Hi All,
I was out last night going through some Herschel's in Ursa Minor and came across NGC 5547 which at 337x looked like it had an extended core or a double core. I went looking online and in LEDA. In a couple of references I see the second core listed as UGC 9095A or PGC 200313. Can I assume those designations are correct? Has anyone double checked the name of the second core area after you did your observation?
Here is some info on NGC 47 from the cseligman.com site:
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NGC 5547 (= PGC 50543, and not = IC 4404)
Discovered (Dec 20, 1797) by William Herschel
Also observed (Jul 24, 1887 and Apr 24, 1900) by Guillaume Bigourdan
A magnitude 13.9 spiral galaxy (type S? pec) in Ursa Minor (RA 14 09 45.3, Dec +78 36 04)
Historical Identification: Per Dreyer, NGC 5547 (= GC 3837, WH III 948, 1860 RA 14 11 36, NPD 10 44.8) is "extremely faint, very small, extended 0°±". The position precesses to RA 14 10 09.6, Dec +78 35 51, about 1.2 arcmin east southeast of the galaxy listed above, the description is a reasonable fit and there is nothing comparable nearby, so the identification is certain.
Discovery Notes: NGC 5547 is misidentified in LEDA (and per Corwin, most likely in other places as well) as also being IC 4404. However, there is no doubt that IC 4404 is actually a star to the east of NGC 5547, as on the second night Bigourdan observed NGC 5547 he also observed IC 4404, and both nights he observed IC 4404 (Aug 22, 1884 and Apr 24, 1900) his positions point exactly at the star.
Physical Information: Based on a recessional velocity of 11700 km/sec, a straightforward calculation indicates that NGC 5547 is about 545 million light years away. However, for objects at such distances we should take into account the expansion of the Universe during the time it took their light to reach us. Doing that shows that the galaxy was about 520 million light years away at the time the light by which we see it was emitted, about 530 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light-travel time). Given that and its apparent size of about 0.6 by 0.4 arcmin, the galaxy is about 90 thousand light years across. The galaxy appears to be binuclear, so it may actually be two galaxies in collision, rather than a single object.
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Thanks in advance,
Matt Orsie
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