TSX), connecting to my camera and then continuously recording the output to a log which you then read in and apply. Even though the log looked pretty terrible a periodic curve was able to be computed and looked a good fit and represented a peak to peak error of +/- 0.5 arcsecs.
Connecting the camera to PHD2 though was somewhat of a challenge, I managed to guide in DEC but the RA was wildly out even though I tried a few different settings for the aggressiveness and Hysteresis which is the previous adjustment percentage to apply as well.
When trying to image with this sort of guide graph from PHD2 the resulting image is trailed. Note the greenness of the image is due to the bayer matrix array of the camera being RGGB and thus 50% of the light is in the green and would be corrected later. The picture below is a zoomed in portion of that image.
So instead I moved to TSX to see if it would guide any better, knowing full well that PHD2 should be able to do this if I could get the right settings. In TSX I took the default values and then choose a guide star and started guiding. The output is fairly similar to PHD2 in the graph and immediately the RA error again could be seen and the resulting trailing of the image taken with EZCAP on the Mac apparent.
At this point I changed the settings for the guiding in TSX noting that the calibration was really quick, almost too quick, with a single move of the scope in either axis which is not enough. So I changed the calibration distance for both axis from 100 pixels to 200 pixels, I also changed the Minimum and Maximum move figures from 0.01 arcsecs and 10 arcsecs to 1 and 2 arcsecs respectively. Finally I added a delay after correct of 2 seconds.
I then started guiding again to look at the results. The new set of data was promising with the RA axis having a lot less correction needed and the scatter graph (to the right) being a tighter set of points which is good and requiring less correction.
Well that was enough tonight and I was pleased with a bit more work being completed on the scope so as the clouds rolled in I packed up and went to bed.
GingerGeek round tonight to align his guide scope, focus it and make sure guiding works. The first thing we had to do though was unplug my camera and then plug his into the Mount Hub Pro due the fuse problem from the last session when it melted through the fuse holder, that will be fixed later this weekend.
Next we slewed to Vega as seen above and took a quick image to see how far out the Esprit 120 is compared to where the OS12″ is pointing so that we can adjust it later.
Espri 120 missalignment from OS12″
So it would seem focusing was a bit more of a challenge than we thought. The first thing is we bought an adapter for the guide scope (aka the finder that came with the Esprit 120) but it did not provide enough back focus for the camera. We had a look round the adapters in the dome and found a nose extension for the Lodestar, however it was not a c-mount end to it so we landed up duck taping it on tonight until GingerGeek can bring round his adapter.
The next challenge was not seeing any stars in the lodestar, after what seemed like a long while we came to the conclusion that the picture we were looking at on the screen in PHD2 was not the camera we thought, it was instead the one from the OS12″ which at this point was not pointing through the slit.
Wrong Lodestar selected
After looking through the settings on PHD2 we found a new setting we had not seen before, which seemed to be because we have multiple ASCOM cameras connected.
Selecting the right camera
The symbol is a double arrow and when clicked a drop down list of 4 Starlight Xpress cameras appeared, so we chose the 4th one which was one of the two Lodestars and that worked.
I then adjusted the guide scope in its two ring holders and aligned close to Vega which we had slewed to. Now the guide scope was spot on and the main scope ever so slightly off. This will be solved when we either shim the scope to align with the OS12″ or when we add/change the way in which it is connected to the losmandy mounting plate.
By 12:40am we had the focus sorted for the guide scope and we moved back in doors to connect back to the 2 cameras for this evening, lodestar and main imaging camera and then the Lakeside focuser to start an autofocus run on the main camera.
Finally starting auto focus
At 1:20am we were still trying to focus as we had not setup the autofocus routing for the Esprit 120 before, the OS12″ is now fine but this was a new challenge. GingerGeek spend an appreciable amount of time changing the step size and other settings in SGPro to effect the focus routine. Finally autofocus did a great job and we landed up at a focus point of 6225 for the Luminance filter. However there was an amount of backlash and this caused the focus point to not be the same in a one direction. GingerGeek needs to find out where he wrote down the figure we measured for backlash so we can add in.
Good auto focus achieved but with slight errorIn focus Luminance Image
Next we slewed to the star near the Elephant Trunk, SAO 33570 and changed the filter to Ha. GingerGeek then started an auto focus run for this filter. As it was now late we were missing setting simple things such as the exposure time increase from 1s to 15s needed to actually register any stars to focus on.
Once focused (ish) as we are tired now, we started a short test image run of 10mins subs for the Ha. GingerGeek showed me the Big Status window which is a much nicer interface to your image progress.
Big Status window
We then had a problem with guiding, there were inconsistent rates between the RA and DEC axis. This caused trailing of stars so we stopped the guiding, however the next image although still out of focus showed promise especially given we were not guiding.
So whilst the wind is blowing a gale and branches have come down off of 300 year old oaks where I live, the weather decided to ease as we went into the evening. There were still gusts of high wind but nothing really to be too concerned about for the dome.
Due to more changes on the mount and the polar alignment changes I needed to do a new TPoint run. I first tried to complete a recalibration run that would add additional data, however after a 30 point run the pointing got worse to the point where I was not landing up on the object but several fields of view. So I bit the bullet and deleted the recalibration data and the original model and started again.
60 point TPoint Run
It took me about 1.5 hours to run 30 points on the East side of the mount and another 1.5 hours to run the next 30 on the West. I was happy with the results and I turned on some new Terms as I went through. As you select the term you can see the resulting change to the position of the telescope. So rightly or wrongly I used this process a few times when the pointing was either not improving or it just needed to improve a little.
TPoint Terms
I also created a Supermodel of the data and once again enabled Protrack. I then went to my usual target of the Elephant Trunk to try and get use to pointing to the right object and then imaging it from SGPro. I decided the easiest thing was to use The SkyX to move to the object as I knew I wanted to be centred on SAO 33570 a star in the trunk. I did this and with my new pointing capability since this evenings TPointing, the scope landed up pointing at pretty much the right area. So instead of Sync and Solve I left it at this location for tonight.
Centred on SAO 33570
The Polar Alignment report produced by TPoint on this new 60 point model showed very little error in either RA or DEC which is a testament to the long hours I put in drift aligning the mount.
Polar Alignment Report
At 2:04 am I then tried to cool the camera but it was non responsive……..this threw me for a while then I remembered the other evening having this same problem which probably meant the camera power was not on.I went into the dome to find that was the case and the reason once again was the fuse on the Mount Hub Pro had melted. I cut this off and put a chocky block in for this evening to bypass the fuse, but I did unplug everything else from the mount hub pro whilst there was no fuse there.
Melted fuse and related spring
Whilst doing this I was reintroduced to nature with a Hornet the size of my thumb bouncing around in the dome. After quickly removing myself from the dome I cam back armed with an insecticide and sprayed the offending hornet. It kealed over and died quickly.
Hornet R.I.P
Next I focused and this worked very well, a nice V curve on the Luminance and then I switched to Ha for the imaging, This would be slightly out but I need to find a strong HA source of stars to be able to focus with Ha.
Nice V Curve
Once again I ran the Image Sequencer to see if this would work given I had made some changes suggested by my good friend Mil Dave to the guider settings in PHD2 and SGPro. However once again I was foiled with some new error messages, I am either getting use to this or possibly very fed up, SGPro may be a great piece of software from a functionality perspective, but it is complex, unintuitive and a pain. The error complained about the PHD2 profile ‘OS 12 Lodestar Guider’ is not valid.
Error PHD2 Profile
This is indeed my profile and is valid so not sure about this, another thing to investigate when I am not so tired. The follow on message was Could not start the autoguider and connect to the equipment so aborting. This is to be expected.
Error connecting to guider
So I went back to Frame and Focus and too a single 5min shot, guiding on a good star that was in the FoV of the Lodestar off-axis guider. I took a 10min image and then a 20min image.
Elephant Trunk Uncalibrated 20min image
Looking at the TPoint model there was a nice improvement for where I started with a with an RMS, Root Mean Square of 100 so when pointing the object I am targeting will be within 100 arc seconds of the centre of the CMOS chip, so 1.7 arc minutes, whereas now it is leas than 1 arc minutes out at 57.9.
I then went back to SGPro to try and fix this error as I don’t like giving up. I changed more settings within SGPRo and PHD2 around the error size for the guider to settle, however SGPro was still waiting for PHD to report it had settled even though it was now guiding.
Error message
I turned off both the Settle At and the Settle Auto Guider check boxes. This then allowed me to bypass the whole settling thing which wis is really not that important to me as I manually setup guiding first and now the sequence has started at last!
Turning off settling guider connection
Finally the guider looks very smooth and the only thing now stopping me from taking some more images is the fact it is 4:28am and I am very tired and it is getting light. So I will disconnect and shut down until the next clear night at a weekend. All in all a very productive night.
Configuring the guider to work with DirectGuide was tonights job, it was so important I have created a separate blog for it. That took the majority of this session before I really did need to go to bed for work tomorrow.
Once setup and now having the ability to reliably guide without the need for an ST-4 cable, I went to take a quick photo again to test the stability of the system. The importance of DirectGuide is worth labouring here as given we have 3 scopes to guide from, there is only 1 ST-4 port. We did not want to keep plugging in and unplugging the different cables, more did we want to build a bespoke connector for all 3, so DirectGuiding is really the only way this would work.
Once complete I once again tried to slew to the exact area for the Elephant Trunk, this has been problematic due to not quite getting sync and solve working, it works sometimes, and locating a star that I can reliably use. I have noted now that HD 205850 in Sky Safari and SAO 33570 in the SkyX represent the pair of stars in the main section of the trunk. I also took another frame nearby to label for future reference.
SAO 33570 centre of Elephant Trunk and SAO 33573 end of the TrunkNearby star pattern SAO 33626
Unfortunately Sync and solve failed and landed up moving the scope to the wrong area, hence I missed the object when trying a longer exposure with the Ha filter. I need to reliably get sync and solve working to be able to use SGPro else I will have to go back to The Sky X that I have used before for image capture which I would prefer not to do given the flexibility of SGPro.
So I landed up pointing at a star UCAC4 739:73701 which was an offset frame from where I needed to be, the purple oblong representing the FoV of where I should have been and the UCAC star showing where I landed up.
Pointing at the wrong object
SGPro did error as mentioned during Sync and Solve as can be seen in the screen grab below. I will talk with GingerGeek to resolve.
So I used to be able to guide on the Paramount ME without the need for an ST-4 guider cable. This is achieved through information being shared about the position of the star to PHD2 and it then sending commands to the relays on the Paramount ME, however I had yet to be able to get this working with the Paramount ME II and using SGPro as the host program.
So for a short period on the evening of 5th August 2019 I ventured out to complete the setup and get the guider working.
As information is key I had spent time re-reading pieces of the Paramount User Manual, The Sky X Manual and the PHD2 Manual, the later having partial information needed to setup, another piece of information was in The Sky X Manual.
So what did I do? Well DirectGuide is a bit like Pulse guiding that is supported on other mounts, however for the Paramount ME II pulse guiding is NOT supported. So you need to configure and setup for Direct Guide, but where?
Looking at the Connect Equipment window in PHD2 you are presented with 3 options, How to connect the camera, how to connect the mount and a 3rd option around how to connect an Aux mount. It is important to understand when to use that 3rd option around Aux mount as that is what can cause confusion when trying to get Direct Guiding to work.
Aux Mount should only be chosen if you are using an ST-4 cable, if you are not then this option should remain set to None. If you inadvertently select ASCOM Telescope Driver for The Sky within this box the mount will not behave correctly. So leave it set to None!
Configuring Camera and Mount ONLY
Camera needs to be set for the camera of choice, for me my trusty Starlight Xpress Lodestar is selected. For the Mount I selected ASCOM Telescope Driver for The Sky. Next you need to configure the Mount by clicking on the spanner and screwdriver icon next to the option.
Under here you can configure The Sky Controller Driver Setup, selecting The Sky version, X Pro for me and various options for the mount itself. The key checkbox is Use DirectGuide. This menu of options is from the ASCOM Chooser and you should select any settings you wish to enable. Mine can be seen below.
ASCOM Chooser for Mount and DirectGuide setting
I quickly configured the Camera also and below are the settings that work well.
SX Lodestar Camera Configuration
On connecting to both the camera and mount, selecting a guide star and calibrating the guider it is apparent that I have configured the setup correctly. All is now well with the guiding and it produces a smooth chart with tonights seeing as can be seen after several dips produced by cloud at the begging of the guider graph.
An unexpected clear spell this evening, I was sitting out on the patio looking at the clouds clearing and so setup the dome to perform the Periodic Error Correction (PEC) analysis for the mount.
To perform this I needed to unplug the hand controller for the MEII, unplug the ST4 guider cable, turn off a bunch of settings within the autoguider software with The SKY X (TSX) and also turn off TPoint.
I then connected the ZWO ASI1600MM to TSX rather than SGPro. This was so that I could record the log needed for the PEC through the autoguider add on software which records in a format that the PEC software requires. The challenge again was that I could not get the ZWO camera to connect in TSX. I just kept getting error 200. Searching TSX forum I finally found the issue and downloaded the latest driver from ZWO but through the link from Software Bisque. To install I needed to log in as Admin.
So I started to record the star movement without performing any guiding. Once done I imported the log file Autoguider.010.log into the PEC portion of TSX.
I then performed a fit so that you could see the sinusoidal waves before I then fitted the correction to it. A quick look using PHD2 Drift Alignment to see what the drift now was, was very promising with a sinusoidal wave over 10-15 minutes.
Final fitted curveModified CurveSinusoidal Drift Alignment check
I then went off and tried to image unguided to see if it made a difference, it had, I recorded a 10min unguided image through the 12″ 2.5m focal length scope with no trailing of Altair.
10min Unguided Altair exposure
I then attempted to slew and take an image of the Elephant Trunk in Ha again, however I was foiled by not only the cloud moving in but also not being able to get past the message Guider Settling. I need to talk through with GingerGeek to see why that is. Meanwhile bedtime for Mr Shave-Wall.
Another evening commissioning the observatory, so tonight was about further refinement of the polar alignment. The main thing was to drift align with PHD again, but this time I would follow the instructions more carefully.
First I had to find a star near the celestial equator which was easier said than done. I little research showed me how to turn on the celestial equator line in The Sky X (TSX), which was essentially a database entry you enable that draws the line across the sphere of the sky using multiple points. The celestial equator is such a line running from East to West passing through the Meridian at an altitude of zero degrees. There were 3 databases to enable in TSX to create the visual effect.
Celestial Equator
I then selected a star on this imaginary line and near the Meridian, the reason for this is that it would display the most movement and thus magnify the error of miss polar alignment.
Star near celestial equator and meridian
Next I performed an autofocus using the Luminance filter this worked well.
Auto Focus
Rasalhauge was the star I choose for drift aligning the first part, a 5 second image within Frame and Focus in SGPro showed it spot on in the middle of the chip once I did a Slew and Solve.
Slew and Solved
Now I needed to find a guide star nearby and place in the Lodestar FoV. This is routinely easy to do with the FoV displays I have placed on TSX.
The first thing to measure was the azimuth polar error and ignoring the RA line ALWAYS, I followed the Dec line and saw it was out by -1.14 and 75px) I adjusted the thruster knobs on the MEII to move the star to the outset edge of the purple circle showing the error. It is a 50/50 guess if you go the right way with the thrusters.
Polar Error in Azimuth
I then drifted again and of course realised I had indeed gone the wrong way as can be seen by the steeper DEC red line and the much larger purple circle.
Larger circle larger error
The graph on PHD2 can start to look fairly flat, so if you want to review the finer data underlying the straight line you can adjust the scale on the axis.
Changing the scale
After getting the line fairly straight I then went on to drift align for the error in altitude. This time selecting a star in the West and near the celestial equator I chose Unukalhai in Serpens Caput.
Star location
Once again I watched the DEC line only and ignored the RA, the DEC line this time reflecting the error in altitude. I then adjusted the mount using the altitude adjustment spanner moving the star again to the outside of the purple circle and then retested, finally getting the error down to a suitably small number. It was now 3am some 5 hours after I started!
Much better DEC line
With now great polar alignment I thought I would attempt an image so wanted to slew to the Elephant Trunk again, IC1396. I performed a slew then plate solved. Of course the centre off the Elephant Trunk is actually the centre of the open cluster which IC1396 represents. I then moved manually to where I knew the nebula to be.
Elephant Trunk Location
Unfortunately at this point I found that guiding, as despite unguided exposures now being a very real possibility, was not working, I could guide East and West but not North and South. I tried multiple settings but by 4am gave up and called it a night. The following day I would test during daylight and realise there was a setting that needed changing in PHD within the profile itself and upon correcting this guiding would then work the following evening.
There were two things I wanted to do tonight, one was to get first light with GingerGeek through the Skywatcher Esprit 120ED, the other was to setup my Esprit 120 on the MyT in the garden and grab a photo of the Moon to celebrate 50 years since Neil and Buzz stepped out onto the lunar surface. As a bonus I wanted to to get the guiding working on the MyT too.
As GingerGeek opened the dome on the IMT3 I setup the portable gear on the patio. I connected the setup to a 12V car battery to see how well it did at running the Mount and the camera. The initial voltage of the battery was 13.1v when I started. I connected the camera to EZCap and the Mount to TheSkyX (TSX).
Meanwhile GingerGeek opened the dome, connected the mount, opened the very geeky but cool Flip Flap covering the Esprit 120 and slewed to a bright star for deterring the focus and the position relative to the 12″ main scope.
Remarkably the focus was fairly near and after a few iterations GingerGeek managed to get the V curve sorted for good focus. Before this was done he setup the Luminance filter on the filter wheel control with SGPro that had not been configured. I then looked at the resulting image and determined the FoV within TSX. The field almost fits the 12″ and so the position is fairly close, close enough for solving and being in the right area for imaging. There was an error by SGPro complaining about 800px difference with what was to be expected, the problem being the difference in the angle of the Esprit 120 vs where the mount knows it is pointing as shown through the 12″.
Despite that we managed to take an image and then move on to see if we could guide with the 12″ off-axis guider for the Esprit. This worked a little but the guider graph was way off at various points, I believe this is potentially either a setup issue on the guider and/or the fact that we are too frequently taking too many images to correct and thus chasing the seeing. I will look at this next time are out.
Back on the portable setup, I managed to very quickly connect, perform polar alignment using the PoleMaster and the new bracket I fitted. I then slewed to a star which was not quite in the FoV so I need to spend more time on this next time I am out. No problems though, I nudged the scope and found the star. Performing a sync on this solved any further slewing problems.
I then waited for the Moon to come up over the roof tops which was unfortunately not until 2am of the 21st thus slightly missing the landing date of 20th by 2 hours (Eagle landed at 9:17pm BST) but non the less still obtaining an image of the Moon to celebrate the 50th anniversary of the first lunar landing at the time Neil put that famous foot on the Moon at 1:56am BST on the 21st July 1969 🙂
Apollo 11 50th Anniversary
GingerGeek managed to get a few images but nothing much was showing on them especially the Elephant Trunk nebula he was imaging, I suspect, but am not sure, the wrong filter was selected so probably OIII rather than Ha as a previous Frame and Focus command through SGPro for 15 seconds showed the Elephant Trunk, at this point we were taking 10 minute exposures so it should have easily been visible. Again another problem to sort next time we are out.
