September 2018

Monday 17/09/18

Plan

  • M33 with 0.6 focal reducer and filter on 130 900mm newt.

Site

  • Cottenham, Cambridgeshire, UK
  • Class 4 bottle
  • Weather
  • Pressure: 1007hPa
  • Wind around 7kph.
  • Temp Around 18C.
  • Dew point 10C.

Log

Tonight was one of those nights where my rig decided to work, more or less perfectly, from the off and surprisingly the weather played ball as well (although the forecast looked pretty dire to start with).

My home made focuser seems to be working well. The interface is a bit clunky at the moment and I’ve still got to plumb it into an ASCOM driver so it will work with the auto focuser stuff in ATP but it worked well manually.

Also my little set of sensors  seemed to work well (or well enough for my needs anyway) giving pressure, temp and dew point.

I was running with my new (cheap) focal reducer which brings my focal length down to about 517mm.

First off I ran a 30 shot series of 60s exposure on M33. That seemed to go well so I upped the exposure time to 2 minutes and ran another 30 shot series.

Since it was about midnight and M45 was in view by then I took a few bonus shots.

Results

Turned out not to be great after an amount of post processing. There’s some vicious vignetting from the focal reducer which my flats don’t seem to want to get rid of. Since i’d left the equipment setup and the focus constant I’ve been experimenting with flat fields. Hopefully this should pay some dividends.

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.

Saturday 1/9/2018

  • Nik 

Plan

M27 second of two nights. 2 or 3 minute exposures.

Site

  • Cottenham, Cambridgeshire, UK
  • Class 4 Bortle

Weather

  • 15% med to low cloud between 9pm and 10pm otherwise clear.
  • Wind around 7kph.
  • Temp Around 18C.

Log

Tonight isn’t going exactly to plan but better than last night.

Last night I didn’t have any trouble with guide setup, tonight it’s caused nothing but trouble. Guess I’m going to have to reserve a night soon to sort it out.

At one point, since I was having no luck taking anything over about 45s, I decided to do a bit of lucky imaging. 15s x 240 – max gain on the camera. I’ve quickly stacked about 50 of them and it doesn’t look half bad.

M27 – Test Stack – 15s x 50 – Max Gain – GPGAM3

For got measure after this run (and another attempt at M27 with a longer exposure) I tried NGC7635.

Results

M27 – 15s x 240 – stacked – GPCAM3 – Max Gain Cut to about 140 frames with FWHM rejection

M27 – 15s x 240 – stacked – Max Gain

NGC7635 – 15s x 150 – Max Gain – Stacked

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.

 

Friday 31/08/2018

  • Nik 

Plan

M27 first of two nights. 2 or 3 minute exposures.

Site

  • Home
  • Cottenham, Cambridgeshire, UK
  • Class 4 Bortle

Weather

  • 15% med to low cloud between 12am and 1am otherwise clear.
  • Wind around 7kph.
  • Temp Around 17C.

Log

Last night was a bit of a disaster as far as getting a good set of observations went.

Night started off fairly well. Got polar alignment very quickly, focusing as well. Then tube managed to hit the tripod whilst going a goto so I lost worm gear alignment with the PEC. So spent first half of the night sorting that out again until it clouded over.

Then I thought it was high time I sorted out the mount limit function so it didn’t happen again. Tried for about an hour but still don’t seem to have got the hang of it. Will have to try another night.

By then it was around one in the morning and the sky had cleared again. Ran a guided 120s x 30 set of exposures on M27 + darks which took me through to four am.

Unfortunately, since M27 had by then dropped down towards the west there’s a terrible light gradient on these, which is a shame because some of the internal detail doesn’t look bad. Home hum. Will try again tomorrow and hopefully get a reasonable result since the weather looks like it’s going to not be my friend for the next week.

The night wasn’t a total loss though. I did finally sort out the issue I was having with my pulse guiding. Turns out I had the RA and DEC pulse guide rates set to x0.1 which wasn’t anywhere near enough to allow any tracking errors to be sorted out. I’ve upped this a bit to x0.4 for both and guiding seems to be a lot happier.

Result

 

M27 – 30 x 120s – AltairAstro GPCAM3 178C3