Image of the day

Captured by
Lawrence Parchman

Sculptor Galaxy (NGC 253)

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Posts Made By: dan kowall

November 21, 2006 04:38 PM Forum: CCD Imaging and Processing/Deep Sky

M45 through my finder scope.

Posted By dan kowall
That's pretty good, Ralph.
Blooming stars and reflections usually plague M45 images, but you've handled it well.

dan

November 24, 2006 02:42 PM Forum: CCD Imaging and Processing/Deep Sky

NGC 2174

Posted By dan kowall
Thanks, guys!
I made it easy on myself and got some good data for this one. Processing sure goes easier and quicker when starting out with lots of signal.

dan

November 25, 2006 01:57 AM Forum: CCD Imaging and Processing/Deep Sky

My perennial attempt at the Horsehead...

Posted By dan kowall
That's looking pretty good, Joe!

dan

November 25, 2006 04:47 PM Forum: CCD Imaging and Processing/Deep Sky

Pacman

Posted By dan kowall
You have excellent detail, David, which means you did a good job of gathering the data.
It's naturally processed, too.
You've clipped your black point just a bit, though. Readjusting that will reveal some hidden nebulosity.
Good job.

dan kowall

November 29, 2006 08:13 PM Forum: Mounts

Homebuilt EQ mounts

Posted By dan kowall
Hi Tony,
I'm amazed at the high quality of mounts that some people have made.
As others pointed out, the cost in materials isn't enormous but the amount of time that you put in building the mount is enormous. I don't think that I would tackle this without having my own machine shop. Having your local machine shop build one-of-a-kind parts gets expensive real fast.
The satisfaction of producing a well-made mount by yourself is, however, as they say, priceless.
Here's one mount project:
http://www.heavensgloryobservatory.com/new_mount_design.htm
If you do buy a commercial mount, there are still many opportunities to do machining, etc. You could keep yourself quite busy making adaptors, custom knobs, and whatnot for various projects. I always find myself doing some metalworking thing for the observatory.

dan kowall
photonhunter.com

December 3, 2006 03:38 PM Forum: CCD Imaging and Processing/Deep Sky

M45 AstroArt4 5"Tmb Apo SXV M25C

Posted By dan kowall
Despite your problems with the reducer, you still have good color and detail in the nebulosity, Dietmar.

dan kowall

December 9, 2006 03:58 PM Forum: CCD Imaging and Processing/Deep Sky

Congrats Dan Kowall

Posted By dan kowall
Thanks, guys.
This one was my first, and I ain't too proud to admit that this was a big thrill for me.

dan

December 10, 2006 02:39 PM Forum: CCD Imaging and Processing/Deep Sky

Sculptor Galaxy

Posted By dan kowall
Well done in all respects, Jim.
It's one of your best.
My regards,

dan

December 18, 2006 02:47 PM Forum: CCD Imaging and Processing/Deep Sky

Another classic: la vie en Rosette

Posted By dan kowall
Gianluca Valentini said:
........so I had some problems starting with the focus: I forgot to lock the focuser and I believe there has been a little sagging of the FSQ focuser since 2 of the 4 20min subexposures were slightly out of focus (could be a temperature change, but I doubt it, since when I refocused and locked the focuser everything went alright..........

I tried many different settings for sky flats (average at 20,30,40 and 50% of the saturation level............ but the images are awful after reduction (dark+flat). All flats are dark subtracted, but the color image turns out to be super grainy after I apply the flats................
Hi Luca,
First of all, your image looks pretty good as is. I'm sure Edith Piaf would approve. You are progressing quickly.

As for focusing, do you have a motorised focuser, e.g. a RoboFocus? The critical focus zone of an FSQ is measured in microns since it is such a fast, f/5, scope. It is extremely difficult to focus an FSQ without being automated with a motor and using software to determine focus.
The FSQ is also famous for being sensitive to changes in temperature when focusing. Some people refocus their FSQ every change of 1-2 degrees C!

As for your flats, it is said that taking good flats is almost an art form.
If your sky flats are less than one minute long, don't subtract a dark from them. It will add more noise to your flat and is not needed in this instance. You will need to subtact a bias from your flats, though.
When making a flat, you should have at least 10-12 subexposures to get good results.
When making a bias, you should have at least 20-30 subexposures.

The best program that I have used for image calibration is CCDStack:
http://www.ccdware.com/products/ccdstack/
Image registration and data rejection algorithms are also excellent with this program.
I hope this helps,

dan

December 18, 2006 02:53 PM Forum: CCD Imaging and Processing/Deep Sky

M39

Posted By dan kowall
That's really nice, Jim.
The stars are naturally processed and the color is good.
Well done.

dan

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