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Contains:  Pin-wheel nebula, M 99, NGC 4254
Getting plate-solving status, please wait...
M99, Coma (St. Katherine's) Pinwheel Galaxy, OSC (UHC-S), 6 Apr 2016, 


            David Dearden
M99, Coma (St. Katherine's) Pinwheel Galaxy, OSC (UHC-S), 6 Apr 2016

M99, Coma (St. Katherine's) Pinwheel Galaxy, OSC (UHC-S), 6 Apr 2016

Technical card

Resolution: 802x645

Dates:April 6, 2016

Frames: 18x600"

Integration: 3.0 hours

Avg. Moon age: 28.40 days

Avg. Moon phase: 1.44% job: 1031384

RA center: 184.714 degrees

DEC center: 14.416 degrees

Pixel scale: 1.867 arcsec/pixel

Orientation: 91.600 degrees

Field radius: 0.267 degrees

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


This was a first-time (for me) attempt at NGC4254, a beautiful spiral galaxy. I did not realize it is in the Messier catalog until I looked it up in Wikipedia (it's M99). Another night of excellent conditions, though I wasted a good bit due to yet another download failure. I used a new USB 3.0 hub with my equipment for this image, and doubt very much the failure was due to the hub; most likely it is the lousy camera driver setup for the DSI IIc. The failure happened not long after I went to bed and before the meridian. Sequence Generator Pro waits for the download when these download failures occur, or in any event I don't have it set correctly to recover. The only way I know to get the camera going again is to disconnected it from Nebulosity and then reconnect; you lose your data from the failed download. The scope tracked up to the EQMOD meridian limit and flipped automatically, so fortunately the mount and gear were protected.

Date: 6-7 Apr 2016
Subject: M99 (NGC 4254), Coma (St. Katherine’s) Pinwheel Galaxy
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 10 °C
Acquisition: Sequence Generator Pro with Nebulosity 4.0.4 ASCOM camera driver
Exposure: 18x600 s
Stacking: Neb 4, bad pixel map, bias included, 40 flats, match histograms, trans+rot align, Deep Sky Stacker 1.5σ κ-σ stack without drizzle.
Processing: StarTools 1.4.305: Crop; Wipe; Develop: 83.00%; HDR:Optimize; Color:Scientific, 200% saturation,; Deconvolute: 2.2 pix; Life:Moderate; Track: Smoothness 87%, 4.5 pix; Magic, shrink 2 pix. Photoshop CS6 + Astronomy Tools: Deep space noise reduction; Increase star color; Gradient Xterminator; Levels; Astroframe.



David Dearden
License: None (All rights reserved)

Sky plot

Sky plot


M99, Coma (St. Katherine's) Pinwheel Galaxy, OSC (UHC-S), 6 Apr 2016, 


            David Dearden