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           NGC 6633  
        Open Cluster in  Ophiuchus
           RA:18h 27m 15s  Dec: +06 30' 30" Distance - ~1293 ly Size 20'x20'

Location & Date
Backyard, Abbott Observatory- Long Island, NY,  May 2022
Orion ED80 F/7 APO, Moonlite focuser, iOptron GEM45G, Pegasus Falcon rotator
Image scale 2.54 arcsec/pixel
Baader  L R G B  filters
CCD temp -15°C
  L- 12 x 3m  Red- 10 x 3m  Green - 10 x 3m  Blue- 10 x 3m  Bin 1x1 per panel
Planning & Acquisition
4-panel mosaic planning & acquisition - Sequence Generator Pro

Astro Pixel Processor -  Calibration, Normalize, Alignment,  Mosaic Combine
Adobe PS -  LRGB combine, Color adjustments, Noise reduction, Sharpen, JPEG conversion
RC-Astro Star XTerminator

This is a 4-panel mosaic


NGC 6633 is a large bright open cluster in the constellation Ophiuchus. Discovered in 1745-46 by Philippe Loys de Chéseaux, it was independently rediscovered by Caroline Herschel in 1783 and included in her brother William's catalog as H VIII.72. Bright enough to be seen with the naked eye, the cluster is considered a fine object for binoculars or small telescopes.

NGC 6633 is also known as the Tweedledum Cluster (paired with IC 4756 as Tweedledee), also as the Captain Hook Cluster. It is also designated Collinder 380 or Melotte 201. Nearly as large as the full moon, the cluster contains 38 known stars and shines with a total magnitude of 4.6; the brightest star is of mag 7.6. Its age has been estimated at 660 million years.

The cluster contains at least one chemically peculiar star - NGC 6633 48 (BD+06 3755).

The 8th-magnitude binary star HD 169959 (NGC 6633 58) is within the line-of-sight of the open cluster but is not physically associated with it

Click on image for full size.
NGC 6633 position shown relative to our location (Sun) in the Milky Way Galaxy
Age: 426 million years
Galatic Longitude: 36
Galatic Latitude: 8.3
Distance from Galatic Plane:243 ly above the galatic plane

Above image and info provided by Our Galaxy 3D Atlas application and used with permission by Otherwise