Image of the day

Captured by
Douglas Rollain

Lion Nebula SH2-132 - RC71

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Posts Made By: Jim Thommes

July 17, 2007 04:35 AM Forum: CCD Imaging and Processing/Deep Sky

vdB132 and NGC6914; Cygnus

Posted By Jim Thommes
Hi Tom,
Well done. I took a look at an old image I had of this area and I can see I really lost out on the blue reflection. I like your idea of adding a clear channel, but it seems that your rg"B" data did pretty well.

July 17, 2007 04:42 AM Forum: CCD Imaging and Processing/Deep Sky

Prawn Nebula - HaRGB

Posted By Jim Thommes
Thanks all for your comments...

Dan, I neglected to mention in my processing details that I did an extinction correction on this image. It is approximate of course based on atmospheric averages rather than any "calibration" I did for my area. At midrange curves I scaled RGB 121:128:135 respectively. This was after G2V calibrationfrom some data taken awhile back on my image train. I know its crude, but it helps.

July 25, 2007 05:10 AM Forum: CCD Imaging and Processing/Deep Sky

M27 with unmodded XTi

Posted By Jim Thommes
Joe,
Very cool image. I believe you got excellent results. Amazing given the breeze, manual guiding and short exposures. Great job.

July 25, 2007 05:15 AM Forum: CCD Imaging and Processing/Deep Sky

A BUSY night...

Posted By Jim Thommes
Whoa! A busy night indeed Ivan. Nice shots. Looks like you were indeed busy and had a lot of fun.

I glad the weather somewhat cooperated. Not much to be done about the mosquitos though. Ah, the pleasures of midsummer astronomy.

July 25, 2007 05:24 AM Forum: CCD Imaging and Processing/Deep Sky

Star Fields and Clusters

Posted By Jim Thommes
Thanks for the comments folks...

Jason, Yes I did get Gemini with the G11. I don't know what it would be like to use a G11 with it - simpler I guess.

Personally, I really like the Gemini. I know some would say it is complicated and non-intuitive. I like the ability to configure the mount just the way I want it (limits, speeds, etc.). I also take the time to build a 6 to 8 star model - I have found that I can land a target on my CCD (doing a 30 minute field) pretty reliably. Doing the model at the start of the session really only takes me about 10 minutes.

July 26, 2007 05:37 AM Forum: CCD Imaging and Processing/Deep Sky

NGC281

Posted By Jim Thommes
Hi Jason,
Nice set up and nice shot. I like the more stretched version on my monitor.

July 29, 2007 04:58 AM Forum: CCD Imaging and Processing/Deep Sky

Lagoon Nebula with a difference

Posted By Jim Thommes
Ha!
Pretty cool Greg.

I have to tell you, the Lagoon really has stars around it. grin


July 29, 2007 05:05 AM Forum: CCD Imaging and Processing/Deep Sky

Crossing The Veil

Posted By Jim Thommes
Really nice image Mario!

Interesting catch on the airplane engines. I guess it just shows that the central flashing light must have been a really fast strobe to not blur the engines.

What would be a nice intellectual exercise would be to assume a reasonable speed for the plane. Compare it to your image scale and derive it's distance from the camera and the apparent time duration of the strobe.

July 29, 2007 05:13 AM Forum: CCD Imaging and Processing/Deep Sky

A short go at the western Veil

Posted By Jim Thommes
Nicely done Tom.

From your subject line I was expecting just the Veil, but of course your image has Pickering's Triangle as well with great detail.

I assume this is Ha. What optics and camera? - they did a nice job with 52 Cygni.

July 30, 2007 01:31 AM Forum: CCD Imaging and Processing/Deep Sky

Sh2-112 - Ha RGB

Posted By Jim Thommes
Thanks all for the comments...

Eric,
Using focal reducers on the C8 is always a bit iffy. In this case I used the Meade 0.33x reducer. I had it spaced from the CCD about 48 mm. For the rated reduction, I think the optimum is 58 mm. It is somewhat forgiving for shorter distances if your imaging set up back focus is short. In fact, it can perform relatively well. Beyond the 58 mm reducer spacing and edge quality deteriorates rapidly.

My chip is 11 mm in diagonal - much bigger and the Meade 0.33x reducer begins to loose it. So small chip size and be sure you don't go over 58 mm and some results can be achieved. Looking closely at the image though, you can see the optics imperfections impacting the edge of the frame.

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