michael.h.f.wilkinson

I have heard of that option, will try to locate it. Given the nature of the data, I could simply combine the blue and green channels for O[III] (with a little H-beta in there maybe) and use the red as H-alpha. I doubt restacking the ton of images with channels separated would show much difference in the data

Couldn't resist having a bit of a tweak to my previous M27 effort. I felt H-alpha was being drowned out by O[III], and as these data were shot through an Optolong L-eNhance filter with an OSC camera, the only option was to tweak curves with Gimp. Previously, I had only boosted the red channel, but wasn't quite satisfied. I therefore reigned in blue and green, only at the higher levels, and feel the result is better balanced. It seems to have removed much of the cyan cast of the stars as well. I also cropped some of the artefacts left by FITSwork's unsharp masking routine. A bit of the H-alpha in the outer shells is coming through, but data are needed, although that doesn't seem likely in the coming week at least. Star colours could also be improved by added unfiltered colour data (prefereably from a dark site). Whatever the shortcomings, I am very pleased with this first real attempt at M27. The previous version was this:

Replace the legs with wooden ones. I did that on an EQ1 tripod, and now have something quite sturdy: I now use it with my P-mount

Lovely image. The result of an epic journey into astrophotography

Having cylindrical astigmatism, I have to wear glasses, and many modern EPs have 16mm or more eye relief, which I have found sufficient for my needs, although 18-20mm is ideal. Longer focal lengths are generally OK, as even the Plossl or Ortho designs have generous eye relief at long focal lengths. The main issue for wide-field observing with the C9.25 (likewise for my C8) is the limitation posed by the 1.25" visual back. This means either a 32 mm Plossl or 24 mm super wide angle (like the MaxVision 24mm 68 deg EPs) give you the maximal field of view. Going to even longer focal lengths gives nothing in terms of FOV. There are two ways around this: If the scope is not an Edge HD type, get the 0.63x focal reducer and insert it between the scope and the visual back. They pop up second hand for little and extend the FOV by 1.58x linearly (or 2.5x in terms of surface area on the sky). This should work well with all your existing kit. The other alternative is to get a 2" visual back, along with a 2" star diagonal, and 2" EPs. More expensive, but certainly worthwhile, I have found. I should add I happily used the focal reducer method for years, it is just that once I needed a 2" visual back for my Vixen flip-mirror, I got lured down the path of 2" EPs.

If you can have a go at the Saturn Nebula (NGC 7009). I once had a look at this one through Olly's 20" Dob (Sir Isaac), and the vivid blue-green colour was just amazing

Managed to grab 2.5 hours and a bit on M27 through the Meade SN6, ASI186MC and Optolong L-eNhance filter last night, and added these to earlier hauls. First without unsharp masking, just stacked and stretched in APP, and a little boost in red in Gimp using curves gives the following result: Using stacking in APP, unsharp masking in FITSwork and stretching in Gimp gives this: The core is slightly less blown out, and more detail is coming out in the outer regions. I think I will run it through my own unsharp masking routine later (gives more control without overshoot effects). Might also want to crop the image a bit

Very nice indeed, lots of detail showing. I am also working on a longer integration of M27, but only have 10.5 hours with the Optolong L-eNhance filter on an OSC camera. Currently grabbing a last batch of 2.5 h before clouds roll in tomorrow.

I will ask my colleagues at the Kapteyn Astronomical Institute in Groningen what they think of the course, if you like

Great minds think alike

Electronic thumb fully charged?

Make sure you get some peanuts

Have you complained at the local planning office in alpha Centauri?

Most likely a Vogon Constructor Fleet coming out of hyperspace 😜

I spotted the bulge during lunchtime here, but no detached prom. There is definitely something lurking around the corner

Another bright supernova is visible. Host galaxy is NGC 2782 in Lynx. The galaxy is a mag 12.3 face-on peculiar spiral. The supernova is listed as mag 13.7, so within reach of my C8 if skies are good. More information here: http://www.rochesterastronomy.org/supernova.html#2020scc

Got 3.5 more hours of data on M27 last night, and the GP mount was tracking like never before. Just stacking these 12840 s of data from the Meade SN6, with ASI183MC and Optolong L-eNhance filter got me this Combining this with the previous 5 hours of data from the same combo got me this: And mixing this with just under 2 h of data with the 80mm and same camera and filter gets me this: Hopefully, I can add more in the coming two nights, to get even more signal in the outer shells. I might also want to do some unsharp masking to prevent blowing out the centre

Larger CO reduces contrast regardless of conditions. Dependence on seeing is largely a function of aperture, mainly because larger apertures can only show more detail than smaller ones if sering allows. I don't ever recall conditions where my C8 showed less detail than my APM 80 mm F/6 triplet. At the same magnification, the image in the C8 was always much brighter and crisper.

The C5 has a larger central obstruction than the Skymax 127. However, the C8, at the same weight as the Skymax 150 can get more detail on planets. I used to have a 6" F/8 Newtonian, which had very good mirrors and a small CO, but the C8 definitely gave more detail on planets, even if contrast at the same exit pupil was a shade less.

I would go for a compact Maksutov, they pack a lot of planetary performance in a portable package. The Skymax 127 is a good choice, although I am also intrigued by the Vixen VMC110L. The Skymax 150 is a much heavier beast, as heavy as my Celestron C8 OTA, which is a really good portable scope, but considerably bigger than the Skymax 125

Just did a reprocess with 1.5x drizzle The 2x TeleXtender data won't really stack well, probably an over-sampling problem. I should get myself a 1.3x or 1.5x tele-centric (Siebert Optics makes those, I gather)

Gathered 3 hours worth of subs on M27 with the Meade SN6 (6" F/5 Schmidt-Newton) and the ASI183MC (non cooled), with an Optolong L-eNhance filter in place. Tracking was a lot better this time round, initially getting 60s subs without problems, but when one of them turned out eggy stars I opted for 30s subs for safety's sake. All 363 of them turned out well, and stacking in APP and curves and crops in Gimp gave this result: The outer shell is quite clearly starting to show. Adding the 2-hours worth of data from September 13 taken with the same rig yields the result below: and a further merge with 6660 s of data taken with the 80mm F/6 and the same camera gets this: I will need far more data to get those outer shell fragments out properly (and most likely from a darker site), but it is fun to see how you can stack loads of data and slowly tease out more. I should also get a substantial number of frames without the filter to get the star colours right

After gathering 3 h of data on M27 with the Meade SN6, I mounted the C8 on the Great Polaris mount, and had a quick go at Mars. I stacked 500 out of roughly 5000 frames grabbed with the ASI183MC. Stacking with AS!3, wavelet sharpening with Registax: Quite pleased with the level of detail showing. I also took a sequence with the Meade 2x TeleXtender, but will process those tomorrow

Got the Meade SN6 Schmidt-Newton out again, grabbing data on M27 first

I started with a home-made 6" F/8 Newtonian on a dob-like mount. I would probably do the same, or buy an 8". The Celestron GP-C8 I got later was a sound investment. I bought it almost 25 years ago, and I still have it.