IMT3 – Page 2 – IMT3b Observatory

Viewing Report 1st June 2020 – IMT3

20:25 – 00:15

Dome once again open to cool down

Solved FoV for Lodestar guider on 12″

Now guiding on star to West side of mount around 0 degrees Dec and near the Meridian to see if problem reoccurs, graph looks ok but there is a slight regular pattern of error.

Slewed to M92 which is a glob currently at Alt +74, Dec 43 and on the East side of the mount where I had issues last night. I plate solved the image.

The auto focus run looked good

Found guide star by moving M92 slightly off centre. Now guiding. All looked good for a short while. So each section of PHD2 graph is 25 points, so when you have 100 points selected there are 4 sections of the graph. This mean each section/column represents own my case 250 seconds as I expose for 10 seconds, so just over 4 minutes per section. So the errors I saw last night were about 12mins apart. This cannot be the work gear as it has a cycle of 2min 29sec. This is from the latest Paramount manual for the MEII.

Tracking at the sidereal rate, one revolution of the worm takes 149.6 seconds (2 minutes 29 seconds).
The right ascension gear has 576 teeth.
The declination gear has 475 teeth.

The error I am seeing is about 4mins. I cannot continue imaging as every few frames are trailed.

Viewing Report 31st May 2020 – IMT3

18:01 – 01:09

Opened dome early to cool down at 6pm.

The first thing to do were Flats for Ha first for the previous night but also for use tonight. I completed this at 22:15

At 22:31 I performed focus run on Luminance which came in at position 59841 with HFR 4.77.

I started an image run as soon as the Pelican Nebula (IC5067) was above the neighbours house. I have set a run of 10 x 600s and 20 x 300s Ha subs guided with the new PHD2 settings to prove the 12″ now works from 1 night to another. Then we can try the Esprit on the next clear night. The guiding at first looked okay.

The resulting image looked very good too

After about 5 frames I suddenly ran into a problem the guiding looked like this

There were large movements in the Dec and the RA would not return to centre. Soon enough SGPro stopped imaging and tried to settle the guider and then further complained about not being able to settle. So I temporarily changed the Hysterisis from 10 to 15 to see if this would get the star back. It did, well just.

The RA axis returns to the centre after quite some time. Is this possibly seeing related or is there something mechanical amiss with the setup?

I did notice the problem one more and then went off to bed left it running 01:09 leaving the possible bump in the worm to resolve itself.

Addendum – So got up this morning and the scope had continued its travel across the heavens. I looked at SGPro and it finished the sequence without any problem. I then looked at PHD2 and expanded the time to include the maximum span possible as it had been trying to guide after loosing the star (I have check boxed Enable Star Mass Detection in the hope this fixes it) and I noticed a problem, which is the recurring South then North oscillation which I now need to investigate as that is the cause of loosing an image due to the star moving. It looks for all the world to be on the worm gear. I will set about measuring the PEC tonight and see if I can see it. It may of course be from when I adjusted the work due to another problem I had and it may not be quite right. I will also ask on the forum.

Viewing Report 30th May 2020 – IMT3

5pm – 3:19am

I opened the dome at 5pm. I wanted to try tonight to sort guiding via PHD2 again on the 12″ this evening and then on Esprit120 if enough time allowed.

I changed the PHD2 Profile for 12″ from 6 calibration steps to 12. Performed calibration. Started test guiding in West at +47 Alt. Tried 300 seconds exposure x2 all good

I Slewed back to the East and to Pelican Nebula. Set the Reverse Dec Output After Meridian Flip tick box again ! It then re-calibrated for this side of the mount.

I have also changed the assume Dec orthogonal to the RA axis.

I reran the calibration a number of times until there was no longer an error at the end of the calibration. There was also trailing of stars. Some of the problem seems to have been an incorrect calibration, we need the RA and DEC rates to be very close indeed. Some of ours this evening were 1.5 arcsec difference. The good calibration we finally settled on was 0.5 arcsec difference. The other change was I went out and tightened up the grub screw holding the Lodestar guider on the prism tube that goes into the OAG body, this was loose and I could move the back end of the guider around. This was due to changing the OAG position recently and clearly not tightening the grub screw in enough.

I then refocused on Lum and then switched to Ha. This is the image after 300s with a much better HFR of 5.21

Pelican 300s in focus with no trailed stars

When I had a bump in the seeing (assumed) the PHD2 graph looked like this

the resulting image of 300s I was in the middle of looked like this :

Image effected by seeing and bump in PHD2 graph

and zoomed in you can see the problem.

Watching Chris Woodhouse’s excellent YouTube video on PHD2 guiding he has also set the min star size to stop it picking up a hot pixel, something we have seen this evening. He has also disabled Star Mass Detection, which stops PHD restarting if it if it thinks another star has been picked even though it may not have, both of these under the brain and guiding tab.

Minimum star HFD and Star Mass Detection changes

It’s now 2:51am, the sky is brightening but the seeing has settled, the mount is behaving and I am taking 600s Ha images of the Pelican Nebula without any trailing of stars. The odd spike sees a jump up to 3 arcsecs occasionally.

The guiding graph below shows a really good small RMS below 1 which is key.

So by 3:19am the sky is really getting bright and showing on the SQM as 18.6 and dropping fast. I have stopped guiding and imaging and will now head to bed. The final focus position for Ha was 59925 so I can grab flats tomorrow! I will then take a look at the Esprit120 tomorrow night.

Viewing Report 29th May 2020 – IMT3

21:05 -2:56am

Currently cooling dome since 8pm.

Logged in at 22:43 to slew to Pelican IC 5067

Esprit 120 FHR was 1.99 for Lum and 2.54 on the Ha

Focused on Deneb , 30 seconds exposure produced HFR 2.23

Solve and sync completed on Deneb in Ha

The focus point for Ha was 6217

Now for a quick frame and focus, 30 seconds exposure

30 seconds Ha on Pelican as Frame and Focus test

That looked good, next up was to see if we can image for 5 minutes unguided and see what the resulting image looked like

Again the resulting image looked very good and no star trails

Clear skies with -18℃ measured by the Infrared sensor on the AAG Cloud-Watcher.

AAG Infrared sensor read -18c so zero clouds

I then tried a 10min image but got clear trailing.

So I set the guiding up with PHD2, went out to the dome and created a dark library as this was not done. I then set about training the guider and then set it running, initially with a 4 second exposure. The resulting guide graph looked a bit bumpy. The ASC looked very clear this evening which was the first time in a while. You could see stars to the left hand edge of the image which is normally obscured by cloud.

We decided to run the guiding assistant in PHD2 and see if there were any changes that needed to be made. It came up with some suggestions including redoing the calibration and changing the calibration step size from 1600 to allow more steps in the calibration, in this case I changed to 1200 to try and go from 3 steps per axis to 8, however I got to 6 steps and this seemed good enough. When I then reran the guiding assistant I no long got the error about calibration. I did have a few suggestions as seen below which I applied.

So the changes made still have not allowed 10mins images, they are still trailed. So that I do not waste any further time this evening I captured 5 minute images instead of 10 minutes and I will relook at the guiding next week when the Moon get brigheter.

At 1:38 we gave up on guiding and switched to 12″, Autofocus on Lum, 63384 HFR 5.4. Took some 5 minute and a single 10 minute frame guided, scope trailing ?

There were three scopes on the Pelican Nebula (IC5070/IC5067) tonight as GingerGeek was imaging with the Tak FSQ85 from his back garden.

Finished to go to bed at 2:56 am, GingerGeek finished the session by taking flats, warming up the CCD and bringing the scope indoors just after 3am.

Rough stack of Ha (5nm) 10×600 seconds, -15℃ From the FSQ85

Viewing Report 26th May 2020 – IMT3

21:00 – 00:46

Opened dome at 4pm to start cooling the 12″, but actually started to play by looking at guider on the 12″ at 9pm. The guider had never really produced round stars and I suspected this was due to it not being pushed all the way in, far enough to be in the sweet spot for focus.

So I took off and adjusted with a spacer of which I had many in different thicknesses. I found the ideal one to fit that would allow the filter wheel Now round stars. Given high cloud I have set running on M5 LRGB, 60 x 60 seconds L / 30 x 60s RGB. Not guiding. Gain 139 Offset 21. Cooler -15. to rotate far enough that it did not fowl the guide camera, which until now it had. Now this was done, it was time to test.

The images were much better, the stars tight and round. I also changed the rotation of the guider so that its chip was square to the rectangular whole in the light pickoff shaft.

So now that was achieved I went off to image M5, but without the guider as I could not find a guide star……..typical. I chose M5 as we have some frames from a previous night in May but focus was not as good as tonight and the ADU was too high. I left the scope running 60 x Luminance and 30 x RGB and went to bed.

Addendum. The dome shut when the Sun started to rise which is fantastic and working as designed. What is not is the AAG must have hung and although I could see in Windows Task Manager it was nowhere to be seen, not in the icon tray or open as a window. Also I forgot to keep the dome log open in TSX so could not see the time stamp of closure. I will have a check list for the next night out. Also I now realise the pick off mirror obscuring the corner of the camera chip for the main camera so I need to either move where the light is picked off from or move the mirror out slightly without effecting the focus.

OAG Pick off mirror obscuring main camera in corner

I have also now started to process the image and on close inspection to the frames I can see the cloud moving across in the Red channel. Here is the results for the processed image.

Viewing Report 23rd May 2020 – IMT3

17:21 – 00:21

It is the hope today that the wind will die down and the clouds will clear, allowing us to go after the elusive comet C/2017 T2 PANSTARRS which will be next to M81 and M82 and should nicely fit in the Tak FS102.

I took a set of darks for the Tak whilst waiting for darkness, then I started to image M101, however very quickly it clouded over and shut the dome.

Calibration of AAG Weather Station – IMT3

Today has been wet, windy and cloudy, which for once is a blessing! Why I hear you ask? Well simply put, to calibrate the hell out of the AAG one needs inclement weather and today has provided that in spades 🙂

So after monitoring the AAG all day here are the final settings. I have changed the limits for the wind only today, but I have extended the time period for the graph from 10mins to 1 hour. The wind has recorded over 1.1 m/s which may not seem a lot but at times has blown garden furniture around and the bins.

Viewing Report 22nd May 2020 – IMT3

23:09 – 00:57

A gusty night, tried M101 but after a few frames it was cloudy. Used the Tak FS102 taking 5 minutes unguided as M101 was at the meridian. Gain 7 and Offset 30 which worked well but this is a faint galaxy.

I was joined by Bob remotely and also tried to get Venus alongside Mercury as they were close together, in the Esprit 120ED on the travel setup and Bob tried through the Tak in IMT3. However I could not locate in the Esprit on the travel setup due to cloud then the roof of the neighbours house. Bob on the other hand could fit either Mercury or Venus in but not both due to the rotation of the camera. It is currently sat at 118 degrees whereas the OS is set to 187. Once both cameras have been cleaned we will set these along with the Esprit on the Paramount MEII to the same field rotation.

AllSkyEye – 0.9.17.1 Pro

So for a short period of time we had settled on using AllSkyEye. Recently we noticed that the author had issued a Kerogram and stretched horizon generate of the latest image but only available in a new Pro Edition.

The Pro edition was only £20 for a 3 user license, the author gives this purchase as a donation to the charity of his choice – good man ! So now we have AllSkyEye Pro in use at the IMT2 and IMT3 domes.

A Keogram is an image composed of slices taken from images in a sequential time order.The slices (which are always taken from the same location and with the same shape) are stitched together to form an image displaying a timeline of the selected part of the image as shown below.

We still have the dark map to take to remove the hot pixels from the image but at the moment it gives us a nice view remotely before we decide to open the dome – that’s if the AAG Cloudwatcher limits agree and it thinks it’s safe to do so of course !

Bob noticed we had our local security guard aka Fluffy watching over his night’s imaging and turning to watch an ISS pass.

Fluffy stands guard at the weather station as the ISS passes over

Viewing Report 15th May 2020 – IMT3

21:58 – 02:02

Just setting up for an imaging run and to test imaging without temp compensation to see if the 12″ keeps focus without it. I started by myself then was joining by GingerGeek and then Bob.

Performed a SGPro autofocus run on Mag 7 star produced focus position of 71,828 @ 4.6 HFR at 14.47℃.

Resulting M98 image from 1st autofocus run

The resulting image was good with good star shapes. Although I suspected at this point the seeing was not excellent.

I let the sequence run for a bit imaging M98 through LRGB and then decided the HFR was gradually getting larger so I performed a 2nd Autofocus run which came in at position 72,215 HFR 5.7 at 13.97℃.

Again I let the sequence continue for at least 4 images and the performed another Autofocus run, note all the time this was on M98 and not slewing away to another star. This came in at focus position 72,697 @HFR 5.7 at 13.82℃.

I continued this routine again and performed another Autofocus run on M98 focus position 73,441 HFR 5.4 at 12.98℃.

I then decided, due to struggling to get a good HFR on focus runs to see if the autofocus was introducing an issue so I changed the autofocus setting from 9 data points to 11 data points to try and get fuller deeper curve. The resulting curve was better and more complete on both sides of the U shape. I then imaged further and then attempted an autofocus with the settings change for the step size from 2500 to 1500 and data points from 11 to 15. This was because I felt we always have a flatfish bottom to the autofocus which at this focal length of 2.5m shows the quality of the seeing with a narrower flat bottom being better seeing. The new autofocus came in at position 73,534 HFR 5.1 at 12.66℃. Meanwhile we kept noticing satellites going across the ASC which I now believe are potentially StarLink so very annoying.

The new autofocus settings seem to work better. Anything less than 1500 step size would be less than the seeing, as proved tonight so I may find that 2000 is ideal, a test for another night. Also noted that Red filter was showing the worst HFR changes due to seeing and humidity was around 75%, again worthy of note to see how good the seeing is. The guiding was all over the place tonight, again another indicator of poor seeing. So all these things are not poor setup or poor software but poor seeing!

This I believe was the ISS going over captured in the ASC.

I was really pleased GingerGeek and I had spent time a week or so ago when the Moon was around working out the location of the Field of View (FoV) indicator on TSX, it makes it much easier to find a guide star, although tonight M98 had a couple strategically placed which was great.

FoV for Off Axis Guider and the OS main camera

By 2pm the cloud had started to appear, first at South Winston with Steve’s setup, then at Mil Dave’s at Tadley and finally here some 15 minutes later. The guide star was lost by PHD and SGPro in a well ordered fashion did what it is really good at and stopped imaging.

SGPro can’t continue imaging due to guide star loss 🙂

Here is where I got up to so LRGB on M98 for the night with 15 x Luminance and 12 x Red, Green and Blue was the original first image for each was there wrong exposure time, so RGB at 2mins and Luminance at 5mins. Very happy for an evening testing and gathering data at the same time.

Here is a set of image statistics charts for each filter for the HFR changing over the evening whilst I refocused. Next time I will focus once and not refocus and see what happens with the temperature drop.

Final look at the AAG weather station as the cloud sensor which is Infrared makes the dome unsafe and shuts it.

Here is the final view from the ASC

and of course to finish the evening off another satellite!

Viewing Report 14th May 2020 – IMT3

21:00 – 23:00

Imaging M99 and Bob did M12 later. Some of the luminance for M12 will need to be thrown as it was too bright, however the RGB data is good. We managed to bag 24 x 5 minutes luminance for M99 and a set of 12 x 2 minutes RGB.

This is a stacked version of the Luminance data.

This is the final imaged that I then processed for M12 on 5th December 2021! This was a combination of 62 x 1min Luminance and 7 x 1min for RGB channels. I need to bring out more of the data from the luminance in retrospect.

Viewing Report – 9th May 2020 – IMT3 – Dark frames, filter

22:05 Frame and focus on 9.26 and 7.64 magnitude stars used before moving to M61 to capture some Lum frames for calibration of flats to solve the doughnut embossing.

22:18 Slewed to M61, performed Solve ‘n’ sync, slew here for centring the object, ran four Luminance subs of 300 seconds each (Bin1x1) at Gain 139 and Offset 21. This was completed by 22:38.

22:45 Chief TOSA then warmed up the CMOS camera, set the filter wheel to the empty slot position, powered off and disconnected the camera and filter wheel. This was so the ASI1600MM and filter wheel could be detached and a blanking filter installed into the empty filter wheel slot position without having to open up the filter wheel. The idea is that we move to the blank filter position when taking Dark subs to prevent light leakage on the Officina Stellare 12-inch.

22:55 Everything was back online and the SGPro profiles were modified to reflect the new blank filter location.

23:13 Unfortunately a dust mote was introduced onto the CMOS sensor window so we sent Chief TOSA back out to the dome to do the job properly this time 🙂 This meant parking the mount, warming up the camera, powering off the camera, remove it, clean the sensor and reattach the camera.

23:24 All reassembled and powered back on, slewed to NGC 4147 (Globular cluster) ready for a a 60 second Lum filter test which showed that a decent cleaning job had been done ….. about time too !

23:40 As it was getting hazy/cloudy it was decided to collect some calibration frames, in this case 25×10 minute dark subs at Gain 39 Offset 21 using the new blank filter.

23:50 We logged off from the remote session and left the dark frame sequence running until it was due to finish in the early morning.

AAG CloudWatcher Installation

We recently decided to replace our existing weather station with one that had better ASCOM integration. I had previously looked at the AAG CloudWatcher but at the time felt it offered more than we need but that turned out to not be the correct choice.

We ordered the AAG with an internal humidity sensor, the optional anemometer, mounting kit and 10 meter communications cable. Due to the ongoing human malware situation it took two weeks for it to arrive from Spain and was delivered to the IMT3 chief TOSA.

Once the new PSU arrived the Chief TOSA then set about removing the existing weather station and installing the AAG cloudwatcher.

All Sky Camera, AAG CloudWatcher, Unihedron SQM and another rain sensor

This also meant connecting the safety relay circuit wires to the Pulsar Dome, installing the AAG software, downloading the ASCOM boltwood driver and configuring SGPro. Within SGPro we have set the safety status set to be “OK to image” where the required conditions are more stringent than the conditions for the dome to open. The reason being that we want the dome to open as the light begins fade and allow the scopes to cool down but not be okay to image until it is dark.

On the first night of operation we ran into a problem. Unlike the other sensor readings and graphs we would see the temperature and cloud readings have an expected shape but the sky brightness sensors kept going up and down at a regular interval then gave the graph a saw-tooth shape.

Unfortunately this resulted in the safety status going on and off until we overrode it. We sent a quick email to Lunatico reporting the symptoms and asking for advice. It didn’t take long for Jaime to reply informing us that another customer reported the same issue and asked for a few days to investigate.

Good to his word we received an email from Jaime explaining the issue and asking if we could perform a firmware upgrade. Now due to the current lockdown restrictions this meant that I had to co-ordinate over the phone with the resident Chief TOSA to physically disconnect and reconnect the power whilst I remotely set the firmware update. The initial issues encountered were due to PEBCAK (Problem Exists Between Chair And Keyboard) as I had not read the documentation correctly !

That evening we watched and the Sky Brightness line graph was now as expected and not looking like a cog shaped wheel. Well done Jaime@Lunatico.es for the quick response and fix, Chief TOSA was a happy dome dwarf again and that’s what counts !

At the moment we are trying to get the cloud sensor to be more accurate to what we visually observe, this is an ongoing effort. We decided to record the AAG Sky Brightness sensor readings at various times and compare with our SQM readings :

Event	SQM	AAG Brightness Value
Civil Darkness	13.08	949
Chief TOSA setting OK to open	13.89	2100
Nautical Darkness	18.92	28588
Astronomical Darkness	19.03	28588

Using the above values it looks like we could reduce our chosen threshold level of 2100 to 1000 in order to allow the dome to open and the scopes to cool down. The Sky Brightness does not appear to change beyond Nautical Darkness. We are now investigating the correct value for the early morning from the AAG logs. This is so we know what the Sky Brightness value should be at which to stop imaging and close the dome in the early morning when unattended.

We still have at lot to configure and read up about using the AAG CloudWatcher but at the moment our initial experience is a positive one. Obviously we will be chatting to Lunatico about our level settings and make some suggestions regarding the software.

Viewing Report 7th May 2020 – IMT3

22:00 -01:00

Bob, GingerGeek and I rationalised the SGPro Profiles and created a smaller set to account for the fact we could now dynamically change the guider in SGPro and also simplify the Gain, Offset and the sensor set temperature within the profiles.

Before we did this GingerGeek recorded the Brightness value from the AAG weather station and the SQM reading as nautical twilight occurred

AAG and SQM readings at Nautical Twilight

We agreed on the following basic parameters for imaging. 3 profiles for the OS OTA at 3 different Gains and Offsets. 1 profile for the Tak with the need to change the parameters of the camera to one of the 3 correct Gain and Offsets now documented in the TOSA manual. Finally 1 profile for the Tak and as it is a CCD then there is no Gain or Offset. We also agreed the premise of exposure times for the 3 OTAs to make calibration frames simpler – 1, 2 minute for RGB on the OS, 5 minutes for Luminance and 10 minutes for narrowband. For the Tak as it is a OSC we agreed on 1, 2 and 5 minutes. For the Sky-Watcher Esprit 1, 2 and 5 minutes for Luminance and 10 minutes for narrowband. We also agreed on the temperature of the scopes to be run at as suggested by Dave Boddington, we have gone for semi-simple. So for the OS and Esprit we will image at -15℃ in Summer and -25℃ in Winter. For the Tak we will image at -20℃ all year round. Note the new Flats are at the new lower 23k ADU setting.

So now all the profiles were changed and setup, we set a sequence running for OS Gain 139 Offset 21 for Flat Darks and Darks 1, 2 and 5 minutes. We will need to do 10 minutes tomorrow night. The Flats incidentally for this set of calibration frames was then completed the following morning by 11am before the Sun got too high and the camera failed to cool to -15℃.

Finally I saved the sequence as calibration frames for OS Gain 139 Offset 21 so that it is now easy to pull this up and redo if needed. I also took Bob’s advice and separated out the Flat Darks, Darks and Flats into different tasks. So tomorrow nights job is narrowband darks using this gain and offset followed by starting the new run for gain 75 and offset 12.

Viewing Report 7th May 2020 – IMT3

20:01 – 01:00

Opened dome early switching the safety for the brightness on the new AAG. The first thing to do tonight was to calibrate a little but more the infrared sensor which informs the cloud coverage. This was suggesting it was Cloudy, borderline Overcast and given it was very clear with a hint at wisps of cloud I adjusted the couple of figures for the sensor, from -17 for Clear to -14 and from -14 for Cloudy to -12.

I then set about taping up the USB and power for the SX camera on the Esprit. This is because the connectors supplied are clearly not in tolerance as I have tried many cables and they call fall out. The tape should suffice for the moment and now the camera reconnects to the NUC computer running SGPro.

GingerGeek and I started to have a look at the sky around 9pm. The sky was not totally clear with some wisps of cloud. We tried to get to a point where we could test guiding the 12″ through the Esprit, however as ever the clouds rolled in. However, during setting up the SX814 camera on the Esprit as the guider and performing a darks calibration run we got an error on the USB bus again (we get lots of USB errors) which not only kicked out the SX814 but also the AAG weather station. The problem was it almost killed the AAG software and we had to cancel the process running to resolve. This meant we lost all the settings in the AAG so we have tried to rebuild as per the new screen shots below.

So instead we re-ran the Flats Calibration Wizard for the OS with the camera set to Gain 139 Offset 21 and also another run at Gain 75 Offset 12. The reason for re-running is that I suspect the flats we have are ever so slightly over exposed at 30-32k rather I prefer them to be at 22-23k.

We also created 2 new profiles that were simply named so we can see them in the list and simplify the naming convention and amount of profiles needed. We will choose the guider on the night within one of the two profiles created. We will also look to review and simply the other profiles for the two additional OTAs tomorrow and delete the remains profiles given the large number we now have.

Viewing Report – 6th May 2020 – IMT3

The plan for the night (to try using the Esprit120 as the guider for the OS 12″ if it is on the West side of the Mount) was scuppered as we couldn’t connect to GingerGeek’s SX814 camera. GingerGeek checked in device manager and COM7 is missing so we suspect the USB cable has dropped out again.

Following on the the news earlier in the day of the SN in M61, I slew to it and grabbed some 300s unguided subs ( which also proves that it is the guiding that is moving the mount unnecessarily … but we knew that already !). Thare was a suggesting on the evenings group Zoom call that the drift might be due to ‘Cone Error’, but I found several posts stating that ‘Cone error does not affect guiding’. After M61 dropped into the weeds I slewed to M3 and grabbed some Luminance frames shutting down very tired at around 4am.

Viewing Report – Cinco de Mayo 2020

Moon 96% Waning.

Our TOSA Manual needs updating now that we have replaced the HiTechAstro Deluxe Cloud Sensor with the Lunático AAG CloudWatcher cloud detector.

New Screens to get familiar with:

Initially I was unable to open the shutter of the dome. Thinking I’d forgotten to reset the HiTechAstro relay I soon realised I had to figure out why the AAG_Cloudwatcher software was reporting Unsafe. GingerGeek spotted that the Brightness level looked like a sawtooth and should settle after a few minutes, which it appeared to do and the dome shutter opened successfully.

Following on from my previous observing session on 1st May when clouds interrupted play just as I was completing a Guiding Assistant run in PHD2, I started tonight’s session with a quick look at Venus before it set below our horizon and then had another go at running the Guiding Assistant in PHD2 for the OS 12″ / Tak FS-102 combination, with the Tak as the guider for the Officina Stellare.

Venus in Ha (because it’s so bright).

Crop

As the Tak has an Alnitak Flip Flat attached to it I added it to the profile I’ve created for the OS12 and Tak combination so that the panel can be opened to allow light through to the camera 🙂

Guiding Assistant completed successfully and values applied for RA MnMo, Dec MnMo and Dec Backlash compensation.

Y scale = 2, Target Radius = 1.5

Sequence running for 2, 5, 7, 10, 12 and 15minutes.

2, 5,& 7 minutes exposures ok but trailing beginning to show at 10 minutes, quite evident at 12 minutes and very evident at 15 minutes.

Added 8 and 9 minutes to sequence, but both of these show signs of stars trailing.

Started a sequence of 24 x 5 minute exposures.

Aborted at frame 20 as the NGC3628 was now below the horizon.

The image has drifted and NGC 3628 has not remained fixed in the frame, so we still have issues with guiding as that is almost certainly the source of the drift.

02:22 Slew to M5, just off centre.

Slew to HIP 74975 to centre and focus.

De-selected guider.

02:57 Slewed to M5 and started a sequence of 24 x Lum and 8 x R,G,B 120s frames.

Sample Luminance frame:

04:08 SQM graph has started to droop. Was 18.2 before 4am, now down to 18

04:10 ASC image brightening quickly

04:15 SQM 17.54

04:24 Camera Warming Up

Disconnected Guider

Telescope Parked and disconnected.

Dome Parked (shutter closed) and disconnected

De-humidifier on.

Camera Power Off

04:30 I’m off to bed

Viewing Report 2nd May 2020 – IMT3

22:00 – 23:59

This evening GingerGeek and I simply set out to align the off axis guider of the OS on TSX. We did this buy focusing on the Moon and adjusting the off axis guider for he crater we were seeing. The resulting image is not very good which give rise to a though that the OAG should move it’s position in the imaging train to give better star renditions, the issue is I think it is as far back as it can go due to the filter wheel.

Viewing Report 1st May 2020 – IMT3

On opening the dome I slewed to Venus hoping to catch it before it disappeared below the horizon. I took a 1s Frame and Focus image just to confirm it was in the centre of the FoV and was puzzled by the resulting image.

At first I thought the 12″ was still covered so called Dave to check. He didn’t think the cover was in place as the last thing he’d done was to take some Flats. Dave confirmed that the cover was not in place but reported that I might be trying to view Venus through the trellis on the fence so I abandoned Venus and slewed to NGC3628 in Leo as it had just crossed the Meridian and I wanted to try and setup a profile to use my Tak FS-102 as a guide scope for Dave’s OS12″.

Previous attempts at guiding the OS with the QHY5 and MiniGuideScope combination had proved worse than imaging with the mount unguided.

Although I suspected we knew the root cause we hadn’t our research 🙁 which soon became apparent. I found a couple of rules of thumb, the first stated that ‘image scale in arc-seconds x 400 = max exposure time is seconds when guiding with a separate guide scope’.

For the ZWO ASI1600MM (3.8um pixel size) on the OS 12″ (2500mm fl)

((3.8/2500) x 206.265) x 400 = 125s

We can do better than that unguided.

The second ‘rule of thumb’ I found stated that the ‘Guide to Main train pixel ratio should not exceed 10:1.

Unfortunately the QHY5 MiniGuideScope to OS12″ ratio is close to 17.8:1, not good.

The QHY5 + MiniGuideScope scale is (3.75/130) x 206.265 = 5.95 arc-sec / pixel.

The OS 12″ + ZWO ASI1600MM scale is (3.8/2500) x 206.265 = 0.31 arc-sec/pixel.

The Tak FS-102 with the QHY168C scale is (3.75/820) x 206.265 = 0.94 arc-sec/pixel

So if we try the OS 12″ with the Tak as the guide scope the ratio is closer to 2.8:1 which sounds like a better proposition.

to be continued …

Viewing Report 24th April 2020 – IMT3

21:23 – 01:29

NGC2903, focus point 73,602 for Lum HFR 5.46 Temp 18.13

NGC4565 @ 00:59

did not work straight away due to centring issues after reading in old image to plate solve and use as basis for slewing scope with SGPro. Finally just did this with TSX and worked.

@01:29 started Lum sequence for NGC4565 at -23℃ and 300 seconds