NGC/IC Project Restoration Effort

===== NGC 5109 = NGC 5113. Both objects were found by William Herschel, N5109 = H II 826 on 17 March 1790, and N5113 = H III 808 eleven months earlier on 24 April 1789. His descriptions are very nearly the same: "F, S, E" and "cF, S, E." John Herschel lists only one galaxy here (h1588) which he identifies as H II 826 (= N5109), in spite of the fact that his father's position for N5109 is a full minute of time and nearly two arcmin off, while that for N5113 is only 10 seconds of time and just over one arcmin off. Sir John's description "vF, pmE, 30sec" is also closer to his father's "cF" for N5113 than it is to the "F" for N5109. Dreyer followed Sir John's lead here, but added a note to the NGC description: "perhaps = N5109." He reinforced this in his 1912 MN paper and collection of Sir William's papers, and suggested that the number N5113 be discarded. Reinmuth agreed, and accepted the equality of the two numbers. CGCG, however, located a small galaxy six arcmin north of the NGC position for N5113, and assigned the number to that galaxy. UGC followed along. Given the data above, and the fact that this galaxy is 1.6 magnitudes fainter than the brighter one, this identification is certainly incorrect. So, I have followed Dreyer (1912) in equating the two NGC numbers. The galaxy itself is a peculiar spiral, with a knotty bar-like structure in the middle. The SDSS image shows that the bulge and nucleus are offset into the northern end of the object, while this knotty structure toward the middle is actually a group of bright HII regions. So, I have taken the nucleus to be located eccentrically in the northern end. Note that many of the published positions, as well as those that I measured earlier, apply to the more centrally-located knots; I've labeled them as such in the table.

===== NGC 5109 18" (5/30/03): fairly faint, nearly edge-on 7:2 NNW-SSE, 1.2'x0.35', broad concentration with a slightly brighter core.