Object of the Week, April 25, 2021 - NGC 4517 (NGC 4437)
NGC 4517 = NGC 4437 (KPG 344 = NGC 4517 + NGC 4517A)
Active Galaxy Nucleus in Virgo
RA (J2000): 12 32 45.6
Dec (J2000): +00 06 59
Vmag: 10.4
Size: 10.5'x1.5'
William Herschel discovered NGC 4517 on 22. Feb 1784 with a slightly false position. His discovery found entry in the NGC as NGC 4517. Later (44 years) on 14. Apr 1828 his son John Herschel "rediscovered" this galaxy with a fault of 5 min of RA, so "his" discovery found entry in the NGC as NGC 4437. Perhaps Steve can give some more information on the confusing discovery and the solution of its faults.
Physical, this large "Sc-type" edge-on galaxy is similar, but somewhat bigger, than our own milky way. It is around 46 million light-years away and belongs to larger LGG 292 group of galaxies. SIMBAD noted the galaxy as "Active Galaxy Nucleus". X-Ray observations found a strong source ULX1 [2011MNRAS.414.1011W] which indicates the existence of a black hole. Some articles mentions globular clusters researches, but unfortunately Goudfrooij et al. [2003MNRAS.343..665G] only found candidates fainter than 21.7 Vmag.
From the observing side the RFGC (Revised Flat Galaxy Catalogue) designation (2315) shows the extreme inclination of this galaxy. The special is a 10.9 Vmag star directly north of the galaxy. It is shaped by lots of HII regions. I mentioned to see this first ones in a quick and dirty look with a 16-inch. Unfortunately I don't find any paper which listed or guide a nomenclature of them. The prominent dark lane should be visible even in smaller aperture. A nice addition is the companion NGC 4517A (UGC 7685) 17' north. It shows a beautiful face-on character with some fainter arms. But now it is your turn to report your experiences with this beauty.
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