Archive for December 1, 2017

NGC 772 – Galaxy In Aries – November 2017 Observer’s Challenge Report #105

December 1, 2017

LVAS Observer’s Challenge:  Click on the following link. 


NGC 772, faint mag. 12 galaxy in Aries 

10-inch reflector at 104x, NGC 772 is faint, difficult with low surface brightness, elongated, but subtle, oriented NW-SE.  The middle is a bit brighter with little concentration.  A pin-point stellar nucleus was noted, however intermittently, and required averted version.  Very soft mostly even halo with the edges fading gradually outwards.  My observing location was from my my 5.0 NELM backyard.  

The last time I observed this galaxy was November 1993, from the same location and telescope.  My notes from that session were almost verbatim to my most recent observation.  A true dark site is necessary to see faint details and structure, especially when using a 10-inch telescope.    Roger Ivester

Pencil sketch 10-inch reflector with a 5.0 NELM


Image and notes by James Dire from Hawaii using a 10-inch Newtonian Reflector


NGC 772
James Dire
LVAS Observer’s Challenge
November 2017

NGC 772 is a fine spiral galaxy in the constellation Aries. The galaxy resides 82 arcminutes east-southeast of the great 4th magnitude binary star Mesarthim, a.k.a. Gamma Arietis. NGC772 is approximately 10th magnitude and is 7 x 4 arcminutes in size.

NGC 772 is nearly face on, but asymmetrical in shape. Its distorted appearance is due to gravitational interactions with NGC 770, a 14th magnitude elliptical galaxy. Distance measurements for the pair range from 87 to 130 million light years. The spiral galaxy is thought to be twice the diameter of the Milky Way Galaxy. Some astronomers classified NGC 772 as a barred spiral while other claim it has no central bar.

I viewed NGC 772 using 190mm, f/5.3 Maksutov Newtonian at 111x. The bight core of the galaxy stood out. With averted vision, I could make out the asymmetrical shape of the spiral arms.

My image of NGC 772 was taken with a 10-inch f/6.9 Newtonian using an SBIG ST-2000XCM CCD camera. The exposure was three hours. The two brightest stars in the image, on the left side near the bottom, are magnitude 11. The faintest stars in the image are magnitude 19.

The second image has arrows showing several of the fainter galaxies around NGC 772. I have labeled them with their best catalog numbers and magnitudes. The faintest of these galaxies is magnitude 18.1.  NGC 770 is the dwarf elliptical galaxy just to the south of NGC 770.

NGC 770 is thought to be a satellite galaxy of NGC 772, but it may have recently (cosmologically speaking) been captured and could be on a collision course with the larger galaxy. NGC 772 is unique in that its outer stars rotate around its core in the opposite direction the core rotates. This just adds to the mystery of how these two galaxies came to be associated with each other.  James Dire

Image by Mario Motta using a 32-inch Telescope from Massachusetts