NGC7635 Bubble Nebula in Red Filter from 18" Cassegrain with collimation tests

Click image to enlarge

Made after collimation tests (see below)

shot on November 13, 2004 from my backyard in Castro Valley, Ca.

Compact Collapsible Cassegrain 18" @f/12.60 (F=5760mm)

IMG6303E camera @-35C

AO7 @ 16 Hz

RCOS Dichroic beam splitter

ST7E guide camera

FLI CFW1 Filter wheel

Optec  Red  filter

15 exposures of 5 minutes through Optec Red Filter (binned 2x2)


--Collimation tests: Shot the same star inside and outside of focus at the center and each corner of the FOV

Need to investigate the asymmetry of left versus right. Suspicion is that a tilt of the imaging train relative to the optical axis is the cause. Needs further investigation.

Inside focus (click to enlarge)

Outside focus (click to enlarge)


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