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Richard,
Will have a look at the gallery and see if I have any images older that those I have already placed on it. 3 at least I suspect, probably going back to mid 90s. Of course, people didn’t usually stack more than 20 or 30 images then (I had to write my own code to do it) – and Pentiums weren’t exactly nippy. Bill Gates declaration that “640kB should be enough for anyone” was already a joke.
Will look this evening.
Grant
EDIT: 1997, 2007, 2017, 2018,2019 now in the gallery…
I would also add in the period when the Eyjafjallajokull volcano in Iceland saw aircraft grounded too – that saw an unusually long run of blue skies too.
It might take some of the fun out of the discussion for the journalist, but by looking at VIIRs imagery for London over (say) the last 10 years you should be able to see what has happened in recent years as the measured upwelling radiance would need to be constant before you could safely attribute more stars to NO2 levels and the ULEZ.
Something like…
The website now actually offers the option for trend analysis on the light pollution levels. Impressive how dark some of the Motorways have become.
Perhaps upwelling blue light is scattered more strongly and never reaches space and so gives a false impression.
By comparison my home location has seen a small rise in light pollution as new house builds seem occupied by people afraid of the dark (despite every phone having a torch inbuilt) – even out here in the boonies where a crime is a major event!
Half decent display here near Salisbury at just after 20:00 UT. Didn’t last long though.
https://britastro.org/observations/observation.php?id=20250416_222637_de6f50341ab31fe8EDIT: I forgot to change the time on my camera. This should read “after 21:00”.
Hmm. I shall have a look at that. Python is very easy so its an attractive option. Wonder if I should stick with ASCOM rather than Alpaca for simplicity but worried anything I do might become redundant in a few years if they are moving away from COM.
Oh well, no excuse then but to use github for the first time and try Visual Studio – which I downloaded years ago and got rid of fairly quickly after I tried to convert a GUI intensive VB6 program to .NET. It wasn’t a happy experience.
Truth be told, a large chunk of my last 10 years has been spent developing software for image processing pretty much in a team of 1. I wrote IDL (or later Python) and its run from command line. My understanding of the ASCOM/Alpaca/Github universe is wafer thin… 🙂
Looks like one of my old laptops is about to be resurrected for this. Be warned, there may be immoderate language…
Does anyone know if theres a latency issue with using Python rather than another language?
Morning Ian,
Thanks for replying. I knew there must be people out there that do this sort of thing but you never get to hear who they are as its a touch niche.
Python sounds great as my progression has been Fortran/Algol/6502/Z80/C/IDL/Python down the decades and I certainly have a spare RPi knocking about…
So, how does it work then? Does it, for every possible taskable type of instruction, issue a command line process calling a Python instance while perhaps storing info in files or environmental variables? I’m intrigued.
I’m fairly certain you can call dlls from Python, so this sounds hopeful.
The ASCOM/Alpaca website said newbies should use their templates – for fear of people picking up bad habits from others – but then failed to say where said templates were. It strikes me as site designed by enthusiasts for other enthusiasts and with way too few examples. Thats said, its a hell of a piece of work.
Sounds rather like a pass of new Starlink satellites.
If you have a look at the Heavens Above website at https://www.heavens-above.com/ you should be able to find out which ones…
This quite good for cloud forecasts too….
https://www.meteoblue.com/en/weather/outdoorsports/seeing/salisbury_united-kingdom_2638664
Yeah, wooden roll off seem less dew laden. I was an occasional user of one thats 10 years old and only now showing need of TLC. I only once encountered water on the scope optics when opening up.
As it happens, I ordered an additional dewheater which arrived yesterday. I will try mounting that down by the mirror cell of my Newtonian and leave it on when not observing. I shall see what happens.
I will also start assembling the RPi bits for a longer term project.
Thanks to everyone for their observations. An alternative view helps.
I think I have to separate the problem into two parts to make it easier to grasp.
During observing: I used to have an AE 10” with thick tube walls and insulating the tube walls certainly seemed to help. The OOUK 12” has much thinner walls on it and so less thermal inertia, so it may not solve the problem entirely but, with a 12” dewheater up by the secondary it may be enough to avoid the faint mistiness on the main mirror I see on some nights. I leave the mirror cell fan running always – drawing a small amount of air down the length of the tube.
During daytime: I’ve been parking the tube inclined upwards at 5 degrees to help the water run off the mirror. I also have both ends open but with a muslin cloth over the end near the eyepiece to catch any smuts from local garden bonfires (it has happened – one of my neighbours went through a pyromaniac phase).
Air is drawn down the tube and out past the main mirror using the small fan in the mirror cell. The rationale was that the mirror front surface would more closely follow the air temperature if the air was moving rather than stagnant. The hope was that any periods of dew would be minimised. That worked badly!
I usually leave a gold coloured accident victim type mylar blanket over the scope to avoid drips from the roof affecting the tube. I tried having a cat blanket underneath the mylar in case that helped, but it didn’t.
I suppose I could increase the fan power or even reverse it so the flow is fast near the mirror and improve heat transfer – but it is heat transfer to the rear of the mirror rather than front. I could put a heater directly behind the fan too… Or even a fan in the tube side (but its a feeble tube anyway and I would rather not weaken it).
Alternatively: I could nearly seal up the tube when not observing and use a Raspberry Pi to monitor the mirror and tube temps (air proxy) with IR sensors and, if need be turn on the heaters and fans accordingly.
An RPi and 12V fan doesn’t use much power and if it worked I could try one of the RPi Zeros instead. I doubt if the heater would be on for long – especially if the tube is insulated. The Rpi would generate a little of its own heat but I have no idea how they cope with sub zero temps.
Has anyone else tried anything like this. What do Planewave and Celestron do with their dew control approaches?
Looks like I need to revisit the power being used.
We had a couple of 2-3C daytime temps followed -4 to-5C nights and now, with a 12C warm, wet front suddenly going through, heres the result….
I’m worrying whether the Pulsar dome is just too damp for C14… The NEQ6 was streaming with water today. I am aware of at least one group I know trying to line a Pulsar dome to stop dripping.
For the record its a 300mm mirror in a 1200mm tube.
Attachments:
I made PV Cep 16.75 (Gaia g unfiltered) on the night of the 2nd.
Picture:https://britastro.org/observations/observation.php?id=20250105_000432_f426e583e7f058d1
I have not yet measured tonight’s images but the activity around the HH region is still going on – its a continuation of what Richard Sargent spotted in November.
Will probably process all my data tomorrow…
