You're Barred

Folks - been a while since I submitted an image. This one was a little disappointing for just over 30 minutes of integration time. It could do with twice that. Still, if you try to ignore the noise, you'll at least see the lovely barred spiral of M109.

Enjoy!

Dave

www.astroshack.net/gallery/galaxies/M109.php

Nice one Dave..that title is very eye catching lol

Nice image Dave,

I notice forefield stars are nice and round. What do you use for guidance?

Great image dave. Looks like a flying disc doesnt it?

If I could be so bold as to suggest. To do this image justice my monitor has to be turned all the way up. This is no problem as I have two, with one turned all up and one set to normal. On the bright monitor this image looks absolutely stunning, on the normal one all that subtle detail is missing.

I'm just concerned that by processing for a brighter monitor your not doing your excellent work the justice it deserves. You dont need to tell me how hard it is to please everyone with a zillion different monitor calibrations but maybe we should aim towards more average monitor settings assuming this is what most people seeing the image might be using.

Maybe we should come up with a standard swatch on which we all agree?

Once again well done of a totally fab image.

I notice forefield stars are nice and round. What do you use for guidance?

Ha John, you havent met Kylie

www.astroshack.net/gallery/equipment/AP1200.php

Kylie -> John, John->Kylie

Aint she a beauty, just like her aussie sister!

Martin - I figured that 'here's an image of M109' as a subject line was a tad run-of-the-mill. The one I chose seemed to be a little more humorous Luckily, its never been said to me, yet...

John - this was unguided. However, with all the tweaking over the last six (yes, six) months I am now able to get 10 minute unguided exposures at 1.4 arcsec/pixel.

Luckily enough, our weather is so poor that I've recently been able to take darks from 5 to 10 minutes duration. So I'm hoping to get some long duration unguided exposures over the coming weeks. However, at these exposure durations and image scale, periodic error seems to be fairly crucial.

I recently took a few runs with PEC software and actually got PE down to a peak-to peak of 1 arcsecond. But then I re-did it after some minor polar alignment tweaks and it degraded to 3 arcsec peak-to-peak. So I've some more work to do.

As a bit of an insight to the other imagers here, if you nail your polar alignment (using drift or a similar technique) any Periodic Error runs you do will be easier/more precise because you'll reduce drift. By way of comparison, I have Kylie aligned to the extent that she drifts about 30 arcsec per hour (both axes). If you can polar align to this kind degree, you'll find even when autoguiding that your images will improve (the guiding corrections will be lower since the guider won't need to send corrections to the mount for both drift and PE).

I think I've got to the level now though that I can't squeeze any more detail out of the DSI at this focal length. So, its time to move up a level. That ATIK looks good

Dave G - I've struggled over this very point for months. I have two monitors - one calibrated using photoshop and the other (brighter) that shows the likes of your images very well. Typically I process with the calibrated monitor then move the image to the second monitor and crank up the levels a bit. I guess that anyone with the monitor levels set too bright will see the warts and all of most images. A swatch is a great idea. I've seen some calibration schemes on some folks astrophotography sites - these certainly help. But as you say, there are zillions of viewers out there...

Just like you, on my calibrated monitor, all the detail is lost. Its a Catch 22...

Of course, astrometry is great. You are forbidden from doing any post processing

Thanks for the feedback - appreciate it

Dave