NSSDC/WDC-A-R&S 82-29 DOCUMENTATION FOR THE MACHINE-READABLE VERSION OF THE REVISED NEW GENERAL CATALOGUE OF NONSTELLAR ASTRONOMICAL OBJECTS Wayne H. Warren Jr. November 1982 National Space Science Data Center (NSSDC)/ World Data Center A for Rockets and Satellites (WDC-A-R&S) National Aeronautics and Space Administration Goddard Space Flight Center Greenbelt, Maryland 20771 DOCUMENTATION FOR THE MACHINE-READABLE VERSION OF THE REVISED NEW GENERAL CATALOGUE OF NONSTELLAR ASTRONOMICAL OBJECTS Wayne H. Warren Jr. ABSTRACT This document provides detailed descriptions of the contents and format of the machine-readable version of the catalogue being distributed by the Astronomical Data Center. Coding for the various scales and abbreviations used in the catalogue are tabulated and certain revisions to the machine version made to improve storage efficiency and notation are described. ii TABLE OF CONTENTS Section 1 - INTRODUCTION ........................................... 1-1 Section 2 - FILE CONTENTS .......................................... 2-1 Section 3 - FILE CHARACTERISTICS ................................... 3-1 Section 4 - REMARKS, MODIFICATIONS AND REFERENCES .................. 4-1 LIST OF TABLES Table 1 - File Contents, Data File ..................................... 2-1 2 - File Contents, Old Description Supplement .................... 2-4 3 - File Contents, New Description Supplement .................... 2-4 4 - File Contents, Cross Reference Supplement .................... 2-5 5 - Dreyer Scales and Old Description Codes ...................... 2-5 6 - New Description Codes and Type 7 Comments .................... 2-8 7 - Cross Reference for RNGC Objects ............................. 2-12 8 - File Characteristics ......................................... 3-1 iii SECTION 1 - INTRODUCTION The Revised New General Catalogue of Nonstellar Astronomical Objects (RNGC) (Sulentic and Tifft 1973) is a modern, revised and expanded version of the New General Catalogue of Nebulae and Clusters of Stars (Dreyer 1888). While incorporating the many corrections to the original edition found over the years, the RNGC objects were verified on Palomar Observatory Sky Survey (POSS) prints and plates for southern objects especially taken for the purpose (about 90 southern objects could not be verified) and are tied to the POSS where possible by the inclusion of rectangular coordinates on the prints. New object descriptions are provided for objects which were examined during the course of the work, Galactic coordinates are given, and new magnitudes are reported along with their sources. This document describes the magnetic tape version of the RNGC, as distributed by the Astronomical Data Center. It is intended to enable users to read and process the data without problems or guesswork. For more extensive descriptions of the data in the RNGC and an explanation of the procedures used to develop or derive them, the published catalogue reference below should be consulted since it contains an extensive introduction with a wealth of valuable information. A copy of this document should be supplied with any machine-readable copy of the catalogue. SOURCE REFERENCE Sulentic, J. W. and Tifft, W. G. 1973, The Revised New General Catalogue of Nonstellar Astronomical Objects (Tucson: The University of Arizona Press). 1-1 SECTION 2 - FILE CONTENTS Byte-by-byte descriptions of the contents of the tape files of the RNGC are given in Tables 1-4. The suggested format specifications are for FORTRAN formatted read statements and can be modified depending upon individual programming and processing requirements. Since data fields contain blanks where data are absent, care must be exercised when processing the data for certain purposes. Alternate format specifications are given in parentheses. Table 1. File Contents. RNGC, Data File Suggested Byte(s) Units Format Description 1- 5 --- I5 The RNGC number (same as the original NGC number). 6 --- A1 Letter designations for anonymous sources near NGC objects or for double or multiple systems having the same assigned number. 7 --- 1X Blank 8- 9 --- I2 Type of object, coded as follows: 1 Open cluster 2 Globular cluster 3 Diffuse nebula 4 Planetary nebula 5 Galaxy 6 Cluster associated with nebulosity 7 Nonexistent 8 Object in Large Magellanic Cloud 9 Object in Small Magellanic Cloud 0 Unverified southern object The codes can be combined to form double digit numbers such as 19 (open cluster in SMC), 38 (diffuse nebula in LMC), or 25 (globular cluster in external galaxy). 10 --- 1X Blank 11- 12 hours I2 Right ascension for equinox 1975. 13 --- 1X Blank 14- 17 min F3.1 R.A. 2-1 Table 1. (continued) Suggested Byte(s) Units Format Description 18 --- 1X Blank 19- 21 deg I3 Declination for equinox 1975. Sign always in byte 19. 22 --- 1X Blank 23- 24 arcmin I2 Dec. 25 --- 1X Blank 26- 31 deg F6.2 Galactic longitude, System II. Not present for nonexistent objects, in which case the field is blank. 32 --- 1X Blank 33- 38 deg F6.2 Galactic latitude, System II. Not present for nonexistent objects, in which case the field is blank. A sign is present in byte 33 only for negative values. 39 --- 1X Blank 40- 42 mm I3 X coordinate on Palomar Observatory Sky Survey (POSS) print. The origin is the lower left corner of the blue print. A position was always determined from the southernmost and westernmost POSS print upon which the object is clearly visible. 43 --- 1X Blank 44- 46 mm I3 Y coordinate on POSS print. 47 --- 1X Blank 48- 51 mag F4.1 Magnitude (rounded to the nearest half magnitude), generally taken from sources having the largest number of objects, in order to have data as homogeneous as possible. Blank if no data present. 52 --- 1X Blank 2-2 Table 1. (continued) Suggested Byte(s) Units Format Description 53 --- A1 Source of magnitude, coded as follows: 1. de Vaucouleurs and de Vaucouleurs 1964. 2. Zwicky et al. 1961-1968. 3. Vorontsov-Velyaminov, Krasnogorskaya, Arhipova 1962-1968. 4. Lindsay 1958. 5. Collinder 1931. 6. Arp 1965. 7. Vorontsov-Velyaminov 1931. 8. Bok and Bok 1962; van den Bergh and Hagen 1968. 54 --- 1X Blank 55- 74 --- 20A1 (5A4) The original visual appearance of the object, as transcribed from Dreyer (1888). Table 5 gives the code translations for the original Dreyer and RNGC codes. Certain codes have been modified from the original computeri...
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