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NGC4547

 

Basic Information


Location and Magnitude


Right Ascension: 12:34:51.8
Declination: +58:55:2
Constellation: UMA
Visual Magnitude: 14.5

Historic Information


Discoverer: Herschel W.
Year of discovery: 1789
Discovery aperture: 18.7

Observational


Summary description: vF, pS, E, vgbM, * 9 f 2', p of 2
Sub-type: E-S0

Corwin's Notes

===== NGC 4547 and 4549. These two galaxies are differently identified in CGCG and MCG. William Herschel found both, measured the brighter south-preceding galaxy twice, but the fainter north-following one just once. His positions reduce to (equinox 1950) N4547 12 32 32 +59 11 N4549 12 33 04 +59 15 These are not the positions used in the NGC, however. Those come from John Herschel. Precessing his measurements gives (again for 1950.0) N4547 12 32 26 +59 10.8 N4549 12 32 33 +59 12.4 At least his relative orientation of the objects is the same as his father's, even though he places the two objects much closer together. And the positions of NGC 4547 agree to within the errors of the Herschels' observations. Checking the GSC and the Sky Survey shows five galaxies in the area. MCG labels MCG +10-18-068 as N4547 and the preceding of the pair MCG +10-18-069 and -070 as N4549, while CGCG labels the pair as NGC 4547/9. The GSC positions of these and the other two in the area are MCG +10-18-068 12 32 16.24 +59 13 35.7 MCG +10-18-069 12 32 34.39 +59 11 31.4 = CGCG 293-030w = N4547 MCG +10-18-070 12 32 37.27 +59 11 16.6 = CGCG 293-030e MCG +10-18-071 12 32 54.48 +59 19 23.4 = VII Zw 473 MCG +10-18-072 12 33 04.01 +59 13 29.4 = N4549: There is also a faint star very close to JH's differential position from the brightest of these five galaxies. It's my guess that this is the object he mistook for the second of the two nebulae. Looking at the descriptions that WH gave the objects, it seems likely to me that the preceding of his two is identical with the brightest object in the area, namely MCG +10-18-069. If so, then WH's relative and absolute positions for the second object point exactly at MCG +10-18-072, making it N4549. The galaxy is faint enough, however, that it ought to be checked at the eyepiece. While I am reasonably sure about its identity as the second of the Herschels' nebulae here, I've still flagged it with a colon.

Steve's Notes

===== NGC 4547 18" (5/12/07): this is a very small and close double system oriented NW-SE. The slightly brighter and larger NW component is very faint, very small, round, 15" diameter while the SE component is extremely faint and small, round, 10" diameter. The pair is cleanly resolved, though the centers are just 27" apart. MCG +10-18-68 lies 3' NW and NGC 4549 is 4.3' NE. Located 3.8' WNW of a mag 10.5 star.