NGC 1553, Dun 331, JH 2630
Gxy in Dor, mag 9.4, size 4.5’, RA 4.270, dec -55.78
Distance 70 million light years? (the average of 5 measurements is 47.7 Mly)
Discovered by Dunlop on Thursday 28/9/1826 at about 3:45am
Located 2d 37m west (pa 252) of mag 3.3 alpha Dor
See map c in post 15
Nearby galaxies include NGCs 1549, 1566 and 1617
Dunlop’s Description Dun 331 [his 9" scope was equivalent to today's 6"]
28/9/1826 “A rather bright nebula about 1’ diameter, very faint at the margin, gradually bright to the centre: a small star north, and another south, both involved in the margin of the nebula. A group of very small stars north.”
http://picasaweb.google.com/dunlop18...28857259884818
http://picasaweb.google.com/dunlop18...58827906396482
Note. In Dunlop’s printed catalogue the RA was out by 1 hr but the RA is correct in his notes.
He missed NGC 1549 which is next to NGC 1553. I think this was because his scope probable had dew on it at the end of the mornings observing run.
The notes are available on microfilm from the national library in Canberra. Reel M 1709
http://catalogue.nla.gov.au/Record/7...tronomer%20%23
John Herschel’s Description JH 2630: [his 18.5" scope was equivalent to today's 16"]
5/12/1834. vB, R, gmbM, 60", between 3 stars;
6/12/1834. B, R, in a triangle formed by 3 stars
See
http://x.astrogeek.org/articles/arti...p?article_id=2
for an explanation of Herschel's abbreviations.
Hartung’s Description
“In this field are two bright nebulae [NGC 1549 and NGC 1553] about 13’ apart . . one is round, about 1.5’ across with very bright nucleus; the other is elliptical, about 2’ x 0.8’ in pa 150 deg, strongly concentrated and even brighter. 7.5cm shows these nebulae plainly.”
http://www.fortunecity.com/roswell/b...20.htm#NGC1553
Visible in 20x80 binoculars (GC)
IIS image by Steven (sjastro)
http://users.westconnect.com.au/~sjastro/ngc1549_53.html
http://www.iceinspace.com.au/forum/s...highlight=1553
X ray image
http://chandra.harvard.edu/photo/2002/1058/