British Astronomical Association
Supporting amateur astronomers since 1890

Secondary menu

Main menu

BAA Gallery Picture of the Week
Image search

Messier 101


Expand image

About this observation
Graham Roberts
Time of observation
29/03/2019 - 22:00
Messier 101
Observing location
Fairvale Observatory – Redhill – Surrey – UK
William Optics GT81 & 50mm guidescope
ZWO1600MM-Cool mono CMOS sensor
L 31 x 180 sec HaRGB each 16×180 sec
Like This Image

Graham comments that: With nearly 5-hours of subs, processing of M101 would be a challenge in order to bring out the galaxy’s colours and perhaps highlight the stellar nursery areas that are found along the spiral arms and are rich in Ha-light.  To do this I first changed the RGB image stack to Lab Colour in Photoshop, increased the saturation in the (a) and (b) channels before returning to RGB mode.  This had the desired effect of successfully enhancing the colours, which can otherwise look washed-out after stacking, stretching and combining.  After this I split the RGB channels and pasted the Ha-stack into the Red channel, before re-combining again into an RGB image, at which point the H II regions along the spiral arms just lit up!  These were both new processing techniques for me that greatly improved the final image and hold great promise for processing HaLRGB objects in the future.

Copyright of all images and other observations submitted to the BAA remains with the owner of the work. Reproduction of the work by third-parties is expressly forbidden without the consent of the copyright holder. For more information, please contact the webmaster.