Chasing the Dark, Starlink and nearly giving up.

The days are long and the nights are short, at the moment there are about 4 hours of usable darkness for Deepsky imaging, fortunately since most of the aircraft have been grounded due to the Covid 19 pandemic, the skys have been much much clearer, this has happened before, I refer you to a previous post of mine about when the Icelandic volcano Eyjafjallajökull, erupted in April 2010, I’m even more convinced now that aircraft emmisions are the cause of so much bad weather and a huge contributor to global warming ( Aircraft operators can plant as many trees as they like, trees will not clean air 31000 to 38000 feet up ). Anyway back to topic, I have booked a weeks holiday to enjoy the weather, not going anywhere just relaxing at home and taking advantage of the clear ( night ) sky, I have done more imaging in the last two nights than i have for a long time, a total of 8 hours gathering narrowband data on IC1396 the Elephants Trunk Nebula in Cepheus, this was added to data that was captured in 2018 giving about 16 hours of exposure.

Elephant Trunk nebula Hubble palette
Elephant Trunk nebula Hubble palette

I must confess, I would have done some imaging a couple of weeks ago – but I had a moment where I seriously considered giving up astro imaging altogether, a couple of weeks ago I happened to be standing in the back garden looking up, when I noticed a satellite passing from west to east, ( nothing odd about this there are roughly 5000 in orbit, under 2000 of those are operational ) then another 30 seconds later following the same path, then another 30 seconds after that and so it went for about fifteen minutes, what I had seen was part of Elon Musks, SpaceX, Starlink satellite constellation, these satellites – when they cross the field of view of a telescope and camera, leave lines in the image as they pass.

Starlink trails, Credit: Victoria Girgis/Lowell Observatory

I phoned a friend of mine, another amateur astronomer to have a look himself, we both agreed it was a sickening thing to see, many non astronomers do not realise the danger to our night sky these things pose, especially as they are already having an impact on the night sky with only 360 them, Mr Musk ( the very same guy who thought it a good idea, albeit an egotistical one to launch a Tesla Roadster, complete with a spacesuit clad dummy into space, from an astronomers point of view he would make an excellent Bond villain ) wants to launch 30,000 of them, to provide global broadband internet coverage.

By the year 2025 SpaceX plan to have 12,000 Starlinks in orbit distributed as follows

  • 7,500 at 340 km altitude
  • 1,600 at 550 km altitude
  • 5,800 at 710 km altitude, data courtesy of Union of Concerned Scientists.

But thats not all, there are other companys that want to launch their own satellite constellations, OneWeb with an initial 800 satellites, Amazon last year announced project Kuiper, with 30,000 satellites and Canadian company Telesat wish to do the same, although they have not as yet said how many satellites they will have.

I set my allsky camera up to see if I could capture some of these rudy things, but all I got was the ISS, at least when you see that, you can think to yourself, there’s people up there, the StarSTINK ( thanks for the name Ron ) satellites should pass over the UK on Wednesday, May 27 at 3.48am GMT, I’ll try again then.

ISS, International Space Staion

The allsky camera works using software to compare one image with the next, any change such as a satellite or meteor triggers a capture sequence, imagine what it will be like when the sky is a moving net of satellites, it will be running a continuous capture sequence.

The issue of trails on deepsky images can be fixed with stacking software and Kappa Sigma Clipping algorithms, which ignore outliers such as satellite trails ( yet to be tested on a stack of badly trailed images ) and cosmic ray action on a camera sensor, but if you just want to lay back and look up at the spendour of the night sky, especially if you live under a dark non light polluted sky – then your view will be spoilt beyond doubt. 

That was why I was ready to give up the ghost, I do like to just stare up at the beauty of the heavens from time to time, is it’s not enough that we pollute the earth for greed, we now need to pollute the night sky as well.

Comet Atlas C/2019 Y4

A clear Saturday night ( shame about the moon ) had me gazing at a comet, this comet was discovered by the ATLAS ( Astronomers do love their acronyms – this one stands for, Asteroid Terrestrial-impact Last Alert System ) survey on December 28, 2019, and it was thought that it might reach naked eye brightness, however on around the 2nd April 2020 the comet underwent a fragmentation event, having thought to have split into at least four pieces, possibly due to outgasing causing an increase in centrifugal spin, this has caused the comet to dim considerably, however it does have a 3.3 million km long tail, more than twice the diameter of the sun.

Updating the comet elements in Cartes du Ciel ( CDC ) meant that once I had done a single star alignment and a quick plate solve of the star field, the telescope then slewed directly to the comet and put it squarely in the middle of the camera sensor, a hell of a lot easier than following a printed star chart and star hopping to the object. 

APT Comet Atlas
APT Comet Atlas

I captured 43 x 120 second exposures through the 8 inch RC and ZWO asi1600mm using a Baader 2 inch clear filter, the moon being three days from full – together with a bright sky glow did give some hard gradients, that were difficult to process out entirely.

Comet Atlas C/2019 Y4
Comet Atlas C/2019 Y4

Capturing so many images meant I could turn the images into a GIF to show the movement of the comet against the background stars. My appologies for the jump in the GIF, I had a go at tracking the comet instead of a star in PHD2 , I was hoping to get a clearer look at the tail, however the comet nucleus was too faint to keep a good lock on it, so I had to revert to star tracking. 

Comet Atlas C2019 Y4 2020-04-04
Comet Atlas C/2019 Y4 – 4th April 2020

Whether this comet holds together enough to brighten again as it approaches the sun, remains to be seen ( no pun intended ).

Clear skies and a bit more rosette

Wow, almost a week of clear skies – and is more than typical I have had a few early 4 am starts, I drive a Cement mixer so I had to choose between imaging and sleep (  The UK Government has allowed construction work to continue, even though Social Distancing is near imposible in construction, therefore I have not self isolated at home and have had to go to work as the spread of the Covid 19 virus continues apace ). The good news is Friday night was clear so I managed to capture another part of the Rosette nebula mosaic project I’m working on, 26 x 180 seconds exposures in Hydrogen Alpha were used to create this image.

Rosette pane 4
Rosette Ha, pane 4

This was combined with the other 3 panes of the mosaic, this will probably be the last addition to this Rosette project till later in the year when the nebula reappears, it is getting darker later and the object lower in the sky, that’s why I only managed to capture 26 images to stack together. 

Rosette 4 pane mosaic Ha
Rosette 4 pane mosaic Ha

Keep well and stay safe, everyone.


Something not astro imaging related

Some info on Social Distancing from the Government.

  • Only go outside for food, health reasons or work (but only if you cannot work from home)
  • If you go out, stay 2 metres (6ft) away from other people at all times
  • Wash your hands as soon as you get home

Do not meet others, even friends or family.

You can spread the virus even if you don’t have symptoms.

Coronaviruses can be spread when people with the virus have close, sustained contact with people who are not infected. This typically means spending more than 15 minutes within two metres of an infected person, such as talking to someone for instance.

The more you come into contact with the droplets from coughs and sneezes of an infected person, the more likely you are to catch the infection. This is why we ask people who have the infection to self-isolate at home and not to go out and about where they can pass it on.

However, on its own self-isolation may not be enough to slow the spread of a virus.

The Government’s new Coronavirus action plan recognises that as we start to see more cases in the UK, and more widespread community transmission of the virus, further measures to reduce the contact people have with each other may be needed.

These measures, sometimes referred to as “social distancing”, could include things like temporarily reducing socialising in public places such as entertainment or sports events, reducing our use of non-essential public transport or recommending more home working.

Social distancing isn’t a new idea that’s come about because of coronavirus. These measures are well-established and have been discussed and planned for many years, including as part of the Government’s preparations for a flu pandemic.

I’ve worked in construction and not every task on a building site can be carried out by one man, but it’s not only construction, two or three man Recycling and Refuse collection teams travel to and from their ” Rounds ” sat in the front of the collection vehicle.

Social Distancing
Social Distancing ?

Social distancing doesn’t work in these cases and thus it seems a portion of the population has been classed as disposable by the UK goverment.

Old and new, Bode’s Galaxy

A rare clear Sunday night, coupled with an even rarer Monday off gave me the opportunity to image M81, in the Constellation Ursa Major, also called Bode’s galaxy after Johann Elert Bode who discovered it in 1774. It is a grand design spiral galaxy about 12 million LY’s away, with a diameter of about 90,000 LY’s. I have imaged this object with a 10 inch Newtonian telescope and a DSLR back in 2016.

Ursa Major
Ursa Major

I imaged it last night through my 8 inch RC and the asi1600mm Pro monochrome camera using a Neodymium filter thats cuts out UV, and reduces star bloating. I captured 26 x 300 second exposures and processed them through Deepsky Stacker and Photoshop.

M81, Neodymium filter
M81, Neodymium filter

I then combined this image with the one from 2016 to produce a clearer colour image.

M81 combined image from 2016 and 2020
M81, combined image from 2016 and 2020

The Rosette nebula is now too low down now to image it until later in the year when it comes back round again, however the galaxy imaging season is here.

The Corona virus ( COVID 19 ) has finally had an effect on the astronomy community, the monthly meetings held by the Somerset Levels Stargazers has been cancelled until further notice, this is understandable as quite a large percentage of the members are of the older age group, I have no doubts that the meeting for the Crewkerne and district Astronomical Society will have a similar announcement  very shortly. On a positive note the cancellation of so many international flights can only have a positive effect on climate change and hopefully produce some clear night skies.

Three more weeks, One more storm

Another three weeks have gone past, with only a few hours of broken clear ( ish ) sky, but nothing I could work with as the wind has been a constant companion. Guiding under such conditions is a waste of time, the telescope gets buffeted around too much – not helped by yet another storm, this time called Jorge ( pronounced “hor-hay” ) named by the Spanish met office, bringing with it snow, ice, strong winds and pummeling rain. This makes the wettest February on record with an average of 202mm of rain.

Yellow weather warning for storm Jorge

The 7 day forecast does not really look great either with more rain for tomorrow, makes you wonder why anyone would bother with astronomy and especially astroimaging in this country, the last 12 months have not been particularly good, with about 14 imaging sessions in total. I’m looking forward to going to a monthly club meeting and being able to show some images again, when though, that’s another matter.

Two weekends, two storms

I have made no more progress towards completing the Ha, 8 pane mosaic of the Rosette nebula, NGC 2237 – around 20 days have passed since I put together 3 panes of the mosaic, since then the weather has been against me. Last weekend here in the UK, we had storm Ciara – that battered the whole country with wind gusts of up to 80mph, bringing yet more flooding to parts of the country already suffering from floods, and now this weekend brings storm Dennis to take over from where Ciara left off.

Storm Dennis
Storm Dennis

The way the weather is going it will be November 2020, before I get the chance to do any more work on NGC 2237, soon the object will be too low down by the time it gets dark, in all I need 36 hours of exposure time to complete the project, 6 clear nights of 6 hours imaging time, is that really too much to expect, I suppose it is with the UK weather, this brings me onto the subject of astrophotography competitions, recently a friend of mine , Ron – suggested I enter some of my images into the BBC’s Sky at night magazine, Insight Investment Astronomy Photographer of the Year 2020 competition, entrants are from all over the world and the overall winner will recieve £10,000 with £1,500 being awarded to winners of individual catagories, I can enter 10 images taken after 1st January 2019, I have gone through my images and only 2 completed images ( taken after 1st January 2019 ) that I consider good enough can be entered, so fingers crossed but I think that imaging from the UK is a bit of a handicap, 10 completed images in a year, what a luxury.

A work in progress

A few days ago we had a spate of clear nights ( sort of ), this gave me the chance to image the Rosette nebula in Monoceros. Now I have imaged this object before, but that was with a small telescope, a 72mm William Optics Megrez refractor – this time I wanted to image this nebula and open cluster NGC 2244 (  the stars of which is formed from this molecular cloud ) with my 8 inch RC telescope for more detail. This rig has a higher magnification and therefore a smaller field of view, this means I cannot get the whole nebula onto the camera sensor, so I have to image several sections ( slightly overlapped ) and put them together as a Mosaic.

NGC2237, the Rosette nebula Ha
NGC2237, the Rosette nebula Ha

I will need 8 images to make this mosaic to cover the whole gas cloud, each image will be made from 30 light frames, each of 3 minutes exposure. I also want to image using the Ha, OIII and SII filters. so lets work this out, 8 mosaic panes x 30 light frames x 3 filters = 720 light frames at 3 minutes exposure = 36 hours total imaging time, obviously more than can be done in a single imaging run, infact if I get 6 hours of clear imaging a night, that’s 6 nights work. 6 clear nights would be a luxury the way things are with the weather at the moment, thank heavens the images are digital and can be saved.

Rosette nebula, Canon EOS40D (modded), WO 72mm Megrez
Rosette nebula, Canon EOS40D (modded), WO 72mm Megrez

As it stands – the spate of clear nights only gave me 2 usable nights, the remaining nights were misty and foggy, sadly sunny days on wet ground lead to misty foggy evenings.

so I have out of the 2 usable nights, 3 mosaic panes of the Rosette nebula in Ha – this definitely going to be a work in progress.

Rosette nebula ( part ) 3 pane mosaic, Ha
Rosette nebula ( part ) 3 pane mosaic, Ha. ( note the Bok globules )


C/2017 T2 (Panstarrs), a circumpolar comet

A few hours of clear sky made imaging comet C/2017 T2 (Panstarrs) possible, the comet was discovered at 20th magnitude in September 2017 when it was 9.3 au ( 1 au is about 93 million miles ) from the Sun, it is now 1.5 au from the Sun and at approximately 10th magnitude. it can be found in the constellation of Perseus, this makes it currently circumpolar, meaning it does not set from UK latitudes.

comet path
Comet Path

The comet can be seen to move againts the background stars over a series of exposures, this is how they are discovered – an image is taken, then another of the same patch of sky a few hours or days later – anything that seems to have moved position is either an asteroid or a comet, comets tend to have a fuzzy appearence to them, as they approach the sun they warm up and produce a coma.

Comet-C2017-T2-Panstarrs, 75 minute interval

I took a total of 20 x 3 minute exposures through a clear filter, only this time instead of guiding on a star, I guided on the comets bright nucleus itself, this stops any elongation of the comet due to exposure lenght, this gives an hour of image data, but when you add dithering between images this gives 75 minutes from first image to last. After processing the images twice, once for the stars and once for the comet, then combining the two images together to give this final image.

Comet C/2017 T2 (Panstarrs)
Comet C/2017 T2 (Panstarrs)

Some of the tail was lost in processing the final image, if you look at the animated image you can see faintly the extent of the tail towards the left of the picture. Hopefully ( weather permitting ) I’ll get another chance to image this as it gets brighter on nearing the Sun.

An Early Christmas Present

After weeks of cloud, rain and wind, months of the rudy stuff actually – the sky cleared just after midnight on Christmas eve, ten minutes into Christmas day the roof on the observatory rolled back once again, the telescope was set up and aligned, the ZWO asi1600mm Pro camera was cooled to -20°C, the Flame nebula in Orion was targeted and imaging was begun. I captured 15 x 300 second exposures through the Ha filter of NGC2024, this star forming region is about 1300 – 1400 light years away and lies close to the star Alnitak – the easternmost of the three stars in Orions belt, it shines energetic Ultraviolet light into the Flame and this knocks electrons away from the huge clouds of Hydrogen gas that reside there. when these electrons recombine with the Ionised gas the clouds glow in Ha light.

NGC2024 Flame Nebula Ha
NGC2024 Flame Nebula Ha

Then as the Flame got too low ( no pun intended ) in the sky to image any longer, I swung onto NGC2264, the Christmas tree cluster in Monoceros, well why not, it’s Christmas. This star forming region and emission nebula lie about 2700 light years from us, the NGC2264 designation refers to the star cluster and the nebulosity including the Cone Nebula and the Fox Fur Nebula, again I captured 15 or so 300 second exposures through the Ha filter.

NGC2264 Christmas Tree Cluster Ha
NGC2264 Christmas Tree Cluster Ha

Then for something completely different, Imaging M101, the Pinwheel Galaxy in Ha, This galaxy is in the constellation of Ursa Major, the Great Bear and is located at the imaginary top point of an equilateral triangle with the stars Alkaid and Mizar, it is a face on spiral galaxy at a distance of 21 Million light years from us and has a large number of H II regions, many of which are very large and bright. H II regions usually accompany the enormous clouds of high density molecular hydrogen gas contracting under their own gravitational force where stars form, H II regions are ionized by extremely bright and hot young stars, hense imaging it through the Ha filter, I had to increase the exposure time to 600 seconds, so only managed to capture 8 images before it started to get too light, but you can see clearly the H II regions.

The forcast is again not good for the coming week, but boy was it good to have a proper imaging session once again, not just the odd hour or so…… Wishing you Clear Skies, a Merry Christmas and a Happy New Year.

Back imaging, for a while anyway

After a day or two longer than four months the sky cleared, for a bit anyway and I did some imaging, that’s crazy – a third of a year between imaging sessions because the sky is cloudy, raining or the air is misty or foggy or just plain rubbish. It’s December and I’ve been in a Tee shirt for heavens sake, anyway back to the imaging, I chose IC405 – The Flaming star nebula in Auriga.


To capture my images I use a nice bit of software called Astro photography tool, it will control the camera, focuser, filterwheel as well as guiding and has a host of usefull features such as bahtinov focus assist and Plate solving to name just a couple, and as with most software it has regular updates when new features are added, great. I started using APT with version 3.52, updating when a new version comes out and during the four months of doing nothing I’ve updated to version 3.81, so last night was the first time using the new version, this update has native support for ZWO cameras and when I connected the ZWO asi1600mm Pro camera I use, naturally I selected ZWO camera from the select camera type window, all good.

APT Select camera type window

Before the update the camera was controlled by the ASCOM driver, ASCOM is the industry standard for astronomy software and it ensures that image aquisition, planetarium, guiding and other astro software are compatible and work together, however some ASCOM drivers are limited in their user adjustability and so camera manufacturers have started having their own native drivers with selectable options, again all good.

I managed to capture five shots of IC405 before ( yes, you guessed it ) the clouds rolled in, so while I waited for them to go away I processed the five images I had, for this I use another bit of software called Deep Sky Stacker to stack the images together after subtracting ” Dark frames ” so as to remove noise from the image, these dark frames I have stored in a Dark Library. first you have to load your images as light frames, then add your dark frames taken with the same camera, same exposure, same binning factor and at the same temperature This is not a problem as I always run the camera at -20 C ( camera noise is very dependant upon camera temperature ), when it’s done you have a nice image to work on in Photoshop for example. However DSS threw up the message that the images and darks were incompatible ?, upon checking the image data for the lights and darks I noticed that the image sizes were different by 4 pixels and this was causing the incompatibility, the image size of the asi1600 camera at 4x binning is 1164 x 880 pixels, this was the size of the darks, however the lights had an image size of 1160 x 880 pixels ( 4 pixels narrower ), how could this be as both the lights and darks were taken with the same camera ?.

It turned out that the native ZWO driver was causing the problem, when I switched back to the ASCOM driver and took an image, the image size was again correct at 1164 x 880 pixels, I’ve informed Ivo at APT and I’ll keep using the ASCOM driver till a fix is sorted. Anyway heres the result of four months worth of waiting, an uncalibrated image made from 5 x 5 minute exposures. Oh and by 11.30pm the sky had still not cleared so I called it a night.

Flaming star nebula
Flaming star nebula uncalibrated