M 99 (Gal)

Galaxy in ComaBerenices
R.A.Dec.SizeMag SBCnt.StTypeDistanceChart
12h 18m 50.7s+14° 24′ 55.5″5.4′9.913.1SA(s)cGal----
M 99 DSS plate
Source: POSS-2 UK Schmidt Red (STScI) | Field: 15′ × 15′

Background

M99 is a face-on grand-design spiral galaxy in Coma Berenices,  50 million light-years away. A member of the Virgo Cluster. Known for its slightly asymmetric spiral arms, possibly the result of a past gravitational interaction with another cluster member.

My Observing Notes

25-cm (Meade 10-inch LX200, The Coffee Grinder): Suggested by Trevor Oates, who was imaging it at the time. A useful side-by-side with his camera: where his 5-minute exposures clearly revealed three bright spiral arms, the 10-inch only uncovered a bright uniform core with a surrounding halo ( 5.4'×4.8') and a slight elongated shape.(Friday, April 2025)

References

Charts

M 99 ultra-wide chart
Ultra-wide view (~25° field)
M 99 wide-field chart
Wide-field view with Telrad rings (4°, 2°, 0.5°)
M 99 finderscope view
Finderscope view (9×50 RACI, ~4.4° TFOV)
M 99 eyepiece view
Eyepiece view — 35 mm Panoptic on 12-inch f/5 (1.6° TFOV)