Discovered by Pierre Méchain in 1781. Messier 100 (M100, aka NGC 4321) is a beautiful example of a grand-design spiral galaxy, and one of the brightest galaxies in the Virgo Cluster, or Coma-Virgo cluster of Galaxies. Like a number of other members of this cluster, it is situated in the southern part of constellation Coma Berenices. On March 15, 1781, Pierre Méchain discovered this object, M100. His friend, Charles Messier, obtained its position on April 13, 1781, and included it in his catalog, immediately before finishing the third, final published edition.
M100 is one of the brightest member galaxies of the Virgo Cluster of galaxies.
M100 is a spiral galaxy, like our Milky Way, and tilted nearly face-on as seen from earth. It is among the first spirals that have been discovered, and listed by Lord Rosse as one of 14 "spiral nebulae" discovered to 1850. The galaxy has two prominent arms of bright blue stars and several fainter arms. The blue stars in the arms are young hot and massive stars which formed recently from density perturbations caused by interactions with neighboring galaxies which are lying just outside our image. Despite its nearly perfect symmetric outline, this galaxy appears slightly asymmetric, as on the southern (lower) side of the nucleus more (or brighter) young stars have formed.
There are MANY tiny background galaxies to see too.
Click on the image above to see it 2x as large.
Telescope: Planewave 12.5" CDK
Camera: Apogee Instruments U16M w 7-position filter wheel and Astrodon Gen II LRGB Filters
Mount: Paramount ME from Software Bisque
Luminance is 23 x 10 min
RGB are 12 / 10 / 9 x 10 min
Acquisition via CCD-Commander and TheSkyX
Calibration and RGB combine done in PixInsight
Luminance layered into the RGB in Photoshop CC 2019 and then a lot of clean-up
Ambient temp about 0C and CCD temp -25C
Lucknow, Ontario, Canada