Spiral Galaxy M91. Image courtesy of NOT
Messier 91 (also known as NGC 4548) is a barred spiral galaxy about 63 million light-years away in the constellation Coma Berenices. It was most probably discovered by Charles Messier in 1781 and independently rediscovered by William Herschel on April 8, 1784. M91 is a member of the Virgo Cluster of galaxies.
1. ^ a b c d e f g h i NASA/IPAC Extragalactic Database. Results for NGC 4548. Retrieved on 2006-12-13.
2. ^ J. L. Tonry, A. Dressler, J. P. Blakeslee, E. A. Ajhar, A. B. Fletcher, G. A. Luppino, M. R. Metzger, C. B. Moore (2001). "The SBF Survey of Galaxy Distances. IV. SBF Magnitudes, Colors, and Distances". Astrophysical Journal 546 (2): 681-693. doi:10.1086/318301.
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