sponsored by psychohistorian.org


Deep Sky Observer's Companion – the online database


Welcome, guest!

If you've already registered, please log in,

or register an observer profile for added functionality.


log in to manage your observing lists























Full database:

Entire DOCdb database of 18,816 objects.



NGC 7646 (17,808 of 18,816)


oc gc pln bn dn gx gxcl ast aka lost




finder chart

altitude today

altitude (year)


½°, , in DOCdb

Warning: date(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected the timezone 'UTC' for now, but please set date.timezone to select your timezone. in /home/yivumoo/public_html/show_object.php on line 167

Warning: fopen(/home/yivumoo/public_html/logs/showobject/20210926.txt): failed to open stream: Disk quota exceeded in /home/yivumoo/public_html/show_object.php on line 168

Warning: fwrite() expects parameter 1 to be resource, boolean given in /home/yivumoo/public_html/show_object.php on line 181

Warning: fclose() expects parameter 1 to be resource, boolean given in /home/yivumoo/public_html/show_object.php on line 182

show browsing

NGC 7646

NGC 7646, IC 5318, LEDA 71338, MCG-02-59-015

RA: 23h 24m 6.8s
Dec: −11° 51′ 37″

Con: Aquarius
Ch: MSA:1328, U2:304, SA:17


(reference key)

Type: galaxy, Sc

Mag: B=14.7, V=14

Size: 0.9′ x 0.6′
PA: 135°

History and Accurate Positions for the NGC/IC Objects (Corwin 2004)

NGC 7646, which may be = IC 5318, is another of the Leander-McCormick nebulae found by Muller, with its discovery announced before a decent position was available. Muller's description (magnitude = 14.5, diameter = 0.2 x 0.1, extended 260 deg) would fit IC 5318 if he saw only the bar of the galaxy. He also has a "*9, PA 10 deg, distance 3.6 arcmin." The star is actually 3.8 arcmin away at PA = 346 deg. Did Muller somehow get his PA into the wrong quadrant? (There is no sketch to help us in this case).

The main thing that makes me question the identification is the star of magnitude 9 or 10 superposed on the galaxy. Muller surely would have mentioned the star had he noticed it -- since the nature of the nebulae was still in debate in the late 1880's, nearby stars were often taken as possibly physically associated with the nebulae.

IC 5318 was found by Herbert Howe, using Chamberlain Observatory's 16-inch refractor. He measured the position of the galaxy, and noted the superposed star but, because of Muller's poor position, did not make a connection with the NGC number. Given the problems with Muller's position and description, we should perhaps simply note the possibility of the identity, and let it go at that.

Published comments

Sulentic & Tifft (1973)

The RNGC (Sulentic and Tifft 1973) notes that this is a galaxy. Their coded description reads S,UHISB,*TIP NP ARM.

Favourite lists

Lacaille's catalogue

The Messier objects

Dunlop's catalogue

The Bennett objects

The Caldwell list

Named DSOs

Object search

First search phrase


Second search phrase

Type of object to include:

open cluster
globular cluster
planetary nebula
bright nebula
dark nebula
galaxy cluster
asterism & stars

The Bug Report

DOCdb is still in beta-release.

Known issues, feature requests, and updates on bug fixes, are here:

> Bug Report


Found a bug? Have a comment or suggestion to improve DOCdb? Please let us know!

> Contact us


DOCdb is a free online resource that exists to promote deep sky observing.

You could help by sharing your observations, writing an article, digitizing and proof-reading historical material, and more.

> Find out more

Everything on DOCdb.net is © 2004-2010 by Auke Slotegraaf, unless stated otherwise or if you can prove you have divine permission to use it. Before using material published here, please consult the Creative Commons Attribution-Non-Commercial-Share Alike 2.5 License. Some material on DOCdb is copyright the individual authors. If in doubt, don't reproduce. And that goes for having children, too. Please note that the recommended browser for DOCdb is Firefox 3.x. You may also get good results with K-Meleon. Good luck if you're using IE. A successful experience with other browsers, including Opera and Safari, may vary.

Warning: Unknown: open(/tmp/sess_32e074e548c6836c4425ea04980f32a2, O_RDWR) failed: Disk quota exceeded (122) in Unknown on line 0

Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct () in Unknown on line 0