Messier 91 (also known as NGC 4548 or M91) is a barred spiral galaxy that is found in the south of Coma Berenices. It is in the local supercluster and is part of the Virgo Cluster of galaxies. It is about 63 million light-years away from our galaxy. It was the last of a group of eight “nebulae” – as galaxies until the next century were not suspected to be visible, the term galaxy being used as a synonym for universe – discovered by Charles Messier in 1781. Among those few Messier objects in the catalogue as the result of bookkeeping mistakes by Messier long-missing; it was not until 1969 that amateur astronomer William C. Williams realized that M91 was NGC 4548, which was catalogued by William Herschel in 1784. Some sources contend the nearby spiral galaxy NGC 4571 was considered as a candidate for this object by Herschel.

Telescope: Astro Physics 175EDF f8.3
Mount: Astro Physics 3600GTO “El Capitan”
Camera: SBIG STT8300
Guider: SBIG FW8G OAG(Guided Filter Wheel)

L: 36×10 mins = 360 mins, R: 21×10 mins = 210 mins, G: 21×10 mins = 210 mins, B: 21×10 mins = 210 mins

Total Imaging Time: 16h 30m

Data Imaged remotely over 5 nights during March 2016.
Data acquisition & Processing by David Churchill.

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