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Contains:  M 7, NGC 6475
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Ptolemy Cluster - m7, 


Ptolemy Cluster - m7
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Ptolemy Cluster - m7

Technical card

Dates:Sept. 30, 2018

Frames: 23x60"

Integration: 0.4 hours

Avg. Moon age: 20.13 days

Avg. Moon phase: 70.83%

Basic astrometry details job: 2284877

RA center: 17h 53' 46"

DEC center: -34° 47' 31"

Pixel scale: 1.150 arcsec/pixel

Orientation: 289.010 degrees

Field radius: 0.479 degrees

Resolution: 2400x1800

Data source: Backyard


I have always enjoyed the Ptolemy Cluster visually due to its bright blue stars seeming to stand out from the background Milky Way.

It includes four Bp/Ap stars which are not well understood. These rotate slowly, have extremely strong magnetic fields, and contain high concentrations of heavy metals such as Chromium, Manganese and Mercury.

Why these stars are so magnetic remains a mystery!



License: Attribution Creative Commons

Sky plot

Sky plot


Ptolemy Cluster - m7,