Observer’s Challenge Link:  

MAY 2016 OBSERVERS CHALLENGE – M-100-1

M100 – NGC 4321 – Galaxy in Coma Berenices 

Date: April 2016
NELM: 5.0
Telescope: 10-inch Newtonian Reflector
Magnification: 57x
Field of View: 1.1º

Description: Low surface brightness, mostly round with a subtle NW-SE elongated halo. Bright nucleus, almost stellar at high magnification. A very dim patch W of the core and a hint of a spiral arm on the SW edge.    Roger Ivester

The following is a pencil sketch using only a No.2 pencil, an eraser, a blank 5 x 8 notecard with the colors inverted using a scanner.  RI 

The following information and image provided by Dr. James Dire from Hawaii.

M100
By James Dire, Ph.D.

M100 is located in the constellation Coma Berenices. It lies 8 degrees east and slightly north of the star Denebola (Beta Leonis). It can be found roughly 40% of the way along a line from Denebola to the star Diadem (Alpha Comae Berenices). At magnitude 9.3, M100 is one of the brightest galaxies in the Coma-Virgo Cluster. M100 was first spied by Pierre Merchain in 1781 and then confirmed by Charles Messier later that year. M100 is a face-on spiral galaxy located 56 million light years away as determined by measuring the periods of Cepheid variable stars in the galaxy.

My image of M100 was taken with a 190mm f/5.3 Maksutov-Newtonian with an SBIG ST-2000XCM CCD camera. The expose was one hour. The galaxy has two main spiral arms with numerous branches. The arms contain many massive, hot, blue giant stars with many HII giant clouds of gas. The nucleus is bright and compact.

The second image has labels for several nearby galaxies and their magnitudes. All are members of the Coma-Virgo cluster.

The following sketch and notes compliments of Jaakko Saloranta of Finland.

Rough sketch made at the eyepiece. 8 inch dobson shows a bright galaxy with a nearly stellar nucleus @ 38x –(66′). Best visible @ 152x (16′) but the spiral structure is very difficult. Flanked nicely by two 14th magnitude stars. Bright, non-stellar nucleus surrounded by a E-W elongated halo. Northern spiral arm is brighter with a brighter spot at the W end. Southern spiral arm is slightly smaller but with two brighter areas visible in the arm in both ends. It takes over an hour to discern the spiral structure properly with this aperture. NGC 4323 and NGC 4328 not looked for.    Jaakko Saloranta 

This entry was posted on May 21, 2016 at 1:33 pm and is filed under Work File Only - Observer's Challenge Reports. You can subscribe via RSS 2.0 feed to this post's comments. Both comments and pings are currently closed.