Explanatory Supplement for the Machine-Readable Version of the IRAS FAINT SOURCE CATALOG |b| > 10 Degrees Version 2.0 Moshir, M. et al. 1989 Notes to the CD-ROM Machine-Readable Version of the IRAS Faint Source Catalog The following text is an exerpt from the original "Explanatory Supplement to the IRAS Faint Source Survey, Version 1" (Moshir et al. 1989). Presented here is Chapter V: "The Formats of the FSS Products", section C.1, and Table II.G.6: "Meaning of the Source Association Fields". The text has been altered slightly to accommodate the changes in version 2.0. The formats and fields of the two machine-readable data files of the catalog are adequately described. For further explanation, the original published explanatory supplement should be consulted. The catalog was received from the Infrared Processing and Analysis Center (IPAC) as two FITS files. These were converted into two ASCII files with the following characteristics: 1. Data File Record Length: 240 Number of Records: 173,044 2. Associations File Rocord Length: 64 Number of Records: 235,935 The entire original published version of the explanatory supplement (version 1) was received as a set of TeX files. The mentioned sections were extracted and converted to ASCII in order to create this document. The TeX files as received were added to the CD-ROM so that one might have access to a complete copy of the published explanatory supplement. However, note that the data pertains to version 2.0, therefore, an addendum file was created in TeX to outline the changes in the 2.0 version. -- Susan Gessner, Space Data and Computing, NASA/GSFC C.1 The Short Machine-Readable Version of the Faint Source Catalog ------------------------------------------------------------------------------- The short FSC tape is presented as FITS table data. In order to do this, the associations block has been split out as a separate file. It takes one 6250-bpi tape to hold all of these files for |b| > 50 degrees. The FITS table format consists of the following: - The catalog is split into two files, one for the non-association data (FSC_DATA) and one for the association data (FSC_ASSOC). - There are two headers, each with 80-byte records, within each file. - The first header in each file identifies that the tape is written in FITS format. - The second header constitutes the FITS keyword file giving the format information for the rest of the file. - The data part (i.e., non-header part) of FSC_DATA has 240-byte records. - The data part of FSC_ASSOC has 64-byte records. - The tape is blocked to multiples of 2880 bytes. Specifically, the formats of the files are as follows: FILE 1: Block 1 - short header file Blocks 2-10 - FSC_DATA header Blocks 11-END - FSC_DATA FILE 2: Block 1 - short header file Blocks 2-4 - FSC_ASSOC header Blocks 5-END - FSC_ASSOC The short header file is given in Table V.C.1. (in the published version of the explanatory supplement.) - 1 - TABLE V.C.4. Format of FSC Data File for Short FSC Tape _______________________________________________________________________________ Start Byte Name Description Units Format _______________________________________________________________________________ 000 NAME * Source Name _ 12A1 012 RAHR Right Ascension 1950 Hour of time I2 014 RAMIN Right Ascension 1950 Minute of time I2 016 RASEC * Right Ascension 1950 deci-Second of time I3 019 DECSGN * Declination Sign +/- A1 020 DECDEG Declination 1950 Arc Degree I2 022 DECMIN Declination 1950 Arc Minute I2 024 DECSEC * Declination 1950 Arc Second I2 026 UNCMAJ * Uncertainty ellipse major axis Arc Second I3 029 UNCMIN * Uncertainty ellipse minor axis Arc Second I3 032 POSANG * Uncertainty ellipse position angle Degree (East I3 of North) 035 NOBS *+ Number of times observed in _ 4I3 each band 047 FNU *+ Flux densities (1 value per Jansky (10^-26 4E9.3 band, non-color corrected) W m-^2 Hz^-1) 083 FQUAL *+ Flux density quality _ 4I1 (1 value per band) 087 RELUNC + Percent relative flux density _ 4I3 uncertainties (1 value/band) 099 MINREL * Minimum percent reliability _ I2 101 MEDSNR *+ SNR in each band _ 4E7.1 129 LOCSNR *+ Local SNR in each band _ 4E7.1 157 AREA *+ Number of pixels above _ 4I3 threshold in each band 169 CATNBR * No. of nearby catalog sources _ I2 171 EXTNBR *+ No. of nearby extractions _ 4I2 in each band 179 CIRRUS * No. of nearby 100-micron-only _ I2 extractions 181 CONFUSE * Confusion flag (1 flag/band, _ A2 hex encoded) 183 NOISCOR + Noise correction factor _ 4F5.2 (1 value per band) 203 NID * No. of positional associations _ I2 205 IDTYPE Type of object _ I2 207 NOISRAT Ratio 85% to 68% of flux _ 4F5.3 distribution (1 value per band) 227 SPARE - 13A1 _______________________________________________________________________________ - 2 - TABLE V.C.4 Format of FSC Data File for Short FSC Tape (continued) NOTES: * Quantities listed in microfiche version of catalog + In the FITS header, these quantities are suffixed by the wavelength. Example: FNU(4) is given as FNU_12, FNU_25, FNU_60, and FNU_100. TABLE V.C.5. Format of Association Data for FSC Tape _______________________________________________________________________________ Start Byte Name Description Units Format _______________________________________________________________________________ 00 NAME * Source Name _ 12A1 12 RECNO * Record No. in main data table _ I6 18 CATNO * Catalog No. _ I2 20 SOURCE * Source ID _ 15A1 35 TYPE * Source Type/Spectral Class _ 5A1 40 RADIUS * Radius vector from IRAS Arc Second I3 source to association 43 POS Position angle from IRAS Degree (East I3 source to association of North) 46 DSTMAJOR Distance from IRAS source to Arc Second I3 association along the IRAS position error major axis 49 DSTMINOR Distance from IRAS source to Arc Second I3 association along the IRAS position error minor axis 52 FIELD1 + Object field #1 Catalog I4 (magnitude/other) dependent 56 FIELD2 + Object field #2 Catalog I4 (magnitude/other) dependent 60 FIELD3 Object field #3 Catalog I4 (magnitude/other) dependent _______________________________________________________________________________ * Quantities listed in printed version of catalog + FIELD1 is listed in microfiche version of catalog, except for catalogs 2 and 19, where FIELD2 is listed. - 3 - Table V.C.2 gives a sample of the header for the non-association data and Table V.C.3 gives a sample of the header for the association data. Tables V.C.4 (FSC data) and V.C.5 (association data) describe each entry in the short catalog tape. All of this information is contained in the actual FITS headers, but is presented here in an easier-to-read format. Those columns that are also included in the microfiche version are marked. Each catalog entry required 240 bytes of ASCII data for the non-association data and NID x 64 bytes of ASCII data for the association data. In these tables the column "Format" refers to the length and type of the (FORTRAN) character field used to read or write each entry. The tape is written with 240-character (ASCII) logical records for the non-association data and with 64-character records for the association data. The number of logical records per physical record is 36 for the headers, ...
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