September 2020

M31 and Molluscs

  • Nik 

I’ve been playing with mosaics recently. Not wanting to hard a target and it being the right time of year for it I’ve been concentrating on the Andromeda Galaxy. Although I’ve been mostly using my 8″ and HyperCam I thought I’d also have a quick go with my ES ED80 and my GPCAM3.

The night before last should (and indeed did) have given me a moonless clear sky and enough time to do a 4 pane mosaic but became an exercise in fixing things.

I’d been running my newly belt modded HEQ5 with my 8″ for the previous week and getting nice steady 5 minute exposures (give of take the odd frame) so loading it up with my 80mm should have been simple right? Wrong. I started off getting a terrible periodic oscillation in the RA.

Bit of digging about on the internet and some prodding later I’m running PhD2 to get a PEC profile in the vague hope that I can cancel it out. Nope that doesn’t work but the graph does show me how bad the osc is.

So at 11pm, I’m standing outside with a torch in my mouth and a set of allen keys trying to adjust the motor plate angle and re-tension the drive belt. Nope, still not playing ball. I think what’s happening is that there is a load of play in the RA worm gears which the general crappiness of the replaced gears was kind of masking + was being kept in check by the weight of my 8″.

Anyway, wasn’t going to get solved that night so we break out the emergency backup mount. This is my ageing EQ3-2 which to it’s credit gave me remarkably few problems once I’d finished aligning it. So back inside (after trapping my finger in the HEQ5 mount whilst putting it away just to add insult to injury).

Focus, check. Alignment, check. Modify APT sequence to fit into remaining time, check. And off we go. Everything now settles down and runs flawlessly until at 1-30 I decide its time for bed.

So, what time do you suppose my camera decided to start playing silly buggers with me? Yup, you guessed it 1-31.

Waking up to find this out and also that a snail had climbed up my mount and into the dewshield of the scope and left slime trails all over my lens really rounded the experience off nicely. So I have two sets of flats from that night, one snailed and the other de-snailed (cleaned).

At least the two panes that I did manage to take make sense as a picture. I shall have to wait for a nother clear moonless night to finish off the original program.