M101 subs sequence

[vernmid]

Hi All,

I was attempting to capture M101 on 31st March. I took 21 x 300s subs (ISO800)  between 21:15 and 23:30. Kit was 130PDS + HEQ5 + Modified 1100d

As a means to finding a method to weed out bad subs I merged my jpeg subs into a short movie, intending to be able to easily compare the details.

I was very interested to see what a difference a few hours made to local light pollution/residual sun light etc. Curse the pesky clock change ;-)

Movie attached for those who might be interested in a sub-sequence. Hope it is of interest to someone

Thanks

Vern

[bobro]

Thanks for that. Agrees with the findings from my location (Bortle 4) where, when imaging with an RGB DSLR, exposures before around 23:00 are not especially worthwhile due to local light pollution (ignoring sun and moon effects). If I can stay up late enough, 1:00 am can provide a very useful darker background that helps with fainter targets.

Note: if your camera subs are jpeg it would be better to change to raw to allow stretching without obvious steps in the image appearance.

 

[vernmid]

Hi bobro

These were also from a Bortle 4, Stockbridge Hampshire. I think I am coming to the same conclusion regarding staying up late, just a pity about the going to work thing!

Subs are raw+jpeg so I get both. Jpegs are just for ease of sorting really.

I was also amazed by how many satellite trails I captured! Maybe 25% of the subs had them but hopefully removed by DSS averaging

Thanks for your comments

Vern

 

 

[bobro]

1 hour ago, vernmid said:

I was also amazed by how many satellite trails I captured! Maybe 25% of the subs had them but hopefully removed by DSS averaging

Hi Vern,

Kappa sigma stacking works better than averaging to remove satellite (and plane) trails as it rejects pixel values that are too different from the other images. It also helps reduce noise in the same way, particularly in conjunction with dithering.

Bob