NGC 6946 (UGC 11597, Arp 29) Galaxy in Cygnus

Located at: RA 20 hours 34 minutes 52 seconds; Dec +60 degrees 09 minutes 15 seconds

Size: 11.6' x 9.8' Magnitude: 9.6 blue Class: SAB(rs)cd HII

North is up

West to the right

Telescope:

 8" f5 Newtonian reflector

Camera:

 ST-8XME, self-guided, binned 1x1, temp -15c, camera control MaxIm DL 4.56

Image:

 Lumicon Red filter, 450 minutes (45 x 10 minute subs), 07/5/6/8/2008; seeing 2.3-3.1 FWHM per CCDStack

Processing:

CCDStack 1.3.7, Photoshop 7.0

Location:

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

Notes:

This image is a work in progress ... I needed to reshoot this galaxy because my previous image was a 70 minute unfiltered image using my film coma corrector (for use with the 2" Lumicon off-axis guider). Since I do not have an adaptor to make the required corrector to focal plane distance, the star images were larger than without the coma corrector. This is my first image with the Lumicon Red filter. I would like to add more exposure time, but for now, this image is better than what I had. NGC 6946 is just under 40 minutes SSE of the rich open cluster NGC 6939.

See the 14.5" version.

From the NGC / IC Project:

Contemporary Visual Observation(s) for NGC 6946

NGC 6946 = UGC 11597 = MCG +10-29-006 = CGCG 304-006 = Arp 29
20 34 52.3 +60 09 14
V = 08.8;  Size 11.5x9.8;  SB = 13.8

18" (10/9/04): viewed type II supernova 2004e, discovered 9/27/04 (13 days ago) 
and appeared at approximately mag 12.8.  It was easily identified using a 
photographic finder chart.  The supernova is located 4.1' E and 1.9' S of the 
nucleus, just west of a pair of mag 13/13.5 stars at 12" separation and was 
comparable to the brighter star of this pair.  A fainter mag 14.4 star is close 
WSW and the three stars plus supernova form a small wedge of Sagitta shaped 
group.  This is the 8th supernova discovered in N6946 since 1917.

17.5" (8/29/92): bright, very large, 6' diameter to main body, elongated 3:2 ~E-
W.  Three arms are visible.  A long bright arm is attached at the north side of 
the core and trails to the east.  This eastern arm splits; a short fainter 
branch bends south following the core and a long curving bright arm terminates 
with a very faint, very small HII knot.  On the west side a fainter arm shoots 
sharply to the north from the core.  These outer arms significantly increase the 
diameter of the main body.  The galaxy has a very large brighter middle but the 
core is just a very small brighter region close SW of the geometric center.  A 
very faint stellar nucleus was seen with direct vision.  Observation from 
12,000' in the White Mountains.

17.5" (8/13/88): main spiral arm very prominent and easily seen to split.

17.5" (9/14/85): bright, large, brighter central core.  A prominent arm attached 
on the NE side of the core and trailing to the east.  This arms splits - the 
shorter arm is close to the core and a brighter region or arm to the west.

13" (7/27/84): bright arm on the east side highly suspected to branch or split 
into two arms.  Also an arm or brighter region seen on the opposite side of the 
galaxy pointing W a short way.

- by Steve Gottlieb