Got another 20 subs at 15-minutes per sub on IC410 last night, so added that to the 20 subs I got the night before and this is the result. Clearly an improvement, so I might try and get another 20 (and another 20?) and see what happens. In the early days of Hyperstar imaging I always went for 100 subs for an ultra clean (high SNR) image, but then the subs were only 1-minute long, so that was a lot easier (on the total time taken). 100 subs at 15-minutes per sub is 25 hours of total data (and with 2 x 200mm lenses) 12.5 hours of actual imaging time. So it would not be too surprising to get a really nice result with all that effort (and data).
