Astroshed Update

  • Nik 

So after much heaving and very precise setting up with the new tube extension the scope fits and clears the sides. It’s definitely touch and go though, I’m having to park the scope in a weird position and remove the counterweights before I put the roof on.

Basically could defo have done with a 6×6 shed. Shame I didn’t have room.

I’ve also cut the top strut and am now using this to close the gap between the two roof panels. The shed may have survived storm Christopher but the roofing felt didn’t.

Might even be a bit of clear sky tonight so fingers crossed for a test run.

January Blues

  • Nik 

So January, what can you say? Orion in the sky, fabulous targets to image, nice long nights.

On the other hand here in Cambridge, wet cloudy skies all month, locked inside (which I fully support by the way), no chance of pointing my scopes at the sky. 🙁

Fortunately this doesn’t mean I’ve got nothing to do.

Computer upgrade

Firstly, I’ve replaced my ageing, slow observatory computer with something a bit more modern (an Intel NUC). Fairly cheap and the RAM and SSD from the old one (A 4 year old dual core GigaByte Brix) swapped right over which keep the cost down a bit.

I managed to try this out just at the end of December and it seemed to work well.

NGC 7635
NGC 7635 - Skywatcher 200PDS + Hypercam 183C Pro + CLS. 31 x 300s exp. Total exp 1h5m

New Observatory Shed

Top of my wish-list from November was a new shed to house my kit.

I decided I didn’t have room in my garden for a 6×6 shed so after some careful calculation I decided to buy a 6×4 because my rig should fit.

My careful reasoning when thus:

  • Base of tripod forms an equilateral  triangle 47″ on a side.
  • That gives an inradius of about 20″ (which is the largest circle that can be contained in the triangle). So if the sweep of the tube rotating on the mount sits within the inradius then all should be good.
  • My biggest scope is under 40″ in length and balances roughly in the middle so should fit within the inradius
  • The smallest dimension of the shed is 48″ so that should leave 4 inch either side of the inradius.

So given the above reasoning I should be able to get away with a 6×4 shed.

I went for a Keter Darwin 6×4 because it was fairly economical as sheds go and plastic. Looking through the manual online it looked like it should be fairly easy to modify the roof to lift off and it was.

Basically I built the shed according to the instructions until I came to assembling the roof. The roof consists of two plastic panels and a top strut which runs along the top and the provides an overhand to the panels to make them water tight.

Rather than screw the panels to the shed I’ve fixed the panels to the shed using 8 hasp locks and I’ve replaced the top strut with a flap of roof felt on one of the panels which folds over the gap at the top. (I may try and reuse the strut at some point but this will do for now).

So far so good, from this point on the fun begins. Turns out that my assumptions about the HEQ5 tripod weren’t correct.

The mount doesn’t centre over the centre of the triangle but is more towards the back two legs (I guess this is so the back two legs of the tripod brace the load). So the sweep of the telescope tube moves backwards towards one wall by more that the 4″ margin I have.

The upshot of this is that the tube hits the walls a various angles.

Luckily there is a solution to this, raise the mount up and move the tripod towards the other wall.

So I’ve brought a load of cocreate blocks and used them to make a base for the tripod.

This raises the mount up high enough so that it sits in the roof (just) and doesn’t hit the walls.

I’ve just ordered an extension tube for the tripod so it’ll be easier to centre the tripod in the shed, and as an added bonus I won’t have to worry about the end of the tube hitting the tripod legs 🙂

HEQ5 Now Working Again!

  • Nik 
I sometimes question the wisdom of taking up a hobby that requires clear skies whilst living in the UK (one of the lowest points in the UK to boot!). Most of September and October have passed with no opportunity to point a tube shaped device at the sky. The clear nights that we have had the seeing has been pretty abismal.

The best shot I managed to get last month was of M1 on a really dodgy night seeing wise using my ES ED80APO and EQ3-2 Pro (which worked remarkably well after sitting in the astroshed for nearly a year). This was made up of 44 x 120s exposures using my GPCAM3.

But enough moaning about the weather!

The HEQ5 with belt mod is now running smoothly. The hardest part of fixing it turned out to be hauling it up to my upstairs office so I had somewhere quiet and dry to fix it and finding a few days where the clouds have cleared so I could point it at the sky to test it.

After an initial try of tweaking the backlash on the RA axis using astro baby’s guide the clicking still remained.

I briefly toyed with the idea that there might be a slight lump on the RA belt, which was reported in one thread, but this turned out not to be the case (just flip the belt over and see if the click happens in the opposite direction of travel).

So I reread the instructions carefully and did the job properly. Clicking disappeared. Movement appeared to be smooth.

My pipe-dream of making a laser spot on the wall to do a star cross test in PHD2 seemed like to much trouble and clear skies were forecast for that night so I just took the plunge and set it up outside and started taking test shots.

First Night of Test Runs

So I started off taking test shots on the first of two nights. The first night I did unguided shots and the second I setup my guide scope. All pictures were taken with my 200PDS and Hypercam. I should point out that although the sky was clear the seeing was bad and the moon was near full. Oh well. The first shot I took was a 60s shot of Almaak. All good so far 🙂

I then took a series of shots of Betelgeuse.

Obviously 300s unguided is to much but 120s looks OK which is about what I’d expect from an HEQ5 and what I could get before I started the belt mod.

Of course the acid test is if I can actually put together a stacked image.

So unguide 60s exp produced this. 1hr 30m of 6os exposures once processed.

So a sucessful first night 🙂

Second Night of Test Runs

The purpose of the second night of testing was to get my guide scope working with the new setup. Again I used my 200PDS and added my StarWave 50mm guide scope and a mono GPCAM AR130.

So I ran the calibration on PHD2 and all seemed to go well.

Next up some single shots of stars. Starting at 180s this time and going up to 600s. Again all seems fine 🙂

So again the acid test, can I take a stack of exposures. Seems to be yes.

12 x 5m exposures

1 x 10m exposures

I really have been tardy lately (well for the last 18 months)

  • Nik 

I really should post here more often. Oh well, here’s an update for the last 18 months.

Firstly Equipment

The ES ED80mm is really superb and I’ve been having fun with that but my dream of only buying reasonably priced equipment is a distant memory.

First off I  bought a new mount, a Skywatcher HEQ5 which has made things easier. A belt drive kit is currently on the way so I can upgrade the drive train.

Then I brought a new camera, an AltairAstro Hypercam 183c PRO.

And finally I’ve also splurged on a Skywatcher 200PDS as a bit of a light bucket.

Secondly Image Processing

Most of last year I was using Siril and GIMP to do most of my processing.

Again, I’ve taken the plunge and brought a copy of PixInsight which seems to be working out OK.

Below is a picture of the bubble nebular that I took. Compare this to the one a couple of posts/1 1/2 years ago.


M27 – Bubble Nebula

  • Skywatcher 200PDS
  • Hypercam 183c PRO
  • 78 x 60s exposures
  • 216 x 30s exposures

2hr 6min Total Exposure

Sunday 20/01/2019

  • Nik 


  • Try removing diagonal from optical train
  • Recalibrate PHD2 after adjustments of RA gear
  • Field test ‘biscuit tin’ control computer


  • Cottenham, Cambridgeshire, UK
  • Class 4 bottle


So finally there’s a bit of clear sky to bed in my new kit (shame it will be cloudy by the time the super wolf blood moon starts it’s eclipse). This includes my new ‘biscuit tin’ control computer and my latest attempt at dialling down the backlash in my RA gear.

I had a try last week but it was far to windy for anything to settle.

So item 1. I wanted to have a try at removing my diagonal from the optical train and replacing it with extenders so I can make the telescope a bit lighter. Unfortunately I didn’t have enough extension tubes so I’ve left the diagonal in.

Item 3. I’ve brought a small single board computer to sit next to my telescope and basically run all my windows software (via remote desktop) and connect inside via Wi-Fi. The whole thing sits in a small biscuit tin, hence my pet name. The whole computer runs off a 2A 12v supply so it will run off my Powertank with a 12v USB adaptor (rather than running of the 1.5A USB outputs on the Powertank). Everything seems to work well and I’ll post the details of the setup.

Item 2. Calibration seems to have worked OK and the backlash is a bit better. Time will tell.

As a test I managed to get about 17 60s exposures to stack of M42 as a test before the cloud closed in again.


Adventures with SkyWatcher EQ3-2 Pro (part 1)

  • Nik 

After the fun with getting guiding working on Saturday night I had even more trouble on Sunday night.

The symptoms were a bit weird. For starters I had no luck getting APT Goto++ working. I’d get within a reasonable distance from the target then the fine adjustment just didn’t seem to work. Then when I did get the target finally centred PHD2 guiding kept drifting off in DEC.

Eventually I gave up trying to image anything and started to diagnose the problem. Running the PHD2 star cross test gave me a T shape with no/not much downward movement in the south direction. I then went back to the Goto++ and yes, when looked closely it was targeting perfectly in the RA but if the target needed adjustment south nothing much was happening.

After a bit of poking about in the dark I found that the retaining blots on the DEC adjuster lose. So at one in the morning I was stripping down the DEC adjuster and readjusting it.

What I think happened is that when I striped the telescope down about a month ago using this guide (which is really good) I’d been really careful to only do the bolts up finger tight (as instructed). Of course one of the bolts had worked lose.

So this time I’ve made sure the retaining bolts and the adjustment bolts are done up quite tight and adjusted them off with the small adjusting grub screw in the middle. I’ve also done the RA again for good measure.

Trying it the next night I was getting 5 minute exposures so I’m happy.

New Kit

  • Nik 

I’ve been splurging some money on some new toys over the last couple of days. Not huge amounts but enough that I don’t want to total all the individual purchases just yet :-s

Firstly, I’ve decided to dabble with a bit of filtering for my horribly light polluted garden. To this end I’m buying a Altair Astro Premium 1.25in CLS-CCD Filter. I’m not expecting miracles at this price but I’m hoping it will let me have a play and see what can be achieved.

Secondly, I’m buying a Altair GPCAM 0.5x Reducer. Again bargain basement price and I just want to see what it can do. Given I have a relatively small CMOS sensor I’m assuming that distortions should be minimal so it may work out quite well.

Thirdly, I’ve finally taken the plunge and am going mobile. I’m buying a 17ah power tank. It’s one of the old lead acid ones rather than the new lithium ones so had a fair chunk of money knocked off a Tring Astronomy Centre as clearance.

That was it until Friday night’s observing run. Trouble with me is that around 2 or 3 am when APT is away doing its thing and there’s not much to do I have these ‘great’ ideas :-s

I got to thinking that it would be nice to have an auto focuser and surely it wouldn’t be that hard to build one bits and pieces lying around. Turns out I’m not the first to have this idea and it all looks doable. I’ll be using a Raspberry Pi Zero I happen to have lying about (thought I had a stepper motor and control board but that turned out to be a DC motor and board so probably no good).

So off I went today onto the internet to find the bits and pieces I need. I didn’t actually buy any of them (well except for a new SD card for the PI and an FTDI cable). Since I’m now going to bolt a computer to the side of my tube I figured I could use it to do temperature and humidity, not to mention GPS.

I also figured I’d write the control interface to the ASCOM driver first before I dove in a brought the bits that involve some degree of mechanical engineering to fit.