Sky Watcher Equinox Pro 80mm OTA + Tele Vue TRF-2008 field flattener + QHY10 camera & William Optics 66mm OTQ with T7C guide camera + TS OAG/flip mirror on HEQ5 Pro & focus points on both scopes with these cameras 20/9/2019:
Over the full moon period we’ve had a couple of clear nights and I’ve taken the chance to get some pictures of the Cygnus Wall in Ha and Oiii. Back in February/March I had an attempt to do this on the Cone nebula but the results were not brilliant (suspect user error is to blame as usual). Here are my results from the same technique on the Cygnus Wall that have come out much better. Possibly part of it is understanding that the Oiii data is considerably weaker than the Hydrogen data and compensating a bit for that.
Anyway- below are the images- they’re 1 hr 20 of Oiii (I took 3 hours but most of them had to be thrown away due to moonlight and cloud) and 2 hr 40 of Ha (only had to reject 2 of these) plus the usual calibration frames.
Firstly – Ha:
Then Oiii (yes, I’m still not great at aiming the camera in the same place on two successive nights, but it’s tricky when you can’t see what it’s taking a picture of!)
Finally- the combination made from feeding the Ha into the Red Channel and the Oiii into the Blue and Green:
Between a busy work week, family commitments and some so-so forecasts it wasn’t looking good for astronomy this weekend, but it turned out pretty well.
Didn’t get out until about 10:30 but tried to make up for lost time by setting both the main scope going and trying out my 50mm lens on the Star Adventurer. I had high hopes for the 50mm lens- it’s another oldie (I’ve had it about 15 years), but online quite a few people are getting great results with them. Well- I’m not in that club (yet). The diaphragm only has five blades and although I stopped it down to f2.8 (it’ll open up to f1.8) all of my stars are pentagons and DSS is refusing to recognise them as stars- so no results from that. Fortunately, the main rig saved the day: I went for NGC6946 – The Fireworks Galaxy with my 200p. Throughout the session low clouds were interrupting the view, and around half the subs were lost, but the ones I did hang onto gave the result below. Over the summer I’ve picked up a second hand Canon 550d that has been home modified with a Peltier cooler and put into a metal case- it’s not pretty, but it seems to be effective. This is 13×4 minute subs and throughout this session it held the temperature down to around 7-8 degrees which I’m pleased with (a couple of degrees below ambient, my 600d usually runs about 10 degrees above ambient and is consequently much noisier). The target itself is quite a bit smaller than I’d anticipated- this is a crop of about 20% of the frame. Despite the small size- I think this is a lovely target- both for its colours and the asymmetry in the arms.
Whilst the cameras were doing their stuff I had the Dob out on the following objects:
The Double-Double- I used Vega to get the finders lined up then dropped down to Epsilon Lyra to check out the seeing. It was a straightforward split, but I could see that the transparency was not great.
M13 & M92 – I often start with these and never get tired of them. In Binoviewers at about 260x they fill the field of view and appear 3 dimensional. For me these are the only types of objects that actually look better in the eyepiece than in a photo; I love the difference in their appearance- M13’s great with lots of features, but a bit of a mess with arms everywhere, whereas M92 is compact and very neat. Just wonderful.
The Veil – I was reading a thread on SGL recently which referenced a Sky and Telescope article on The Veil (https://www.skyandtelescope.com/astronomy-blogs/explore-night-bob-king/explore-veil-nebula/) . Using this as a guide, and with an Oiii filter a 30mm eyepiece (55x) and a coat over my head I managed to explore just about the whole thing. I’m a bit prone to hopping from object to object whilst observing, so it was great to really take my time in the tranquillity of the small hours and drink it all in with nothing but the odd clunk of a shutter release and that American woman with the nice voice who commentates on APT saying “Dithering started…” softly in the background. Ahhh… a very nice dither contemplating the remnants of a supernova.
I was on the Veil for over half an hour and loved every minute of it, but decided with to move on with the Oiii filter and go check out M27. This is normally not a problem, but by this point the transparency had deteriorated so much I was unable to hop to it. Altair was the only nearby star that was naked eye visible and despite several attempts I just couldn’t find the stars in the finder to hop up to M27. Reluctant to retire I switched up to the North East to check out M31 as the skies looked better in that direction. Before I could get to it a bank of cloud blotted it out. Time for bed…
I managed to pop out briefly whilst doing other things on Saturday evening and set the imaging rig running on M13. This was a bit of an experiment: I’ve imaged M13 before, but with my guide camera on a smaller scope using the short exposure method. Whilst I was quite pleased with those outcomes (see https://roslistonastronomy.uk/catching-up-on-images) , I wanted to see how it would look with more integration time and a DSLR chip. This is 22x 4 min subs plus calibration frames and I am really pleased with it. As a bonus for the last half-hour it was running I sat outside with Sam observing the sky primarily with Mark 1 eyeballs. After a while we were both able to pick out the Milky Way running up through Cassiopeia and Cygnus despite the local light pollution. A real pleasure!
Two layers of Cuprinol later (left over from my wife’s fence painting project earlier in the year), the new mobile wooden HEQ5/EQ6 will be ready for vanishing with yacht varnish once it dries – and with high humidity levels at present and low temperatures I think it might take a few days before it properly dries out from the water based Cuprinol. That’s the price you pay for using left over stuff!
Now that I am doing astrophotography, it is important that I create stable, mobile base to allow me to roll the mount in and out of the log cabin. The more that can remain set-up between sessions, the easier it will be to image – especially important in the UK as weather liable to deteriorate again quickly.
Angella & Alan came around today and helped me build a fantastic base – thanks Angella & Alan!
Paul has come up with this ingenious solution to the problem of a cricked neck when looking through the polarscope on these popular Sky Watcher mounts.
The photos below show how the 90 degree viewer and fitting are assembled, noting the nut used to clamp it together.
Paul has very kindly made one of these for me using a second hand Nikon DR3 right angle camera attachment off ebay (approx. £6). He has made the hole in the plastic fitting a tight fit on the short thread of the DR3 such that no nut is needed. He has learnt how to carefully enlage the bore of the plastic fitting so it is a snug fit in the polarscope eyepiece…a bit tedious because it’s trial and error and must be done very carefully to ensure that the bore is not accidently made too large. Patience needed and lots of cups ot tea! The finished product is a tight fit and needs screwing onto the thread of the viewer. It should be a snug push fit onto the polarscope eyepiece. Paul used a 32mm Waste Compression End Plug costing £1.50 from “Discount DIY Store”, Swadlincote High Street, Swadlincote, Derbyshire, UK.
In use: Fit collar to viewer first, then push it onto polarscope eyepiece as far as possible – see photo. Try different angular positions if its too tight to go on. The collar should go over the eyepiece and over the polarscope tube as well.
To focus polarscope, Paul has found that he needs to unscrew eyepiece about 5mm so he fitted an 0-ring onto the thread for eyepiece to clamp against and keep eyepiece tight in the focused position.