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NGC 4298 & 4302, OSC (UHC-S), 11 May 2016 (automated refocusing first light)

Technical card

Resolution: 776x437

Dates: May 11, 2016

Baader Planetarium UHC-S Filter: 30x300"
Baader Planetarium UHC-S Filter: 4x600"

Integration: 3.2 hours

Avg. Moon age: 4.69 days

Avg. Moon phase: 22.86% job: 1073433

Locations: Mapleton Lateral Observatory, Mapleton, Utah, United States


This was my first-time observation of this interesting galaxy pair, and the first time I have been able to try automated refocusing using Robert Brown's MyFocuserPro. The focuser and the Sequence Generator Pro focusing algorithm both worked very well. This was also my first use of a cheap gamepad with EQMOD to move my mount around without having to carry my laptop out to my scope. That made lining up on a sync star (Arcturus in this case) really easy. Finally, I put my old Orion Accufocus DC focus motor controlled through a Shoestring FCUSB on my ST-80 guide scope, so now I can remotely focus both the ST-80 and the AT8IN. I tried a lot of new things on this image (it has been raining for quite a while!) and I'm happy with all of them. I did still end up throwing out some subs as I had quite a bit of differential flexure. In fact, I started out with 10-minute subs but decided to drop back to 5 minutes because flexure was blurring the 10-minute data. I should be able to tighten things up and do a little better, but ultimately I'm sure I'll end up using an off-axis guider or something similar. Anyway, because of the flexure and problems getting framed exactly the same after the meridian flip, I ended up having to crop a lot off this image to remove stacking artifacts.

Date: 10-11 May 2016
Subject: NGC 4298 & 4302
Scope: AT8IN+High Point Scientific Coma Corrector
Filter: Baader Planetarium UHC-S
Mount: EQ-6 (EQMOD)+PEC
Guiding: Orion ST-80 + Antares 0.5x focal reducer + DSI Ic + PHD (Win 7 ASCOM)
Camera: DSI IIc, no chiller CCD 5 °C
Acquisition: Sequence Generator Pro with Nebulosity 4.0.4 ASCOM camera driver
Exposure: 4x600+29x300 s
Stacking: Neb 4, bad pixel map, bias included, 33 flats, match histograms, trans+rot align, Neb 4 40-60%tile stack.
Processing: StarTools 1.4.316: Crop; Wipe; Develop: 80.80%; HDR:Optimize; Color:Scientific, 200% saturation, red bias reduce 1.43; Deconvolute: 2.6 pix; Track: Smoothness 87%, 6.3 pix; Magic, shrink 2 pix. Photoshop CS6 + Astronomy Tools: Deep space noise reduction; Levels; Increase star color; make stars smaller; Astroframe.



David Dearden


NGC 4298 & 4302, OSC (UHC-S), 11 May 2016 (automated refocusing first light), David Dearden