ONIKKINEN

JWST is an off-axis three mirror anastigmat: https://en.wikipedia.org/wiki/Three-mirror_anastigmat Sounds like a star-trek word, i like it. As far as im aware no commercially available telescope has this kind of design right now.

Beautiful shot! Quite unlike the usual view of this galaxy through the murk and dust in the way.

This video is relevant to the sub length topic. Youll find that in most conditions much shorter subs do the job just fine. Longer is better, true but not worth guiding related frame losses.

M81/M82? NGC2403 would be available too, if a bit small for your focal length.

Sure, its possible. Not sure how that will effect the final signal to noise ratio but i would expect it to be a bit lower than just stacking everything at once, especially if sigma clipping is used. I would stack the 1hr stacks with sigma clipping to remove satellite trails and other outliers and then just a simple average combination for the 4x1hr stacks. The easiest way to do this would be to use the same single sub frame for all the stacks as a reference frame, that way you dont need registration and the final stacks do not have rotation differences, since they were all stacked on the same sub. Also, the intermediate stacks must be the same size, so mosaic and intersection modes are out of the question, the standard mode (which stacks to your selected reference frame) must be used. Doing this you can just stack the final stacks with no star alignment and average combination, and of course no calibration frames since they were already applied previously.

Narrowband especially from darker skies will still benefit from longer subs. Broadband from light pollution swamps read noise in a few seconds with an IMX571 which is where the short subs are ok - idea comes from.

https://www.amazon.co.uk/GL-iNet-GL-MT300N-V2-Converter-Pre-installed-Performance/dp/B073TSK26W/ref=mp_s_a_1_3?crid=13TX4R9UHW1DP&keywords=travel+router&qid=1641926555&sprefix=travel+roulet%2Caps%2C213&sr=8-3 One of these connected to the mini-pc creates its own wifi with no actual internet required at any point. Only time you need peripherals is when initially setting this up just the first time, other than that its always headless. Connect to this PC from this local wifi with any device running RDP. Thats how i use my win-10 mini pc using an android tablet.

I think you understood it a bit upside down. Exclude counterweight means counterweights do not subtract from the payload rating. So ignore the counterweight when measuring scope weight. If they did subtract, many mounts could only mount their own counterweights and not much else.

ahh, sorry meant the 2600 version exists as a rising cam version. No idea about the 294.

The rising cam version exists also. Much cheaper but does the same job, and has no "CMOS quirks" of ampglow, starburst etc.

There is actually a collimation tool that has this kind of concentric ring arrangement built in, no software needed. That would be the Concenter eyepiece: https://www.firstlightoptics.com/other-collimation-tools/ts-concenter-2-adjustment-eyepiece-for-newtonian-telescopes.html The view from this towards the secondary looks like so: There is no room for guessing, i can immediately see that while its pretty good, its not perfect. Since there are a lot of rings you are guaranteed to have a focuser position where the rings are the exact same size as the edge of the secondary. Very easy tool to use, and most importantly very difficult to misunderstand! In this example the uncoated rough mirror edges are blackened, so its even easier. You can also collimate the primary with this and there is no need to take offset or mirror center mark into account since the collimation happens using the outer edge of the mirror.

https://ecoflow.com/products/ecoflow-river-portable-power-station This one will definitely run your laptop from an AC- powerbrick, i ran my fridge with this during a blackout for a test and it does work under heavy loads admirably. Though it wont power a laptop for long probably since the inverter side of the powerbank wastes fair bit of energy.

I seal all of my expensive electronics in a rugged carrying case when outside and only open it after about an hour from bringing it inside. This prevents dew from the temperature difference from forming on them and hopefully makes them last longer. I have 2 cameras, the handset and a mini-pc (and some cables that absolutely must not break) in it. This might not be an issue for most but i have a 40 degree temperature difference between inside and outside at this time of year and everything gets wet immediately when brought inside. The scope, eyepieces and other optical equipment is left uncapped to dry over night. Sometimes i have to dry my newtonian OTA with a towel if it was very humid outside.

Take the intact tripod bolt with you to the shop and ask them to re-thread with the same threads as the bolt to make sure the correct threads are applied, as @david_taurus83 said it is probably an M12 metric thread.

You can try re-tapping the thread with a thread tap of the right size. Im not certain but i think these are 3/8 inch photothreads. I would start with a thread file to try and clean what remains of the thread. Start from the back where the threads are most likely still in decent condition. Clean up the thread with the thread file as much as possible before trying to re-tap. Then try to carefully go along the same path where the thread used to be, or you will just end up destroying more of it. It will never be the same again with retapped threads of the same size since a lot of the material was lost, but it could work if you dont use too much force when threading into the mount again. There are also thread inserts that you could try to drill into the existing hole but this i wouldn't try myself if i wasn't comfortable with this kind of thing. The thread file and a thread tap + wrench will cost you not that much, but isn't guaranteed to work. But also probably wont make things worse. The best bet would be to take the mount to a local machine shop and ask them about refitting a threaded insert to the hole. Its not a huge ordeal and probably not that expensive. Its far from completely destroyed so entirely fixable.

Most folks use light panels of some sort. Its an extra trinket to carry out and set up but worth it in my opinion since flats are probably the most important type of calibration frame. There are expensive options: https://www.teleskop-express.de/shop/index.php/cat/c229_Flat-Field-foils-and-boxes.html And cheap options: https://www.amazon.co.uk/Drawing-Tracing-Ultra-Thin-Adjustable-Brightness/dp/B072F8T5FH/ref=sr_1_29?crid=12P09PNJDKODH&keywords=agptek+light+panel&qid=1641750123&s=kitchen&sprefix=agptek+light+panel%2Ckitchen%2C83&sr=1-29 I use the latter. These cheap drawing tracing tablets feel like toys and probably wont last long but they are very cheap and do the same thing. The dedicated flat field panels are dimmable to whatever level you want and some can work with capture software (like NINA) to automatically take the ideal flat exposure.

The gradient is blotchy and difficult to remove. I end up with a similar result as you with most methods. I could probably brute force this with GradientXterminator plugin in Photoshop, but it looks difficult to deal with. Looks a lot like a light leak to the sensor somehow IMO. Also since you are using a newtonian it is possible your collimation has changed since shooting the lights and taking the flats, which is why flats are best taken straight after the session. This needs to be blocked so that no light can enter during shooting. It could be the culprit here. But one more thing you can try other than re-shoot the frames is to do the background extraction per sub. This works well for linear gradients, but if each sub has a nonlinear gradient due to light leaks it may not work that well. To do this you should use the "seqsubsky" command in Siril before stacking. After pre-processing you can run this command by inputting "seqsubsky pp_light 1" to the console. In here seqsubsky is the command, pp_light is the sequence name in question and 1 is the degree order of the extraction. 1 is linear 2 is less linear etc, usually only the first order extraction works well for individual subs. If you used one of the scripts built in to Siril to do the whole process you can add the command line in to the script you used. You can open the .SSF files with Windows word pad. I am not quite sure to which point the command goes, but it might be the one i marked. An easier way (which i use) would be to use Sirilic, a software that uses Siril for stacking but makes all the data usage much simpler with a drag and drop interface. No need to manually faff with folders with Sirilic. Here: https://siril.org/docs/sirilic/#download In Sirilic the "subsky" command does the background extraction per sub. Set to 0 for no extraction, 1 for linear extraction. Higher than 1 will probably not work well but you could always try. Its a lot to think about, sorry if it sounds like im rambling 😅

Attention everyone having USB issues! I just received a brand new AZ-EQ6 and the Prolific USB to Serial drivers from Skywatchers site DO NOT work with the mount. Skywatcher is probably using whatever chips they have on hand due to the global chip shortages and have failed to update the driver download section on their website. I had to manually install the newest version of Prolific drivers for the handset OR mount USB connectors to be picked up by device manager as working COM ports. Here are the correct drivers: http://www.prolific.com.tw/US/ShowProduct.aspx?p_id=225&pcid=41

Difficult to tell from the screenshot if something is wrong, can you post the raw stack? Im banking towards background extraction going wrong. I use Siril a lot and sometimes its just difficult to use and should be done on the individual subs before stacking. There is a method to do this in Siril with the seqsubsky console command but i would like to try on the stack first if thats ok.

No problems with the flat. Nicely illuminated with no overexposed pixels at all. There are some 0-value pixels in the red channel but i dont think its the issue here. Not sure how to go about fixing that either, maybe trying to take a longer exposure flat by dimming down the light source since this is a 1/200s flat exposure? A couple of T-shirt layers more with sky flats or the monitor method with a dimmable light source, but anyway thats beside the point. You get this view in Siril by putting the preview mode to "Histogram" in the bottom and selecting the rainbow false color mode from the bottom tool panel. Very easy to see what is what especially with flats. This is a pretty good flat although the optical axis is not exactly center to the camera (collimation or tilt). Do you get the gray uneven blotches on the raw stack before background extraction? Ill go with either a) light leaks during capture (difficult to remove) or b) something wrong with the background removal process.

Can you attach the raw flat file so i could have a look? That is a good method by the way, unless the sky was somehow unevenly lit at the time. AV mode in DSLRs always produced decently illuminated flats for me so i wouldn't worry about the method. But if you want to test another method you can just point the camera and telescope (or lens or whatever) to a computer screen/tv/tablet that is showing a white screen with the minimum brightness setting. Take at least 30 flats and move the telescope around the screen and rotate it in your hands during this to make any possible defects in the screen even out in stacking.

Looks a bit like light leak from the viewfinder if you used a DSLR. The viewfinder is a light pathway to the sensor and some light will leak there if its not blocked. On my first session out with a DSLR i had a red light headlamp on pretty much the whole night and occasionally i would point it towards the camera. It left a red blotch on all the frames that looks a lot like what you have here. This would not be removable with flats and would conveniently explain why the weird shape remains after taking flats. Or could just be that the flats you took were not that great, so how did you take the flats?

This looks like the secondary mirror was not perfectly centered under the focuser, which in my experience causes asymmetric flats (and other issues). Take a look at some examples from my previous flats. These screenshots have been taken with the false color and histogram preview modes in Siril, very quick to see differences. Also there is a change of camera, hence the very different look to them. One of the first flats i ever took, in almost stock collimation with my VX8 which after inspection with proper tools i found to be not well centered. Not a huge change in collimation, but a huge effect. On the bottom we see shutter shadow from a DSLR not quite being fast enough for flats. On the left side we see the same thing as in your example, an asymmetric brightess change. One of my more recent flats with care taken to achieve as good a collimation as i can, but you can still see the red bright regions are not perfectly centered and probably some tilt remains. But the asymmetry is mostly gone because i centered the secondary with a concenter eyepiece. Also, this process includes adjusting the focuser and not just the secondary so yes one could say the secondary and focuser were out of collimation.

Might be you 😁. We definitely agree on the brain part, but i think this issue also exists without platesolving. Just as well one could do 3 star alignment perfectly, slew to target and go to sleep and wake up the next day to unusable frames, in fact i think this is more likely without platesolving since you are just using your eyes to determine whether or not you have the target framed. If its an obscure/dim target with poorly defined edges and hard to recognize features its very likely you will end up missing and failing. I have a running project where i am shooting IFN that is only visible after about 2 hours of integration and there isn't even a hint of this structure in a single sub so i could never frame it properly without platesolving. Also this area of the sky has few defining features that could be used as pointers so not helpful to just eyeball these things. I had the camera at an angle of 82 degrees instead of 90 on the first session, so no i will have to check every time that the platesolver does indeed report the 82 degrees and once it does im all set and the framing can not fail. I think platesolving is 90% solutions to problems and 10% possible added problems with software (which will definitely happen at one point). If one follows what the platesolver is doing and understand the parameters that must be set for it to do what you want, it will end up saving about an hour per session and almost never cause problems. @ollypenrice @malc-c This talk about Argonavis control systems and permanent observatories is a solution to most problems, including this one. If the setup is made of premium parts (Argonavis is in the Mesu?) and permanently placed then the align points would be faster and better as it introduces no extra spanners in the works. This way also every night works the same, as the mount is fixed in an observatory and not moved each night so the alignment points do not have to be remade. For most users though who set up and tear down each night, or at the very least carry the mount in one go already assembled from a shed/from indoors will absolutely find platesolving a blessing and a solution to many problems including the one OP is having. Same was with my EQM35, i could do 3 star alignment perfectly with a star exactly centered on my DSLR crosshairs and still have a +/-10 arcminute deviation from where its supposed to point, which would be easily enough to ruin most targets. That would be because the pointing accuracy of Synscan mounts are quoted as 6 arcminutes at best.

I received a Skywatcher product today (AZEQ6) and with it came a leaflet with Skywatcher products advertised in it. I noticed that there is a mount that i do not recognize at all. Doesn't look like anything from Skywatchers current catalogue, is it a new mount?