Omega Centauri and Orion Nebula - [ED120 OTA and QHY12 CCD]

[Eden (Brett)]

Hi All,

This is my first astrophotography post and I am still a relative newcomer to the art, but don't hold back -- any and all critique would be appreciated.

Many of the images I have taken so far with the QHY12 have been lacklustre, simply because I haven't taken the time to determine the optimal gain and offset parameters when imaging. Last night I bit the bullet and spent the better part trying to nail these values down and came away with a couple of reasonable shots.

I also learned a lesson in focus. Normally I use the focus assistant supplied as part of QHY's EZCap program to establish focus before imaging. After doing a 5 minute exposure of Omega Centauri and checking the resulting image, focus appeared to be OK but I decided to check it anyway using Nebulosity which I had never done prior.

Much to my surprise, I was quite a bit out of focus and was subsequently rewarded with considerably more stars (both images of Omega Centauri attached for comparison).

Images I have taken of the Orion Nebulae in the past have resulted in the core being blown out, obscuring a good deal of the gaseous region. Although the focus was slightly off on this shot, I am pleased with the results using improved gain and offset values. The attached image is a single 5 minute exposure.

No darks or bias frames used but because of nearby streetlight I have used a UHC-S filter. Colour stretching was done using Maxim.

More about the QHY12 in a future post and as for the Crayford focuser supplied with the Skywatcher ED120 Black Diamond, that's another post begging to be written.

Cheers,
Brett

[WingnutR32 (Sam)]

Nice captures, Brett.

If you have not attempted yet, try acquiring multiple frames of each image and then use a free program like DSS (deepskystacker), which will allow you to combine/stack them all, providing you with a deeper image.

There are a lot of friendly people on IIS to help you with the entire process if you get hung up somewhere.

As for Orion's core being blown out, you can use some techniques in Photoshop or other smart photo software that will allow you to mask the core and add a deeper image over it, this will preserve the inner Triangulum.

[Eden (Brett)]

Thanks a lot for your advice, Sam. I did as you suggested and in revisiting Omega Centauri, collected several 6 minute exposures and stacked them. I tried DeepSkyStacker but unfortunately it kept generating an error message "Out Of Memory" -- it appears to have a 512Mb limit either in it's working set or on the generated output, so I went ahead and stacked them in Maxim instead.

I was pleasantly surprised to see a couple of galaxies in the resulting image, including a fairly prominent elliptical in the top left corner.

Full-sized version is available here:
http://s596.photobucket.com/user/Tau...tauri.png.html

Being one of my favourites in the night sky I am looking forward to seeing how far I can go with this target. Thanks again for your help, Sam.

Cheers,
Brett

[WingnutR32 (Sam)]

Well done, Brett, that is a great image.

If DeepSkyStacker is causing you problems, it may pay to look for the latest Beta version available on the Yahoo! Group.

Having said that, MaximDL with its stacking and alignment routines work quite well and is what I continue to use.