Horsehead M13 Horsehead

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Date: May 29, 2006
Exposure: LRGB 72:50:60:50 : 23 x 180 L, 10 x 300 R, 12 x 300 G, and 10 x 300 B
Processing: CCDSoftV5 for image acquisition, MaxIm for Image calibration,(5 flats each RGB, dark subtracted and median combined, 20 bias frames median combined, 10-900s darks median combined), alignment, normalization, color combining. PixInsight for background correction and color gradient removal. Photoshop CS for final color balance and jpg conversion.
Conditions: Average, Mag 3-4 Skies
Scope: RCOS 16" Truss
Camera: SBIG STL-6303, Astrodon LRGB filters, -20°
Comments: This is my first attempt at imaging a Globular Cluster with the RCOS scope and the STL-6303 camera. I used some time before I started and took some test exposures to find the "blooming" point and to make sure that when I reduced the exposure time to be under that point that I was still overcoming the readout noise of the camera. I was lucky in that the first night had pretty good seeing and the luminance exposures stayed around 2" FWHM. I was interupted by clouds and had to finish 2 nights later and the seeing wasn't as good, but I just needed G and B exposures so the final image didn't suffer too much.