2022 August 6 ~ Cr 399 (Brocchi's Cluster) in the constellation Vulpecula
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Photographed at Algonquin Provincial Park, Ontario, Canada, between 00.44 and 01.05 EDT
(285 km by road north of Toronto)
* Temperature 18° C.
* Altitude of the cluster at time of exposures: 62°, declining to 59°
* Total exposure time: 10 minutes
* 660 mm focal length telescope
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Description:
One of the easiest asterisms (groupings of stars) to spot with the unaided eye - and a lovely object in binoculars or a very wide-field telescope - is Collinder 399, also known as "Brocchi's cluster" or the "Coat Hanger" because of its distinctive shape.
From Wikipedia:
"Brocchi's Cluster (also known as Collinder 399, or Al Sufi's Cluster) is a random grouping of stars located in the constellation Vulpecula near the border with Sagitta. The members of the star cluster form an asterism which has given rise to its name as the Coathanger.
It was first described by the Persian astronomer Al Sufi in his Book of Fixed Stars in 964. In the 17th century, it was independently rediscovered by the Italian astronomer G. B. Hodierna. In the 1920s, Dalmero Francis Brocchi, an amateur astronomer and chart maker for the American Association of Variable Star Observers (AAVSO), created a map of this object for use in calibrating photometers. In 1931, Swedish astronomer Per Collinder listed it in his catalogue of open clusters.
The status of this group as a star cluster has changed in recent years. The group was considered to be a cluster for most of the 20th century. Looking at a variety of criteria, however, a study in 1970 concluded that only 6 of the brightest stars formed an actual cluster. Several independent studies since 1998 have now determined that this object is not a true cluster at all, but rather just a chance alignment of stars. These recent studies have generally based their findings on improved measurements of parallax and proper motion provided by the Hipparcos satellite which were first published in 1997."
To the left of centre is the smaller, richer star cluster NGC 6802, and near the top edge, right of centre is the small hydrogen II gas cloud Sh2-83.
For a version of this photo WITH LABELS, click on your screen to the RIGHT of the photo, or click here:
www.flickr.com/photos/97587627@N06/52270260404
___________________________________________
Technical information:
Nikon D810a camera body on on Tele Vue 127is (127 mm - 5" - diameter) apochromatic refracting telescope, mounted on Sky-Watcher EQ6-R Pro mount
Ten stacked subframes; each frame:
ISO 4000; 1 minute exposure at f/5.2, unguided
(with LENR - long exposure noise reduction)
Subframes stacked in RegiStar;
Processed in Photoshop CS6 (brightness, contrast, levels, colour balance)
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2022 August 6 ~ Cr 399 (Brocchi's Cluster) in the constellation Vulpecula
***************************************************************************
Photographed at Algonquin Provincial Park, Ontario, Canada, between 00.44 and 01.05 EDT
(285 km by road north of Toronto)
* Temperature 18° C.
* Altitude of the cluster at time of exposures: 62°, declining to 59°
* Total exposure time: 10 minutes
* 660 mm focal length telescope
___________________________________________
Description:
One of the easiest asterisms (groupings of stars) to spot with the unaided eye - and a lovely object in binoculars or a very wide-field telescope - is Collinder 399, also known as "Brocchi's cluster" or the "Coat Hanger" because of its distinctive shape.
From Wikipedia:
"Brocchi's Cluster (also known as Collinder 399, or Al Sufi's Cluster) is a random grouping of stars located in the constellation Vulpecula near the border with Sagitta. The members of the star cluster form an asterism which has given rise to its name as the Coathanger.
It was first described by the Persian astronomer Al Sufi in his Book of Fixed Stars in 964. In the 17th century, it was independently rediscovered by the Italian astronomer G. B. Hodierna. In the 1920s, Dalmero Francis Brocchi, an amateur astronomer and chart maker for the American Association of Variable Star Observers (AAVSO), created a map of this object for use in calibrating photometers. In 1931, Swedish astronomer Per Collinder listed it in his catalogue of open clusters.
The status of this group as a star cluster has changed in recent years. The group was considered to be a cluster for most of the 20th century. Looking at a variety of criteria, however, a study in 1970 concluded that only 6 of the brightest stars formed an actual cluster. Several independent studies since 1998 have now determined that this object is not a true cluster at all, but rather just a chance alignment of stars. These recent studies have generally based their findings on improved measurements of parallax and proper motion provided by the Hipparcos satellite which were first published in 1997."
To the left of centre is the smaller, richer star cluster NGC 6802, and near the top edge, right of centre is the small hydrogen II gas cloud Sh2-83.
For a version of this photo WITH LABELS, click on your screen to the RIGHT of the photo, or click here:
www.flickr.com/photos/97587627@N06/52270260404
___________________________________________
Technical information:
Nikon D810a camera body on on Tele Vue 127is (127 mm - 5" - diameter) apochromatic refracting telescope, mounted on Sky-Watcher EQ6-R Pro mount
Ten stacked subframes; each frame:
ISO 4000; 1 minute exposure at f/5.2, unguided
(with LENR - long exposure noise reduction)
Subframes stacked in RegiStar;
Processed in Photoshop CS6 (brightness, contrast, levels, colour balance)
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