OPEN STAR CLUSTERS
M-11 (NGC-6705): An exceptional galactic open cluster, located in the constellation
of Scutum. This rich cluster contains 400 stars brighter than 14th magnitude. Its visual
size is approximately 12 minutes of arc, which at its accepted distance of 5500 light
years translates to a diameter of approximately 20 light years.
NOTE: This image was captured on 8/24/06, and is an integration of ten 30 second
exposures through the 80mm f/7.5 ED Apochromatic Refractor. The images were
combined and processed in Maxim DL Essentials, with additional post-processing in
Photoshop CS.
of Scutum. This rich cluster contains 400 stars brighter than 14th magnitude. Its visual
size is approximately 12 minutes of arc, which at its accepted distance of 5500 light
years translates to a diameter of approximately 20 light years.
NOTE: This image was captured on 8/24/06, and is an integration of ten 30 second
exposures through the 80mm f/7.5 ED Apochromatic Refractor. The images were
combined and processed in Maxim DL Essentials, with additional post-processing in
Photoshop CS.
(CLICK ON THUMBNAIL IMAGE FOR FULL-SIZE VIEW)
M-71 (NGC-6838): Located in the constellation Sagitta, approximately midway between
Delta and Gamma Sagittae. A rich and compact cluster of faint stars. Its visual size is
approximately 6 minutes of arc, which at its accepted distance of 18,000 light years
corresponds to a diameter of approximately 30 light years. M-71 is an unusual cluster
whose precise classification is somewhat in doubt. Harlow Shapley and R.J. Trumpler
both classified it as an open cluster, but in most modern publications it is listed as a
globular cluster. The H-R diagram shows a red giant sequence resembling that of a
globular cluster, but spectroscopy shows that the member stars are metal-rich, which
does not support classification as a globular.
NOTE: This image was captured on 8/24/06, and is an integration of fifteen 40 second
exposures through the 80mm f/7.5 ED Apochromatic Refractor. The images were
combined and processed in Maxim DL Essentials, with additional post-processing in
Photoshop CS.
Delta and Gamma Sagittae. A rich and compact cluster of faint stars. Its visual size is
approximately 6 minutes of arc, which at its accepted distance of 18,000 light years
corresponds to a diameter of approximately 30 light years. M-71 is an unusual cluster
whose precise classification is somewhat in doubt. Harlow Shapley and R.J. Trumpler
both classified it as an open cluster, but in most modern publications it is listed as a
globular cluster. The H-R diagram shows a red giant sequence resembling that of a
globular cluster, but spectroscopy shows that the member stars are metal-rich, which
does not support classification as a globular.
NOTE: This image was captured on 8/24/06, and is an integration of fifteen 40 second
exposures through the 80mm f/7.5 ED Apochromatic Refractor. The images were
combined and processed in Maxim DL Essentials, with additional post-processing in
Photoshop CS.
NGC-7789: Located in the constellation of Cassiopeia, between the stars Rho and Sigma
Cassiopeiae. A very rich galactic open star cluster. It contains almost 1,000 stars, and its
visual size is approximately 20 minutes of arc, which translates to an actual diameter of
about 50 light years, given its accepted distance of 6,000 light years. Spectroscopic
study reveals this cluster to be much older than most open clusters.
NOTE: This image was captured on 9/1/06, and is an integration of ten 90 second
exposures through the 80mm f/7.5 ED Apochromatic Refractor. The images were
combined and processed in Maxim DL Essentials, with additional post-processing in
Photoshop CS.
Cassiopeiae. A very rich galactic open star cluster. It contains almost 1,000 stars, and its
visual size is approximately 20 minutes of arc, which translates to an actual diameter of
about 50 light years, given its accepted distance of 6,000 light years. Spectroscopic
study reveals this cluster to be much older than most open clusters.
NOTE: This image was captured on 9/1/06, and is an integration of ten 90 second
exposures through the 80mm f/7.5 ED Apochromatic Refractor. The images were
combined and processed in Maxim DL Essentials, with additional post-processing in
Photoshop CS.
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M-46 (NGC-2437): Located in the constellation of Puppis, about 14 degrees east of the
brilliant star Sirius (Alpha Canis Majoris). Discovered by Charles Messier in 1771. It con-
tains about 200 stars ranging from 10th magnitude down to 14th magnitude and has a
visual size of approximately 25 minutes of arc. The brightest members are blue giants of
spectral class AO, each having a true luminosity of over 100 times that of the sun. This
cluster lies at a distance of about 5400 light years from earth. A curious feature of this
cluster is the presence of the small planetary nebula NGC-2438, located approximately
7 arcminutes north of the center of the cluster. It shows up in this CCD image just to the
lower left of the center of the frame. It is believed that the nebula is not actually a
member of M-46, as its radial velocity indicates that it is probably 3300 light years from
earth. This means that it is an "optical" or "line of sight" member of the cluster.
NOTE: This image was captured on the evening of January 25th, 2007, and is an
integration of thirty 20 second exposures through an 80mm f/7.5 ED Apochromatic
Refractor. The images were combined and processed in Maxim DL Essentials, with
additional post-processing in Photoshop CS.
brilliant star Sirius (Alpha Canis Majoris). Discovered by Charles Messier in 1771. It con-
tains about 200 stars ranging from 10th magnitude down to 14th magnitude and has a
visual size of approximately 25 minutes of arc. The brightest members are blue giants of
spectral class AO, each having a true luminosity of over 100 times that of the sun. This
cluster lies at a distance of about 5400 light years from earth. A curious feature of this
cluster is the presence of the small planetary nebula NGC-2438, located approximately
7 arcminutes north of the center of the cluster. It shows up in this CCD image just to the
lower left of the center of the frame. It is believed that the nebula is not actually a
member of M-46, as its radial velocity indicates that it is probably 3300 light years from
earth. This means that it is an "optical" or "line of sight" member of the cluster.
NOTE: This image was captured on the evening of January 25th, 2007, and is an
integration of thirty 20 second exposures through an 80mm f/7.5 ED Apochromatic
Refractor. The images were combined and processed in Maxim DL Essentials, with
additional post-processing in Photoshop CS.
M-36 (NGC-1960): Located in the constellation of Auriga. A bright open star cluster con-
taining about 60 stars ranging in magnitudes from 9 to 14. Most of the brighter members
are all B-type blue-white stars. This is one of the younger open clusters in the milky way.
It lies at a distance of approximately 4100 light years from earth. At this distance, the
angular size of the cluster, 12 arcminutes, translates to an actual diameter of about 14
light years. NOTE: This image was captured on the evening of October 30, 2008, and is
an integration of twenty-five 25 second exposures through an 80mm APO refractor at
f/3.75. The images were combined and processed in Maxim DL Essentials, with additional
post-processing using Photoshop CS and Noiseware.
taining about 60 stars ranging in magnitudes from 9 to 14. Most of the brighter members
are all B-type blue-white stars. This is one of the younger open clusters in the milky way.
It lies at a distance of approximately 4100 light years from earth. At this distance, the
angular size of the cluster, 12 arcminutes, translates to an actual diameter of about 14
light years. NOTE: This image was captured on the evening of October 30, 2008, and is
an integration of twenty-five 25 second exposures through an 80mm APO refractor at
f/3.75. The images were combined and processed in Maxim DL Essentials, with additional
post-processing using Photoshop CS and Noiseware.
M-37 (NGC-2099):_A superbly rich open cluster in Auriga, considered one of the finest of
the three Messier open clusters in that constellation. M-37 contains over 150 stars ranging
in magnitude from 9 to 12.5. The stellar population of this cluster is very different from
M-36, and suggests that the cluster is much older. It also contains several red giants, which
stand out like rubys in a field of white diamonds. M-37 lies at a distance of 4700 light years
and is approximately 25 light years in diameter. NOTE: This image was captured on the
evening of October 30, 2008, and is an integration of twenty-five 25 second exposures
through an 80mm APO refractor at f/3.75. The images were combined and processed in
Maxim DL Essentials, with additional post-processing in Photoshop CS and Noiseware.
the three Messier open clusters in that constellation. M-37 contains over 150 stars ranging
in magnitude from 9 to 12.5. The stellar population of this cluster is very different from
M-36, and suggests that the cluster is much older. It also contains several red giants, which
stand out like rubys in a field of white diamonds. M-37 lies at a distance of 4700 light years
and is approximately 25 light years in diameter. NOTE: This image was captured on the
evening of October 30, 2008, and is an integration of twenty-five 25 second exposures
through an 80mm APO refractor at f/3.75. The images were combined and processed in
Maxim DL Essentials, with additional post-processing in Photoshop CS and Noiseware.
M-38 (NGC- 1912) and NGC-1907 (to the right - west): M-38 is a large bright open cluster
in Auriga, located about 2.3 degrees NW of M-36. It is a scattered group of irregular form,
oriented NW to SE. It is approximately 20 arcminutes in diameter, which at its calculated
distance of 4200 light years corresponds to an actual diameter of about 25 light years.
The smaller, more compact open cluster NGC-1907 lies just at the west edge of the field of
this image. NOTE: This image captured on October 30, 2008. It is an integration of twenty-five
25 second exposures through the 80mm APO refractor at f/3.75. Combined and processed in
Maxim DL Essentials, with post-processing using Photoshop CS and Noiseware.
in Auriga, located about 2.3 degrees NW of M-36. It is a scattered group of irregular form,
oriented NW to SE. It is approximately 20 arcminutes in diameter, which at its calculated
distance of 4200 light years corresponds to an actual diameter of about 25 light years.
The smaller, more compact open cluster NGC-1907 lies just at the west edge of the field of
this image. NOTE: This image captured on October 30, 2008. It is an integration of twenty-five
25 second exposures through the 80mm APO refractor at f/3.75. Combined and processed in
Maxim DL Essentials, with post-processing using Photoshop CS and Noiseware.
M-35 (NGC-2168) and NGC-2158: M-35 is a beautiful open star cluster in the constellation of
Gemini. First cataloged by de Cheseaux in 1745 and cataloged by Messier in 1764 as the 35th
object on his list. Visually, M-35 is about 30 arcminutes in diameter when viewed through
modest sized telescopes. It lies at a distance of approximately 2200 light years from earth. It
containsabout 120 stars ranging from B3 to G0 in the main sequence. Most of the members
are 8th to10th magnitude. About 1/2 degree SW (upper right in the image) from M-35 is the
very rich and distant cluster NGC-2158. This cluster is actually the same physical size as M-35,
but lies over 8 times further away than M-35. Modern measurements place its distance at over
18,000 light years. Through 8 to 12 inch telescopes, NGC-2158 appears as a very rich
compressed cluster,somewhat triangular in shape, with a misty, granular texture.
NOTE: This image was captured on the morning of 11/25/08, and is an integration of twenty-
five 120-second sub-exposures through an 80mm APO refractor at f/3.75. Images captured and
combined in Maxim DL Essentials, with post-processing in Photoshop CS and NoiseWare.
Gemini. First cataloged by de Cheseaux in 1745 and cataloged by Messier in 1764 as the 35th
object on his list. Visually, M-35 is about 30 arcminutes in diameter when viewed through
modest sized telescopes. It lies at a distance of approximately 2200 light years from earth. It
containsabout 120 stars ranging from B3 to G0 in the main sequence. Most of the members
are 8th to10th magnitude. About 1/2 degree SW (upper right in the image) from M-35 is the
very rich and distant cluster NGC-2158. This cluster is actually the same physical size as M-35,
but lies over 8 times further away than M-35. Modern measurements place its distance at over
18,000 light years. Through 8 to 12 inch telescopes, NGC-2158 appears as a very rich
compressed cluster,somewhat triangular in shape, with a misty, granular texture.
NOTE: This image was captured on the morning of 11/25/08, and is an integration of twenty-
five 120-second sub-exposures through an 80mm APO refractor at f/3.75. Images captured and
combined in Maxim DL Essentials, with post-processing in Photoshop CS and NoiseWare.