Spring Objects Master Objects List  |  Search  |  TOC Back  |  Up  |  Next
Open Cluster M7
Messier 7
Exposure Data
  • Image Field of View: 2.73° x 1.82°
  • Camera Field of View: 14.82° x 9.92°
  • Scope: Nikkor 85 mm f/1.4 AIS
  • Focal Length: 85 mm
  • Focal Ratio: f/4.5
  • Camera: Canon 20Da
  • ISO: 1600
  • Exposure: 6 x 180 seconds (18 minutes total)
  • Filter: IDAS LPS
  • SQM: 20.81

Messier 7 is Ptolemy's cluster in Scorpius.

M7 shines at magnitude 3.3 and has an apparent diameter of 75 arcminutes. It is one of the most prominent open clusters in the sky and can easily be observed with the unaided eye from a dark-sky observing site.

M7 contains 100 stars and lies 800 to 1,000 light-years from Earth. M7 was known to Ptolemy in 130 C.E., and was observed by Hodierna before 1654.

M7 is estimated to be 220 million years old.

North is to the top in the above image.

Messier 7
  • Catalogs: M7, NGC 6475
  • Common Name: Ptolemy's Cluster
  • Object Type: Open Cluster
  • Magnitude: 3.3v
  • Size: 75'
  • Constellation: Scorpius
  • Image Field Centered At:
    • RA: 17h 53m 45s
    • Dec: -34° 47' 01"



Spring Objects Master Objects List  |  Search  |  TOC Back  |  Up  |  Next