M 108 (NGC 3556) Galaxy in Ursa Major

Located at: RA 11 hours 11 minutes 30 seconds, Dec +55 degrees 40 minutes 19 seconds

Size: 8.7' x 2.2' Magnitude: 10.7 blue Class: SB(s)cd sp HII

North is up

West to the right


 8" f5 Newtonian reflector


  ST-8XME, self-guided, binned 1x1, temp -20 & -25c, camera control MaxIm DL 4.56


Lumicon Red filter, 720 minutes (72 x 10 minute subs), 04/3/4/5/6/2009; seeing 2.2-4.5 FWHM per CCDStack


CCDStack, Photoshop 7.0


 Rolling Roof Observatory, Thousand Oaks, CA 91360 (+34d 13m 29s -118h 52m 20s)


I made a strategic mistake in re-imaging M 108. I had started the night wanting to re-image M 97 (slight focus problem), but at the last minute centered on M 108. I had forgotten that I have a decent image taken last year with the Deep Sky filter. Even though this image is four hours longer ... it is essentially similar to the 470 minute Deep Sky filter image. This image was taken with a lot of moon in the sky for the entire sequence (new Moon April 9). See the 14.5" version.

From the the NGC / IC Project:

Contemporary Visual Observation(s) for NGC 3556

NGC 3556 = M108 = U06225 = MCG +09-18-098 = CGCG 267-048 = CGCG 268-001 = PGC 
11 11 31.8 +55 40 14
V = 10.0;  Size 8.7x2.2;  SB = 13.1;  PA = 80d

17.5": very bright, very large, edge-on 4:1 WSW-ENE, 8.0'x2.0'.  A mag 12 star 
is superimposed just westW of center (V = 12.5) appearing similar to a bright 
stellar nucleus.  Two fainter stars are also superimposed E of the core.  A 
bright knot is visible west of the core (1.3' W of the star) and the region near 
the core appears dusty.  A mag 12 star is just S of the W end 4.9' from the 

13": fairly bright, very elongated, stellar nucleus.

- by Steve Gottlieb