discardedastro

29 minutes ago, Ags said:

In space they can't hear you PARTY!!!!

18 minutes ago, nephilim said:

The EQ6 R plus 250 Quattro come in at 50kg then you need to add on the weight of all your other bits, its not a weight i'd fancy just 'nipping out' with. It might sound ok right now but imaging carrying all that out, setting up & then 20 mins later the sky clouds over & you have to strip it all down & take it back inside, that scenario would get boring pretty quickly for me

100% fantastic point. If you've got space and security to allow it, a Telegizmos scope cover is a hugely worthwhile invesment - my EQ6-R and 200PDS live outside, fully set up with cameras + computers + optics, 24/7/365 and setup is 5 minutes and shutdown the same. The EQ6-R has some bolts that will rust - all the shiny ones are just coated mild steel and the coating will not last - but it's an easy and cheap job to swap those for stainless steel (see my thread below, which is also hopefully helpful in getting to know the EQ6-R, fantastic mount that it is for the money).

For AP, being able to leave stuff in situ rather than having to redo alignment steps and repeat flat frames can make setup and running much simpler, and makes for easier calibration of imagery after the fact.

If you're going to be carting stuff about all the time, A) plan for a Polemaster or similar to make polar alignment less time-consuming and B- consider weight and portability as important as optical quality...

I'll add to the camera discussion - NASA's been doing a lot of complex missions with little or no imagery for a very long time. You can make lots and lots of inferences with high confidence in space with well-known systems and good data, and JWST is probably the most overanalysed (and well-instrumented) bit of kit in space right now.

I'm sure this is just to let everyone rest. Human factors are well understood to be a major cause of failure in any operational environment, and sending everyone home to sleep and giving some of the support teams a bit more time to think is definitely the right message to give everyone working on the thing - take your time, don't rush, nothing's time-critical, get it right, and we're not going to stick to the schedule if it needs to move out a bit.

Absolutely sensible engineering - humans are part of the system too!

I'll +1 the commentary above around visual vs imaging. I have a separate visual scope - I briefly had one doing dual duty but DSO AP demands consistency of configuration (e.g. flat calibration frames are invalidated the second that anything rotates or shifts around) and that makes for painful swaps to/from imaging.

I've been imaging with the 200PDS for a long while and it's a great platform but needs some work to be a really solid high-end AP platform - nothing much optically but plenty mechanically. I imagine the 250PDS and Quattro will be similar.

• Focus - are you going to hand-focus and maintain/monitor? If not, you're going to need a focus motor (not too expensive) and I would strongly strongly recommend replacing the focuser (Baader Steeltrak NT worked great for me, but plenty of other options out there).
• Baffling/caps - cheap and easy to do, don't forget to at least cap/baffle the primary to avoid light leakage!
• Guiding - if you intend to do much really deep-sky imaging you'll need to guide, which means an off-axis guider (definitely the preferable option for Newts because the light shares fate with imaging light and so you don't have issues with differential flexure) or piggyback scope. Backfocus can be challenging with DSLRs when you have an OAG in.

The 200PDS is quite a long system - I use a ZWO ASI183MM and that's got a tiny sensor, so is a very narrow FoV system overall. That works for a lot of my imaging work but it's definitely oversampling on the sensor. Have a play with https://astronomy.tools/calculators/ccd_suitability to get a feel for that.

The f/4 is not the scope I'd go for if I wanted a widefield astrograph-style instrument - I'd probably err towards APOs rather than Newtonians. Don't forget you will need coma correction whichever way you go for Newts, and potentially field flatteners for APOs, so budget for that.

Paracorr is the right answer for CC of Newts, in my view, though the GSO CC is also alright by many accounts. All optical chains are only as good as their weakest link, so I wouldn't skimp on the CC - I did and regretted it. Don't forget to also budget something for collimation tools for Newtonians, so at minimum a good laser + reasonable barlow and a Cheshire/Concenter.

Probably best to avoid the 190MN if you want to do more DSO imaging, if you ask me.

Looks good - I'm steeling myself to drop the cell out of my OO VX16 tomorrow and do a similar cleaning exercise! The complete absence of clear skies made me reconsider leaving it till summer - why not now?

I'm going to do a good clean as well as bolting/tapping some more bits to both the mount and tube to properly secure the Telrad and prepare for some encoders I hope to fit sometime this year. The whole thing needs a bit of a clean, some paint, and a bit more flocking.

My VX16 came with two (fabric) tube caps, which are both of Astrozap make, but I'm not a fan of these. I keep my OTA outside under a Telegizmos 365 cover, so something which is weather-permeable isn't ideal and I've had condensation drip from the inside of the TG cover onto the tube cap and from there onto the back of the secondary where it's caused a lot of rusting on the secondary adjustment knobs - this can't be doing anything else any good, either!

I'm planning to drop the primary and secondary out, replace the knobs+screw on the secondary spider and treat it all with ACF50, and refit - but am considering making a lightweight plywood tube cover. I'm replacing the tube edging with some rubber-and-steel stuff because the provided plastic is cracked and broken, so I think a simple bit of thin waterproof ply to cover the end with some locating dowels to hold it in place should do a lot better than the fabric.

I'd definitely cover the bottom end with a fabric cap at least to keep dust out if it's kept somewhere reasonably dusty. I'm doing all my cleaning on an unsealed concrete floor, which makes for more of a challenge!

3 hours ago, Mr Spock said:

Hopefully someone will get the reference 

Frell, it's been a while!

6 hours ago, GavStar said:

This photo was taken from the top of BBC Television Centre - definitely an urban location! 🤣

I used to work across the road in BBC Research & Development's offices - no doubt that it's urban! Be amazed if you can see a thing from there. Lovely old building, or at least it was before the renovations, I've not been since as I changed jobs...

The thing that completely revolutionised my observing was a big aperture scope. But largely in the sense that I realised that it doesn't magically fix everything and you still need good eyepieces, observing skills, knowledge of how to find things and how to observe them, etc.

The 183 might be a pretty good match to the Redcat - I was looking at a Redcat as a potential piggyback option for it if I ever wanted to add a slightly bigger sensor to my DSO scope to widen the FOV!

In terms of calibration and darks - below is the superbias, dark frame, and a single luminance 120s exposure post-calibration, all auto-stretched in PI. The actual intensity of the amp glow isn't huge for shorter exposures - the glow's not very visible on a 120s image in practice, so the calibration sorts it nicely. On longer exposures it's more challenging but I can reliably calibrate out stuff up to about 600s, 900s is a bit iffy sometimes.

At 300s you can see it's a bit trickier to cal out the glow, though with dithering it's manageable. On dimmer targets like Ha it's definitely more of a challenge as the background level is much lower compared to the glow. On brighter stuff like the above it's pretty easy to "outrun" the glow's gain over time. So if you were looking for OSC and relatively bright targets I'd say it's fine. The dark frame below is 900s, which is as bad as it gets - you can also see the corner glow.

Hope that helps!

Edit: And all those Ha frames came together pretty well when integrated, but you do end up with that stacked glow if you can't cal it out - I've done better calibration removal since I processed this though:

Basically banding is in the sensor and is a result of how the camera/sensor reads out pixels/data or inconsistency in the sensitivity of specific pixels in the sensor. Lots of things can cause it, but it is tied to camera/sensor, so calibration helps. Calibration can't magically restore missing data, though - hence why dithering is important, to put those objects on "good" pixels often enough that you actually get data for those regions of the image.

With that much banding you need to at least move 10-20% of your image size over the course of imaging, I'd say. So work out roughly how many subs you're doing and adjust dither movements accordingly!

How many darks/biases/flats you need is best experimentally determined, but yes, more is almost always better. I do 25 flats per filter, 100 frames of bias, 50-100 frames of dark on an ASI183MM-PRO (which is cooled, so that all gets done at -15c)

Random dithering every frame is pretty common. Also worth checking how much you're dithering by in practice, i.e. with widefield you may need to be dithering a fair bit to move the image around a meaningful amount.

I find dark frames are easy to sort - pick a cloudy night when it's cold and just run the camera doing darks all evening. I usually do around 100 120s exposures for darks, which is probably overkill but can't hurt! Alternatively, put it in your fridge if you can't wait and are confident that the optical train/telescope itself isn't introducing any constant light sources. I'd definitely look to do more biases, too, or use a tool like PixInsight's superbias to extrapolate.

Looking good regardless though!

Yeah, "12V" is generally considered to be a 13.6V nominal voltage in practice and you'll want a couple of volts of headroom to accommodate short-term slump from a supply, especially if it's a switched-mode type. Set it at 13.6V unloaded off a voltmeter, see how much it slumps under load (best if you can stick a min/max voltmeter on it and look at the minimum) and adjust up if needed.

If it's slumping way down - below 11V, for instance - then you're going to need something with a few more amps in it! If you have an oscilloscope this can be really helpful for debugging short transients which can be harder to spot but can effect drive circuits and level converters e.g. for 5V rails powering microcontrollers.

So as a bit of a follow on from this...

I took some more data over a couple more nights and sat down and processed it all properly.

Setup was as above - an ASI183MM-PRO imaging, ASI174 Mini guiding via an OAG, Paracorr coma corrector, ZWO mini EFW with Baader LRGB filters. Scope is 200PDS with EQ6-R Pro mount. Focuser is a Baader Steeltrak driven by a Primaluce Sesto Senso. Software again KStars/Ekos/INDI.

Skies were pretty good for me Fri/Sat this weekend and I had some leave booked, so pushed on through the nights to get plenty of data in. There were a few cloudy spells but all in all it was a pretty good run and I only discarded about 20 images total.

Total acquisition time was about 9 hours - about 110 L, and around 55 of RGB, all 120 second exposures.

Processing workflow - I tried to keep this very simple. I did the usual subframe selection and weighting routine, blink to ditch a few images with Starlink in, and cosmetic correction. Integration used the GSD method with local normalisation. Did MureDenoise on all frames with 32 cycles and then DBE before combining, Photometric colour calibration, SCNR, stretching, LRGBCombination with chrominance noise reduction, and final TGVDenoise. I also rotated this version to be mostly "upright" without significant cropping.

All in all quite happy - the colours I found really hard to balance here and I might revisit the data to see if I can reduce the mottling in the darker regions of the image and improve the contrast in the brighter regions.

13 hours ago, Dr_Ju_ju said:

only the adapter plate, never the mount, you won't know where the swarf can wheedle its' way into....

To be fair, pretty safe if we're talking the base of the mount - there's no precision mechanics down that side of things (see my rebuild thread for photos) so it's safe enough and if that's where it's "wrong" I'd fix that rather than making a plate that's now wrong for everything except that mount!

I'd break out the 200/400 and have at it. You do want to avoid swarf landing anywhere on the mount, though - so throw a bit of masking tape or similar over all the rotational gaps, connectors, etc, and/or cover everything in paper/plastic with taped edges, then give it a careful brush/blow down afterwards. Pretty safe if you're doing this with the mount on its side, though, where the swarf will fall down.

I've now run this for a while with some actual stars to look at, so I think I can call this a success, and figured I'd show my working to demonstrate the improvement.

Previously my guiding performance was limited to circa ~1" RMS in good conditions, such as the ~4h session shown below.

Post-upgrade that's fallen to circa ~0.5" RMS. Note that this graph is zoomed in to explore some detail. That's pretty consistent across a couple of nights of imaging now, so is a result I definitely think I can stand behind. I've not dug into any FFT analysis of the guide logs yet but there's nothing obvious glaring out - the peaks in the below graph are well aligned with dithering as expected and there's nothing significantly systematically wrong.

Is a 1" to 0.5" guiding improvement worth £200 in new bearings and a weekend of fiddling? Depends on your application, and for most, probably not. But it was a lot of fun, I now understand my mount much more, and I've undoubtedly increased the longevity of my mount overall, stored outside as it is. So I'll count this one as a success!

The magnetic locks are a really nice idea as a way to automatically add some significant hold-down force - that should help a lot against wind!

The whole setup looks great - what position sensing approach are you using to check for parked vs non-parked?

5 minutes ago, wimvb said:

It occurred to me that if you make a ring out of plastic, you don't really need the clips anymore. You replace them with the ring. As with tht clips, the ring should not press down on the mirror, or you get so called pinched optics.

That's a thought. Bit of neoprene or cork on the back so the contact surface isn't liable to scratch the mirror and damage coatings, and you'd be set. Hum...

8 hours ago, wimvb said:

Similar to what I had until a few years ago. I went from running Kstars indoors to running it all on the Pi on top of my telescope, because whenever I lost wifi connection to my setup, the whole imaging session would come to a halt. So now I have the whole data capture software, including Kstars and PHD, on one Pi on the telescope and I connect to that Pi with RDP. If I lose connection, any sequence will continue running. At the end of an imaging night, or the next morning, I transfer all image files with FileZilla to my laptop.

If you PM me and send me the L master, I can have a look at it, and maybe come up with a recipe. But as I said earlier, deconvolution on nebulae won't always improve the image. And in your case, the diffraction halo around the bright stars complicate the process. If you don't mind tinkering, you could look into making a ring that sits on top of the mirror clamps, so that these are hidden. That way you can avoid the diffraction from the mirror clips.

 

Cheers,

Yeah - I'm fully cabled end-to-end with good quality Ethernet so connection dropouts aren't really a thing, but if it were a bit spotty then doing it all at the scope end would definitely be sensible!

integration_lum.xisf

L master's above - don't mind sharing that for all. I've had good results in some cases with deconvolution on nebulae but it's been fairly hit and miss in my trials.

Making a ring over the mirror clips I can definitely do pretty readily - I need to take the mirror out for a clean at some point anyway (it's been a few years and it's not had an easy life) so could sort it then - I figure a flat black acrylic ring in 2mm acrylic I can get cut very easily to the right size and then paint in ultra-matte black and secure with extra-long screws to the mirror clips or something. Would also help cut down stray light from the back of the tube, though that's also largely covered. It hadn't clicked that the mirror clips were what I was seeing there! Diffraction spikes from the spider are of course largely unavoidable, but I can fix the clip issue at least.

Yeah - I was struggling to avoid unnatural-looking stars with deconv. I really need to spend some quality time with the Deconvolution process to work out a good base recipe for my images, heavily oversampled as they are the defaults don't work terribly well.

Just the two Pis really - one on the telescope itself running INDI and all the device drivers, one in the house running KStars and PHD2. I also have an all-sky camera box which is run by a Pi, and the whole setup relies on a big Supermicro JBOD/NAS (30T of ZFS storage, ish, for now) to store raw data once captured and a big Ryzen workstation for PixInsight. I VNC to the KStars Pi to drive the capture process, and a script shoves all the raw data and logs/configuration from all the programs and devices into the NAS nightly.

First one of the season! Back up and shooting on my rebuilt mount.

Setup is my usual: ASI183MM-PRO imaging, ASI174 Mini guiding via an OAG, Paracorr coma corrector, ZWO mini EFW with Baader LRGB filters. Scope is 200PDS with EQ6-R Pro mount. Focuser is a Baader Steeltrak driven by a Primaluce Sesto Senso.

Edit: Almost forgot! Acquisition was 40xL, 20xRGB, all 120s exposures, so a total of about 3 hours of integration, bortle 4 skies and a half moon.

Software is Ekos/KStars and INDI on a collection of Pis, PHD2 for guiding using the new multistar feature, and post-processing exclusively in PixInsight. Pretty simple workflow - calibrated, DBE'd, used MureDenoise, tried deconvolution but found I couldn't lose the ringing too readily from the brighter stars and so left it out. Photometric colour calibration. Combined LRGB, final DBE and a bit of curves/saturation to taste, and final denoising with MLT.

Really happy with this, not least because it's the first shot I've done on the EQ6-R I rebuilt!

Cross-posting this for those who are interested in pulling their EQ6-R apart, now I've got it back together and it's working again!

Just to round this thread out - it works after reassembly! I've not yet fiddled with it beyond making sure it's happy, balanced, and not binding - the way the clouds are going all I get to do tonight is basically this. However, it's looking quite good. Certainly not a regression, which was my main worry. Backlash looks OK, but can probably be improved a little for Dec with some careful fettling. Overall looking promising.

3 hours ago, ItsmeMaw said:

Just recently bought and received my EQ6 but haven't set it up yet.

I'm in central Florida, the heat and humidity is brutal probably 300 days a year. Its not like it will get wet if I set it up in the observatory, but I worry about all the humidity. 

What are your thoughts on protecting it? This will be my only mount and it has to out last me!

So I've got mine 24/7 in a damp British rural garden - there is a small river about 35m from the mount and we're in a low part of the country so it gets humid, and I have no observatory - this thing lives under a Telegizmos 365 cover. Leaving aside coastal areas where salt spray is a concern, this is as bad as it gets!

This thing will corrode in lots of places externally because the material quality isn't great - as you'd expect from a mount at this price point.

I would personally recommend replacing all the fasteners you can access with proper stainless steel ones - the stock ones are coated and this fails within 2-3 years.

• It's all standard metric (none of that silly Imperial nonsense, sorry) so you can just buy M4 (10/20/30mm) screws and grub screws (mostly M4, 4-8mm long) and remove the originals one at a time and replace. The grub screws on the worm carriers and the worm carrier mounting bolts are worth doing along with the dovetail mounting (3 screws at top of Dec). The flatheads in various places seem to be stainless, so don't worry about those.
• The handle is mounted by some particularly chunky screws - this is M6 I think. These corrode, too.
• The big alt/az adjustment bolts? They'll corrode, too, as will the spring on the altitude adjustment handle. I pulled these all out, coated them in an Ambersil corrosion inhibitor, and then put them back in with some corrosion-inhibiting anti-seize. The spring got a second coat of ACF-50 inhibitor.
• The counterweight bar will also corrode since it's just coated. Most anti-corrosion products tend to be slippery, so you're best off getting your countweights in broadly the right spot and then coating around. The counterweights are painted and will absolutely corrode, so a fresh coat of paint if there's any nicks or dings (any enamel paint will do) and again treat with a corrosion inhibitor.
• The tripod bottom mounting rod and threads? You guessed it. Treat as the alt/az bolts.
• The tripod's at least aluminium, so that doesn't rust!

Other than that, I'd give everything a careful coat of ACF-50 or similar once all's said and done to act as a final protective layer. In an observatory you'll probably fare much better than I have, especially if you're able to run a dehumidifier continuously. Internally there's some mild steel parts (e.g. worm gears) so keeping it as dry as possible is a Good Plan.

3 hours ago, SupernovaF1 said:

I use it on a 200pds with equipment (two big and heavy dovetails, nuc, pegasus powerbox, etc) without issues.

The problem with these similar newtonians isnt generally weight, but wind. 

 

Edit: in my case also helped to add a third counterweight and keep them closer to the RA axis.

Absolutely on the wind front. The EQ6-R will handle quite a big scope - but in quiet conditions. If it's a bit breezy, you'll find it wandering a little - unavoidable on any mount at some point due to flexure of everything and "easily" fixed with a windbreak and/or observatory!

I've not touched the worms in the end except to lube them (with Superlube PTFE). Here's hoping that'll be fine!

Sat down and did (most) of the rest today. Back to having taken some photos, too!

First, some essential tools, in retrospect. The first is self-explanatory and optional.

Next, the bearing retaining nut tool - note the hole in the top, you'll need a suitable bar or dowel to apply enough force if your nuts are properly stuck, but it's just the tool for the job and £15.

Lastly, the Knipex pin nut tool mentioned early in the thread - this is essential if you want to avoid mucking around with oil filter removal tools, works a treat, £50.

So - cleaning everything went fine except for the worms. Here's one of the pinions getting a bath.

This is one of the worms post-bath - note the rust in the well of the threads where some water lingered.

Carriers all got a careful clean (incl ultrasonic bath, because why not) after some deburring to get the worst offenders.

Worth noting all the grubs are M4 except the end nut securing grubs on the Dec axis which are M5.

As with every other fastener I could, grubs in the carriers were all swapped for some stainless steel ones.

This is the only bit I couldn't sort out as well as I'd have liked - the top bearing on the Dec axis wasn't budging and unfortunately the end nut is inset within the dovetail carrier mounting area so the Knipex nut tool won't loosen it. In the end I settled for cleaning this up as best I could to remove all the grease before applying some fresh stuff in the places I wanted grease and reassembling.

The good news is that following the Astro-Baby EQ6 guide, everything went back together exactly as you'd expect. Of note - you can leave the optical encoder off the RA axis worm drive and fit it through the opened electronics area without issue, so don't bother fitting that because you'll be wanting access to the nut behind the encoder plate to tune the worm meshing.

I think the only other thing I'd note was that it was much easier to fit both the top bearings for the RA axis (with washers between them) than fit the RA housing bearing to the base and then try to fit the inner surface on the RA motion stage. The tolerances on the outer surface are much more generous and make this task much simpler.

I used a lithium EP grease for all the bearing surfaces and packing the taper bearings (the others were pre-lubed and sealed) and bearing fitting, white synthetic lithium PTFE on all the other contact surfaces, copaslip on things like the clutch threads which are meant to move (somewhat), low-strength threadlock on anything that shouldn't move, and

So everything is now back together. I've not yet fitted the electronics board, the covers, or the alt/az bolts - I'm going to spend an evening or two fiddling with worm meshing, but it's already feeling pretty good. I'll power it up and see how it binds in a bit!

Cleaned up everything and learned that the worm gears are mild steel or similar, not stainless or anything - left one in the ultrasonic cleaner (with fresh water) for a little while longer than ideal, and a thin black layer had formed with a small amount of rust pitting underneath when I returned. Will clean the other carefully by hand; have cleaned up the rusted one and there doesn't appear to be much if any lasting surface damage; I gave everything a good look under the microscope before and after cleaning and it looks fine. Surface finish isn't great, though - even on the one that didn't get a dunk. It's not terrible, but quite rough when you get in close.

I'm planning to very gently give everything some wet 1200 grit (finest I have) as best I can, and then will give it all a coat of corrosion inhibitor and then reassemble the carriers with usual EP lithium grease. Sadly I can't find anyone producing these, so not an option to replace or upgrade as far as I can see. More photos to come later!

So the mystery is revealed - after properly getting in and cleaning up the worm holders, there was an overabundance of pale blue threadlocking compound sat in the threads previously occupied by the slotted nut. Maybe Skywatcher went through a threadlock phase for worm end float adjustment nuts? I was planing to put a tiny amount in just to stop anything wandering but not quite that much!

Anyway, rest of the teardown has gone precisely as all the existing guides suggest it should - no surprises and nice and easy. The worms, bearings, and carriers are all out. I've cleaned up the carriers and deburred a whole bunch of edges, degreased everything thoroughly, took the rough edges off the flat surfaces with 1200 grit wet on a surface plate (barely ground anything off, but enough to give a nice finish), and everything now looks OK.

There's still quite a bit of dirt in the worms, so I'm going to drop them in the ultrasonic cleaner at work tomorrow along with the worm carriers and the pinions for good measure; I've also got a good stereomicroscope in the lab so will have a quick look at the worm and pinion surfaces for fun.

Then it's back on to reassembly! I've completely failed to find 0.5mm Teflon washers of the right size so the originals are going back in; I've opted for steel shims if I do need to adjust anything and have some 0.1, 0.2 and 0.3mm shim stock of the right dimensions for the big bearings from https://springfasteners.co.uk/.