This is a rework of a picture I took last year. The only difference is that the one taken last year (http://geza.zenfolio.com/p17317512/h35d67999#h35d67999
) used a wider field of view camera lens. This region is just to the south of the very popular North America and Pelican nebula complex.
The image quality is poorer than usual, as I bumped into an issue I couldn't resolve out in the filed as I was shooting. More details on this are below if you care.
Date: July 6, 2013
Time: 10:45 pm - 3:00 am
Camera: SBIG STF-8300M
CCD Temperature: -6 C
Optics: Takahashi Sky 90 II @ 406 mm fl (f/4.5)
Filter: Astrodon 5 nm H-alpha
Light frames: 14x15 min
Dark frames: none
Flat frames: 7
Guiding: Orion SSAG @ Orion finder (~162 mm)
Mount: Losmandy GM-8
Processing: Stacking in DeepSkyStacker, Curves and Levels PSCS6.
Other notes: I was very surprised to see nobody on the mountain. While I am usually happy when I have the mountain to myself, this night I would not have minded some company as I heard a couple of gun shots fired in the distance. I just turned up the music a bit to tune out the gun shots.
From a technical point of view, this was a very frustrating night. Two of my 16 frames came out with massive field rotation, and I was not able to resolve the issue in the field - I checked the CAA and the focus lock for slop but they were fine. Only after the session (and after 5 hours of sleep) did I bother to check the tube rings (made by Parallax). Indeed, the rings were the weakest connection, but even this required substantial torque to rotate the rig. The curious thing is that I have never loosened those screws, so I don't quite understand why the scope moved now and not earlier ... For now I added a couple of layers of double sided sticky tape between the tube rings and the scope. Hopefully, this issue is now resolved. The field rotation between frames resulted in some star trailing in the corners. While it's not ugly, it is noticeable, and I am not happy about it. On the other hand, I can call myself lucky that I got any data out of this night at all.