Deep Sky Object in Spring
NGC4548 (M91, Galaxy in Coma Berenices)

Date & Time: Apr 9 2004, from 20:19 to 20:38 JST(+0900)
Composed 3 shots with 8 minutes exposed
Optical: Meade 25cm(10") Schmidt-Cassegrain with conversion lens (f=1600mm, F6.3)
Auto-guided with Meade LX200 Equatorial & Pictor 201XT
Digital Camera: Fujifilm FinePix S2 Pro
Location: Ooizumi vil., Yamanashi pref.

Camera Settings: Recording Format...12bit CCD-RAW, converted to 16bit TIFF(3024×2016)
CCD Sensitivity...ISO1600, White Balance...Auto

NGC4548 (M91) / Galaxy, type SB(rs)b I-II
R.A.12h 35m 26.3s (2000.0)
Dec.+14° 29' 49" (2000.0)
Apparent Size5.4×4.3'
Radial Velocity+803km/s
Distance53 million light yrs.
Group of GalaxiesVirgo Cluster
Other IDsUGC7753, MCG3-32-75
NGC4548 is a bared galaxy in Coma Berenices, belongs to the Virgo Cluster. The galaxy has a diameter of about 5 arc minutes and 11th magnitude, considerably dimmed and it's difficult to find it with finder scopes, and you need larger telescopes to appreciate it. The galaxy has bars structure in east-west direction and fairly opened arms are coiled up from tips of the bars.
Though I've written a Messier's number of M91 in parenthesis, actually there is no corresponding object at the position where C. Messier recorded. It's considered that he might mistake M91 for M58. But according to recent studies, it's most convincing that the NGC4548 is equivalent to M91. Though there are some other opinions like that M91 may be NGC4571 lying just southeast of NGC4548, I'd like to adopt an opinion of that NGC4548 corresponds to M91.


M95, M96 & M105

Copyright(c) 2004 by Naoyuki Kurita, All rights reserved.
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