Detecting pressure waves from the Tonga Eruption (2022/01/15)

On January 15th 2022 at 15:10 AEDT (04:10 GMT) theΒ Hunga Tonga Hunga Ha’apai underwater volcano near Tonga erupted. Hunga Tonga-Hunga Ha’apai is 1.8 kilometres tall and 20 kilometres wide, but most of it is underwater, with the top 100 metres visible above sea level. The pressure wave generated by the explosion blasted through the atmosphere atΒ more than 1000 kilometres per hour.

Dave mentioned to me that the people had registered a pressure increase on their monitoring devices due to the pressure wave and checking the internet the Met Office has issued a nice graph on Twitter.

On the observatory Grafana dashboard I could indeed see two pressure waves at the correct time. We only record the pressure every 60 seconds because for astronomy that’s all we need so we do not have the resolution of others but the height of the two events are in the correct range compared to the graph above.

Double pressure wave

The first pressure wave arrived (19:13-19:24) we was 2hPa increase as we have lost some resolution due to sampling period and the Met Office is ~2.5 hPa. We could change the sampling to be lower (15 or 30 secs) as storage is not an issue and then we would have caught a nice defined peak. The second pressure wave (2022/1/16 01:55-2:14) and we measured ~1hPa drop and again was lower than the Met Office due to our sampling period.

Our auxiliary pressure monitoring install was down during this period as the box appeared to have been restarted/rebooted and the ASCOM Alpaca instance was not running which was unfortunate πŸ™

The Night Sky Observer Guide Series

When I started attending the Practical Astronomy Show held at Kettering I picked up my first copy of “The Night Sky Observers Guide Volume 4 – The Glories Of The Milky Way to -54Β°” written by George Robert Kepple and published by Willmann-Bell inc. These were sold at the Kettering show by the very helpful and knowledgeable staff of The Webb Deep-Sky Society for around Β£20.

Then in December 2019 ‘The Global Human Malware’ happened and the world went nuts, the Astronomy shows were cancelled year on year and I forgot to complete acquiring the rest of the series. Then suddenly in late 2020 it was announced that the publishers Willmann-Bell had closed and their entire portfolio went out of print.

Unfortunately I did not see the announcement until late Jan 2021, however I managed to obtain a copy of “Volume 2 – Spring & Summer” (ISBN 0-943396-60-3 (V2)) from Zoltan at 356 Astronomy but he told me he was out of stock for the rest of the series.

I contacted the Webb Deep-Sky Society to see if they had any available copies in stock. The president of the society Owen Brazell very promptly replied but informed me that they had sold their remaining stock just days before. He was extremely helpful in trying to help me source any remaining stock but eventually to no avail ! I recommend any avid astronomer should consider subscribing to the Webb Deep-Sky Society here …… I just did πŸ™‚

Example of Webb Deep Sky Society Digital Issue

Fast forward to 16th August 2021 and it was announced that the American Astronomical Society would acquire the inventory and related assets of Willmann-Bell. Luckily by January 2022 I noticed that FLO (First Light Optics) in the UK had managed to obtain a few copies and I promptly ordered a copy of “Volume 1 – Autumn & Winter” (ISBN 0-943396-58-1 (V1)) for Β£35.

Well, it arrived this morning and I apologised to my regular postman for having to carry it around by hand all morning.

As with the other volumes the information, maps, diagrams and descriptions are very useful for planning imaging or observing sessions.

The King of the Northern Winter Constellations – Orion
The fantastic Perseus Galaxy Cluster

I now have only Volume 4 “The Southern Skies” left to purchase but as that would only be a reference for objects I can’t see from the UK it would go mostly underused unless I start using my remote telescope account or travel around or below the equator.

I would like to thank Owen Brazell for all his time and for the ongoing activities of the Webb Deep Sky Society and hopefully we will see them at the next Practical Astronomy Show in March 2022 …. fingers crossed !

PixInsight – Load Default Project/Process Icons

So whilst Dave was processing our M45 QHY268C data, he mentioned how it is frustrating that he has to reload his process icons for his workflow every single time.

After finishing the communications/process diagram for IMT I decided to have a quick look if it was possible. Watching PixInsight startup I noticed access to a few files – banner and startup.scp. For me these were located in the C:\Program Files\PixInsight\etc\startup directory.

Looking through the documentation it seemed possible to add statements to the file which was possible once I had modified it as Administrator.

Method 1 – Load Process Icons

This will load just the process icons into the current workspace on startup. Add the line below to the bottom of C:\Program Files\PixInsight\etc\startup\startup.scp :

open "C:\Users\gingergeek\Pixinsight\Pixinsight DSW Process Icons V10.1.6.xpsm"

Save the file and restart pixinsight.

Method 2 – Load An Empty Project With Process Icons

Another method (preferred) is to create a new project (Empty-process-icons.pxiproject), load in the process icons. Save the project and then change the properties to make it read-only so you can’t accidentally overwrite it later on.

Add the line below to the bottom of C:\Program Files\PixInsight\etc\startup\startup.scp :

open "C:\Users\gingergeek\Pixinsight\Empty-process-icons.pxiproject"

Save the file and restart pixinsight.

I also modified the banner file (in the same directory as startup.scp) so it would show the IMT3b designation. I generator the ASCII art from one of the many online sites, if I can remember which one I will link it here.

\x1b[1;38;2;255;000;000mβ–ˆβ–ˆβ•—β–ˆβ–ˆβ–ˆβ•— β–ˆβ–ˆβ–ˆβ•—β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ•—β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ•— β–ˆβ–ˆβ•—\x1b[39;21m
\x1b[1;38;2;230;000;000mβ–ˆβ–ˆβ•‘β–ˆβ–ˆβ–ˆβ–ˆβ•— β–ˆβ–ˆβ–ˆβ–ˆβ•‘β•šβ•β•β–ˆβ–ˆβ•”β•β•β•β•šβ•β•β•β•β–ˆβ–ˆβ•—β–ˆβ–ˆβ•‘\x1b[39;21m
\x1b[1;38;2;204;000;102mβ–ˆβ–ˆβ•‘β–ˆβ–ˆβ•”β–ˆβ–ˆβ–ˆβ–ˆβ•”β–ˆβ–ˆβ•‘ β–ˆβ–ˆβ•‘ β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ•”β•β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ•—\x1b[39;21m
\x1b[1;38;2;179;000;153mβ–ˆβ–ˆβ•‘β–ˆβ–ˆβ•‘β•šβ–ˆβ–ˆβ•”β•β–ˆβ–ˆβ•‘ β–ˆβ–ˆβ•‘ β•šβ•β•β•β–ˆβ–ˆβ•—β–ˆβ–ˆβ•”β•β•β–ˆβ–ˆβ•—\x1b[39;21m
\x1b[1;38;2;153;000;204mβ–ˆβ–ˆβ•‘β–ˆβ–ˆβ•‘ β•šβ•β• β–ˆβ–ˆβ•‘ β–ˆβ–ˆβ•‘ β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ•”β•β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ•”β•\x1b[39;21m
\x1b[1;38;2;128;000;255mβ•šβ•β•β•šβ•β• β•šβ•β• β•šβ•β• β•šβ•β•β•β•β•β• β•šβ•β•β•β•β•β•\x1b[39;21m
Our new PixInsight default project with process icons

Thoughts

The downside to both these methods is that if PixInsight is upgraded/reinstalled then you will lose the settings – not a disaster to be honest as they are easy to put back into place.

Processed Image (M45)

So visiting Dave one evening as we have not met for a while whilst I was updating software Dave processed the QHY268C data we took of M45.

M45 – PixInsight Processed Image

So I’m disappointed that although the image is a good first start I forgot to change the change setting on the gain which in SGPro is in the event settings and not in the top level sequence display πŸ™

Dave ran the image through the annotate function of PixInsight. The galaxy PGC13696 near the bottom of the image is actually 232 million light years away.

M45 – PixInsight Annotated Image

Viewing Report 10/11th December 2021

Unusually it was a clear Friday evening. I did plan to be ready to go as soon at the pole star was visible but my imaging PC insisted on updates and the local hard disk was running at 10MB/s (replacement SSD on the way).

By the time I was ready, mount setup, polar aligned and balanced it was already late. I decided not to use the latest SGPro or NINA beta but just use the existing SGPro version. I was delayed starting as I was having issues with SGPro hanging when it couldn’t talk to the SQM (ASCOM Conditions Observing Hub) on a previous COM port, I need to report this back to the devs as a bug.

At this point Peg-Leg Dave joined me on a video call and we discussed imaging M45 in different modes on the QHY268C OSC. So we moved the scope to Alp Ari and proceeded to plate solve in SGPro, sync’d the scope Cartes Du Ciel and calibrated OpenPHD2.

Using the SGPro framing and mosaic wizard to decide on the framing for the target sequence I wanted as much of the reflection nebula as possible rather than being dead center.

M45 – SGPro Framing Wizard (FSQ85/QHY268C)

I’ve used the multi-star guiding in OpenPHD2 since it was first released in an earlier beta and I know Dave is looking forward to using it when he moves from using an OAG on his 12-inch RC to a 90mm guide scope to make it easier to get more guide stars or even one star.

Multi-Star Guiding in OpenPHD2

Whilst trying some mode/exposure tests the guiding started acting up in RA, so parking the mount and disengaging the clutches I redid the balance of the scope. It was only marginally off but it was enough to cause issues for the CEM60 …. it is not forgiving !

We decided to increase the Gain/Offset to 15/75 and use the Extended Full-Well mode (#2) of the QHY268C, testing the star brightness levels of various exposure times we opted for 180 seconds as that was under the maximum brightness level.

As I currently have no IP camera outside I like to see the mount position using GSPoint3D as I like to view where it is especially during meridian flips. NINA has this built-in now in the recent version 2.0 betas. As SGPro lacks this functionality I can use the view via this is standalone version that connects to the ASCOM mount.

Mount/Telescope virtual view
M45 – Pre Meridian Flip

SGPro paused the guiding just prior to the meridian flip. Following the automated flip, the guider and the imaging sequence automatically restarted after a plate solve and auto centering were performed.

Inverted shot of M45 (180s) – Post Meridian Flip

It gradually got cloudier just after midnight and the quality of the subs declined so I decided to stop acquiring data even though we really wanted over 4 hours of exposure.

I proceeded to take calibration frames. Using a target ADU of ~23,000 the SGPro flat wizard on the Pegasus FlatMaster (100%) gave an exposure time of 9.68s for the Optolong L-Pro filter, 25 flat-frames were taken followed by 25 dark-flat frames of the same exposure time and finally 25 dark frames of 180 seconds.

It was at this point that I realised that the FITs header showed a gain level of 0 and not 15, the offset was correct but I can’t be sure if the EFW mode was used as it’s not in the FITs headers. Only when using the native driver in NINA can you set the mode within the sequence, in SGPro the mode is set in the external ASCOM driver when the camera is not active in SGPro even though though it’s in the ASCOM API as the Camera.ReadoutModes property.

Also for some reason the default setting in the QHY driver is to NOT disable the overscan area which means I have black borders on my images which will make processing the data in Pixinsight a challenge !

I actually got to bed after 3am even though I had planned to stay up until the dawn. Next morning I noticed that my counter-weight had slipped and rotated on the bar. This may have also caused some of the issues with the guiding so I need to set-up earlier and check things more thoroughly in future to avoid these mistakes.

So although it’s not the data we planned it will be worth processing over a wine. The evening was a really a useful experiment and hopefully lessons will be learned …. if I remember the next time.

1st Exoclock Conference & IMT3b

25/09 AM – Exoclock Video Conference Day 1

So I had planned to sit in on the Exoclock Annual meeting all day for both days but in the end I could only attend for the pre-lunch meetings as I had promised Dave that I would assist at the IMT3b observatory. So I will catch up on the afternoon talks when they are made available online.

The talks were varied and included experts from the Ariel Mission, Twinkle Mission, JPL, Telescope Live, BAA , members of the Exoclock project followed by workshops of which again I really wanted to be present to participate in the CMOS workshop but I couldn’t.

1st Exoclock Annual Meeting Agenda

25/09 PM – IMT3b Warm Room & Donkey Work

We shutdown the dome computers, network and whilst Bob started on the warm room electrics Dave and I proceeded to 1 ton of scalpings from the front of the house into wheelbarrows and then push them up the garden to be stored ready for the warm room patio construction. It was a very humid day and we were both sweating heavily by the end of it.

The dome computers were repowered and outstanding software updates applied (BIOS, Windows updates, windows software and RPi4 OS & software) before the Autumn imaging sessions begin in earnest.

The day was rounded off by relaxing with a glass of red wine and dinner with Bob, Dave and the family. As the evening turned out to be cloudy there would be no imaging so it was an early night ready for the hard graft on the following afternoon.

26/09 AM – Exoclock Video Conference Day 2

Another set of fine talks and I especially thought it was a nice touch that an artist Lea who won the new Exoclock Logo Competition was awarded some imaging time on Telescope Live.

Lea took a bit a time explaining her background and how she formulated the design for the new logo.

New logo courtesy of Lea Changeat

It was even better that not being an astronomer she was persuaded to undertake some Exoplanet observations and report on her experience.

26/09 PM – IMT3b Warm Room Windows

The 7ft double glazed windows were put by Dave, Luke and Tim and myself. It was nerve racking as we manhandled the two panes from near the side of the main house up steps and along the garden with the Tim and Luke taking the awkward window corners whilst Dave and I used floor tile clamps on the glass.

The warm room aka “Wooden GreenHouse”

Bob came over to complete the electrics for the warm room and I left when Dave started stretching on tiptoes to put in the red & white light fittings. I figured I could complete the remaining software updates remotely.

The AAG software was updated to 9.1.4 from the old 8.1.0 version, we still need to investigate the wind sensor reading with Jamie from AAG.

AAG 8.1.0 sensor limits
AAG 9.1.4 sensor limits and new sensors

So we now access to the Humidity sensor settings and the appropriate alert levels. Previously I had to rely on both ASCOM local conditions and internal dome humidity via ASCOM (BlueAstro StickStation) but I wonder if we want to trigger an unsafe state by including the humidity thresholds.

FSQ85 Flattener & QHY286C CMOS

I’ve taken the plunge and dipped my toe into the CMOS world. Since I didn’t have any OSC experience I chatted with DSW (has a QHY186c) and decided on the QHY286C. This I purchased from Bern at ModernAstronomy who has always provided excellent service.

The issue with APS-C sensors when coupled with the Takahashi FSQ85 is that the edges start to show signs of star elongation, I already see this on my Atik460. This can be corrected with the FSQ-85 flattener (ordered from FirstLightOptics) which has the effect of slightly increasing the focal length but also reduces the back focus from the native 197.5mm to 56mm.

Effective Focal Length455mm (f/5.4)
Image Circle Diameter44mm
Metal Back Focus56mm
FSQ-85 EDX with Flattener 1.01x

This means that I can’t use my existing Atik OAG->Atik EFW2 and Atik460 because it’s total distance is 59mm (22mm+24mm+13mm) so it’s out by 2mm even once you include the filter effect on the back focus. Note – This is also true for my Starlight Xpress configuration.

I do not understand why Atik could not have got to within the 55-56mm range by shaving off a mm here and there πŸ™ I may need to replace all Atik gear when I convert to mono CMOS or replace the OAG with a guide scope.

So onto the QHY268C, the OSC CMOS unfortunately has a CAA tilt adapter instead of a direct thread connection. This wastes 11mm of precious back focus giving a total distance of 23.5mm whereas the recently released QHY286M CMOS has a 12.5mm back focus !!!!

Also the QHY268C does not have an IR/UV cut filter in place so you need to buy an additional filter and holder and add that to the cost and factor in the adapter and distance needed …. I’m starting to regret this purchase more and more !

Source – QHYCCD.com

Back to the Takahashi Flattener (TKA37852), the back focus is 56.2mm but we add on the filter thickness as it changes the light path (2mm/3=0.66mm) so ~57mm (56.9mm), the imaging train is as follows :


Adapter
Distance (mm)Accumulated Distance (mm)Connector
OU03122M54(M) -> M54(M)
QHY 02077046M54(F)
QHY Spacers14.420.4screw
QHY OAG-M1030.4screw
QHY 0200552.532.9screw
inc filter0.633.5
QHY CAA adapter639.5screw
QHY268C CMOS17.557screw
FSQ85 Flattener to QHY268C imaging train

The combined weight is 1365g so I may need to adjust the balance of the scope a little as it heavier than my Atik460/EFW2/OAG setup at 1080g.

Completed – Imaging train ready for first light

I may have to adjust the spacers a little but I won’t know until I have received a 2-inch Optolong L-Pro light pollution filter which is currently on back order from FLO.

Transmission chart for Optolong L-Pro

QHY268M

The recently released mono version of the QHY268 looks like it has a proper screw face plate with a more acceptable back focus of 12.5mm. This is more reasonable and would allow me to couple a filter wheel and OAG as well not requiring a IR/UV cut filter.

Like SyedT on StarGazersLounge I could go back to using a guide scope and ditch the OAG and then the imaging train could incorporate a rotator :

ComponentDistance (mm)
QHY268M CMOS12.5
QHYCFW3M-US17.5
M54 (M) to M54 (M) adapter2
Pegasus Falcon Rotator18
M54 extension ring5
M54 (M) to M54 (M)2
Total57
FSQ85 Flattener/QHY268M Imaging Train – Credit SyedT

I was thinking of a rotator for the remote Esprit120 which has a generous back focus of 76mm so I should have no problems there but that will be another adventure for the future !

CPRE Star Count 2021

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.

Source – CPRE

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 πŸ™

Suburban Sites

ObserverStar Count
Jim9
GeekBoy10
GeekGirl11
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.

ObserverStar Count
Giles9
Stephen et al13
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.

ObserverStar Count
Dave23
Daughter & Boyfriend27
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 !

Lakeside Focuser broken (23rd Jan)

So whilst Dave was in his garden using the binoculars and failing down holes in the process I was setting up to relearn how to take images ….. it’s been that long and the weather hasn’t helped.

So all was going well except that the Moon was bright and right near the winter nebulas. Even how bright the moon was I decided to use the time and practice using the Monkey Head Nebula as my target.

The tripod was levelled and the iOptron CEM60 polar aligned, the scope was balanced, the Atik460 CCD was cooled (-25℃), OpenPHD calibrated, the plate solver completed and the successfully sync’d and . The first step was to autofocus on a decent bright set of stars before the imaging run.

That was when the night was over ! SGPro set about running it’s autofocus but strange things were happening. SGPro was reporting that the LakeSide Astro focuser position was changing but the star HFR profile was not changing and the V curve remained flat. Since the focuser position was “changing” I did not think to go out into the garden with a red torch for an hour.

Upon inspection it was fairly obvious why it wasn’t working and inside the issue was proved to be a disconnected wire on the motor port.

Hmm …. I wonder what the issue could be !

I thought it would be prudent to double check which of the two spare connectors the wire came from and indeed it is the top one.

Source – Stargazers Lounge

Removing the heat shrink outer and you can see that there is barely any wire left since the majority of it was left in the solder when it broke off. This will require a wire extension and the old solder with the remains of the wire removed first before new solder being reapplied.

View of full cup connector with solder and empty cup connector

So since I’m really bad at soldering and I was worried about having to replace the whole unit (Β£90) I asked a friend who is fairly handy at this to perform the fix for me.

Optec Flip-Flat Service – Vendor Review

So during the ongoing Human Malware situation we have been concentrating on imaging asteroids, comets and more recently performing exoplanet measurements on the 12inch RC than long exposure deep sky astrophotography.

Astronomy is one those hobbies that is for most part is sole activity for the dark early hours of the morning and these days is usually done remotely. It was therefore disappointing that when one of the team went to use the Sky-Watcher Esprit 120ED for a night of astrophotography and found that he was unable to open the Optec Alnitak Flip-Flat. As the lockdown and travel restrictions progressed due to the initial wave of the human malware situation the issue was soon forgotten as we continued our focus to performing exoplanet observations on the 12inch RC for the ESA Ariel Mission.

Now that IMT3 has been decommissioned ready for it to be reborn as IMT3b at it’s new rural darker sky site I decided to take the opportunity to retrieve the FlipFlat and diagnose the issue at home on my desk.

Using the Alnitak controller software, I could hear the motor running but it never seemed to complete the close or open. All it continued to display was the TIMEDOUT message as shown below.

Timing out !

I sent an email off to the vendor I purchased it from but after a month I got no reply. In the hope I would not be left with an expensive paperweight I reached out to Optec. After quite a few weeks of getting no reply I was pleasantly surprised to receive a message from Jeff Dickerman (President) of Optec. Jeff apologised for not responding earlier and offered to help resolving the issue. The error message seemed to be a known issue and it was generally an easy resolution which required taking the box apart. Jeff sent me instructions on how to take the unit apart and fix the problem.

You’ll see the motor is attached to an internal wall with a modified shoulder screw and stack of Belleville washers.  These spring washers are used to allow the arm to slip when someone grabs the lamp and physically tries to force the cover closed.  Unfortunately they can also allow the arm to slip during an open or close operation which leads to that dreaded “TIMED OUT” message.  Optec have redesigned the stack a bit to eliminate this issue going forward. 

To correct, you might be able to adjust the washer stack by removing the lock nut and sliding off the washer stack to the pivot arm.  Check carefully to see if the shoulder screw protrudes beyond the pivot arm.  If so, rather than installing the cork washer next, install a 5/16” ID washer first to cover the exposed shoulder.  Next add the cork washer and stack of Belleville washers.  Finally screw the lock nut back in place and tighten while holding the shoulder screw near the motor (this is important to avoid breaking the internal motor gears).

Step 1 – Pry open clamshell
Step 2 – Shows what to secure
Step 3 – Tools needed
Step 4 –
Step 5 – Check shoulder visibility
Step 5a – Shoulder
Step 6 – Washer Stack

In the end I decided to courier the unit back to Optec for repair as I did not want to render my unit completely useless in case I made a mistake.

I’m extremely grateful to Jeff, Tina and the team at Optec for all there help, patience and understanding. I’m a very happy customer and the flip-flat will be rejoining the Esprit120 when the IMT relocation is complete at it’s new rural location. I can then do a Homer Simpson and annoy Dave with “Flap goes open, flap goes shut, flap goes open ……”

AllSkyEye – 0.9.17.1 Pro

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

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

Latest Image with custom text overlays
Latest Image Horizon Projection

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

Keogram

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

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

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

AAG CloudWatcher Installation

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

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

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

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

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

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

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

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

New Firmware 5.73 loaded

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

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

EventSQMAAG Brightness Value
Civil Darkness13.08949
Chief TOSA setting OK to open 13.892100
Nautical Darkness18.9228588
Astronomical Darkness19.0328588

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

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

TOSA Web Status

During one of our video sessions whilst watching the T-point run, Chief TOSA Dave mentioned about how it would be nice to see status information of observatory operations in a simple web page.

Since I’d never used Node-Red but had used ASCOM Alpaca via Python I thought this may be the time to learn something new. As I was designing this for Dave I decided to keep the layout, presentation simple along with colour coding in the spirit of Fisher Price toys.

The safety monitor is always visible across all tabs, the colour changes depending on the threshold levels we decide on.

ASCOM Alpaca Weather Conditions

Likewise the main equipment tab displays the equipment status and allows us to select which camera, focuser or filter wheel to monitor.

ASCOM Equipment Status

This project is still very much a work in progress but there is many different ways that the same thing can be accomplished.

All Sky Camera Experiment

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

All Sky Camera Initial Thoughts

I find I notice some interesting things on the All Sky Camera, which is a USB 3 ZWO ASI120MC-S CMOS camera inside a purpose built casing and clear dome. Firstly I land up with beautiful clouds rolling past. I also noticed the light pollution as I mentioned in a previous post from the bathroom window upstairs. This image is when I had the camera on the ground by the observatory as I was testing the maximum length of powered USB I could get away with before data loss caused issues.

Bathroom light on

When the light is turned off it is noticeably darker.

Bathroom light off

Sometimes I get visitors to the camera.

Daytime visitor

and sometimes I unexpectedly capture a meteor πŸ™‚

Raindrop, Clouds and Meteor

So it transpires I can use a single 3m powered USB cable to the USB hub, I cannot use 2 x 3m powered USB as that causes data loss and hangs and I cannot use a single unpowered cable either.

Viewing Report 8-9th September 2019 – Local Sky Quality

So recently the local Hampshire Council has been turning off local street lights at 1am and turning them back on at 4am. Now of course this was in a bid to reduce running costs but there is a positive to this change of heart.

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.