discardedastro

That's true, and could make sense if basically ended up with a dead short through the motor - easy fix if so, and a cheap thing to try out; they're easy enough to get hold of.

Well, it's a Microchip PIC16F628A microcontroller, which is well-suited to DC control applications: https://ww1.microchip.com/downloads/en/DeviceDoc/40044G.pdf Plus a pair of SSRs - presumably either wired for a direction switch and on/off, or to drive one way or the other from a common rail. Looks like a couple of optoisolators, and then the usual glue to make 5V from a 12V supply for the PIC and make the PIC tick. Hard to say what's toasted but if you can trace motor +/- to the driving components you might have a shot. Otherwise, making a new equivalent of this would be pretty easy if that's what you're looking to do - you can sub an Arduino of any flavour for the PIC, SSRs are cheap as chips (and available on breakout boards, for ease of wiring etc), and presumably your inputs to this are just open/shut plus a few switch NO/NC contacts for limit switches, which the Arduino should be able to internally manage (worst case you'd need an external pull-up resistor or two).

To be devil's advocate - the 200P will probably work. It just may be a bit more challenging to work with. You can't easily "convert" between them, but if you have it, it'll certainly do fine for starters. It may just restrict you later down the line because of the limited backfocus - meaning that the camera will have to be close to the tube of the telescope, you won't be able to put much kit like filter wheels in the way. On the 200PDS, to get focus with a regular eyepiece a quite chunky extension tube is needed (2.5" or so if memory serves); when imaging you can take up almost all of this with extra optical bits like a filter wheel or coma corrector. In the 200P, the prime focus point is much closer to the body of the telescope, so as long as you're just putting a camera in without too great a flange-to-sensor distance, odds are good. So if exchanging it wouldn't be an option, don't despair! It's also a great scope for visual use should you ever want to upgrade the imaging rig later.

This may well be true of mirrors without coatings, but silicon dioxide and friends do not react to saltwater. May well need cleaning more often, mind you, which might lead to quicker coating failure...

Definitely look second hand for a DSLR in that price range. One camera for both AP and DSOs is a tricky call; you may do better to specialise initially. DSOs are by far the more challenging as ideally you want a cooled sensor so are in to specialist cameras (~£400 second-hand, £700+ new, and up from there); planetary targets are much brighter so don't need a cooled sensor or such high sensitivity. You could look at things like the ZWO ASI120MC or 294 - these are fine for planetary (less good than a DSLR for resolution, but with faster refresh rates for lucky imaging) and can be repurposed as a guide camera if you want to transition to DSOs (and for most DSOs, guiding becomes a requirement pretty quickly).

For a dob, a wrap-around shield to give the secondary a little more cover is a no-brainer in my view; straps don't tend to really help, since the optics are decoupled from the outer tube. Big dobs can benefit from primary heating, but realistically if the primary's dewed up your conditions are probably poor enough to not be worth it. Glue-on secondary heaters can be a useful addition but definitely try passive methods (shields) before you muck about with that, since getting the wiring onto the spider without causing issues can be fiddly.

They are coated, yes - this is actually why you must not touch the surface (outside of extremely careful and delicate wet (lubricated) cleaning, very very occasionally). If the coating starts to go, the mirror surface itself can eventually degrade, until re-coating is the only way to resolve it (dissolving the aluminium coating off, and re-coating it in a vacuum chamber, a very specialist activity). Your 130P will last for years and years before it's at risk of that if looked after properly.

They've got the launch vehicles, and crucially rapid turnaround capability. Putting the required lander/vehicle assembly together and into orbit isn't that hard - Falcon Heavy would provide adequate capacity, and they could readily launch in pieces and build up in orbit if they needed to get something larger across. But I doubt that'll happen for 2023. Artemis has focused on SLS which while it will undoubtedly produce a rocket, it's something so cost-inefficient it's unlikely it'll ever see much use. That appears to be starting to - beside the now-frequent Falcon flights and promising flights from Rocket Lab, Blue Origin, and others - become obvious to NASA admins, so I expect that some repurposing will occur to exclude SLS or at least remove it from the "must use" stack. But we'll see. Dragon and other crewed vehicles aren't going to stand still, either.

Open the view settings (F4) in Stellarium, look under Markings, and you'll find options for the equator and meridian - they're not visible by default.

I sort of agree. Moving to a pay-for-upgrades subscription model will help, but I think they should reduce the cost and make it a flat subscription model (i.e. stay subscribed or you can't use it) to use all new versions. That actually encourages everyone to be on the latest version, means your users all benefit each other by running and reporting issues on the most recent version (rather than having your feedback come in for a dozen or more old versions, many of which won't be supported), and means there's only one version to improve, fix, develop, etc. It's also liable to bring in an actual consistent and dependable revenue stream rather than lots of stop-start sort-of-subscriptions from end users. Making it a true subscription model is much more sustainable, and would allow for a lower cost per user.

My initial reading of it was that 3.x is the last "permanently licensed" version, and once you're on a subscription you're then obligated to keep that running. However, down near the bottom: "When your subscription expires, you will be able to use the most recent version of SGPro at the time of expiry." So I'm wrong on that 🙂 I'd almost go so far as to say that this isn't a subscription model - it's a pay-per-upgrade model. That's fine when it comes to feature gating - but the issue with this model always comes down to support. If something breaks or you find a bug in 4.0, but 4.1 is already out, will they go back and fix 4.0? If so, this creates a huge amount of extra work - they now have to fix every prior version and do new releases for them all, etc. If they don't, then your only way to fix a bug is to pay the upgrade cost and get back on the "most recent" train to receive the bugfix update. The most cost-concsious development shops will refuse to do support for old versions and only deal with support queries on the latest - which does rather play into "just paying for support" as noted above.

I will say that I used SGP when I was starting out, and moved to KStars/INDI about a month after, and haven't touched it since. It's pretty powerful software, but people are increasingly moving away from the monolithic ASCOM-centric world of Windows PCs next to telescopes for imaging applications, so I'm sure that's detracted somewhat from their userbase. The range of open source software aside from KStars/INDI is ever-expanding, too, and is functionally nearly as capable. SGP is definitely power-user software, but for a niche. I do think the subscription model is a great way to ensure software gets ongoing support, especially for software with pretty small userbases like most AP software is; I've been a FOSS maintainer for over a decade and motivation to carry on maintaining software is a big issue. For commercial devs I'm sure it's the same. At the end of the day if you rely solely on the number of incoming new astrophotographers willing to drop cash on software for your ongoing revenue stream, that's going to be a struggle. £50 is a bit steep, I'd agree, especially given the high cost of entry. £50 a year only would be OK for good software - consider it in the general scope of costs one typically incurs in maintaining, upgrading telescopes etc. But it's £50 a year plus £100+ to start, which is starting to get to serious money. If we were talking £50 plus £20 a year or something, that'd be fair enough. I guess they figure there's enough power users who want SGP...

That's definitely much better - I'd probably have another go and see if you can improve things, and definitely look repeat the same with the RA. But if you're guiding at 0.7" RMS that's widely accepted as being the limit of good guiding with this mount, so could consider that "done"! How much backlash will affect you is largely a function of how aggressive your guiding has to be - if you nudge PHD2 a bit towards avoiding direction switches (i.e. use the ResistSwitch algorithm and adjust a bit) then you can reduce backlash impact a little. But RA is generally going to be doing some back-and-forth so is worth making sure it's good and tight.

You can definitely run all this off a Pi4, yes. I do everything but the obsy motor control on my rig today with a Pi4 without issue.

I've only just seen this and it's made me realise I don't actually need to make a walk-in structure to achieve my ambitions of unattended imaging. My day job involves (amongst other bits and pieces) designing equipment cabinets for telecoms stuff, so I'm quite happy working in that smaller form factor. Only snag for me is that my scope is a 200PDS, which is a little larger, but actually could still work just fine mounted lower to the ground and in a short-height enclosure. I think I'll work out what the envelope would have to look like, but it'd definitely be a lot cheaper and easier to build something at that sort of scale, maybe around a very basic/small-scale concrete pier. That or swap the 200PDS for a smaller frac 🙂 What're your plans for v3? What has and hasn't worked well?

+1 to being super careful with the adjustments. Keeping track of what you've done is also really important I found - I marked each screw with a number and put a reference mark on the side for rotational measurement so I could write it all down. I did my adjustment without the scope attached - seemed easier and it appears to have worked well - but scope-on is probably going to give a better result owing to it being under "correct" mechanical load at that point. Any non-direct-drive mount will suffer from mechanical tolerances not being 100% and thus some backlash - more expensive stuff like the GM1000 has tighter tolerances but you're still trying to make two gearing surfaces be perfectly in contact in something made up of different materials, changing temperatures, etc. Stuff like the Mesu or ASA mounts which are direct-drive or friction drive (i.e. there's no potential for functional "slop" in mechanical interfaces beyond the motor itself) naturally has effectively no backlash (or at least not in the mechanics of it all) but you're 3-5 times the cost of the EQ6-R at that point.

That does look like a lot of backlash. I'd probably look at doing the backlash adjustment routine - this is documented a few pages back, and is pretty straightforward with some allan keys and a bit of patience. The motion looks good and consistent once you're past the backlash, so it's likely you've just got some excessive spacing in the gear train causing that, which is easily fixed with that adjustment routine.

I did - but it may have been user error. I had cinched everything up adequately (I think!) having balanced the dec axis during the day, but I had just spent a good hour carefully coating the exposed metalwork (excepting things near bearing/contact surfaces) with ACF-50 rust inhibitor, which is also a pretty good lubricant - so my hands weren't terribly grippy. The default knobs aren't terribly good to start with, so I think I must've just misjudged things. Having said that, wouldn't mind having something with chunkier knobs on it, and slightly better tolerancing! The stock saddle is definitely very sloppy in terms of the contact surfaces, being painted rather than anodised.

Right - but if you're worried about import duties etc I'd maybe see if FLO can offer it. I imagine they'd get a fair few takers (after a little slip of my stock saddle, I think I'd consider one as an upgrade).

Given FLO stock ADM I would imagine they'd be able to source the EQ6-R part if it isn't just https://www.firstlightoptics.com/adm-replacement-saddles/adm-dual-saddle-upgrade-for-heq5-neq6-avx-zeq-ioptron.html

Honestly, the best approach I've used is either long focus exposures - which will average out atmospheric turbulence - using software to measure FWHM or similar. That combined with using parfocal filters and focusing with L, which is never going to be perfect but if you've got a motor focuser and parfocal filter system is a pretty viable option. For the 600D you should be able to take 10s exposures or similar and get a reasonable exposure on a mask.

That's not normal, at least on the Nikon ones - you can have a 0s interval with a 60s exposure without issue.

If your calibration data doesn't change, yes. Generally I keep my "calibrated but unprocessed" raw data from each night for this reason - get to the point where you've applied darks, flats, etc, and store the raw images. Not sure exactly how you'd achieve this with DSS, but I think there's an option to export calibrated data rather than going straight to stacking. The advantage of this approach is you can then register all your images without having to recalibrate each set. I do this consistently now and have combined data from 4-5 nights of data capture in the past - it makes combining later data super straightforward as (in PixInsight at least) you just process your latest night's data till you're ready to register, and then throw everything in and process it all as one big dataset without treating each night differently (I will usually do this and then do filtering of bad frames, though will always discard clearly broken frames in advance).

What's your processing workflow look like to get it to that point? Can you post some raw data? I would guess at some stage you're exacerbating an issue with the raw data in your processing.

Looking at the EQ6 puck for the Altair, maybe - it looks like it might have the required side-fit bolts. Given the costs are pretty similar I'd go for the ADM myself - guaranteed to fit as it's stated in the part description, and the ADM stuff is good quality in my experience. For those wondering about long-term use outside, I've just done my "annual external service" - haven't stripped anything down but did move everything to a new observing position and while doing that I also went over all the surfaces that have started to rust with a corrosion inhibitor (ACF-50). The parts that are corroding on mine after a few years outside are almost entirely cosmetic - basically all the exposed shiny screw heads, bolts, and threads - none of it is stainless etc. The only points of concern I have are the spring on the lower altitude bolt, which has corroded on the surface entirely, and the smaller screws holding covers on, just because there's not so much material in there. The tripod has seized on one leg, but they're cheap and cheerful so hardly unexpected - might treat it to a little pier or a Berlebach this year if it's not getting the obsy. The counterweights are variable but largely starting to rust where the paint surface has been scraped. The counterweight bar is also corroding in spots along its entire length. I think I'll try and find equivalent fasteners in stainless for as many of the exposed bolts as I can, and next time I've got it inside for a service I'll swap them. The counterweight bar etc I can't do anything about I don't think. This is under a Telegizmos 365 cover on soft ground near (25m from) a minor stream of water in Oxfordshire, as a point of reference - fairly damp but no salt.