Contains: Sombrero galaxy, M 104, NGC 4594
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M104, Sombrero Galaxy, MyFocuser Pro 1st Light, OSC (UHC-S), 3-4 May 2016

Technical card

Resolution: 786x650

Dates: May 4, 2016

Frames: 18x600"

Integration: 3.0 hours

Avg. Moon age: 26.84 days

Avg. Moon phase: 7.95%

Astrometry.net job: 1063917

RA center: 189.977 degrees

DEC center: -11.632 degrees

Pixel scale: 1.865 arcsec/pixel

Orientation: -177.073 degrees

Field radius: 0.264 degrees

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

Description

This was a first use of my new MyFocuserPro digital stepper motor-based focuser. It performed quite well and positioning looks to be very reproducible. Unfortunately, the focusing algorithm in Sequence Generator Pro 2.5.0.23 wasn't up to the task for automatic focusing, but I understand this is a known issue (problems with scopes that have a central obstruction, like my Newtonian) that has been addressed in the 2.5.1 beta, so I downloaded that and will try it next time I'm on the sky. Otherwise, it was also a night of multiple mess-ups. I guess I was just too excited about using the new focuser, or maybe senility is creeping in. I started my session and the goto wasn't very good because I'd forgotten to lock the clutch on the Dec axis. So I fixed that and found Arcturus and dialed in the focuser. Then I did a goto to the Sombrero and again I was a little bit off, but close enough. After finding I couldn't make autofocus work very well, I went ahead and started my session and the guiding was pretty good. I got to the meridian flip and it failed! The mount simply failed to flip. I looked outside and saw the counterweight shaft sticking right up at the meridian. I had forgotten to install the counterweights! I'm amazed that I was able to do anything under those conditions; I guess I was just lucky about where the Sombrero Galaxy was in the sky relative to the balance point of my mount. So I installed the counterweights, re-parked and re-set the mount, and continued. Unfortunately, last night was one where focus did degrade as time went on, so I threw out some subs. The resulting image is perhaps not as good as my 2013 image (and maybe I should add in the 2013 data to improve it).

B revision: darkened the background!

Date: 3-4 May 2016
Subject: M104, Sombrero Galaxy
Scope: AT8IN+High Point Scientific Coma Corrector
Filter: Baader Planetarium UHC-S
Mount: EQ-6 (EQMOD)+AutoPEC
Guiding: Orion ST-80 + Antares 0.5x focal reducer + DSI Ic + PHD 2.6.1.1 (Win 7 ASCOM)
Camera: DSI IIc, no chiller CCD 15 °C
Acquisition: Sequence Generator Pro 2.5.0.23 with Nebulosity 4.1 ASCOM camera driver
Exposure: 18x600 s
Stacking: Neb 4, bad pixel map, bias included, 33 flats, nebula filter, match histograms, trans+rot align, Deep Sky Stacker 1.5σ κ-σ stack without drizzle.
Processing: StarTools 1.4.316: Crop; Wipe; Develop: 85.77%; HDR:Optimize; Contrast; Color:Scientific, 200% saturation, red bias reduce 1.70; Deconvolute: 2.5 pix; Track: Smoothness 87%, 4.5 pix; Magic, shrink 2 pix. Photoshop CS6 + Astronomy Tools: Deep space noise reduction; Increase star color; layer masked unsharp mask for dust lane; Astroframe.

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Author

David Dearden
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M104, Sombrero Galaxy, MyFocuser Pro 1st Light, OSC (UHC-S), 3-4 May 2016, David Dearden