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That’s a novel approach combining narrow and broadband panels in a mosaic, but I think it really works. There must be other locations where this would work, e.g M45 and the Spaghetti Nebula?

I have only had a little 60 mm guidescope on my RASA8, and anything substantial will be located well away from the mount axis so this won’t be ideal.

I’m looking to convert my 16” SW flextube Dobsonian to a light weight mirror box/truss tube design. Take a look at “The Dobsonian Telescope” by David Kriege and Richard Berry, another very detailed how to design and build guide. It’s available on the internet as a pdf download.

My Altair 107 mm Starwave APO which was purchased via Modern Astronomy, came with an optical test report. I posted this with the ad in the for sale section of SGL:

I had a Altair Starwave 107mm APO, it was a fine scope, I only sold it as I had moved on to larger Esprit refractors. I think it is a rebranded scope, somebody more knowledgeable than me can perhaps tell us from which presumably Asian manufacturer they all originate from.

Thanks for the offer. I have located a copy of “The Dobsonian Telescope, a practical manual for building large aperture telescopes” by David Kriege and Richard Berry which looks to be a similarly comprehensive guide. I was just wondering if someone had specifically pulled a flextube apart and gone this route but I suppose that if you are buying new you will pick the design of scope that suits. Having used the 16” flextube my personal view is that maybe SW should have stopped at the 12” and moved to their Stargate design for the larger apertures.

Fair play to you Dave, I thought I had a small FOV with my Esprit 150/ASI 178 set up (0.47 arcsec per pixel unbinned) but some of these groups are tiny. Remarkable how similar HCG 41 is to the Box (HCG 61).

When I decided to get a scope for visual astronomy I knew I wanted plenty of aperture so it was always going to be a Dobsonian. I had a hankering for a 16" Explore Scientific Ultra Light but with a budget of around £1K I was going to wait forever for one to come up second hand. However I did acquire a used 16" SW Goto Flextube with a broken Syncscan (subsequently fixed, thanks @malc-c) and although the views through it are all that I expected, it is just so darn heavy and bulky to move from the garage and around the house and into the back garden. It's mounted on a 4 wheel trolley but I still have to dismantle the side gate to get it through! So I'm thinking it would be a nice project to take the key components (optics, mirror cell, top assembly?) and make a light weight mirror box/truss tube Obsession/David Lukehurst style scope. I am just wondering, has this been tried before?

Sorry a bit late to this one. Here is my contribution, processed in APP, PI and AP. Like @wimvb I saw some edge artefacts on the LHS and bottom RH corner which intruded on the FOV, but rather than crop these out I tried to fix these with AP remove background tool, but I had to over darken the background to make them less noticeable. BlurXterminator and NoiseXterminator also applied in PI.

Just stuck my head out the door to see if it was clear and saw these blue and gold halos around the moon.

A tool bag through bins, awesome! Presumably through a 16” Dob it should be possible to see what size spanners are inside?☺️

Although I’m primarily a galaxy imager I can’t ignore a moonlit clear night, so I’ve switched to Ha and NBZ filters and found a bit of hydrogen that fits my current tiny FOV setup.

Great image! Looks like some really extended spiral arms on NGC 974, and some IFN coming through also, or is that the sky conditions?

It’s great to see your hard won images in print. Every year I put a photo album together and use My-Picture.co.uk to print it, for less than £20.

Not many deep sky animations in the challenge so I thought I would give the Crab Nebula Pulsar another go. The pulsar is rotating at 30 times a second so the idea is if the light path from the star can be interrupted at the same frequency it should be possible to take subs that will capture the different light outputs from the pulsar. This is done by placing a light tight rotating disk in the imaging train running at the required rpm, in this case an 8 vane rotor rotating at 225 rpm. Here is a video of it running up, the tricky part is making it nicely balanced so it doesn't impart any vibration onto the OTA. rotatingvane - Made with Clipchamp.mp4 The actual pulsar can be easily identified on an extended integration, this is 52 x 2 mins with the Esprit 150/ASI 178: A series of 100 subs were taken using 10, 20, and 30 second exposures, then it is a case of sorting these into those with the brightest and dimmest pulsar and stacking these. In practice it is not quite so straightforward as the crab nebula was climbing ever higher in the sky as the session progressed, so the later subs were of better quality. The end result is a gif of a very close crop of the pulsar and an adjacent star, hopefully the change in the pulsar light output is noticeable. A few mind blowing facts about the pulsar, it is about as big as a city but is 1.5x the mass of the sun and spinning at 30 times a second...

Wonderful image Dave, I really like the surrounding dust and the colour of the Flame Nebula.👍

I subscribed to S&T in the late 1980s, IMHO it was way better than AN back then. I remember the review of the SBIG ST-4, it sent me down a very deep rabbit hole…☺️

Planewave type kit at (sort of) SW prices? I’ll keep watching this space.

Here is a link to a thread where I attempted to image a medium sized galaxy with a RASA8 and a small pixel CMOS camera, and compared the results with a 1050mm FL 6” APO. The RASA came second.

These days it is indeed relatively straightforward to image the Horsehead, especially with the sensitive CMOS sensors. But back in the film emulsion days it was a real challenge to photograph. I was elated to capture it on a 15 minute exposure from a proper dark sky location.

This is not my area of expertise, but one other comment I would make is that from my mid UK location this object doesn’t get above 30 deg altitude, this is not helpful for any type of faint diffuse object. I am only an occasional visual observer but I have glimpsed the Flame nebula with a 16” Dobsonian from my Bortle 5 location, but B33, no chance.

Thanks for the replies, I use an ASI 120 mini which is a few years old now, and a wholesale shift in the image would certainly result in the effect I’m seeing. It didn’t happen for the first 3 hrs of the session so maybe it is temperature related. Anyway, I have another 120 of more recent vintage, so I’ll swap them out and see what happens.

Last night the atmosphere settled down a bit and my rig was guiding consistently at 0.4-0.5 arcsecs total RMS. However just before and after a meridian flip, PHD reported “No guide stars detected” for a couple of exposure cycles and then carried on as if nothing had happened. There was no cloud about and no drop in the star SNR value. Note there was also no star lost or star mass changed message and the camera status stayed connected. Anybody else seen this?

Yes, and it hasn't missed a beat since your upgrade was fitted.👍 There was only one unattended session as the cloud interruptions were just too frequent. I got good at estimating how many subs I could squeeze in before the cloud bank that appeared on the Western horizon moved across to obscure the target in the East.

Here is another small and seldom imaged galaxy, NGC 660 in Pisces. The outer ring of the galaxy is tilted at about 60 degrees to the central core, probably caused by tidal interaction with UGC 1195 (outside of this FOV). This is evident by the cross over of the dust lanes, hence my attempt at a popular name . This one was a war of attrition with the October and November weather, taking 6 sessions, snatching subs here and there in between the passing clouds. All these weather systems equal turbulent air so thank goodness for BlurXtermintor. Capture details: Esprit150/ASI178 dual rig L 215 x 2 mins R 69 x 2mins G 74 x 2 mins B 77 x 2 mins Total 14.5 hrs integration, thanks for looking. Annotated