M20 Trifid Nebula



Scope: C8  f/4.8, Location: Laguna Mountains, CA,   1 July 2005  Camera: Artemis285

Exposure: 10 x 60 sec Luminance exposures (1x1) with IR block, 6 x 180 sec H-Alpha Exposure (1x1) 7 x 45 sec RGB exposures (2x2).

Processing: Images were captured Artemis Capture (as FITs). Aligned/stacked in Registax 3 and saved as FITS. Luminance, H-Alpha,  and Color channels were scaled and rough color balanced in Astroart. Channels were co-registered in Astroart. The IR Block exposure was the main exposure for the luminance construction - the H-Alpha exposure was combined with the IR Block for improved contrast on the nebula and smaller star sizes. The combine was a selective mask similar to fellow astronomer Don Waid's High Pass Sharpening method.  Final LRGB combine was done in Photoshop using Luminance Layering (or LLRGB).  Color balancing and final touches were done in Photoshop.   Final Image size is approximately 1392x1040.

North is up in this image. The image was guided for all exposures. M20 is a frequently imaged and popular object for observation. This image uses a narrowband HA exposure to add contrast to the red hues. M20 is a combined emission (red) and reflection (blue) nebula in the constellation of Sagittarius. Its distance is not precisely known. Estimates range from 2,200 to 7,600 light years. This image replaces an earlier image that can be seen in the Archives here.  Horizontal FOV is 30'

Image center is approximately - Equatorial 2000: RA: 18h 02m 16s Dec: -2258'22


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