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. |