IMT – Page 7 – IMT3b Observatory

Exoplanet WASP-74b (30-31/7/2020) – IMT3

Started around 21:15, Guiding by 22:02, Capture started 22:22, Finished at 03:31.

Dave and I are part of the amateur exoplanet monitoring effort for the ESA Ariel mission. We decided that we would allocate some time to try and provide observing data towards the project whenever we could.

Part of this requires some forward planning such as looking at the upcoming transit visible and their associated time. This is due to the altitude of the object, the ingress and the egress times of the projected transit.

Prior to this we had discussed in advance which object to target for the chosen evening. All the hard work of choosing objects is done by the Exospies project website as they list the candidates they need data for via a schedule. So it’s a simple task for use to go through the list and work out what fits best for us.

Unfortunately whilst opening the dome to cool down I decided to review the schedule but I was hit with a server 500 error from the website. In a panic that I might miss the start of the event I scoured the internet for alternate exoplanet transit time websites and found the excellent Exoplanet Transit Database of the Czech Astronomical Society.

Later on I found https://www.exoworldsspies.com/en/scheduler/ as well which will be useful in the future, especially for looking at past events.

I had issues with focus drift all night due to the temperature fluctuations but at a recent Zoom session it was discussed that images can be out of focus with no detrimental effect on the measurements :

I was unable to auto focus successfully maybe due to the low altitude and seeing. I also discovered that temperature compensation was enabled so we probably need to remeasure the temperature compensation coefficients so the focus deltas are better between the par focal filters.

The object was at a relative low altitude, the outside temperature was warm and although the skies appeared clear our AAG CloudWatcher sensors via the Grafana dashboard told a different story. For us a truly clear sky is anything equal or lower than -18℃.

Sky Temperature – it was clear but it wasn’t !

After performing a meridian flip, resumed the guiding I started to feel tired so I set my alarm for 3am and went to bed. Unfortunately there appeared to be a guiding issue at some point shortly I went to bed.

Guiding issues shortly after meridian flip

This was investigated using the phdLogViewer and shown to be a loss of guide star and didn’t recover for around 18 minutes.

The guiding issue also caused the image to shift so the target and reference stars moved. We need this in frame in order to run the frames through the provided HOPs data analysis program which hopefully won’t have a problem in reading them. That’s an exercise for this weekend and hopefully we will have enough data to yield a decent light curve that we can submit.

Viewing Report 25th July 2020 – IMT3

21:47 – 00:23

GingerGeek and I were out imaging tonight. The sky unexpectedly cleared and we thought given the impending move of IMT3 to another site that we would try to gather some more data on M57, specifically LRGB and some additional Ha on the 12″.

We ran Autofocus on Luminance which gave 60,671 at 20.64℃ and HFR 6.5. We then started to image and after a few frames the temperature started to drop. In the main this is because we opened the dome last minute rather than a minimum of 2 hours before we used it so the dome was warm and now cooling down the optical train shifts.

We refocused to 62,712 on luminance at 19.10 with an of HFR 5.15. We then ran the image acquisition and below is a screenshot of the guiding, which looked like it was going to cause an issue but it was ok. If it had then it would have been the local fog rather than anything on the mount. At midnight we performed a Meridian flip nice and early which afforded us to leave the observatory running and go to bed. Notice the graph below, the yellow line drops as we performed the meridian flip, this is due to the dome now shielding against next doors light !!!!!!!

Guiding ok, notice the drop in the graph

The neighbours light continue to be a pain as can be seen here, I really cannot wait to move the observatory to it’s new dark site.

Finally managed to capture LRGB and Ha, below the RGB and Ha frames can be seen in PI. Note the central star is not visible in the Ha frame,

Finally I stacked 1 of each colour without calibration to see what it would look like.

So we left the observatory imaging, I had a quick peek outside around 12:30am and there was water running off the dome and the outside windows of the orangery! The Observatory ran until the dome shut at 3:58am (it woke me up) when the light levels started to rise.

Viewing Report 22nd July 2020 – IMT3

21:28 – 23:24

I opened the dome at 8:30pm and then went off to do some more work. A few calls later and it was time to come back and see if I could grab comet C/2020 F3 NEOWISE which had now moved further West and further in altitude over the past week, meaning it should be visible from the dome. Below is Arcturus as I performed a quick sync.

Below you can see Arcturus on The Sky X with the dome slit showing and the obstructions from the horizon also present.

Comet NEOWISE can be seen just above next doors tree.

A quick peek with the camera and I could just make out the comet.

Clearly more clouds rolled in which is typical

Looking at the cameras in the dome I could see the cloud bank of cloud (picture top right)

Fortunately the comet could be seen at the back of the cloud bank.

45 second exposure of Comet C/2020 F3 NEOWISE

So I set about quickly taking some images before the comet disappeared behind the tree.

90 second exposure of Comet C/2020 F3 NEOWISE

The other useful thing tonight was using the monitoring GingerGeek put together. Below are a selection of shots from the website.

The chart below shows the light cloud cover and the sky temperature is representative of the sky clarity and relates to cloud coverage too. The scale is inverted to -18℃ is a cloudless beautifully clear night sky, which tonight was not!

IMT Conditions Summary – Fisherprice style 🙂

At least there was no rain 🙂

This image below shows the cloud bank just North West of Reading that was a problem.

This next chart is from the data produced by the AAG CloudWatcher weather station. Note the sky temperature is nowhere near the -18℃ to be clear.

And finally the all sky cam just as I packed up showing the clouds clearing

Viewing Report 17th July 2020 – IMT3

22:05 – 02:00

Tonight I thought I would take some more images of M57 through the 12″ in OIII and then Ha. I first got the OIII filter focused at position 62,500 with a temperature of 22.42℃, I took 10 more images at 600 seconds.

Guiding was good even though there was high level cloud, seeing was good

Ha was then started at 00:44 after meridian flip. I spent some time looking at comet C/2020 F3 NEOWISE through 100mm binoculars with Helen, Ezri and her boyfriend Luke. Then we took some photos with the 50mm lens on the 6D.

I went to bed at 2am and left it running. In the morning I noticed I had 10 good images then the image moved due to guiding problems due to cloud.

Viewing Report 11th July 2020 – IMT3

21:00 – 01:55

GingerGeek and I decided to go after M57 the planetary nebula in Lyra. I had seen a lovely photo on Flickr with the outer Ha/OIII halo showing which resembled a splat of paint, taken with 9 x 1200 seconds Ha, 3 x 1200 seconds OIII and 9 x 600 seconds luminance. So we decided to go try. It would also add to my ongoing collection of Messier objects.

The resulting image of M57 was rather small as can be seen above. We initially set an autofocus run on Ha which came in at 67,213. We then focused on OIII at 67,178. After a few frames we noticed that the focus point had shifted ever-so, thus we refocused at 23:33 for OIII and to a position of 63,610.

The OIII focus exposure length was 20 seconds on a magnitude 4 star which completed very nicely. By the time we had gathered OIII for 9 x 600 seconds the clouds rolled in. We took Flats. GingerGeek ran the whole session remotely whilst I directed 🙂

Darkness Testing 20th June 2020 – IMT3

20:00 – 23:48

Tonight GingerGeek came over for a bit of social distancing friendly astronomy along with a bottle of Malbec wine. The idea was to calibrate the AAG, specifically when it goes from Very Bright to Light to Dark and at those points what the SQM value is along with the Sun’s position below the horizon. The AAG needs to get to 2100 which is dark, light is 5 and very light is 0.

The first time we noticed the values starting to change on the AAG brightness when it moved from its continuous reading throughout the day was at 21:47 when the Sun was -3.45 degrees below the horizon and the SQM was 10.15.

Within seconds the AAG read 9 and was already on Light vs Very Light and the Sun was now -3.54 degrees below the horizon and the SQM read 10.28.

It took almost half an hour for the AAG to get to dark. At 22:16 the AAG finally reached 2100, the SQM was at 13.97 and Sun was at -6.52 degrees below the horizon.

GingerGeek had also developed a new server for IMT3 to visualise some of the data from the observatory. The Grafana dashboard charts below show the data along with the Sun altitude.

Looking at the last 24 hours shows the effect of the light nights on the SQM. The raised values after 4am went the value should be reducing or zero is the effect of a cat or bird covering the sensor. Also worthy of note is the sky temperature which shows the effect of cloud as the SkyTemperature increases. A truly clear sky would yield a value of -18℃ or better.

We also took darks on the ASC and applied them since we had never bothered to do it before. The shot below shows the before and after effect of applying the dark/bad pixel map. The whole image looks a lot cleaner and darker, although there seems to be some negative representation going on with dark pixels.

The setting that needed to be changed in the ASC software took GingerGeek a while to find.

During the daytime the ASC looked awful but remote the darkframe reference file and just applying the badpixel map seem to be better. Tonight’s set of images will show if this is better or not.

The only other odd thing that happened tonight was the dome closed without the safety setting it off. Not sure why yet ……

Viewing Report 13th June 2020 – IMT3

23:31 – 04:02

So I opened the dome late this evening as it was not due to be clear. However an opening in the cloud meant I could test guiding again on the 12″, especially whilst it was light in the late Spring weeks.

The first job was as always to focus which brought me to a reading of 61944 at 19.83℃.

Another small job was to sort the guider FoV out. I went ahead and used M92 to align the guider.

The final FoV settings are here for completness.

Set AS1600 to Gain and Offset 10 due to cluster being very bright and I needed to set a standard of 60 seconds minimum exposure. Gain 139 and Offset 21 gas saturated unless I selected 15 seconds, Gain 75 and Offset 12 saturated at 30 seconds so hence 10 and 10 which came in about 58k ADU.

I then performed a slew to a nearby star so I could centre the scope, there platsolve completed successfully and I updated TSX and the FoV for the 12″ with the new angle.

The first image of 60 seconds came down and was out of focus, I then realised changing the profile SGPro forgot the autofocus setting, so I had to stop the run, delete the images and set the original focus point then rerun.

Next I ran a few images but then to my horror I had the same guiding issue, where the star moves being dragged up and down in a periodic way. I slewed elsewhere and tried again and the problem did not occur. I was near M92 and just East of the Meridian and quite high up. Not sure why that is a problem.

I could not resolve, I waited a while then performed a meridian flip and low and behold the problem went away, again not sure why. I still have this terrible noise coming from the RA motor/gear area. I decided to bite the bullet and take off various caps on the scope listening and looking inside. I decided it was not after all, the through the mount cabling but coming from the RA gear itself, so I looked for the MEII guide for removing the worm block and then followed the instructions to take off the RA cover.

This gave me instant feedback on what the issue was, the belts driving the axis were making a noise. On looking through forums on Bisque.com I found a few people with similar issues and needing to grease the belts, they were told Lubriplate was a good grease. This is an American grease so I will find a similar here and then apply, I will ask Bob first for his suggestion.

So the night wore on and the LRGB frames of M92 I thought I would take whilst testing guiding progressed. At one point the imaging stopped due to cloud. I just caught the dome before it closed to change the safety sensor due to cloud. When it cleared it never really cleared, with the sky temperature reading about -14℃.

Nearing the end of the imaging session, I had caught about 15 frames of each of the filters.

The guider was behaving mostly with he odd funny jolt. By 3:30 am the sky was lightening very quickly.

By this time I had stopped guiding and imaging. I closed the dome, slewed the scope to the flat panel and proceeded to take a set of LRGB flats for Gain 10 Offset 0 and also Gain 139 and Offset 21 as request from the previous nights imaging.

Viewing Report 12th June 2020 – IMT3

22:09 – 02:02

It was unexpectedly clear this evening so I opened the dome late, so no cooling down.

Focus 60,279 Lum filter at 19.93℃

Slewed to Arp 286 as I had seen on Flickr and wanted to see what it looked like in 12″. I noted I needed a new set of Darks for the Lodestar off axis guider after we had changed the driver recently, so I set about taking those with PHD2.

The problem I then saw was no guide star in the FoV! I really need a rotator!!!!!

So I will image without the guider. The first image jumped as I realised the auto-guider was still on and trying to track nothing sending the mount this way and that. So I disabled and set about running 3 x LRGB for 300 seconds a piece

The first image was Luminance and looked ok, although bright due to high level cloud and no astronomical darkness this time of year. I also noted the mark on the filter caused by the LensPen! I won’t use that again. However I do expect that to come out with the flat so not too bothered. Also I could go clean it I just don’t want more dust on the filter so will leave until I have a reason to take the camera off again.

For reference here is the luminance flat.

Next up was Red filter for 300 seconds

Then Green filter

Then finally Blue filter.

So I left it to run for 3 x 300 seconds each filter. Meanwhile Mil Dave came online and opened his dome and we decided to go for a joint target to see how they compare. Given Arp 286 was below Dave’s hedge I mentioned the Coddington Nebula IC2574 which is actually a galaxy, being the object in my latest image from the travel rig with the Esprit120 and the comet passing. It has some interesting star clusters in it. We agreed on luminance and 300 seconds. Here is Dave’s result ….

Meanwhile the humidity kept rising

At just gone midnight I finished the short run on Arp 286 and slewed to Coddington to catch up with Mil Dave. First I did a quick refocus as the temperature had dropped about 2℃ since I started.

The refocus put me near but not near enough so I changed to 62,056 for a better HFR which worked. Then I went on to do Coddington and here is my result.

I had problems with unguided exposure, then had a problem finding a guide star, then the object was behind a tree!

So next I slewed to Mil Dave’s choice of object, here is Mil Dave’s image

I managed to find a guide star straight away and grabbed this

Notice my screen stretch is different hence the bright background. It is just a quick screen grab off the NUC. My turn to pick now, so went for several objects but all behind offending hedges at Mil Dave’s house. So I sent Dave off to choose one. He came back shortly with Arp 278. So off we set. Here is mine.

and of course Mil Daves….but no, he forgot to save it 🙁

So my object next, I selected one nearby to save the rather long dome rotation I just did, and the resulting loud noise when it jammed! I need to look at that. Meanwhile Mil Dave trundled his round manually. So I choose NGC 7331, also known as C30 and Herschel H53-1, so also on my list for the Herschel 400. This is what I got.

Meanwhile the cloud from the South East started to creep in and my daughter, who just came in even at this hour of 1:36 said it was foggy outside.

Dave’s grabbed the NGC 7331 below.

I was about to suggest a Sharpless object when the clouds rolled in enough for me to shut the dome. It was reading -4.8℃ sky temperature and the limit was less than 30 for overcast, so I manual overrode.

Just before it shut this is the image I got of SH2-126 which is impossible to see since it probably needs the Ha filter rather than luminance.

Well a good night all round, given we thought it was going to be cloudy it was nice to come out and play with Mil Dave and go hunting faint fuzzies, so a goodnight from me and a goodnight from him ?

Viewing Report 2nd June 2020 – IMT3

20:28 – 00:30

After a day of checking the mount and spending some 3 hours resetting the RA and DEC cam stop and spring plungers I have come out to see if I have resolved the image or made it worse. I can still hear the squeaking of the cables in the Through the mount position as the worm turns so I do need to remove 1 or 2 of them to free it up. However I no longer hear the knocking, tapping and grinding of the Dec axis. I am also going to capture some PEC data for Tom on the Software Bisque forum to look at. GingerGeek with his usual smoking jacket turned up to assist from a distance.

Whilst trying to find a star we came across a galaxy, NGC 5646 H126-1, which looked very interesting for the 12″, so we will come back and image that at a later date. We are in a rush for the clouds as it is to cloud over by 11:30pm. What we need to do is disable PEC, disable TPoint and Protrack and the guider relays then point at a star and guide without applying any corrections as per page 147 of the MEII manual for 15 minutes.

I went out to the dome and set with the help of GingerGeek the camera on the back of the 12″ to as close to 0 degrees as possible, in our case 0.81 degrees after plate solving.

We slewed to a start neat declination 0 and close to the Meridian on the East side of the mount called Tycho 326:747 and at 22:37 started to look at the auto-guider settings. The star was at DEC +01° 34′ 10.909″ and RA 14h 45m 20.1920. The auto-guider log in question for tonight was “Autoguider.018.log”. The star looked good in the main ZWO ASI1600mm camera which we would use to guide and collect the data. We did notice as per the image below over 15 minutes the star drifting East, so the polar alignment is out. More importantly we got the 15 minutes of data in the log as the clouds started to roll in, as can be seen in the star brightness below.

The resulting log file was read into the Sky’s PEC and the raw data shown below one we clicked ‘Fit’ on the data which scales it to this chart. The peak to peak was 0.7 arcsecs. We applied this to the mount –

Next whilst GingerGeek went off to get his beauty sleep…..he really needs it 🙂 I set about slewing to a bright star in the vicinity and calibrating the guider, since I had rotated the camera. The calibration was successful even though the RA looked slights odd as a fit. The different in the RA and Dec rate was potentially due to position on the sky and the error in the RA plotting data. I will go back and do another calibration next time it is clear.

I then slewed to M92, could not find a guide star very suitable so moved around a bit and then started to guide and see what the graph looked like. What surprised me was the the amplitude of the guiding was only 0.36 arcsecs which is really low and no guiding issues as I saw before. It looks like the adjustments to the spring plungers and cam stops may have been the cause and fix.

Guiding graph at +74 deg altitude and near M92

I performed a quick focus run whilst pausing the guiding and got 61836 and HFR 4.4 which is vert good for this scope.

Meanwhile the clouds from the North had started to drift in which was going to stop play 🙁

I managed to get a single frame and focus on M92 of 20s before the clouds stopped the guiding. So I shut up the dome, sent the logs to Software Bisque, or the chap on the forum who was kind enough to help and went off to bed.

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 28th May 2020 – Travel Setup – Combe Gibbet

19:30 – 03:48

Another visit to Combe Gibbet tonight with another astronomer, GingerGeek. After forcing him to leave the comfort and safety of his own home, where his girlfriend gives him tea, coffee and beer and with the luxury of mains electricity, he joined me at the very dark, very blustery sight near 1,000 ft up in the North Downs of Berkshire, formally Hampshire, they moved the line!

We left at 7:30pm and after the 50min trip arrived at the long road up to and past the Gibbet, which is really not much of a road at all.

Not a road, looking down the bottom part of the track

We drove carefully to the top, both parked our cars and set about setting up for the evening. GingerGeek had his Tak FSQ85 on his CEM 60 iOptron mount whilst I setup my usual array of large 4″ binoculars and at first the Mak 180 on the Paramount MyT. Later I would swap to the Esprit 120ED. To celebrate the outing, little geek had brought some beer 🙂

The Sun soon started to set, the day trippers hung around to watch the sunset and then were gone. I started looking at the Moon through the Altair Astro binoculars which is just a wonderful sight. A Camera cannot capture the experience of seeing the Moon with its Earthshine and in full as the FoV is 1 degree in the binoculars was a wonderful framing.

Moon through binos taken afocal with iPhone 6sPlus

Next up was Venus before it sets, it is amazing just how bright it still is given its phase. I found in the binoculars eventually as it was hidden behind that cloud band in the distance. I then tried to get it in the Mak180, when a few new things happened. Firstly I could not slew to it as I had yet to polar align, so I had to place the scope in the right place. At the focal length of the Mak180, some 2.7m it is difficult to find something faint behind cloud just by pointing. I eventually gave up. I then noticed my laptop power had diminished by nearly 30% over about 20-25 minutes, this was due to Firecapture just hogging the USB bus capturing 100’s fps. So I was going to start the night short on juice! So I turned Firecapture off whilst I went to find Mercury in the binoculars.

Venus through 4″ binos taken afocal with iPhone 6sPlus

Mercury was a challenge, so much so I could not find it, I put that down to that not well placed cloud band. Meanwhile I pointed the Mak180 at the Moon to have a look, but by the time I had finished I the laptop was done to 53% !!!! Not so good.

So it was time to chat to GingerGeek (GG) before I put the Esprit 120 on the mount. GG was having lots of problems setting up. Firstly he had swapped the rings on the mount for the Tak that day and was struggling to balance the scope. It was so bad the scope kept dropping nose first then camera first and then either way depending on its orientation. Eventually, after much cursing, actually a lot of cursing, GG settled for the imbalance and continued to setup, unfortunately not before he knocked his beer over in his boot of the car ? fortunately I did not laugh too much ??

I went back to my setup, placed the Esprit on the mount and then set about getting focus with Ezcap, the software that comes with the ZWO camera. I do find the software very straight forwards and does what it says on the tin as it were. I then slewed to one of the open clusters I wanted to image and realised it resided in the North and that the twilight was still very much apparent so not suitable for imaging. Instead I settled for M51 high up as to the West was the Moon.

It is a lovely image at 5 minutes, I could see instantly at least 4 other galaxies and the colour of the main Messier galaxy was very pleasing. I look forward to processing the resulting subs. I set the timer for 1 hour (12x300secs) and went back off for veggie soup, cheese rolls, brownies and coffee that GG had kindly brought along.

GG at this point was having issues focusing for his 5 minutes shot of the Pelican in Ha, he had made some other changes to the software before heading up the hill too which was confounding him. After some more time he finally had focus and started to image. However whilst a few of the images were okay, the resulting imbalance and gusts of wind made it difficult to keep pin sharp images. It should also be notes at this point that GG and I were running from the same car battery, although GG was only running the camera from it, the mount was running from his Lithium battery.

Stunning Pelican Nebula – 300s Ha uncalibrated

At just before 1am the inverter connected to the spare car battery turned off due to loading and power. Everything stopped for both of us ??? however GGs mount kept running due to the Lithium battery. I closed down my setup and allowed GG to reset his camera and reconnect, he then went on to start imaging, however the resulting image had moved significantly and GG decided to give up. So we spend the next 40 minutes packing up. Whilst this was going on we looked at Saturn and Jupiter through the binoculars which was a wonderful sight. Now for the 50 minute drive home to unload the car just before dawn, although by 2am it was clearly getting lighter.

Guiding graph on Esprit 120 Paramount MyT last night, all over the place with wind

The SQM for the site last night was 20.91 although the Moon was very bright. The site is also very dusty, and my laptop was covered in the morning. Another incident was that I inadvertently unscrewed the cover from the guider as I transferred from one scope to another and the glass cover fell out, I now have dust and dirt on the sensor to clean. It is not a great design by ZWO for the ASI290MC as it really needs a locking grub screw to top that happening or a reverse thread.

Herbig-Haro object at the end of the long feature can just be seen.

GGs image has set us on a little project to image the HH 555 bipolar jet at the end of the major turn of gas in the Pelican Nebula. We will attempt over the next few nights to get an image from both the Esprit 120 ED Pro from the IMT3 dome in Ha and also from the OS 12″ to see what it looks like compared to the Tak FSQ85. Another good social distancing astronomy session ? goodnight.

Image Processing Notes for CMOS Using Flat Darks

I thought I ought to document this so that I remember this is now the new normal for making a flat master for my CMOS camera, the ZWO ASI1600MM. The problem I found again after not processing images for some time, was that the normal way of processing without Flat Darks produces a master flat with embossed, so raised doughnuts across the image.

Batchpreprocessing – > Darks tab -> Optimization Threshold -> move from 3 to 10 – > this removes the dark entirely and also removes the amp glow but introduces loads of noise so clearly not right at all. So I contacted my friend Dave Boddington who is a bit of an expert on this topic and he gave me some good advice that has of course worked.

So first let’s detail what I am calibrating. On the 20th April 2020 I took a set go Ha frames of M84, these were 300s exposure and with a Gain of 193 and I believe an Offset of 21, however we had some changes over the previous week so driver the Offset is no longer stored in the FITS header. It was when we were using the ZWO native driver. The temperature of the cooler was set to -26℃. I have 8 of these frames.

I also have a set of 10 darks at the same settings. However when using the Statistics tool Dave noticed the Mean of the image was 800 and the Mean of the Ha frame was 353. This is in a 16 bit notation. The camera however is a 12 bit camera and this means the Mean for the dark is 50 and the Mean for the Ha is 22, so a difference of 28 in 12 bit and 447 in 16 bit. I will come back to this later.

First I created a Master Dark for the Ha frames using the normal ImageIntegration settings. I did not calibrate darks with Bias as you do not need bias with a CMOS cooled camera. Next I created a Master Flat Dark for the Flat frames using the same ImageIntegration settings.

Single 300s Dark with hot pixels and amp glow

Then I found the Ha images did not need to have the flats applied so I skipped that step for the narrowband images. Next I Calibrated the Ha lights with ImageCalibration and because of that discrepancy above which looks like it was induced by having the Offset for the darks set to 12 and the Offset for the lights set to 21 I added 600 as suggested by Dave Boddington to the Output Pedestal in the Output files section of ImageCalibration. I made sure Evaluate Noise was ticked and that both Calibrate and Optimise were unticked in the Master Dark section. Master Bias was unticked and so was Master Flat for the narrow band images as mentioned.

This created a clean set of calibrated Ha lights that did not require flats to be applied.

Calibrated 300s Ha light with Master Dark

Next I had some issues in Star Aligning the frames. The error I received was ‘Unable to find an initial set of putative star pair matches’, due to the frames being very sparsely filled with stars and the background being quite light compared to the stars. A quick look on the PI forum showed increasing the Noise Reduction in the Star Detection section from 0 to 4 sorted the issue, with all but 1 frame being aligned. I was then down to 7 x 300s Ha lights. The final frame was very light due to cloud.

7 x 300s Ha Calibrated with Darks, Aligned and stacked

I then integrated these 7 frames together. I had a challenge with trying to get the hot pixels in a few areas to disappear using Cosmetic Correction and pixel rejection during stacking so I will remove these after by hand before combining into the larger set

So in essence what I have learnt is that I need to have really clean filters and camera glass. That all the doughnuts are on the those surfaces and not anywhere else. That the flats must be between 22k and 26k for the CMOS cameras, although this has some tolerance either way. That I need to set the camera to the right Gain, Offset and Temp as the lights and that I need the right flats for the right lights!

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 25th May 2020 – Travel Setup

19:00 – 05:00

So back off to Combe Gibbet again tonight for hopefully a full night until dawn and with a coat. I met with my friend Alan for once again some social distancing astronomy. Again Alan had a much better 4×4 car to get up to the gibbet than my little electric Nissan Leaf, however once again I managed to make it there.

Sunsetting with Esprit 120 and Alan in his chair

After setting up, it quickly became apparent that I forgot the guide camera as it was still attached to the Mak180 that I thought I would leave at home tonight ?

So despite the slight setback I polar aligned on the uneven ground and managed to get the scope pointing in the right direction. It took me a while to work out why it was not pointing at the objects when slewing with a perfect alignment, then I realised I had the location set incorrectly. A quick look at my GPS on my phone and I input the coordinates into The SkyX and the target was nearly spot on. I adjusted, performed a sync and then was able to slew continuously thought the night with the object in the FoV.

As I was challenged with no guider I could only take 2 minute images and if in the West low down then 1min. So I stetted for those 2 exposures along with 30 seconds for one particular object.

Below are the lost of targets I went after and imaged. I tried to get 15-20 minutes in total for each. We had some early night high cloud, the wind had again dyed down after sunset and although cold, we were both wrapped up warm, although later in the night Alan became cold so wrapped himself up in the dog blanket from the car ?

First up was M44 Beehive Open Cluster, which filled the view nicely so I took 20 x 60 seconds, careful not to saturate the stars. The QHY168C camera was set to Gain 7 and Offset 30 with a temperature of -20℃.

I then tried SH2-129 emission nebula but no luck, it was not registering at all at such short an exposure. I had a similar issue with SH2-155 Cave nebula. Both of these I will try again when I have my guider.

I then slewed to NGC 6888 Crescent nebula and took 20 subs of 120 seconds.

Next tried to image Trio in Leo M65, M66 and the NGC but I realised I had already imaged, although not processed and the image trailed at 1 minute due to its westerly location. So instead I headed for NGC 7243, a lovely Open Cluster in Lacerta and part of the Herschel 400 at 60 second exposure.

Next I looked at the double cluster in Perseus and decided to quickly take a few images with the Esprit 120 ED even though it was not on my original target list. Due to its bright stars I took 40 x 30 seconds.

Now it was time to grab an image of Comet c/2017 T2 PANSTARRS which was located near a galaxy called the Coddington Nebula. I purposely got the comet at the very edge of the frame to get the galaxy in, although I noticed the tail was pointing in the opposite direction than shown on Sky Safari.

Comet C/2017 T2 PANSTARRS and Coddington Nebula

The night wass really dark, even though it is not true astronomical darkness, the location really helps. The image quality is also much better. I slewed to NGC 7000 the North American nebula that Alan was also imaging. Again 60 seconds was probably not long enough so I need to come back to this object when I get my guide camera fitted.

Finally just as dawn was approaching and the light was clearly increasing, I took a few images of Comet C/2020 F8 SWAN to see if I could see it. Was was apparent was it was super faint even at 60 seconds !

So as dawn approached, Alan and I took flats, darks and flat darks.

During the night we viewed through the 4″ binoculars the Moon, Venus, Mercury, Double cluster, M39 Open cluster, M57 Ring Nebula, Alberio, M56 Globular Cluster, Saturn and Jupiter. Unfortunately I packed up the binoculars before I remembered Mars was up ! So packed up the car, ands drove very tired 50 minutes home.

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.