sponsored by psychohistorian.org
RA: 07h 13m 36s
Dec: −31° 02′ 0″
Con: Canis Major
Ch: MSA:369, U2:361, SA:19
Ref: SIMBAD, DAML02, Archinal&Hynes (2003)
Type: open cluster, 33p
Mag: B=?, V=3.6
A revisit to the region of Collinder 132 using Carte du Ciel and Astrographic Catalogue plates. A&A 521, A39.
"Collinder 132 is a controversial open cluster located at Canis Major (l = 243.3, b = −9.2, RA = 7h14m, Dec = −31°10). During the last 30 years, different authors have given different interpretations
about its nature.
It was first recognized as a physical group by Collinder (1931) in the Franklin Adams plates. He found an open cluster characterized by a low concentration of stars, containing 18 stars at a distance of 270 pc within an area of 85arcmin.
With photoelectric UBV measurements for 35 stars and H-beta measurements for 18 stars, Clariá (1977) detected two open clusters in the region: Cr132a and Cr132b. The former has 12 stars at a distance of 560 pc and the latter 8 stars at 330 pc.
Eggen (1983) found two groups in this region by intermediate-band and H-beta photometry for 14 stars. He concluded that one group was connected with Collinder 140 and another group contained members of the CMa OB2 association. They have the following number of members and distances: four stars at 490 pc for the first one, six stars at 832 pc for the other group.
Baumgardt (1998) discussed the nature of the object using parallaxes, proper motion and photometry data from the Hipparcos and ACT catalogues. He concluded the presence of an association in agreement to Eggen’s second group and the probable existance of an open cluster with five members. He also suggested that the association, composed by six members, might be connected with Collinder 121.
Robichon et al. (1999) found eigth members at a distance of 650 pc with Hipparcos data. Dias et al. (2002) determined the mean absolute proper motion of the cluster and found 110 members through Tycho-2 proper motion data.
More recently, Kharchenko et al. (2005) estimated the mean absolute proper motion and found seven members with the ASCC-2.5 catalogue data, and the distance estimated was 411 pc. Caballero & Dinis (2008) applyed the DBSCAN data clustering algorithm to find spatial overdensities in the region and detected 11 members at 450 pc.
The data used in this work come from the Córdoba CdC and AC plates. Each Córdoba plate covers an area of 2deg × 2deg in the sky with a platescale of 1arcmin/mm. Carte du Ciel plates have three equal consecutive exposures of 20 min each, resulting in an equilateral triangle image of approximately 7.0arcsec per side for every star. The Astrogaphic Catalogue plate has four exposures of 5 min, 5 min, 80 s and 8 s shifted in declination. All plates have a superimposed grid with 5 mm separation between lines.
The photographic plates were digitized by the MAMA measuring machine from the Paris Observatory... with a spatial resolution of 10 micron/px.
We try to resolve the discrepancy present in the literature about the region of the open cluster Cr132. We developed a model based on stellar positions and proper motions to analyse a stellar region where moving groups can be found. These astrometric data were taken from the CCAC catalogue. It was constructed by reducing four CdC and one AC plates between 1913.16 and 1923.13 from the Córdoba Astronomical Observatory.
From the analysis of the proper motion distribution and stellar projected density in a region containing 491 stars, it is possible to detect an open cluster whose centre has been newly determined. The mean proper motion was calculated, and initially 13 stars were found as astrometric members. The photometric Tycho-2 data available for eight astrometric members confirmed that only six are cluster members and locate the cluster at 360 pc from the Sun. Our results determined that the angular diameter is 20arcmin."
RA = 108.347 degrees; Dec = -31.011
Tom Lorenzin, in the electronic version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "4M; 1.5 degree diameter; 25-plus members; large and sparse; splendid binocular object."
Location:Blesfontein Guest Farm,Sutherland.
Sky Conditions:The most crystal clear sky possible.Dark moon and stars magnitude 6 and fainter are visible with the naked eye.Excellent clean sky,limited star flickering and brilliant objects.
This open cluster is very large which consists of 8th to 9th magnitude stars whereby the stars in this cluster is arranged in a north south to west east direction.The stars in this open cluster is not separated and that most of the stars in this cluster have bright and faint stars mixed together.This open cluster measures 19.5'x9.7'.Chart No.98,NSOG Vol.1.
The Messier objects
The Bennett objects
The Caldwell list
DOCdb is still in beta-release.
Known issues, feature requests, and updates on bug fixes, are here:
Found a bug? Have a comment or suggestion to improve DOCdb? Please let us know!
DOCdb is a free online resource that exists to promote deep sky observing.
You could help by sharing your observations, writing an article, digitizing and proof-reading historical material, and more.
Everything on DOCdb.net is © 2004-2010 by Auke Slotegraaf, unless stated otherwise or if you can prove you have divine permission to use it. Before using material published here, please consult the Creative Commons Attribution-Non-Commercial-Share Alike 2.5 License. Some material on DOCdb is copyright the individual authors. If in doubt, don't reproduce. And that goes for having children, too. Please note that the recommended browser for DOCdb is Firefox 3.x. You may also get good results with K-Meleon. Good luck if you're using IE. A successful experience with other browsers, including Opera and Safari, may vary.