michael.h.f.wilkinson

Difficult to say. My best guess would be contrails of planes that were on roughly parallel courses.

UHC filters only work well for emission nebulae, not galaxies or reflection nebulae, so they certainly have the ir limitations. For most emission nebulae, they work very well

What magnification were you using. I can pick it out quite readily with 16x80 from a dark site, so it isn't a very hard object. I do notice using a UHC filter in my C8 at 65.5x (with the Nagler 31T5) helps a lot

In my Celestron C8 I find that I generally work at focal lengths of 7 to 10 mm for planets, equivalent to an exit pupil of 0.7 to 1.0 for an F/10 scope. A 6 mm can work under good conditions, and if conditions are outstanding, I might go for a 5 mm, but that only on moon and Mars. You might want to consider the Pentax XF 8.5 mm (I used to have one, but replaced it with a Tele-Vue Delos 8 mm). The Pentax XF 8.5 is very good value for money, I feel. There are plenty of other choices. In my light-weight travel kit I have Vixen SLVs of 5, 9, and 15 mm which are all excellent, Pentax XW quality for a much lower price, at the cost of a smaller FOV (50 deg vs 70 deg). If you don't mind the short eye relief, a Plossl or Ortho of around 7 mm would work

Superb shots, as ever

Sounds very interesting. Have imported it into Stellarium

Indeed, the image is way out of focus. Stars will then appear as (faint) images of the shape of the aperture, complete with secondary mirror and spider vanes

Thanks, but these are not the mosaics. The H-alpha ones in a separate post are

Got up early this morning (4:15), and went to a dark spot north of the city of Groningen. Venus was above the horizon, but rather worryingly red, due to some thin cloud near the eastern horizon. I got out the Helios LightQuest 16x80s and tried my luck on comets 2P (Encke), and 103P (Hartley), but no luck in the bright moonlight. I will try them with a telescope later. As it was rising, Venus turned a healthier colour, so I focused my attention on Leo's head. I spotted a compact, fuzzy blob, with the faintest hint of thin gas tail, and the slightest green tinge close to epsilon Leonis. I first wondered whether it might be a star made blurry by the haze on the horizon, but all the other objects in the FOV were pinpoint. In averted vision, I kept catching tantalizing hint of a thin straight tail, and the coma stayed obstinately fuzzy, so I reckon that is comet C/2023 P1 (Nishimura) bagged, especially because it was in exactly the right spot according to the map from comet chasing. Comet number 36 bagged. I had another go at Encke and Hartley, but no luck. The 6" F/5 Schmidt-Newton might fare better, all the more so in less moonlight.

Very nice indeed.

Very nice indeed. The ASI178MM is great for this kind of work. I use mine for most of my WL and Ca-K disks

Very interesting. Looks genuine indeed

I also find just scooting along the Milky Way with a wide-field instrument (be it binoculars or telescopes) very relaxing, even if I have seen many of the objects hundreds of times. It makes me feel at home in the universe.

Two contenders here: The APM 80mm F/6 which gives 5.3 degrees FOV with the Nagler 31T5, and 5.75 degrees with the Vixen LVW 42. Here it is shown with the ES 12 mm 92 deg EP, which at 40x still yields an impressive 2.3 deg true FOV The other is the inimitable Meade SN6 6" F/5 Schmidt-Newton which with the Nagler 31T5 gives me 3.33 degrees on the sky, which makes this a great comet hunter.

I am more-or-less forced to use a wider field as I am using the little 6" Schmidt-Newton. It really needs a darker sky than I have to get the faint stuff

That is absolutely stunning! M27 is one of my favourite targets, whether imaging or observing with telescope or even just binoculars. Haven't had a chance to get more data on this target this summer, alas, the weather has been that bad. Your image really shows there is a lot more detail to be got outside the "apple core" part than I have manage to capture so far.

Wonderful result

Very nice indeed. Given the low read noise of CMOS chips, little if anything is lost in shorter exposures. Stacking does take longer, of course.

That is a lovely mosaic. Love the crisp, but natural look. It is so easy to overcook these images.

Stunning mosaic!

That is lovely!

Actually, in this comparison, you have to be very careful what you mean. If for a given aperture you image at F/2 and have a smaller chip, so you have the same area on the sky as with F/10 and a 5x bigger chip, all things are essentially equal. However, if you use the same chip in both configurations, you are capturing a larger area on the sky, and therefore capturing more photons. In practice, if I have a 22 mm diagonal chip (matched to the RASA 8 image circle), and use the same chip at normal F/10 focus of a Celestron C8, you are gathering 25x more light on the chip. You are sacrificing resolution to do so, but with modern small pixel devices this might not be an issue. If you have a chip of 48mm (which is pushing the C8 beyond its limits, but could work on bigger SCTs) you gain a factor of 4.76 in area on the sky, but still lag well behind the RASA (by a factor of 5.25). The number of photons for any object fitting in the FOV provided by the chip used only depends on the aperture, not on the speed, of course, but using the same chip, you do gather more photons in total, because you are imaging more objects.

I get a bit more contrast with the continuum filter. A regular green filter or even O-III also work

Really like the new version, background dark enough and contrast looks natural

Very nice indeed. I would do some background removal so you get a darker, and colour neutral background, which increases contrast on those images.