ONIKKINEN

Nice elevation of 52 degrees but seeing was not so great that night at 2.5'' fwhm and an index of 1 forecasted. I dont believe the seeing index really seemed like it was so bad, but definitely not good seeing either. I think i was also too hasty with beginning imaging and there might have been some tube currents still. All with my 8'' newt and a ZWO ASI678MC. Mosaic from 5 panels through the paracorr at f/5 and approx 1015mm focal length. Downsized to 75%, this one was definitely too early for the thermals to settle in the scope but it still works for me. Just 1000 frames per panel but still totals 40 gigabytes in the end. Then Copernicus, with a new barlow: the APM 2.7x coma correcting one. Not sure exactly what the barlow factor is here with my adapter train but i am estimating somewhere around 2.3-2.4x based on some crater size measurements. Assuming i found the correct crater sizes of course. I think this one was a little bit too early too for thermals to have settled properly. Then up next is Plato which i think turned out the best from all of these: Then lastly the Clavius-Tycho region centered on nothing in particular. Just looked interesting when slewing around the terminator looking for something to shoot with a wider view. Overall looks like the APM 2.7x barlow does fight coma quite well. Maybe the edges are starting to look less than ideal especially on the last one which has a wider ROI but its still miles ahead just a normal barlow or trying to get a barlow and a comacorrector working in tandem so turned out a good purchase.

The Altair one: https://www.altairastro.com/altair-hypercam-26c-aps-c-colour-tec-astronomy-camera-16bit-6451-p.asp is nicely priced right now. Would probably buy one of these were i in the market of buying another IMX571 camera right now. Mono versions also exist, and i think the altair one is a good deal in that front too.

I also would prefer to image something else next year, which is why its gotten all the hours of the past few months. Next years galaxy season will be spent on something else, not sure what yet. Probably some obscure Abell cluster as i too am a fan of deep fields. This season was not too bad actually. 8 Moonless or not too much Moonlight type nights in 3 months is a luxury one shouldn't get used to round here. Last year my "big time dump" target was the coma cluster, which got only 9 hours so quite happy with this years weather so far.

The problem i have with trying to go to a HDR type process where everything is allowed to be at its best colour and levels wise is that the image starts to look too flat to my liking - like the galaxies and dust start to meld into one and its difficult to say which is which which bothers me a bit. Its partially intentional for this reason that the bright objects are a little bit on the too bright side. This rendition is the result of 2 different stretches exported from Siril and blended for best (or least worst) effect for objects where applicable, in Photoshop of course. Will definitely process this again, and again and again. The file name (composite8) should also give some clues as to how many attempts the learning process went through

M81 and M82, an iconic duo presented here with a rich background including an elusive extended halo of M81, IFN both on our end of space and M81's end and of course an uncountable number of faint background galaxies just about everywhere in the image. I have been sitting on the image for a while now and was not sure if i liked the product yet, as it was challenging to process in a way that gives the extremely bright (for the image) galaxies, the ridiculously faint dusty parts and the background objects enough room to be observable but not detract from the experience of viewing the others. I think this version sits quite well with me so i will go with that. Image scale is about 2'' per pixel here and around 10 of the 35h are with an Antlia Triband RGB ultra filter, to try and uncover some of the Ha emissions a bit better. Started imaging in late December and have poured every second of available decent quality clear sky on it since which totals 8 nights 😬. Average sky conditions would probably fall between bortle 4 and 5, somewhere around SQM 20.6 i suppose. 2 nights had very bright aurora that lifted the background electron rate by 2-3x for a few hours and butchered the background gradients but those are not that hard to get rid of so nothing lost. Original plan was to image this all the way to the end of the imaging year 4 weeks from now, but current forecasts indicate that the currently ongoing moonless period will have no clear sky, and the final moonless period of the astro year in April will have short nights so this might be all she wrote for this year. ASTAP annotated image with HyperLeda galaxies for those who want to cruise around the image and look for the most distant object shown. Upscaled to make it easier to see the small fuzzies. The vast majority of background objects are not annotated here which i find very interesting. I have been cruising around the image and the furthest object with a definite distance i can find is the galaxy cluster just above M82 with approx 3 billion light years. But there are so many barely a pixel type fuzzies here that my educated guess is that some are quite a lot further away than that but which one and how far, i cant tell right now. Comments, criticism, suggestions all welcome! Thanks for looking

Spectacular image, love everything about it. The usually mighty horsehead and flame area is just a tiny footnote in the incredibly busy surrounding area here. The setup that took the image looks funny to me, there is about 3x more not-telescope than telescope in there! Cant fault it though when this is what it outputs.

No need to really set up anything in that case, the Asi air software should deal with plate solving and auto centering on its own.

You could set up platesolving and not need an actual finder in that case. Would be by far the least head achy solution since you already need a computer of some kind to do the guiding and so will have solved almost all of the troubles to set up platesolving. What software is running the rig? Different ways to do it in each one.

First blow all the dust and particulates off with a hand bulb so that you dont run this in later and scratch the lens. You could also use a lens brush at this point to lightly try and remove bigger particulates that the air blower did not remove. (lens cleaning kits can have everything you need) Then clean with some kind of lens cleaning fluid or diluted isopropyl alcohol with some kind of sealed and very clean cloth. Could be cotton swabs/pads or lens cleaning cloths sold in camera stores, just make sure it has no grit that could scratch the lens. Apply only a small amount of the fluid. If you use too much the fluid can get past the lens and get inside the CC, which will be impossible to remove and leave some residues. If in doubt, use less pressure and less fluid and never rub with force. You can always repeat the cleaning but cant clean away a scratch. Finally wipe with a clean microfiber cloth. In short: Dont scratch it and dont douse the lens in fluid

I replaced the flimsy VX8 aluminium tube with a thicker carbon tube from Klaus helmi not too long ago last year. I ordered mine to be a little bit longer than the original to act as a dew shield like suggested above although looks like mine is a little bit shorter (maybe should have asked 5-10cm more). Pretty sure he will make your tube with exactly the measurements you give him, so no worries about getting a different sized one than your mirror cell allows as long as you measure what you want. The new one is 5mm thick whereas the old one was maybe 1mm, so the rings will not fit the thicker tube diameter but i wanted to upgrade them anyway since they are not very robust in the VX lineup of scopes. Looking at the bill i ended up paying 386€ including shipping for the 8'' tube with no holes pre drilled so i wouldn't call it all that expensive if you look at the prices of premade carbon tubes sold in TS such as this one: https://www.teleskop-express.de/shop/product_info.php/info/p14357_TS-Optics-Carbon-Tube-Upgrade-for-the-DIY-of-a-8--Newtonian-telescope.html . Very robust (mine was 5mm thickness with some kind of sandwiched core) and thermally stable* even in difficult conditions: *Takes longer to cool down though since its much thicker, consider having some kind of fan on the mirror cell to help with cooldown times. One thing to keep in mind though is that you probably should prepare for a wait time of several months. He did originally mention in e-mails that it would take a few weeks instead of months, but it kept being delayed for many reasons and took about 6 months if i recall correctly. Long delivery times seem to be a common experience with ordering these tubes so i would prepare to not see it in a while regardless of the original shipping estimate. It is well worth the wait though, so its not a real gripe i have with the product. Would buy one again if a future scope could use a better tube, highly recommended even with the waiting time!

The secondary mirror also greatly limits the available fully illuminated circle so a bigger focuser would not help you all the way here. Newts primarily intended for visual use already have an undersized secondary that will vignette at 1x with a decent sized sensor. Coma increases a lot with a reducer too so not really all that great an option. If you really want to have a reducer for a newt the best option available is probably either the ASA 0.73x corrector or the Starizona Apex 0.75x one. Both are expensive and require a 2 inch focuser so also a dead end without modifications.

I have been satisfied with my Ecoflow River 300 until the last couple of times, so more than 2 years now. I had a low temperature discharge warning appear and the power station either shut off or just drained unexpectedly fast and died on me one night. I have since built a very simple insulative box around it from the packaging it came in + some tape and it seems to have done the trick. Even after a full night out in -10c it felt kind of lukewarm inside the box, i am guessing the battery produces a little bit of heat of its own so the insulation works really well. The River 300 is no longer being sold and has been replaced with the River 2. My River 300 is rated down to -20c and is built on a 28v battery natively, so the voltage can be regulated downwards to 13.6v even in very cold environments and when the battery has lost most of its charge. The newer River 2, as far as i can tell, is natively 12.8v and rated only to -10c so you will definitely need to build some kind of insulative box with that. At least would think so, its of course possible the newer version is just better since it has the new LiFePo cells but seems a bit iffy to me that they have decided to rate it only down to -10c. Just thought to mention it since it seems you too will be using it mostly in a cold environment based on your location. Have looked at a new power station myself and it seems there really arent any sold at the moment that advertise use down to -20c, so insulating the battery might be necessary anyway.

Another frost covered session last night: The duct tape looking thing with blinking lights and cables going in and out of it looks a bit suspect. Dont think i want to be seen in the public carrying that 😬. But its just an insulated box and a solution to the power station throwing a temper tantrum last time when it shut down due to a low temperature discharge warning. Bits of the packaging it came in, duct tape, aluminium tape and a total cost of 0€ so perfect for the job as far as im concerned. At the end of the session i thought to look inside the focuser and saw the secondary mirror had partially frozen. First time i have seen this: Didn't seem to have a significant effect on the images. Edge of field stars might have some extra fuzz and diffraction artifacts, and the flats are only applied well to the latter images (as i took flats last) but the overcorrection seems to be small for the early night ones so i dont think i lost anything to it which is good to know in the future. The primary looks really bad in the image but that's because im shining a light down the tube and focusing on it, it really isn't bad at all and not something i have considered cleaning even a little bit.

I was in the other end of the lot to you, did wonder why someone left so early with so good weather. Did have some technical issues at first too, i think i was barely running smoothly by the time you left. Seeing turned out excellent towards the end of the night (2" stars) so stayed until 05 myself. That cold charge protection thing has caught me off guard a couple of times, try putting it inside your jacket and sweater (or whatever layer) for a while. My tablet recovers to a point where it starts charging in a few minutes.

Was out imaging last night and saw the light show (in southern Finland). Was incredibly strong for a good while, maybe for as long as an hour. Not quite as strong as the massive flare a few weeks back but still a proper show with some naked eye red visible too. Occasional pulses of light at the zenith too. Didn't take any presentable quality images but found it curious that it effected my 8'' newtonian imaging with a fairly narrow 1.5 degree field of view. Below is all of the nights data plotted in Siril with background intensity: The big mountain that sees more than a doubling of the background electron rate is not cloud, its the Aurora! This turned the location temporarily from a roughly SQM 20.8 location to an SQM 19.9 location (according to ASTAP measurements). The most surprising thing here is that i was imaging M81, which was very close to the zenith at the time, so there was aurora skyglow all over the place.

There could be obvious rust/water damage somewhere in the innards or the lubricant could have thinned out and mixed with water from the outside which would freeze at night. Hard to say by just guessing, youll know more when the mount is in pieces.

All the same, Skywatcher mounts are really rough out of the factory. I only used mine a couple of times before putting in new bearings and better grease.

Link doesn't seem to work for me. My AZ-EQ6 is not a particularly good copy but it doesnt seem to be all that picky about cold weather - as in i see no change in performance after having just set up and after having allowed the mount to cool down to ambient which is on both sides of -10c this time of year. Maybe yours could use some servicing? The RA axis in mine was particularly tight when i got it, the locknut that holds the entire axis in place was put in way too tight, like an impact wrench tightness or something. Was really difficult to get out but once i did it started rotating much smoother. Still not butter smooth and balancing is a bit of guess work on the RA axis but much better.

Have you completely disassembled the mount yet? I mean completely taken apart and not just the worm and its carrier. Should give some better insight as to what is binding.

For sequences containing less than 2048 images the sequence can be created with just the use of symbolic links, so it takes no actual disk space when imported to Siril. After registration there will be actual written files on the disk though, and this is pretty much the minimum disk space requirement for Siril. So there is a little bit of a tip here to try and make the sequence be less than that if you want to save on disk space temporarily. For more than 2048 you will need to write all the files into a .FITS cube (single .FITS file with 3000 layers) for them to be stackable. APP and as far as i know every other software has to do something like this under the covers as Windows OS prevents you from having more than 2048 files open at the same time so they have to be written to a single temporary file one way or another. There is a trick to remove atmospheric dispersion, but it takes some effort. I also image with a colour camera, but i dont treat the data as colour data really at any point. I calibrate the data and then use the "seqsplit_cfa" command to split the OSC data into its raw 4 monochrome channels without debayering. This results in 1 red, 1 blue, and 2 separate green images per input sub and also effectively bins them x2. Then i stack them using a single reference frame for all the RGB channels, this aligns everything to one sub in the stacking phase so no colour channel separation due to atmospheric dispersion is possible (never seen lopsided RGB in a star this way). The second option is to extract RGB layers as mono images from the stacked colour image, register them against each other (green channel probably best for reference) and recomposite back to an RGB image. That works almost all the time too. The cfa split method does require some extra effort, but it gets the job done well in the end. Not sure how practical it would be for you since you have 3000 images to begin with, so you would have 12 000 after the split! You could also batch bin the files with ASTAP and stacking should be much easier. Or use superpixel debayering with APP which also halves the image size and so should make the subsequent processes run much faster. No easy cheats available for dealing with large stacks im afraid, its all a compromise of some kind which is why i have a 1tb SSD that i really treat as a 500gb SSD with the other 500gb reserved for stacking purposes.

Really nice with only 4s subs and a relatively short integration of those. Surprised to see so many background galaxies for sure. Try Siril? Siril, at least for my computer, appears to be about 5x faster (at least) compared to APP or PixInsight (or anything i have tried) with large stacks. Yesterday i stacked 80gb of files - around 3000 subs and it took maybe an hour including registration, normalization and weighted rejection stacking (files were already calibrated though).

I would try it in the finder foot at first. If you start seeing suspicious star shapes but guiding reports everything is ok you have flexure and need to think of something else. But chances are high that wont happen so start with the finder shoe. The problem might not be with the connection between the guidescope foot and the finder shoe, but the tube under the finder shoe which might buckle and bend under gravity in different orientations of the tube. Not sure if that's a problem with the 150PDS but with my thin aluminum tube VX8 it was. Balancing the tube is solved by rotating the tube in its rings so that the camera and guide scope both point towards the ground with the center of mass in the middle (so neither should point directly down).

Superb!

If the input gradient is linear, which it is if flats have worked well, and there are no obvious flaws in the setup the output gradient should be linear too. This is how i thought it went: The gradient could be a complete 180 in a third night and it would more or less cancel out and still be a linear gradient, but now to some other direction. Another reason why i dont think its a good idea to automate BE on a per-sub basis is that there isn't a complete picture of the signal available in the background of the image and so accurate placement of background samplers is impossible. True signal will be treated as background in that case and some will be lost and also since the background extraction has very noisy data to make the decisions on - surely the end result will be noisier (=less accurate) too. I tested this with a fairly challenging dataset below, where there is a little bit of IFN in the background to ruin the automatic removal process by making the samplers placed on the single sub guaranteed to be inaccurate. For images without IFN you can have any number of things that do the same thing such as fainter stars, faint Ha nebulosity in nebulous regions etc. Images shown in the Histogram preview mode and false colour rendering to show issues obviously. Without gradient removal: With per-sub gradient removal: To my eyes it looks like the gradient removal process has created the issues rather than solved them. Your mileage will most likely vary, but since the Siril tool is so simple to use and so effective, i really dont think its worth it to try and automate it pre-stacking. By the way i will mention that i kind of moved the goalposts in this argument to my favour by picking this particular image where i know automatic BE fails. Of course there might be many images where such issues do not arise.

Any particular reason for removing the background on a per-sub basis rather than from the final image? I know the Siril tutorial mentions that it can be done both ways but i think its better to let the gradients be until the images are stacked. The per-sub extraction should be used as the last resort if the tool is unable to deal with the gradients in the stacked image for some reason. From personal experience that only happens when flats dont match the lights in orientation/tilt and there is a severe local light pollution gradient such as a light that shines directly down the tube causing reflections and all sorts of issues. The new tool introduced in 1.10 and afterwards can deal with very cursed gradients and have not seen an image that was not fixable. I am not mathematically oriented so cant give you an equation that would prove why BE before stacking is worse but i would assume removing the gradient before stacking makes the subs more noisy (as noise stays, cant remove that with background extraction) and so a less efficient end result as the subs now have worse SNR pre stacking. Sure the gradient will evolve with the night but typically it wont do a full 180 and whatever direction is towards the ground in the image will always have the worst gradient so the gradient doesn't get to be all that complex if flats have worked out ok and the locale isn't completely ruined by some nearby lights.