The Campaign for the Protection of Rural England (CPRE) was running it’s annual star count for 2021 from 6th – 14th February.
Basically in order to assess the effect that unnecessary man-made light pollution has on the quality of our life’s the CPRE want people to count the stars they can see within a box formed by the brightest stars in the constellation of Orion (not including the four main stars that form the box) and submit their observations.
Credit – https://cpre.org.uk
A couple of us arranged to get together remotely and count the stars we could see at 8pm on 10/2/2021 when Orion was near it’s highest point in the South. Of course at this time of night the light pollution is also fairly high 🙁
Suburban Sites
Observer
Star Count
Jim
9
GeekBoy
10
GeekGirl
11
Neil
12
Observation – 20:00 10/2/2021
The SQM (Sky Quality Monitor) reading for our (GeekBoy/GeekGirl) location at that time was 19.92 mags/arcsec2 which places it around a Bortle class 5 sky (NELM 5.6-6.0). Of course later on during the night, once the causes of light pollution subside I normally get a reading of 20.6 mags/arcsec2.
Observer
Star Count
Giles
9
Stephen et al
13
Observation – 20:00 12/02/2021
Rural Dark Site
Dave got out with his family to star count from his rural dark site and the comparison is stark ! There may be an age effect on the eye sight here as they are from the same time/location but either way it’s shows what can be seen in the absence of excessive light ingress.
Observer
Star Count
Dave
23
Daughter & Boyfriend
27
Observation – 21:40 10/02/2021
Well that was a bit of fun and a welcome distraction in the current never ending lockdown – thank you guys !
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.
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 :
SGPro Image History
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 !
Sky Temperature – T’was warm !
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.
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.
New IMT3 Grafana dashboard
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.
Shows the entire night
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.
Before and after applying darks
The setting that needed to be changed in the ASC software took GingerGeek a while to find.
ASC Setting to apply darks
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 ……
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 🙂
Beer O’Clock!
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.
M51 300s Image uncalibrated
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.
crop of uncalibrated 300s M51
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.
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.
New set of simplified profiles
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℃.
Flat Darks for new profileDarks for new profileFlats for new profile
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.
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.
Tape for USB cable
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.
AAG Weather Station New Settings
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.
At the IMT we were experiencing stability issues with the ZWO ASI120MC USB3 camera on the MAC/NUC so we decided to move it to it’s own Raspberry Pi4 (4GB) as a cheap experiment.
The Raspberry Pi4 has the advantage of improved networking and connectivity including USB3. One of the downsides of the RPi4 is the increased heat generated by the CPU which is mitigated by housing it in a FLiRC passive case to dissipate the heat and prevent thermal throttling.
Additionally in order to prevent SD card wear and improve the I/O throughput we configured the RPi4 just to boot off the SD card but serve the rest of the file systems from a SSD connected via USB3.
AllSky Camera Software
Using the open-source AllSky Camera project for ASI camera support we gain some advantages. The main advantage is that it’s open source (served via Git), provides an admin and public web portal which is addressed locally as http://allsky.local and the software can be set to start on system startup.
Admin Web Portal
The allskycam software can restart on system reboot but it can also be stopped/restarted via the web admin portal.
The configuration is simple and the mode/behaviour of the software can be controlled via the GUI or via a settings.json file from the command line.
Admin Portal – Camera Settings
I recommend you take the time to create a dark reference image, again this is done via the GUI panel as long exposure frame will show extensive hot pixels.
RGB24 image hot pixels with no dark applied
Non Admin Web Portal
This is accessed via the address http://allsky.local/allsky-website and provides the latest captured image, a constellation overlay and the ability to view time-lapses and star trails.
Local network web site for non admin users
One of the nice features of the software is it’s ability to create a time-lapse of acquired images for the previous night. The following video shows the debayer issues as well as the dewing of the dome cover.
Time Lapse of evening showing dew issues/grayscale bayer
Bob is due to connect up the resistor ring he’s placed around the camera which hopefully should fix the dome dewing we encountered on the first night.
So it remains for us to fix and implement the following :
Resolve the lack of colour images (RGB24)
Image quality breakup
Resolve dark daytime images
Secure copy latest image/time-lapse to an external public website
Scale VirtualSky constellation overlay (180 degrees) down to 150 degrees
Apart from the various benefits of darker nights such as better sleeping patterns for humans alongside a bat friendly environment then the benefits for astronomers cannot be understated.
We use a Sky Quality Meter from Unihedron in order to measure the seeing conditions and record it in the long exposure deep sky objects we try to image.
Below is the graph for the entire night of 8/9th September 2019 and the effect of bathroom light close by can be observed at around 21:20. This clearly demonstrates how bad local light pollution can be. By 4:30am the astronomical darkness window had passed and the SQM was dropping.
The effect of the new street light policy at 1am is obvious as an increase from a SQM reading from 20.4 to a maximum of 20.59 is observed until 4am when the street light came back on again and the sky quality immediately drops.
This places the local area as bortle class 4 ( 21.69–20.49) and a long way from a rural setting (21.69-21.89) or even Kielder Water (21.88) which can only get worse with more housing developments and unnecessary outdoor lighting.
So although we are grateful for improvement in the local dark skies it would be great to see the lights staying off for longer in winter so we can attempt to get better images. Hopefully we can start to come close to appreciate what people saw before the intrusion of unnecessary artificial lights in our life bloated out the wonders of the night sky without having to resort to traveling to the top of La Palma.
