M109 - Galaxy in Ursa Major

Object data: M109 (NGC 3992) is a barred spiral galaxy with a beautiful structure located 55 million light years distant in the constellation of Ursa Major, just 40' SE of the star Gamma Ursae Majoris (Phad, or Phecda). It is thus quite easy to find in binoculars, though only as a faint fuzzy patch since its visual magnitude is only 9.8. It was discovered by Pierre Méchain (Charles Messier's assistant) on March 12, 1781, and initially classified by Charles Messier as number 99 but added to the "official" Messier catalog as M109 in 1953 by Owen Gingerich. William Herschel found this galaxy independently on April 12, 1789. This mag 9.8 galaxy has quite low surface brightness.

Date: 08/02/05
Location: Southern France
Conditions: Calm, no dew, transparency=8, seeing=7
Optics: Ritchey-Chretien 12.5" f/9 (from RCOS)
Mount: AP 900 GTO on Portable Pier
Camera: SBIG ST-8E / CFW-8
Guiding: Integral ST-8E autoguider
Exposure: LRGB: Luminance: 8x15 minutes; RGB: 15:15:30 minutes binned 2x2

Processing: Image acquisition and initial processing was done using Maxim DL, subsequent processing was done using RegiStar and Photoshop. The processing method has been recently updated based on Russell Croman's resources page and advice from Adam Block for which I am indebted.

Notes: This is my first attempt at M109 - the outer parts have quite low surface brightness making it relatively difficult to record.





All text and images Copyright © 1997-2022 by Philip Perkins. All rights reserved.