rotatux

Yet another summer DSO catched in my early september sessions. I find this looks like more a horseshoe than a swan; I have read the swan could be seen with a different orientation, and less exposure (such as Herschel's drawings). Interesting facts: The nebula is estimated about 15 ly diameter at a distance of 5-6000 ly (~1/20 milky way diameter), and weights 800 solar masses; Its cluster hosts 800 stars, is forming another thousand in the outer regions, and would be aged "just" 1 million years. Gear: Olympus E-PL6 with Skywatcher 130PDS 632mm/4.86 and SWCC at f/4.55 on Omegon EQ-300 tracking RA Capture: 24 lights × 40s × 3200 ISO, master dark Site: deep country 26km from Limoges, France Sky: good (given bortle class 3, usual sqm >21), subject high enough for no LP Processing: Regim 3.4, Fotoxx 12.01+

Continuing to develop the series of summer DSOs I catched on early september. My first try at it catched "the pillars" but was very noisy and poor quality. This one is much better, but still perfectible (esp. bright stars). I was surprised to read from Wikipedia, that M16 originally refers not to the nebula (IC 4703) but to the open star cluster (NGC 6611) born from it. The pillars are also only 3 ly long, which seems small given how far and that one small earth-based scope can resolve details in them. Gear: Olympus E-PL6 with Skywatcher 130PDS 632mm/4.86 and SWCC at f/4.55 on Omegon EQ-300 tracking RA Capture: 21 lights (/64% keep) × 40s × 3200 ISO, master dark Site: deep country 26km from Limoges, France Sky: good (given bortle class 3, usual sqm >21) Processing: Regim 3.4, Fotoxx 12.01+

M31 is the main subject, with NGC206 the blueish patch top-left a cluster of young stars, M32 top-center and M110 truncated bottom-center satellite galaxies. After a failed attempt last year, I restart this subject on my newton with higher exposure, better framing, and the EQ mount which should allow not to drop too much borders (the alt-az moves were too big and random for this very wide subject). Framing isn't perfect, as I caught the wrong diagonal to get M110 entirely in the frame. Must remember this next time – though on the field it may be difficult to tell which side is which. This intermediate result is now much better than last year, and starts to show details. Gear: Olympus E-PL6 with Skywatcher 130PDS 632mm/4.86 and SWCC at f/4.35 on Omegon EQ-300 tracking RA Capture: 21 average lights × 40s × 2500 ISO, 33 darks Site: deep country 26km from Limoges, France Sky: good (given bortle class 3, usual sqm >21) Processing: Regim 3.4, Fotoxx 12.01+

Early september I could add 2 new little sessions to my previous windy try at this subject. Now stars have a much better shape. Still needs more subs to allow for more stretching and uncover more clearly the blue nebulosity around the main, red part. Gear: Olympus E-PL6 with Skywatcher 130PDS 632mm/4.86 and SWCC at f/4.55 on different mounts Capture: blend of 9 x 30s 3200 ISO on Celestron Nexstar SLT tracking Alt-Az + 13 x 40s 1600 ISO + 10 x 30s + 4 x 40s 3200 ISO on Omegon EQ-300 tracking RA (total exposure: a bit less than 21mn) Site: deep country 26km from Limoges, France Sky: good (given bortle class 3, usual sqm >21) Processing: Regim 3.4, Fotoxx 12.01+

This last september's nights are giving better images than previous years. With only 30s subs but much better stars since no wind this time. (30s only, limited by bad PA on my EQ after /me forgot the tablet hosting my PA helper) So for the first time I combined images from 2 separate sessions, framing being (purposedly) similar. Gear: Olympus E-PL6 with Skywatcher 130PDS 632mm/4.86 and SWCC at f/4.55 Capture: blend of * [2017-05-24] 14x30s 3200i on Celestron Nexstar SLT tracking Alt-Az (23 darks) * [2018-09-01] 17x40s 1600i on Omegon EQ-300 tracking RA (15 darks) * [2018-09-07] 12x30s 3200i on Omegon EQ-300 tracking RA (13 darks) for a total of ~24min. Site: deep country 26km from Limoges, France Sky: very good (bortle class 3) with a bit of LP low on horizon Processing: Regim 3.4, Fotoxx 12.01+

Since years I do astro-imaging, I rarely had opportunity to shot the full moon, always being clouded out or too clumsy to get out. This was taken not with video but rather raw burst shooting since my camera is limited to low-freq FullHD video (and also 1600 ISO in video ). This is more painful in post-processing, but at least gives higher resolution, and hope for better eventual quality. Bursts are generally 15-20 shots in 2-3 seconds, then pause for card saving, then go for another burst. The MFT sensor still isn't square enough to capture the whole moon with the long-focal Mak, so it's a bit truncated at poles ? Gear: Olympus E-PL6 with Celestron Mak127 1500mm/11.8 on Celestron Nexstar SLT tracking alt-az Capture: 48 lights x 1/400 s x 1600 ISO (don't remember about master bias) Site: city 50km from Paris, France Sky: mostly clear from usual LP (given Bortle class 8-9) Processing: CvAstroAlign 0.1.4, Fotoxx 12.01+

This is the three prominent stars in the Eagle constellation (Alshain, Altair and Tarazed), with nebulosity from the Milky Way on the right side. Right next to Tarazed is "Barnard E" dark cloud, easily recognized from its shape, but which I didn't know of at first. There's an unknown artifact above Altair and Tarazed. Though it looks like it with its greenish color, from general advice this was not a comet, but would rather be a lens' reflection (though I never had this kind of reflection with this lens in other shots -- in fixed position in the subs while all the FoV was moving slightly) Gear: Olympus E-PL6 with Minolta MD Rokkor 50mm/1.7 at f/4.0 and didymium filter on Omegon EQ-300 tracking RA Capture: 3 lights x 60s x 1600 ISO, master dark Site: near country 50km from Paris, France Sky: nearly good, no moon Processing: Regim 3.4, Fotoxx 12.01+

Still trying to get most nebulosity and color from this region. Colors ok, nice stars from the lens' blades, but needs more work for nebulosity. Gear: Olympus E-PL6 with Minolta MD-Rokkor 50mm/1.7 at f/4.0 and didymium LP filter on Celestron Nexstar SLT tracking alt-az Capture: 21 lights x 30s x 3200 ISO, master dark Site: deep country 26km from Limoges, France Sky: good to average Processing: Regim 3.4, Fotoxx 12.01+

A wide field around Antares. Unfortenately some high clouds rolled in, and are lit by the nearest-6km town. Left of the image has a part of the milky way, where the only clouds which can be seen are galactic ones Gear: Olympus E-PL6 with Panasonic Lumix G 25mm/1.7 at f/2.8 without filter on Celestron Nexstar SLT tracking alt-az Capture: 10 lights x 20s x 2500 ISO, master dark Site: deep country 26km from Limoges, France Sky: good to average Processing: Regim 3.4, Fotoxx 12.01+

Just for compleness I wanted to test the kit zoom lens which came with my PEN body. It turned out pretty well and it's wide open ! There's just a bit of purple aberration / coma but it's certainly not as dominant as aberrations of the Pany 25. Will have to try it at another focal some other time (and maybe do flats). The FoV is nice also, though quite not like ultra-wide. Gear: Olympus E-PL6 with M.Zuiko 14-42mm/3.5-5.6 at 14mm/3.5, no filter on Celestron Nexstar SLT tracking alt-az Capture: 9 lights x 60s x 1250 ISO, master dark Site: deep country 26km from Limoges, France Sky: good (not measured, usually SQM around 21.4) Processing: Regim 3.4, Fotoxx 12.01+

Another test shot for the Pana 25. This one renders quite better, though big stars are still saturated. (and constellation is quite unrecognizable) Color calibration was quite difficult with Regim, because this operation is designed for small fields. I had to solve and CC on a smaller sub-field of the image, and it still has too many stars to choose from. Gear: Olympus E-PL6 with Panasonic 25mm/1.7 at F/2.8 on Celestron Nexstar SLT tracking alt-az Capture: 20 lights x 20s x 2500 ISO, master dark Site: deep country 26km from Limoges, France Sky: good (not measured, usually SQM around 21.4) Processing: Regim 3.4, Fotoxx 12.01+

Another test shot for brand new lens (same night as other tests of the same lens). California is barely visible. Heart and Sould can be half-guessed if you know where they are :-/ Gear: Olympus E-PL6 with Panasonic 25mm/1.7 at F/2.5 on poorly-tracked panoramic head and static tripod Capture: 36 lights x 10s x 1600 ISO, master bias and flat Site: deep country 26km from Limoges, France Sky: good (not measured, usually SQM around 21.4) Processing: Regim 3.4, Fotoxx 12.01+

Another test shot for brand new lens (same night as other tests of the same lens). Again, main stars and their colors are not distinct enough. Gear: Olympus E-PL6 with Panasonic 25mm/1.7 at F/2.5 on poorly-tracked panoramic head and static tripod Capture: 16 lights x 10s x 1600 ISO, master bias Site: deep country 26km from Limoges, France Sky: good (not measured, usually SQM around 21.4) Processing: Regim 3.4, Fotoxx 12.01+

Auriga - The constellation This is a comparison shot took with my brand new Pana 25mm/1.7 lens. I find my previous shot of this subject with a Pentacon 29mm/2.8 possibly better. Maybe I closed the new lens too much, hence muting the "big stars" effect. Gear: Olympus E-PL6 with Panasonic 25mm/1.7 at F/2.5 on poorly-tracked panoramic head and static triped Capture: 38 lights x 10s x 1600 ISO, master bias, master flat Sky: good Site: deep country 26km from Limoges, France Processing: Regim 3.4, Fotoxx 12.01+

This is a HTML page with Javascript to compute Polaris Hour Angle for your current location and local date-time. This page will work in any ES5/6 conformant browser (tested in Palemoon/Linux and Chrome/Android). It is to be used with a polar finder in the field alignment process for equatorial mounts. I was fed up by Android bloated (no less than 1.5MB) apps for the purpose, so I searched for backing equations and integrated them as a web page. Download: polfinder ha greenwhich.html Usage: First, make a new copy for each of your observing locations, and edit each file to change the location's name and longitude (arc minute is enough). Then open the page in your browser ; Refresh the page to recalculate with the current time.