Aramcheck

Thanks folks! I'd had a bad day yesterday trying to get the camera to play nice with Windows 10 etc, so missed fitting the stopping collar to the Baader coma corrector. All is now ok (fingers crossed). Ta @alacant for the compression ring suggestion - I've just ordered a couple, although with the stopping collar in place, the camera seems to be held a bit better than it was yesterday. Cheers Ivor

Thanks @Davey-T - I think the problem was that I didn't fit the "stopping ring"... Hopefully I'll have another go tomorrow!

I'm afraid I couldn't resist FLO's sale on ZWO cameras & have splashed out on an ASI2600MC Pro, but I'm having problems finding focus. Previously I've used a DSLR with a Baader Coma Corrector... The ASI2600 manual shows that the sensor to camera front plate distance is 17.5mm, which with the two supplied extenders gives a back focus of 55mm (17.5 + 21 + 16.5mm). Onto that I've fitted the Baader Coma Corrector. Is this correct? If so, how far should the camera be inserted into the focuser drawtube? I've tried focusing in the daytime with the scope pointed at the most distant object I can see from the garden, but still can't get it into focus at any distance... Also - with the DLSR I used to put the camera strap around the OTA, just in case the two fiddly screws didn't hold the weight. Is there anything I can do to hold the ASI2600 more securely? Many thanks! Ivor

We don't get many clear nights so I have to try no matter what time of year, although our observable sky view is limited by houses/trees/streetlights. Here's NGC5466 from the 12th & 16th June. About 2 1/2 hours total. Canon 600d DLSR (astromodified), IDAS D2 filter, SW200dps & Bortle 7 skies. NGC5466 is notable for it's 'blue' horizontal branch. It's quite a loose globular cluster & has lost many of it's stars due to tidal perturbations. Cheers Ivor

a) Here's a single 180s frame from the end of May. Taken with IDAS D2 LP filter & Canon 600d - Bortle 7 skies. I've debayered & applied an Auto-Stretch. b) Rough process of 104 subs taken May 2020 / 2021. Both images reduced in size by 50%. Cheers Ivor

Thanks @ollypenrice. I had hoped to avoid a painting solution, as it goes against the Pixinsight ethos. (and my copy of PS is so old I have to run it on a virtual PC + it only works with 8 bit images.) Your third option sounded the best for me, so I've just tried making a mask of the spike area using CloneStamp + Convolution to blur the edges. With the mask applied I then did a CurvesTransformation. That left the affected area slightly too dark, so I then used Ron Brecher's PixelMath expression(s) for reducing DLSR mottle. That seems to have done the trick! Many thanks IVor

Hi, I recently took 5 hours of subs on M109 using SW200dps & Canon 600d (astromodified) from our Bortle 7 back garden. When processing in Pixinsight I noticed what looked like an aircraft contrail running near vertically through the stacked image. Closer inspection shows that it is however a diffraction spike from Phecda (a Mag 2.4 star about 40 arcmins from M109). Other than resorting to CloneStamp to paint over the area, is there any way to create a mask? I've tried taking a crude B&W mask on a cloned image & using Convolution to blur the edges, but the results still weren't perfect. The spike can be seen more easily at the bottom half of the image. Many thanks Ivor

Here's my attempt - processed in Pixinsight. Cheers Ivor

Thanks for all the replies - I've tried a couple of different settings & I'll be using a setting of either 2 or 3 in future and probably dithering every other sub, just to maximise our rather limited spells of clear skies. Cheers Ivor

A couple of nights ago I had a bash at M81 & M82 with the SW 200dps & Canon 600d on an AZ-EQ6 GT Pro GEQ/AZ mount. I'm using a SW 50mm finderscope as guidescope fitted with a ZWO 120MM. Took 90 x 180 second subs, but had to ditch 10 where the dithering timed out in APT after 180s & the next exposure started before the mount had finished in Declination. In APT I had the dithering distance set to 4 & to dither after each image. According to a formula I found on another forum this equates to a max distance of roughly 50 pixels. Would setting the APT distance to 2 (25 pixels) be too severe? What about setting the program to dither after every other exposure, in order to increase the amount of subs in a given time-frame. Any help much appreciated! Ivor

From the evening of 3rd into the morning of the 4th April. 89 x 180s subs (4 hours 27mins total) with SW130dps, Canon 600d (astromodified), IDAS D2 LP filter & EQ6 mount & Bortle 7 skies. Would have gotten more, but meridian flip & precarious camera battery change ate into available time... Question is how does the Camera angle in Stellarium's Occular plug-in relate to the physical camera angle on the newtonian scope? I was faffing around trying to get the the camera at 120 deg. (according to the Stellarium image) in order to get a god framing of the 3 galaxies. After a few attempts & then knocking the focus & I settled on just getting them in the frame, even though not perfect. Looking at Stellarium this turned out to be about -120 deg, so should I have mounted the camera upside down? Many thanks! Ivor

Too late for competition, but I thought I'd post anyway - great set of data - thanks! Processed in Pixinsight: Demure DeNoise to all masters then... Luminance:- DBE -> Deconvolution -> Noise Reduction with MLT -> Mild STF/HT; then galaxy core masked & further STF/HT; galaxy core mask inverted & CT to brighten core. 2 clones made & HDRMT applied to enhance large scale structure + small scale structure, then Pixel Math to blend results with original. Red+Green+Blue:- Channel Combination -> PCC -> DBE; 2 stage STF/HT as per Luminance ->LRGB Combination -> ACDNR -> Curves Transformation to tweak saturation. Cheers Ivor

I find it interesting that we only see the Flaming Star nebula due to the eruptive variable O-type star AE Auriga, which is a runaway star from the trapezium region of M42. According to Wikipedia it was ejected from the Orion Nebula about 2 million years ago, so it's just a fluke that now it's passing through that region & ionizing the hydrogen gas. Cheers Ivor

These have I think all been mentioned, but may be worth looking at:- https://www.bbc.co.uk/news/uk-scotland-south-scotland-17988825 https://commonslibrary.parliament.uk/research-briefings/cdp-2017-0241/ In the US there have been studies on the financial benefits from Dark Sky tourism, which are summarised on this IDA page: https://www.darksky.org/3-benefits-of-a-dark-sky-designation/ There are also largely unquantified financial benefits in increased (& better quality) crop pollination from nocturnal insects (eg peas, rapeseed & elder flower). There is mention of "a study of soya-bean farms in Illinois which found that the light from adjacent roads and passing cars could be delaying the maturation of crops by up to seven weeks, as well as reducing yield." in the Jan 2018 'Dark Side of Light' article in Nature:- https://www.nature.com/articles/d41586-018-00665-7 (link to original paper is in article too) There is also the artificial light at night database, which contains over 2000 research papers on all aspects of the light pollution. Unfortunately public access has been disabled at the moment, but I hope that isn't permanent:- http://alandb.darksky.org/ Cheers Ivor

NGC1579 from last weekend... A bit close to the near full moon & high humidity, but I had to have a go given the lack of clear skies over the last few months. 78 x 180 sec subs over two nights (3 hours 53 mins) SW200dps + EQ6, Canon 600d (astromodified) & IDAS D2 LP filter. Cheers Ivor

Last weekend was our first decent length of 'clear' since early October... Bagged a few images including 41 x 3min subs of the Crab Nebula. SW200dps + EQ6 mount. Canon 600d (astromodified) & IDAS D2 LP filter. Bortle 7 (NELM 4.81) skies... Image attached is heavily cropped... I made a few attempts at processing & whilst later renditions improved the background, I haven't managed to match the quality of the nebula from this first attempt. Processed in PixInsight with a further pass through Topaz DeNoise. Cheers Ivor

Looks to me like your focus is way off & the scope is out of collimation? Here's the first image stretched... Cheers Ivor

I think it's lens flare, but as I don't have any camera lenses I can't advise on that (so far I've only taken prime focus pictures with the DLSR attached to a 'scope). I've read that it can be reduced by more careful processing, i.e. creating & applying a mask of the flare when stretching... It may be worth trying to take some images without the filter, to check that isn't the problem & also with different lens if you have one. Colours are largely down to the the choices made in processing. You can alter the colour saturation, to help bring out the nebulous regions, but you'd benefit I think from a longer total exposure time. Here's a DLSR image of the same region but with 230mins total exposure:- https://britastro.org/observations/observation.php?id=20190204_195500_3b5f179fe8536100 M42 - Orion Nebula, is quite bright in comparison to the Barnard's Loop, so it'll be difficult to bring out the loop without blowing-out the core of M42... (You can always process the image twice & then combine them) The amount of detail you can capture is down to the resolution of the equipment (focal length and camera pixel size) & sky conditions. The Canon 550d has a pixel size of 4.3 microns, so with a 50mm lens the resolution won't be better than 17.74 arcseconds/pixel. (See https://astronomy.tools/calculators/ccd) M42 is about 52 arcmins across (i.e 52 x 60 = 3120 arc seconds), so will only cover about 175 pixels on the camera. Longer focal length lens (or scope) will enable you to see more detail, but then you won't see as much of the sky... Hopefully somebody more knowledgeable will chime in & provide some better advice! Cheers Ivor

Thanks for sharing the data. I had a very quick go... but I think dealing with the flare on the bright stars will be a challenge! Cheers Ivor

There's a plugin you can try for Photoshop called Gradient Xterminator. It has a free trial:- https://www.rc-astro.com/resources/GradientXTerminator/ I use Pixinsight which has a process called DBE (Dynamic Background Extraction). Other software have similar tools (Siril, APP & Startools). In Gimp or PS you can also create your own gradients & then subtract them... Ultimately it's whatever works best for you. Cheers Ivor

I did, but I'm not sure whether it helped... I also discarded an earlier version which looked too blue to my eyes. Cheers Ivor

Why bother with AP? - For me it's a way to see stuff that I wouldn't otherwise have a chance of finding in our light polluted skies. It's also a challenge to get the best data you can & to learn how to process it. Just finding & verifying this stuff is real is a buzz! I also find it fascinating to plate-solve & annotate the processed image to identify very distant galaxies & then calculate their distance by looking up the redshift/radial velocity on Simbad. Finding a few pixels that represent light from a galaxy that has taken 1-2 billion years to reach the camera is mind-boggling. It's also nice to sit outside whilst the scope/camera/computer is doing its stuff. I've seen some spectacular shooting stars... and (with the light pollution) I can see the bats and the occasional flock of migrating birds. It's peaceful just watching the few stars we can see stars revolve... Also using a pair of bins & my pocket Sky & Telescope atlas to identify & learn where things are is neat. Cheers Ivor

Thanks folks! I'm not entirely convinced that it's a stray diffraction spike, given the distance but I think I'll have to wait & see... It's nearly a month now since we had any suitable clear skies! I still suspect that it was something to do with the camera orientation, so will have to have a play around if the problem occurs again. BTW I have flocked the OTA, but haven't painted the outer focus tube black yet. @ollypenrice - Thanks - I find trying to get the colours look right is always a bit problematic. I use Pixinsight's 'Photometric Colour Calibration' but still have to adjust the R-G-B histograms if I use the ArcSin stretch (my preferred option now on the RGB as I tend to extract & process Luminance separately). Thanks again everybody. Cheers Ivor

This was 117 mins in Bortle 6 with a SW 130dps & a Canon 600d (astromodified):- https://stargazerslounge.com/topic/369470-m33-130dps-odd-light-artifact/ It would have been longer but clouds stopped play (again) & at the here at the moment clear skies are few and far between. IMHO Bias / Flats & Darks are a must. (You'll have to check processing with & without darks - I find it's better to use darks). Vertical lines on the 2nd image looks (to me) like bias. If APP does deconvolution then try that to reduce star bloat... It took me a while to get settings right in Pixinsight... Noise is inherent with a DLSR, unless cooled. You can eliminate it to some extent in processing. Cheers Ivor

Thanks very much for sharing the stacked data! If you use APT to control your camera, have a look at the Framing Mask feature (see:-https://www.astrophotography.app/usersguide/framing_masks.htm#) which is supposed to help framing between different sessions. (I've had no experience with it yet - clear nights here have been few & far between!) Anyway here's my quick process of the data - I couldn't get rid of the line at the bottom left... Cheers Ivor