M67

[alan4908]

An LRGB image of the open cluster M67 that was previously posted in the Deep Sky imaging section. It represents just under 3.4 hours integration time and was taken with my SW Esprit 150 and SX Trius 814 camera.

The image was captured with relatively short (300s) sub exposures, mainly in an attempt to avoid camera non-linear effects from bright stars.  It was processed with four software packages:

CCDstack: calibration, registration, data rejection, stacking, DDP stretch.

PS: colour enhancement, colour linear stretch, mask generation, noise reduction

Pixinsight: gradient reduction (DBE) and Photometric colour calibration.

Neat Image: background noise reduction

To avoid excessive star bloat and to maximize star colour, I also decided to process the image using two different Digital Development Process stretches of the Lum, a high one, targeting any dim objects and a low one, targeting the bright stars. The result image was then blended together in PS with an appropriate mask. 

Alan

LIGHTS: L:9, R:13, G:9, B:10 x 300s, DARKS:30, BIAS:100, FLATS:40 all at -20C.