Equipment for Astronomy

Weekend Opportunism

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.

Friday Night:
Imaging-
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.

Observing-

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…

Saturday:

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!

Painting/staining of new HEQ5/EQ6 mobile base with Cuprinol now completed

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!

Andy

Focusing QHY10 with Tele Vue TRF-2008 Reducer-flattener in situ for first time during day on Sky Watcher Equinox Pro 80mm OTA

I added my Tele Vue TRF-2008 Reducer-flattener into the imaging train for my QHY10 camera on my Sky Watcher Equinox Pro 80mm telescope today. As first step, I decided to try focusing it during the day. This needed me to reduce the aperture by 70% with aperture mask as well using minimum 1/10000 second exposure setting in Nebulosity 4 for the camera and also aim as the darkest part of the daytime garden.

Following image shows bottom garden in focus with QHY10 only attached to telescope:

In the following image, I added in my Tele Vue TRF-2008 Reducer-flattener and TS Optics off axis guider/flip mirror together into the imaging train – as you can see I could not obtain focus even when the focuser was fully racked in as far as it would go (needed to go in not out – could see focus improve as I did so):

Finally, in this image, you can see that I obtained focus with the Tele Vue TRF-2008 Reducer-flattener and QHY10 but without the TS Optics off axis guider/flip mirror, so sadly I won’t be able to use the TS OAG/FM with the TRF-2008 and my QHY10:

Focus was achieved at the end of the garden with QHY10 and Tele Vue TRF-2008 Reducer-flattener with a setting of 17mm on the focus tube of the Equinox 80mm OTA. Note 35mm of T2-adapters were used as spacer between the TRF-2008 and QHY10 as advised in the TRF-2008 manual.

Next step is to try focusing at night and find alternative way of finding my objects than the TS OAG/FM as I am keen to use the TRF-2008.

Andy

Making base for HEQ5/EQ6 Andy & Alan+Angella from RAG 3/9/2019

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!

Andy

Focuser slippage in my Sky Watcher Equinox Pro 80mm OTA

Last night I found a significant slippage problem on my Equinox 80.

I have managed to solve this after reading relevant internet resources. There is a small hex screw just behind the locking thumb screw that can be tightened to prevent slippage but this needs to be done carefully and in very small increments to prevent excess pressure causing damage to the focuser tube.

Internet resources:

https://stargazerslounge.com/topic/232789-equinox-80-focuser-problem

https://www.firstlightoptics.com/blog/adjusting-skywatcher-equinox-focuser-tension.html

https://stargazerslounge.com/topic/134026-equinox-80-focuser-adjusting/#comment-1337450

https://stargazerslounge.com/topic/74335-refractor-focuser-slipping/#comment-722461

https://stargazerslounge.com/topic/194211-equinox-80-focus-slippage-problem/#comment-2033890

https://stargazerslounge.com/topic/134026-equinox-80-focuser-adjusting/#comment-1336086

Andy

Photos of my own Equinox 80 today when I adjusted the focuser tension, showing the hex screw being tightened:

TEC (thermoelectric cooler) on QHY10 camera

As you can see from screenshot below, this is working although I am not sure why the temperature seems to be so low today…

Andy

As I watched it dropped even further – see below – this shows temperature just as I changed set point from -10 C to +5 C but has not had any chance to go up yet. Note I did not set it to – 19.5 C (never set it below -10 C today) !! Last night temperature also seemed but haywire although previous occasion I was outside it reflected the set point quite well.

Temperature correctly went to 5 C

I don’t think there is any problem – when I left it long enough it did seem to stabilise close to set temperature although with big fluctuation past set points before coming back and settling (in this case went up to 15 C before coming back to 5.6 C – I then set it to -10 C again and this time it went down to -11.7 C which in past I have noticed is where it seems to go when I set -10 C on TEC in Nebulosity 4).

When I watched it further, temperature went up to -3.1 C. Perhaps it is too much to ask camera to cool to -10 C and stay there in relatively hot day time? Current temperature in Lichfield 15 C.

Mind you then it did this…..

I have noticed that once it has cooled itself right down, if I then change the set temperature to higher temperature, it can take a long time to get there – I guess because the body of the camera is very cold and there is no active heating element.