M36

Folks - after diving Kylie into the ground (long story and a bent dew-shield and split cable later...) I calmed down enough to shoot the core of M36. I gave this a go because I've managed to get the mount even closer to perfect polar alignment. I can keep a star cetered in a 15 arcminute square field in the same spot for over 4 minutes now. I kept the exposure long to tryand get some dimmer stars in the field but without burning the image out. Another challenge was the breeze. Evidently not a challenge in the slightest for Kylie....

All in all, after a fraught evening, I was pretty pleased with progress.

I have a ton more images to process - watch this space and enjoy.
Cheers
Dave McD




Image details:

Object - M36
Date/time - 27/09/05 00:27 UTC to 27/09/05 00:37 UTC
Exposure - 30 sec
Image no. - 20
Imager - DSI
Mount - AP1200
Scope - C8 SCT with 6.3 focal reducer
Software - Autostar suite, Photoshop 7, FITS plugin

its like one of those sky1 series, "shen slewing goes wrong". :lol:
I know the feeling, my camera doesn't clear the mount, and if I slew too near the pole, bammm :shock:

Nice image, tracking looks bang on.!

That is a nice miage alright. Even in black and white, its still got plenty of detail there. Nice work Dave!

Seanie.

Cheers lads.

Dave - luckily, all the gear cleared the mount (except the dew dewshield) but the Dec cable was wrapped aroung the Dec head so tight I couldn;t slip it off. So I had to reverse up hte motor. I think slightly loose clutched prevented even more damage... 'When GEM's go berserk' - could be an 18 rated program!

Tracking is very very close now - over the next while I'll tweak it even more then program the PEC. I'm hoping to 5 minute unguided exposures without any trailing, at this field of view. Then I'm going to have a go at a few dim nebulas. And I'll have a bash at doing colour Seanie!

Cheers

Dave

Great progress Dave. Looks like you've gotten that polar alignment well sorted. Nice image!!

I did a bit of a calculation and assuming you havent cropped that image your DSI/C8 combo gives an image scale of 1.6(H) x 1.22(V) arcsecs per pixel. Now i estimate the faintest stars on the image to be 4-6 pixels across. thus having a horizontal full width of 6.4-9.6 arcsecs. Knowing that the tracking looks totally perfect( Just look at those lovely round stars) means that you could probably tighten the focus a tad. See if you cant get that focus inside 3 pixels!!

That mount is such a sweetie, does she have a sister?

Cheers Dave - there was a small bit of cropping - maybe 10% horizontal and vertical.

The calculated image scale at F6.3 is 1.4 arcsec/pixel with a FOV of 10 * 13 arcmins. At F10, its 0.88 arcsec/pixel and FOV 6.3 * 8.4 arcmin. However, I have to admit to a bit of confusion on DSI pixel sizes and array size so I may be a tad out. I've seen 10 x 10 pixel size and 9.6 x 7.5 from different sources, which doesn't help.

The reason the stars are somewhat bloated is that I have the IR filter removed. In the early days, it was adding too much crud to the image and I hadn't taken any flat frames. That's another next step

Focus is bang on though - if you're a little out of focus with the SCT, you end up with doughnuts. I take about 15 mins or so to focus on a vriety of bright, medium and dim stars. If I get lucky, I check focus on the moon or a planet. I'm usually bang on.

With the IR filter, I'd expect even tighter stars. But with me going for nebulas next (I have a Lumicon UHC filter) I'm not sure I can or should use these in tandem....

As for a sister, There may be a smaller sibling soon - an AP900. But that would be greedy...

Cheers

Dave McD