IMT – Page 7 – IMT3b Observatory

Viewing Report 24th May 2020 – Travel Setup

19:00 – 01:12

Tonight I traveled 50mins and 26 miles to Combe Gibbet, a high point for us in the South of England called the North Downs in Berkshire, which at 940ft above sea level places it in the wind, so it is cold but affords a distance from many towns, so it is dark. The is indeed a Gibbet at the top if one should want to take a hanged man or woman and display them for all the surrounding villages to see ? very barbaric, but part of our history.

The car was packed with various astronomy gear, the Mak180 for Lunar and planets.

The Esprit 120 ED Pro.

And of course the Altair Astro 4″ binoculars with my Paramount MyT mount.

I met a a social distance my friend Lawrence who was in a much better car than myself more suitable for the off-road terrain of getting to and just past the gibbet. Lawrence brought his trusty binoculars and his deck chair. Meanwhile I setup the 4″ Altair binoculars, the Mak180 OTA on the Paramount MyT and my Canon 6D on a tripod.

As the Sun set from this location we spied Venus first and took a look through the binos.

I captured some frames in the Mak180 with the ZWO 294MC camera. We then moved to the sliver of a Moon 2.8% illuminated and 1.6 days old. I placed the Mak180 on this for a few frames also. Lastly we moved the binos to Mercury, which is unbelievably small. Very faint in the twilight sky and surprisingly faint in the binos. I once again slewed the Mak180 and captured some 4GB files.

We then went a hunting for comet C/2020 F8 SWAN but it did not appear in the star field where it should be despite being able to see Mag 8.9 star. The comet was purportedly magnitude 5.8 but this was not the case. I checked my ephemeris on both SkySafari and The SkyX and I wass definetly in the right part of the sky and confirmed the star paterns from my star hoping, but alas no comet.

So although the wind was now dying down both Lawrence and I were cold so at just gone midnight we packed up and set off home. I must remover by coat tomorrow!

Addendum, I had read an article the following day that the comet may have broken up but I cannot yet confirm this.

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.

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.

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 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 – 26th April 2020 – Travel Setup

22:20 – 01:32

I have placed new filter, Baader IR-Pass 685nm from Mark Radice on the ZWO tonight and aimed to go after Venus on the Mak180 and capture another phase of the planet. I recorded several sets of data although noticed the filter does produce a somewhat pinky image.

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

Viewing Report 25th April 2020 – IMT3

22:20 – 01:32

Imaging M85 LRGB through the OS12 at 300 seconds, Gain 139 Offset 12, temperature -23℃

Went off to bed and left Bob with scope imaging until morning light.

Viewing Report 21st April 2020 – IMT3

Viewing time period – 22:05 – 03:36

Update on viewing with Bob running IMT3 for the night.

So after joining the BAS Zoom session I asked what others were imaging and got a spiral galaxy NGC4535 from Trevor and the Needle NGC4565 from Mil Dave.

I slewed to NGC4535 which included a meridian flip and found it pretty much in the centre of the fov. Started a sequence of 3, 5, 10, 12, 15, 20 minute subs but aborted after the 15min subs as trailing was evident. Focus could also have been improved.

NGC4535 and NGC4565 were approaching the meridian so I did a flip to Praecipua in Leo Minor and then a slew to some nearby fainter stars to do a focus run. Start Focus position was 75542 at a temp of 14.14. After focus run the new focus position was 73335 HFR 4.7 98%.

Now slewed to NGC4565 and set a sequence of 12.5m (750s), 13.5m (810s), 14.5m (870s) subs going trying to establish where the limit is for unguided in these conditions. The first 750s sub was fine but the 810s was just showing a little elongation. I aborted the 870s sub and started a run of 12.5m (750s) subs going to see how consistent the results are … will need to look at these in the morning but I think this is about the limit and would probably back off to just 10m subs to provide a bit of a buffer.

Viewing Report 20th April 2020 – IMT3

Viewing time period – 20:15 – 23:46

TONIGHTS TARGETS

H56-1 / NGC2903-OS-Ha-300s x 12 – Done

NGC3395-OS-Ha-300s x 24 – no Ha so aborted

M94-OS-Ha-300s x 8 – Done

M85-OS-Ha-300s x 24 – no Ha so ignoring

Flats () Darks () FlatDarks ()

Camera Temp -26℃

WORKFLOW

Cool down scope and dome – done
Turn off Dehumidifier – done
Turn off fans on scope – done
Find home – done
Slew to nearby star to target – done
Select filter and focus – done 74,517 Ha – done
Slew to target and take a test image using Frame and Focus – done
Solve and Sync and then right mouse click on object and Slew Here – done
Setup SGPro Sequence with details – done
Make sure guider connected and calibrate – done
When guiding run sequence – done

Tonight we will take a bunch of Ha images for 4 targets we have been imaging recently with Ha data being provided through the 12″. I have selected the 4 objects in order of passing across the Meridian first. We should aim to get 2hrs of Ha in each, in which case we may need to take the rest tomorrow.

Auto focus run before dark on Ha using 20s subs @ 21:00 focus position is now 74,517 at focuser temp 15.84℃

Autoguiding on 10s with one of the 2 stars in the FoV of the guider for OS12.

@21:17 started taking the first image. Noticed quickly the guiding in Dec went up, so stopped and recalibrated guider. Then started guiding on 8 second subs.

So the sequence is now running and taking frames of the first target in Ha NGC2903 aka H56-1.

After 12 x 300 seconds on NGC2903 I slewed to NGC3395 and took the first Ha image, but unfortunately it was very dim so not worth pursuing. Instead I have now switched to M94 which is currently on the East side of the Meridian. I will take 24 x 300 seconds Ha with no guiding. It will require a meridian flip in about 90 minutes. I will then leave Bob to complete the Ha on M94 for the rest of the night as M85 does not have any Ha within it.

Bob continued and had a little success, cloud rolled in at 23:46 so frame 9 onwards are no good so we got 8 frames in total for M94, we will continue another night. The shutter was closed as Bob did the meridian flip due to cloud.

I tried to take calibration frames the following day at 7pm when the outside temp was 15.5℃, the inside was 18.5℃ but the ASI camera on the OS12 would not get lower than -25℃. I now concur for with Bob and GingerGeek that we should lower the cooling temp to -20℃ for the remainder of the Spring and Summer returning to closer to -30℃ in the Autumn / Winter. For now I had to wait for the temperature to drop outside and thus inside to cool down the final 1℃ to take the calibration frames. By 20:22 the temp outside had dropped to 12℃ and the internal temp to 15.8℃ which was enough to cool the camera to -26℃.

Viewing Report 19th April 2020 – IMT3

Viewing time period – 21:16 – 23:24

So first I could not see any USB devices that were plugged in to the USB hub on the mount. A reboot of the mount fixed that problem. Next I could not auto focus, I did not get to the bottom of that so tried to focus manually best I could. Then PHD2 settings were wrong for the OS12 and the associated lodestar guider, the calibration steps were 100 rather than 400, the min move was 0.66 rather than 0.18. I had taken screen shots before on the blog so changed them back, I am not sure why they have changed. I then managed to calibrate the guider on the OS12, given I have taken off the camera to clean the filters the other day.

@22:15 I started imaging RGB on M94 on the OS12.

The guiding was not bad after calibration. I set to expose once every 8 seconds on the only guide star in the FoV.

What I do need to do is set the FoV indicator in TSX for the Lodestar guider to the correct position to help find a guide star. Else I really should try to guide with one of the other scopes. I am now off to bed, I will leave the scope collecting the rest of the green, 2 left and the final 12 blue. Then Bob will take over imaging for the rest of the night.

Bob took over Green which lost the guide star, so he performed a meridian flip, continued on the Green and then took some Blue. Bob then took some HA, OIII, SII at 5 and 10 minutes for a test. The Ha would be useful for the galaxy as an LRGBHa image. Bob turned in at 2:50am.

I also noticed this morning that the Offset was wrong in the ASI camera profile which was called ZWO camera in the dropdown and in fact was set to 50 rather than 21 for this Gain which was correctly set at 139. I have also changed the OSA12 No Guider profile to use the ASI2 camera rather than the ZWO one, not sure the difference. I have adjusted the setting back to 21 so all the OS12 profiles now use Gain 139 Offset 21 as their standard. If we want the other 2 setting that need changing for each time we run, along with subsequent darks and flats etc would be Gain 0 Offset 10 and Gain 75 Offset 12. For the moment the Darks and Flats etc from last night are Offset 50 so we can only use for last nights images.

Viewing Report 18th April 2020 – IMT3

Viewing time period – 21:19 – 23:23

Slewed Tak to M53 started to take colour frames. Clouded up around 11pm so shut dome and took darks, flats and flat darks.

Viewing Report 15th April 2020 – IMT3 – Final TPoint…..

Viewing time period – 18:16 – 23:15

Here is my workflow so I can repeat each night until this is finished.

Open dome – done

cool down – done

turn off dehumidifier – done

turn off fans on scope – done

find home – done

focus – done 60,535 clear

remove existing model – done

slew and sync to nearby star – done

make sure scale is correct -done

make sure image link to all sky database is selected – done

start TPoint run – done @ 21:13

Complete TPoint – 93 points done, paused TPointing at 23:15

Turn on Dehumidifer – done

Note that tonight I found the dome was definitely not lining up with the 12″ OTA. We have noticed this gradually becoming as problem over the past weeks and months. I am not sure if this is a problem with software, hardware, a change in settings or the temperature of the dome in some way has effected this. To this end I will set about a calibration run of the dome tomorrow to see if that can rectify the issue.

Viewing Report 16th April 2020 – IMT3 – Final TPoint again…..

Viewing time period – 20:59 – 23:42

Here is my workflow so I can repeat each night until this is finished.

Open dome – done

cool down – done

turn off dehumidifier – done

turn off fans on scope – done

find home – not needed

focus – done 59,659 clear – done

slew and sync to nearby star – done at 21:06 as not dark enough before then

make sure scale is correct -done

make sure image link to all sky database is selected – done

start TPoint run at point 93 – done @ 21:10

Complete TPoint – 231 points done at 23:46 including checking 5min unguided exposure which was fine

Turn on Dehumidifer – done

So what did I learn tonight? It was worth doing the TPoint model. The resulting pointing accuracy is much better with objects being almost centre off the chip. Unguided images on the 12″ look good at 5mins, I will try longer when the clouds and rain disappear. That following a documented approach helps as above. The adjustments to the worm and the loose weight helped. That fixing the dome rotation slippage on the encoder today helped.

I mentioned above the dome slipping on the encoder, this was because of the small weak spring that is used on the dome, which is not good enough and over the past year has stretched beyond its limit. This means as the dome rotates and the dome shudders due to the joins in the dome not being flush (another issue) and thus the spring is stretched. This meant that some of the time the encoder wheel seen below was not touching the dome and therefore lost around 30-40 degrees. To rectify I have temporarily stretched and tightened the spring which we will replace later with a more suitable one.

Encoder spring now stretched to fix problem

Viewing Report 14th April 2020 – IMT3 – Last TPoint…..

Viewing time period – 20:30 – 22:30

Tried again to get the TPoint completed tonight but hit with a load of issues which I will try to sort tomorrow. FoV in TSX was wrong. Not plate solving in TSX. Focus potentially an issue. Use of All Sky Image Link for Scripted Image Link needed to be selected from the Image Link –> All Sky tab. Image scale in various places was incorrect again and should be 0.32. Managed to get to 10 points with 3 failed. Clearly something has changed given this worked a week ago. I will attempt a go tomorrow night to resolve. Meanwhile I have left Bob to image. In hindsight we should also be leaving the observatory running all night as when I got up at 4am it was crystal clear and dome was closed as nothing planned, so a default object and scope setting should be used and left running. However, Bob did manage to grab some frames in the clear of M53 until what looks like 3am so that is better than nothing.