NGC 457, ET Cluster (David Dearden)

NGC 457, ET Cluster

The ET cluster was a very easy find; there are bright stars with which to line up the Telrad and I found it on the first try. Conditions, especially seeing, are quite good tonight. I'm attempting to do a bit better with the coma corrector so I increased the distance between the corrector and the image plane by about 15 mm and refocused. I think it looks better but won't really be able to tell until I process things. (It is not better. It is much worse.) Also, tonight I'm guiding at 4x rather than the usual 2x; I spent a lot of time tonight trying to figure out why my tracking has been poor as of late and finally decided the most important factor is still the tightness of the clutch. There is a lot wrong with this image in that the coma corrector spacing is obviously bad and the IR filter was not inserted, but I’m including it here anyway.

I attempted to fix up some of the mess using StarTools 1.3 to do the post-processing.

Date: 5 Nov 2012

Subject: NGC 457 “ET” Cluster

Scope: AT8IN+High Point Scientific coma corrector+0.5x Antares telereducer

Filter: None (and I do mean “NONE” in that I inadvertently left off the IR filter)

Mount: CG-5 (Synta motors)

Guiding: Orion ST80 + DSI Ic + PHD 1.13.6

Camera: DSI IIc (1.5 A, 6.0 V T = 4 °C)

Acquisition: Nebulosity 3.1.2, no dither

Exposure: 82/90 x 60 s

Stacking: Neb 3, bad pixel map & flats, bias included, normalize first, trans+rot align, 1.5 SD stack

Processing: Neb 3 slight power stretch, Keller stretch, saturation boost; CS6 GradientXTerminator (bad vignetting despite the flats), Astronomy Tools deep space & space noise reduction, star color enhance.

Original
Final
B

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