alacant

So focusing with the mask will leave you with coloured halos around bright stars. Use it to get you close, then lose it. Now, using zoomed in live view on the same star, adjust in tiny amounts until the blue [1] halo just disappears. Cheers and HTH [1] not familiar with the 600 so the residual halo may be red; same idea.

I adjusted: - colour- it looks great on a 'phone, a little green on a computer screen. But hey, I'm absolutely hopeless at colour. - the bg DSLR with a 135 so give it a big dither between frames to minimise mottle. Cheers and HTH

Hi Amazing detail for just 90 minutes. Love it. I've had a go at altering the image. With your permission I'll post it here as it's difficult to describe otherwise. Cheers

Is it a case watching a star for the duration? Presumably you'd issue NSEW via the handbox if the star moves away from the cross hairs.

Dunno. Here's George Ritchie -the guy responsible for the 1901 plate- looking into a large telescope. There's also a guide telescope pictured. I'm by no means certain, but I believe they had quite good tracking and guided by observing a star via a second telescope then using mechanical connections to the mount, the aim being to keep the cross hairs over that same star for as long an exposure as you needed. or I suppose until your patience ran out. I see you can still purchase cross hair eyepieces these days. I wonder if anyone here has tried guiding like that? Presumably back then, one got only one go at getting it right. Cheers

Hi everyone Not seen many of these so far this season so... Thanks for looking and do remind me how this should be done! nt150s + UHC ~5h calib-apilado siril 3.0.0a proc. st 1.9.558b

Hi You don't need an Internet connection. Just setup ad-hoc/link local only between the two boxes. If it's still rubbish, use a long cable. Cheers

Hi Give yourself a chance. No need to learn new software. Get one of the new generation mini-pcs with say 16Gb RAM and a nice SSD. Install Ubuntu, kstars and whatever else you like. Stable wifi and vnc, cheaper than a Pi and will run all night every night. In real time. Cheers and HTH

Hi 294, so isn't this simply a case of putting the dessicant tablets in the microwave oven for a minute or so? To gain access, remove the 4 screws at the sensor end and use tweezers to extract the tablets. Cheers

Hi I don't think the gso/ts OTA diameter is excessive, so with decent flat frames, you should be OK. Cheers

Hi Yes, exactly that. Our cheepo UHC destroys the stars; colour, brightness... everything. I think the only way for a realistic star field would be to take unfiltered frames. Cheers.

Hi everyone A positive from Ritchie's 3 hour plate using the 23-1/2" f4 at Yerkes in 1901 alongside our -far less of an achievement- 3 hour 2023 attempt with a 6" f5. Love the twentieth century stars, sadly lacking in our effort.

Hi everyone Not much 130pds activity recently so, here's one from the current heatwave in south eastern Spain. We found some blue bits in the sea of red, aka Cygnus. Thanks for looking and heat or no heat, don't forget your humble 130s. ngc6914 apil siril 1.3.0a proc st 1.9.588b ~4h uhc

Hi So long as you understand what the script is doing, enabling you to troubleshoot should anything go wrong, and the results are acceptable to you, then perfect. OTOH, using Siril manually takes only a few more clicks, plus you can use methods -such as our minimalist approach- for which there is no script; the operator is in control rather than the script. Cheers

Which alternatives did you have in mind?

Hi Unless you have a camera which has sensor amplifier glow, we find that dark frames introduce more problems than they solve. That, added to the fact that with many cameras it is not possible to match the temperature of the dark and light frames leads us to the simplified approach. Perhaps best to try both and see which you prefer. No two cameras are alike so generalisations only go so far. NP: But as @AstroMunirecommends, a bit of rtfm goes a long way. Cheers and HTH

Everyone can help by testing: Latest git here. We use Siril only for calibration, registration and stacking. If you really do need to use bg-extract, simply put the points manually yourself to coincide with a few reasonably dark and well spaced patches. With a UHC, you'll probably find that you don't need to. Aww, pity. At this game, you need patience. Cheers and thanks for your comment

The simplest possible. Calibrate: light and flat frames offset removal only. No automated scripts. No darks. No extract Ha-Oiii stuff. No star processing or any other distraction. No nonsense! Register: two pass Stack: sigma low 5 high 2 That's it. Cheers and HTH

Hi everyone Along with our cheepo UHC filter, this was doable probably because the moon was low toward Sagittarius. Unfortunately it flares bright stars toward the edges. I'm told I need to get the filter in front of the sensor, rather than on the telescope side of the cc. It's never straightforward... Not keen on current processing trends; IMO, stars make the image. Leave them out and the image looks flat, lifeless... Thanks for looking and do post your uhc images, especially if you had a go at full moon. pn208 ~3h apilado: siril 1.3.0a. proc:st 1.9.557 hoo oiii en nbaccent

Really? Entering; =600 into the bias field is more complicated than taking and processing and a sequence of non temperature matched dark frames?!

Hi Unless you're directly below one, I think you're going to be pleasantly surprised. The light-up-the-sky lamps of old have been replaced by well designed low energy versions. The moon is likely to form far more of a challenge. Here's a worst case scenario; shot from around 10km north of Alicante a few days before San Juan. Yes, there's contamination, but hey, it's not bad. ... but with modern gradient removal algorithms, a few taps and you're ready to process. If you really are troubled by this, you have access to a very low contamination zone looking south east over the Mediterranean: the beach😉 Cheers and HTH

Hi What problems are you having? Cheers

Yes. https://siril.org/tutorials/synthetic-biases/ HTH

Hi Keep it simple... D5300, so best to lose any type of dark frame. Noise will be better controlled simply by subtracting the offset; Nikon NEF usually set 600 . Don't bother with in-camera bias. We recommend Siril for all calibration and stacking. Cheers and HTH

Hi everyone Given that spacing an unknown ff on a cheap refractor in the dark wasn't frustrating enough, I decided to complicate it still further by adding the latest AliExpress UHC to the mix. So, here we are with a 72ed, an undocumented ff and an -optimistically named- angeleyes uhc filter Apart from obliterating most of the stars, the combination seems to work. The optical struggle is outlined in this thread. Thanks for looking and clear skies.