The Pleiades (M45)
Characteristics:
Magnitude: 1.6
Distance: 380 light years
RA: 3h 46m 31s
Dec: 23 degrees 57' 36"
Description:
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 appears
to surround many of the stars (although is most likely not physically
associated with the cluster). 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.
Photographic Details:
Date: November 8, 2004
Scope: Takahashi
Sky 90 at f4.5 with field flattener/focal reducer, on the G11 Losmandy
Mount. I made a circular rim out of PVC tubing which fitted over
the dew shield of the Sky90 and permitted placement of an elastic band
to form an "X". This created the star spikes shown above for the
brighter stars. A photograph of this device is shown here (this
could also
be accomplished with kite string or fishing line).
Autoguider: STV with e-finder.
Camera: SXV-H9.
Filter: Astronomik Clear, R, G, B type II filter set.
Exposures:
L:R:G:B. 15 x 5'
for Luminance (75 minutes total for L); 4 x 5' for R and G (20 minutes
total for R and G); 5 x 5' for B (25 minutes total
for B), all unbinned.
Conditions: Temperature 32 degrees F; excellent
transparency; above average seeing; occasional breeze; cloudy early in
the
evening, crystal clear by midnight.
Post-processing: No darks,
flats, or bias frames used. Alignment done in ImagesPlus
(IP). Combined using Min-Max Excluded option in IP. DDP was
performed in ImagesPlus
(IP). Subsequent
levels and curves adjustments in Photoshop CS (16 bit format).
Please
note: Graphics on this website may not be reproduced without
author permission.
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