The Pleiades (M45)

All Images Copyright Steve Cannistra

Please click here for a higher resolution image.

Magnitude:  1.6
Distance: 380 light years
RA: 3h 46m 31s
Dec: 23 degrees 57' 36"

The Pleiades
(M45, the "Seven Sisters") convey a sense of stately, quiet winter beauty.  This open star cluster has been recognized since antiquity, with the oldest recorded observation being approximately 1000 years BC.  Within this cluster, it is possible to resolve between 7-11 stars with the naked eye, depending upon seeing conditions (and eyesight!).  Through the telescope, the cluster is known to contain about 500 stars that are gravitationally bound to each other.   The age of this cluster is estimated to be about 65 million years old, meaning that it was "born" around the time of the dinosaur extinction.  The beauty of this cluster is due to the impressive amount of blue nebulosity that surrounds many of the stars, most notably Merope (surrounded by the brightest reflection nebulae of this group, NGC 1435).   In contrast to emission nebulae, the blue color of this nebula is due to reflected light from nearby young stars.  During visual observation, there is a hint of nebulosity in a small scope such as an 8" SCT, although the full extent can only be observed in longer exposure photos such as this one.  Please click here for a higher resolution image.

Photographic Details:

Date:  November 22, 2003
Scope:  Takahashi Sky 90 at f4.5 with field flattener/focal reducer, piggybacked on LX90 (which is mounted on a Meade Superwedge).
Autoguider:  STV with e-finder.
Camera:  Canon 10D.
Filter:  IDAS LPS.
Exposures:  12 x 5' at ISO 800.
Conditions:  Temperature 35 degrees F; below average transparency; average seeing; very dewy; calm.
Raw conversion, adaptive dark frame calibration, alignment, min/max excluded averaging done in ImagesPlus; Levels, curves, and layer mask adjustments in Photoshop.  I was not satisfied with my initial processing, since star coloration was washed out in the process of curves adjustment.  I reprocessed this on 12/21/03 using a mask to protect the stars from bloating and color loss, resulting in a more pleasing image (also check high resolution link).

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