Messier 91 (NGC 4548)

Sketch of Messier 91 (M91 / NGC 4548)

Sketch of Messier 91 (NGC 4548)

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Observation Notes:

M91 appeared circular with a strongly condensed core. A prominent bar crossed the disc at a PA of about 80 degrees. The western half of this bar appeared to be a bit brighter. I couldn’t detect any hint of the extended spiral arm structure.

Sketch/DSS Photo Comparison of Messier 91 (M91 / NGC 4548)

Sketch/DSS Photo Comparison of Messier 91 (NGC 4548)

Object Information:

M91 is a barred spiral galaxy in the Virgo cluster that is receding at about 400 km/sec. Since the cluster as a whole is receding at 1,100 km/sec, the galaxy moving through the cluster at 700 km/sec. It was discovered by Charles Messier in 1781, and is also cataloged as NGC 4548, UGC 7753, MCG+03-32-075, H II-120, h 1345, GC 3093, CGCG 099.096, VCC 1615, IRAS 12328+1446, PGC 41934.

Subject M91 (NGC 4548)
Classification Barred Spiral Galaxy (SBb)
Position* Coma Berenices [RA: 12:35:27.2 / Dec: +14:29:48]
Size* 5.4′ x 4.3′ – PA: 150° (Bar = 65 °)
Brightness* 10.4 vMag; 11.0 bMag; 13.6 Surface Brightness
Date/Time APR 27, 2009 – 12:50 AM (APR 27, 2009 – 07:50 UT)
Observing Loc. Flagstaff, Arizona – Home
Instrument Orion SkyQuest XT8 Dobsonian (203 mm dia./1200 mm F/L)
Eyepieces/Mag. Pentax XW10 (120X)
Conditions Clear, calm, porch lights
Seeing 5/10
Transparency Mag 5.8 NELM
*Sources SEDS; NGC/IC Project; DSS; Starry Night Pro Plus 5; Atlas of the Messier Objects – Ronald Stoyan

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