whitfieldp

The original 6yr old Skywatcher neoprene belts on my Stellardrive AZEQ5GT were starting to give up the ghost so I replaced them yesterday with Continental Synchroflex T2.5/145/08 polyurethane/steel belts (Dave Woods suggested a PU/steel combo). Things looked pretty good after running in for just an an hour so went to M81/M82 for some data. This is the PEC analysis for a guided 2hr stint with my 102mm triplet/QHY9 - not too shabby... Not worth running with a PEC correction at this rate. Got eighteen 10min Ha subs last night and didn't drop one 🤗 Looking forward to seeing how they do after running in for a while....

I've had mine for 6 years and yes that cable is a bit of a worry at times - I never found a source for a ready-made spare. One thing I would suggest doing is check to make sure that the strain relief clamps are actually clamping onto something substantial. The insulation had been trimmed back too far on mine so it wasn't. I packed out around the wires with electrical tape and now it's much more secure. Pam

This may be of interest to one or two folk.... The 36mm unmounted version of the L-Pro filter are like rocking horse s**t. (I'm looking to replace my luminance filter, and ideally wanted to match the filter thickness of all my other filters. The L-Pro seems to be the only one that's 2mm) Despite global lack of availability Cyclops Optics have been able to get one for me 😀 CS Pam

OK - now got the background level where I want it in the composite image without clipping. A bit of work with Topaz Labs Detail sharpened up the nebula detail as well 😃

HIya all I got about 8.5hrs of data on the M27 a week or so ago in both broadband and narrow band so some experimenting beckoned! LRGB and a combined LRGB-HSO image came out of Astropixel Processor. The background of the latter could do with tweaking a touch but not too bad. I've used APP for a some time but I bit the bullet and bought Pixinsight - mainly for the star masks initially. To damp down the stars and bring out the details in the nebula I set out to produce a SHO nebula with RGB starfield. Starnet was used to separate each and processed separately before recombining them using pixelmath. I dropped the lum data entirely and might have damped down the stars a little too much. I might do another version where they are a bit more pronounced. Methinks I'll be using a combination the APP and Pixinsight for a while yet while I figure out Pixinsight. I might never drop APP entirely as it does such a good job with stacking but who knows? The data were collected over 4 nights of variable seeing. All filters were binned 1x1 using a QHY9 mono camera, Explore Scientific CF102 triplet (pixel scale = 1.56 arcseconds per pixel) and a Darkframe Stellardrive-tuned Skywatcher AZEQ5. Broadband subs were 180s and narrowband subs 600s. The only dropped subs were down to clouds/satellite trails with guiding RMS in the range of 0.5-0.75 arcseconds for what is a challenging long, 11kg payload on a AZEQ5 (I'm very good at balancing!). With guiding way lower than the image pixel scale the HFR in the subs was very consistent. CS Pam

My rig is way better optimized for nebulae, so galaxy season is never the most satisfying time of year. For a change I did a bit of experimentation this year rather than cycling through the usual larger galaxy targets. Now I've pretty much given up for summer I can look back and take stock. After capturing the extremely distant (12 billion light yr) QSO APM 08279+5255 for pure curiosity in April, I saw Galactic Hunter’s video on the Twin Quasar QSO 0957+561A&B. The gravitationally lensed QSOs have a separation of 6 arcseconds and located conveniently in Ursa Major so decided it was worth a shot. Being a scientist, (possibly a bit sad that a professional chemist has a science-based hobby but there you have it!) I did a quick back-of-the-envelope first…. • Dawes limit for 102mm aperture = 1.14”. Image scale of my QHY9 mono (5.4 micron pixel size) with my 102mm ES102CF triplet at F/7 = 1.56”/pixel. (Being generous we’ll make that 4 pixels separation) • The ultimate resolution of a 102mm aperture scope makes it feasible. Classical physics spoil the party a little as points are smeared out into Airey disks on the sensor, their radius given by the equation: (1.22 x wavelength x focal length)/aperture = 4.4 microns for green at 520nm (up to 6 microns for limit of red light in my L filter of 700nm). That’s around a single 5.4 micron pixel for my QHY9. Depending on where the centre points of the QSO are, the separation in the camera if going to be a maximum of 2 pixels resolvable separation using the native pixel resolution. So possible but right at the bleeding edge and quite possibly a complete waste of decent imaging time. 🥴 Other main limiting factors… • Seeing – I’m in the Northern England so it usually sucks (1.5” if I’m lucky, 0.9” on the odd occasion I win the lottery). • Focus – autofocus in NINA using a Moonlite CF2 with a stepper pretty much nails that. • Mount. I still use a 2015 vintage AZ-EQ5 GT on spine-friendly grounds on one of the original and much-maligned tri-piers. The pier has a DIY ‘shrinker’ that does an excellent job of stiffening it. The mount head was recently rebuilt by DarkFrame Optics to their StellarDrive standard. As a result it has negligible stiction so balance is very important. My imaging rig has quite a long moment arm so DEC is particularly tricky – an ADM dovetail clamp as a small moveable counterweight is very useful for fine tuning. • Light pollution - the objects are magnitude +16.7 so not particularly challenging in terms of sky brightness. Data acquisition and processing. 10 May 2021. • 1x1 binned luminance data with a IDAS LPS P2 filter. • Stable temperature and a carbon fibre tube so very little focus drift. • Over a period of 3hrs guiding total RMS (excluding dither) was 0.63” so less than 50% of the imaging pixel scale – a decent figure for a EQ6-R but this is an AZ-EQ5 carrying 22lbs so not too shabby. 😍 • I stacked 29 five-minute dithered subs for the final result in AstroPixel Processor. • To reduce the ‘Minecraft’-like stars in the crop it was 2x drizzled and sharpened slightly in the Topaz Labs Detail plugin. Conclusions… 1. I definitely managed to split them! Galactic Hunter used a Stellarvue SVX130, AstroPhysics Mach1 and QHY600C so my setup is rather more on the budget end 😂 2. Scope and camera are well matched – no shock there as they were chosen that way. 3. The Stellardrive AZ-EQ5 drops out of the equation with my current pixel scale - I don't need a larger mount for the time being which is good news for my back. It’s tracking far below 1 arcsecond RMS, so subs are usually excluded due to ‘Musk-related events’. 4. The drizzling feature in APP works really well and doesn’t always need as much in the way of drizzling statistics as I expected. This was a potential concern with the fewer, longer subs typical using the CCD versus a typical CMOS 5. I now know I can get very close to the resolution limit of my setup – going further would require lots of pennies 😳 (EdgeHD and QHY268 together with their price-tags come to mind). Now I can say 'Been there - Done that - No t-shirt available'. Come the return of darker nights in late August/September I can go back to my nice picturesque large clouds of glowing gas…….. 😎 Clear skies Pam

I've probably done M81/M82 three or four times before in past years but decided to experiment a bit this time around - my setup is way more nebula-friendly than galaxy-friendly anyway. Data for this was collected by dodging cloud over 6 nights between 1-16 April. Out of 9.5hrs data on this 4.5hrs was collected in Ha to see if I could drag any more detail out of the structure and gas surrounding the galaxies. That's a nutty thing to do but that's the nature of an experiment..... It was processed as (HaL)(HaR)GB, processed/combined in APP and postprocessed using Topaz Labs tools in Paint Shop Pro. A bit like the Hickson 44 image this was processed more to see how far I could push my optics rather than out-and-out eye candy. The effect of the Ha on the Cigar is mainly to bring out detail in the red tendrils of gas coming out of the galactic centre. In Bodes Galaxy it added definition (i.e. some clumpiness) into the spirals and a bit more to the red in the outer regions. In future years I'll probably add data to this image rather than replace it as the individual subs were about as good as they'll get without a new scope/camera. Pam

It's a push with my setup (F/7 102mm APO, QHY9 mono CCD) but I did collect some data on Hickson 44 over 4 nights in mid-to-late April as a change from the usual Messier objects. My native pixel scale is 1.56 arcseconds per pixel so this was heavy on luminance to let me 2x2 drizzle and crop to a better FOV without suffering too much with noise. There's a bit over 6hrs data here - only 30-40mins each for R,G and B as I wasn't aiming for a heavily saturated image. Just getting the distorsion in the central galaxy with some semblence of definition was good enough for me. I've taken data from a number of flashier Messier galaxies as well since April but this one is somehow a more satisfying result. Pam

Greetings all. Encoders are a powerful tool for precision science/engineering - just a quick cautionary note though. The terms precision and accuracy are not interchangable - there are explanations using the analogy of darts/archery that are easy to find online. The number of ticks per revolution will give you the maximum resolution but real-life accuracy is never that good. I know someone who built a bit of analytical equipment for certifying standards using Heidenhain RON905 encoders (well known for many years as excellent bits of kit). If you read the brochure linked on the page the positional error and system accuracy of different encoder models are frequently quite different. Much of the expense in a system goes into reducing the gap between theory and practice, the gap for the RON905 is very small. https://www.heidenhain.co.uk/en_UK/products/angle-encoders/sealed-angle-encoders/ron-905/product/detail/229352-01/

Thanks for the link - I downloaded the MilliQuas data previously as a spreadsheet which is rather less user-friendly Pam

It should be a decent enough camera if it's been treated well. My QHY9 mono is still going strong after 6 years so there's nothing inherently wrong with the older QHY CCD cameras. The videos I've seen suggest the ZWO cameras have a weaker cooler than mine (QHY8Pro looks to be specced the same) but in the UK that's not a biggie. Optimally you'd be using longer subs with the QHY8 versus 12-14 bit CMOS - if your mount can handle it then great, if not then the approach with lots of shorter subs will work better. CCDs tend to be more power-hungry too. Probably the biggest gotcha in this case is the pixel size as it's pretty big on the QHY8 at 7.8 microns. It will either suit your image train (if it does then most CMOS sensors will be well oversampled) or it won't so worth using the bintel calculator to check. Pam

I targeted the last two but many folk would regard them as wasted imaging time as there isn't much eye-candy in there. It is very enlightening to plate solve images after the fact and find all the stuff hidden in the background. I did a recent long integration on M101 and found loads of stuff in Astap that I otherwise didn't know about Pam

The QSO next to the Owl was purely by accident, the later ones were deliberately targeted. There's really not much visually interesting in the frame with QSO APM 08270+5255 so you're not likely to get that by accident. The twin quasar has a decent sized galaxy in the wider field but isn't exactly APOD fodder either! Pam oops just seen I've replied to the same post twice - sorry

There are a number of images with QSOs on my Astrobin. The original one from 13 April was of the Owl Nebula and Surfboard Galaxy when I accidentally found out about the QSO close to the Owl Nebula. I've deliberately targeted a couple of different QSOs since just because of my curious nature....

My 6 year old QHY9 mono has the same KAF8300 sensor that I run at -15degC. I tested -20degC and there was minimal added reduction in noise for me at least. My darks have no-where near that number of hot pixels, even with 600s at higher gain for narrow-band or binned 2x2. I don't have a stretched jpg to hand and my APP masters are 32-bit but I could probaby rustle something up if anyone is really that interested. At room temperature I vaguely remember a column or two but they disappear on cooling. Maybe I got lucky but it doesn't seem to be inherent to the sensor chip. I'll keep using my QHY9 until it dies. The final images look good and the pixel size is a perfect match to my optics. Alot of CMOS sensors would be way oversampled and the 16-bit ones are still a bit pricey at the moment. Pam

One thing to bear in mind is that all things being equal Poisson counting statistics go as square root of the counting time. Halving the noise to impact the signal-to-noise needs quadruple the counting time. That being said the variation in sky conditions means things aren't equal. Replacing data from nights with iffy conditions with data from good conditions can have a massive impact on the final image. Throwing out a full night of subs can be a bit painful but can pay dividends. It's always subjective figuring out when you've reached the point of diminishing returns but you do get to the point where another hour really doesn't do much

Since the post referencing Astrobin was posted on 13 April, the same day I posted my Astrobin image there's a better than average chance that the Owl Nebula image with the position of QSO J111504.4+55043 marked was mine. (label in image has a typo 🙄) https://www.astrobin.com/sprrw0/B/?nc=user I've since followed that up with two other QSO images... QSO APM08279+5255 is supposely the most distant object that can easily be seen with amateur equipment (due to gravitational lensing) with a light travel time of just over 12 billion years (red shift of 3.9). It's magnitude +15.2 so it's not hard to catch as a tiny dot in amongst lots of other tiny dots, but the frame doesn't look very picturesque if that's what you're after. https://www.astrobin.com/tbb34u/?nc=user The twin quasar QSO 0957+561A and B on the last night of astro-dark a couple of days ago after seeing it on a Galactic Hunter video. This isn't is distant with a red-shift of 'only' 1.4 but was the first identified object showing gravitational lensing. It's magnitude +16.7 and I managed to split it with my 102mm APO with 300s subs. Theoretical separation is about 2 pixels for my image train so quite a challenge for the mount https://www.astrobin.com/kr0dsn/D/?nc=user Another good resource for identifying many quasars is the optional Hyperleda catalog for ASTAP that will identify objects after plate solving. Stellarium has a decent quasar plugin as well that has the brighter ones. Pam