M33_CSI (M0): Catalog of M33 Clusters, HII Regions, Etc. (19930508)
FILE: m33_csi.m0 (248 objects)
CONTENTS: Catalog of M33 Clusters, HII Regions and other objects
DATASET: This file is part of HyperSky dataset M-8 (M8.2), version 19930508 Availability on HyperSky CD-ROM: Vol. 1 (1993)
DESCRIPTION: This file contains a compiled catalog of 248 star clusters, HII regions, and other unclassified objects in the nearby spiral (Sc) galaxy M33. M33 is a Local Group member also known as the Triangulum galaxy and as NGC 598; its position is RA=1h 33.9m, Dec=+30 39' (2000). Because M33 is so nearby, so open, and nearly face-on, detailed studies of its structure and composition are easier than similar studies of more distant galaxies.
The HyperSky file for this catalog is a "small-scale" datafile. That is, the file covers only the very small area of the sky occupied by M33. HyperSky treats such small-scale files in a special way: it will display only the outline of the catalog area, NOT its contents, until you reduce the HyperSky field scale appropriately. For this file, you must reduce your HyperSky vertical field scale to 2.7 degrees or less before you can see individual catalog objects. A 1-degree HyperSky field scale gives perhaps the best overview of M33. A scale <= 30 arc minutes (30') is suggested to allow adequate separation of catalog objects for easy identification.
Data for m33_csi.m0 has been extracted from the paper "The CLUSTER SYSTEM OF M33", by C.A. Christian and R.A. Schommer (The Astrophysical Journal Supplement Series, 49:405-424, 1982 July).
For some of the cataloged objects, the paper presents BVR photometry done in Sept 1986 with the Galileo/Institute for Astronomy(IFA) Texas Instruments 500 x 500 CCD, mounted on the IFA 2.2-meter telescope at Mauna Kea.
Most of the observed objects are thought to be star clusters. They range in visual magnitude from 17.0 < V < 19.5, and fall in a fairly uniform B-V range of 0.0 < B-V < 0.8 magnitude. Most of these clusters resemble "populous" clusters found in the Large Magellanic Cloud. A small number of red objects (B-V > 0.6 mag), were also seen in the photometry; this group probably includes some globular clusters.
A HyperSky position-list of objects having B-V photometry can be generated by using the HyperSky position search menues to find all file objects having string *B-V* in their description.
DATA: The HyperSky datafile contains the following data from the paper:
POSITION: Object positions are stored in the HyperSky file for equinox 1950 with position accuracies of 1 second RA and 1" Dec, as provided in the paper.
MAG: Magnitudes were not provided for most objects; those included are visual(V) magnitudes.
IDENTIFICATION: A number preceded by one of three letters: C,H,u. C-numbers are used in the paper to indicate potential clusters; H-numbers are used in the paper to indicate HII regions, and u-numbers indicate "unclassified" objects in the paper (u is lower case since it has been added for the HyperSky data file; unclassified objects were not given a letter prefix in the paper).
For both C- and H-numbers, notes occasionally indicate that the object is not really a cluster or HII region; some are galaxies for example.
COMMENTS: The comment lines contain the following additional information, provided if available for each object:
* B-V and U-B magnitude color differences.
* short remarks ("galaxy", "stellar?", etc)
* abbreviated annotations: numbers in the paper "Remarks" column referred to longer comments after the catalog listings. Some of these comments have been abbreviated and added. For example, "red" may refer to the longer comment 4: "Red on grism plates".