constellation of Cassiopeia

[happy-kat]

Taken December on a very cold but clear night from a suburban back garden illuminated by street lights.

12 lights (1 x 5 minutes 8 x 3 minutes 2 x 2 minutes 1 x 1.5 minutes) 28 x flats 15 x dark flats 30 x bias total 34 minutes

Manual barn door tracker, unmodded Canon 1100d 40mm pancake lens f4 ISO 400

I find that the 10 second window works well if I work the mount behind the clock I can reliably get 2-3 minute exposures, bad star shapes occur when I get ahead of the clock, so I work behind it with a 5 second float. (assuming 400/40 gives 10 seconds before trails evident on static mount)

Stacked in DSS, cropped and processed in StarTools saved as jpg (gave higher compression on file size). In StarTools I added refraction spikes to highlight the constellation stars. I have had a lot of trail and error testing in DSS as 2 of the frames had really strong aeroplane trails and a 3rd a flaring satellite, being on the Gatwick flight path and the airport is less than 20 miles away one image had a big 4 jet with blazing landing lights on and my usual preferred option of kappa-sigma clipping (does a great job on star shape) wasn't removing them even with a reference frame selected, so had to use median on the lights which may have cost some detail. 

I did have two lots of data for this area giving over an hours worth, but they were  from two different nights a week apart and the ISO was different, the focus was not on the spot on the first lot and they didn't combine well in DSS.

I have created so many processes of this target, it is both a learning experience but also a time gobbler.

Astrometry.net was used to plate solve the image. There are a lot of bits in that area from the Double Custer to Caroline's Rose Cluster. 

 

This if my home made barn door tracker. It is designed to sit on a flat chair and with three adjustable feet can be set level, I sit next to it and work the turning cd disk (under the bottom board out of sight). The black circle is the button battery for a red led that shines unto the winding disk so i can can where the pointer is. The red dot finder enables the tracker hinge to be aligned with Polaris and the camera sits on the ball head with it's own red dot finder. The angle of the board's mount support for the actual barn door which is fixed to it is set for my latitude. This mount is rock steady.