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The Integral Sign Galaxy
Edge-on Spiral Galaxy
aka MCG 12-7-28, UGC 3697
RA: 07h11m22.0s, Dec: +71°50'10" (2000) in Camelopardus
Magnitude: 14.60
Size: 3.2'x 0.4'
Redshift (z): 0.01
Light Time: 0.1 Gyr
Mean Surface Br. 23.4 Mag/arc-secē

Minimum requirements to detect: 8-inch scope under dark skies

The Integral Sign Galaxy (UGC 3697, MCG 12-7-28, PGC 20348) is a tiny, faint, very thin edge-on galaxy in Camelopardus. This one makes for an interesting sight because it is so very thin. It is also somewhat of a challenge.

This galaxy subtends 3.5' x 0.2' and is listed as 13.1 magnitude, but it appears to be to be somewhat fainter and will probably require excellent conditions to glimpse in an 8-inch. Its mean surface brightness is relatively high (22.5 mag/arc-sec2) so it may help to use as much magnification as conditions will permit.

Users of larger aperture instruments (> 16") should look for the curving ends to the disk that are so obvious in photographs and which lend this galaxy its name.

I observed Uppsala 3697 with my 18-inch Dob. Here are my notes:

This tiny, 13th-magnitude, edge-on spiral galaxy is a wonderful discovery. It lies between two 6-7th magnitude stars, which makes it an easy find. At 100x all I could make out was the hint of something nebulous at this position. The best view was at 165x, where it appears as a long, very thin streak. It gave the impression of a dark lane running along its length, but I think that was probably an illusion. I could hold the galaxy visible with averted vision. 425x proved to be too much magnification, at least on this night. The light was spread out such that the galaxy would only appear intermittently with averted vision. 

This image from the DSS shows a 20' x 20' field around Uppsala 3697. North is down and east is to the right.


This is the view of the field in a 8-inch at 100x.

Millennium Star Atlas Vol I Chart 16
Sky Atlas 2000 Chart 1
Uranometria 2000 Vol I Chart 21
Uranometria 2nd Ed. Chart 15
Herald-Bobroff Astroatlas B-02 C-16