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Contains:  M 7, NGC 6475
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M7 - Ptolemy's Cluster, 


            Michael Feigenbaum
M7 - Ptolemy's Cluster
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M7 - Ptolemy's Cluster

Technical card

Imaging telescopes or lenses:Vixen R200SS

Imaging cameras:ZWO ASI1600MM

Mounts:Orion HDX110 EQ-G

Guiding telescopes or lenses:ZWO 30F4 Guidescope

Guiding cameras:ZWO ASI 120 MC

Software:PixInsightStark Labs Nebulocity 4Stark Labs PHD 2.6DSS

Filters:Astronomik Red 1.25"Astronomik Blue 1.25"Astronomik Green 1.25" CCD Filter

Dates:June 21, 2019June 22, 2019

Astronomik Blue 1.25": 99x60" (gain: 139.00) -5C
Astronomik Green 1.25" CCD Filter: 100x60" (gain: 139.00) -5C
Astronomik Red 1.25": 100x60" (gain: 139.00) -5C

Integration: 5.0 hours

Darks: ~60

Flats: ~50

Bias: ~500

Avg. Moon age: 19.10 days

Avg. Moon phase: 80.03%

Bortle Dark-Sky Scale: 4.33

Mean SQM: 20.70 job: 2757473

RA center: 17h 53' 26"

DEC center: -34° 45' 18"

Pixel scale: 0.972 arcsec/pixel

Orientation: 219.974 degrees

Field radius: 0.599 degrees

Resolution: 3416x2836

Locations: Papago Butte, near Maricopa, AZ, United States

Data source: Backyard


Ptolemy's Cluster (Messier 7) is one of the most beautiful clusters, to my eye anyway, because of its location in the heart of the galaxy. So the cluster has the backdrop of the multitude of stars, gas, and dust that constitute the morphology of this part of the sky.

According to, this cluster is about 220mm years old lying approximately 980lys from our solar system. There are about 80 stars in the cluster, many of which are very massive young blue stars.

From my location, this object is very low on the Southern horizon. But I think I had pretty good seeing last night an came out with a passable image. There s just so many interesting things in Scorpius and Sagittarius that I am trying to image them even though they are not well placed for me at my latitude.

Anyway, any comments/criticism always welcome!
CS to all!!



Michael Feigenbaum
License: None (All rights reserved)


  • M7 - Ptolemy's Cluster, 


            Michael Feigenbaum
  • M7 - Ptolemy's Cluster, 


            Michael Feigenbaum
  • Final
    M7 - Ptolemy's Cluster, 


            Michael Feigenbaum


Description: this one represents a little different approach to the stretch. Perhaps the bright stars look a little better? I backed off a little on the lightness which I believe results in a more realistic depiction of the cluster as well.

Sky plot

Sky plot


M7 - Ptolemy's Cluster, 


            Michael Feigenbaum