[Adapted from the Explanatory Supplement to the IRAS Serendipitous Survey Catalog]

The SSC is distributed as an ASCII file, with each source occupying three or more 80-byte records, as described in Table 1.
Table 1. Format of the SSC
Start Byte Name Description Units Format
00 NAME Source Name   11A1
11 HOUR Right Ascension 1950 Hours I2
13 MINUTE Right Ascension1950 Minutes I2
15 SECOND Right Ascension 1950 Deci-seconds I3
18 DSIGN Declination Sign ± 1A1
19 DECDEG Declination 1950 Degree I2
21 DECMIN Declination 1950 Arcmin I2
23 DECSEC Declination 1950 Arcsec I2
25 SPARE 1 spare byte   1A1
30 FLUX Averaged Non-color corrected flux densities (1 value per band) Jansky (1E-26 W m-2 Hz-1) 4E9.3
66 FQUAL Flux Density Quality (1 value per band)   4I1
70 RGRID Reference Grid Number   I5
76 SPARE 9 spare bytes   9A1
---- New Record ----
80 RELUNC Percent Relative Flux Density Uncertainties (1 value per band)   4I3
92 TLSNR 10x Local Singal-to-Noise Ratio (1 value per band)   4I4
108 CC Point Source Correlation Coefficient (1 value per band)   4A1
112 TRFLUX 10 x F(c)/F(r)   4I2
120 POSDRS12 Right Ascension Delta Sign ± 1A1
121 POSDR12 Right Asension Delta Arcsec I3
124 POSDDS12 Declination Delta Sign ± 1A1
125 POSDD12 Declination Delta Arcsec I3
128 Repeat for 25 micron band
136 Repeat for 60 micron band
144 Repeat for 100 micron band
152 PNEARC Number of Sources in Confusion Window (1 value per band)   4I1
156 NID Number of Positional Associations   I2
158 IDTYPE Type of Object   I1
159 SPARE 1 spare byte   1A1
---- New Record ----
160 CATNO Catalog Number   I2
162 SOURCE Source ID   15A1
177 IDTYPE Source Type/Spectral Class   5A1
182 RADIUS Radius Vector from SSC Position to Association Arcsec I3
185 POS Position Angle from SSC Position to Association Degree (E of N) I3
188 FIELD1 Object Field #1 Catalog dependent I4
192 FIELD2 Object Field #1 Catalog dependent I4
196 FIELD3 Object Field #1 Catalog dependent I4
200-240 Continuation of Associations in Blocks of 40 Bytes

The following are brief descriptions of the individual entries in the table above.

Source Name: NAME, APPNAME
The SSC source name is constructed as for PSC sources and is derived from its position by combining the hours, minutes and tenths of minutes of right ascension and the sign, degrees and minutes of the declination. In obtaining the minutes of right ascension and declination for the name, the positions were truncated. If sources within a field have duplicate positional names, they are distinguished by an appended letter (APPNAME), starting with the letter A. See Source Designations for IRAS Catalogs.
As in the PSC, positions are given for the equinox 1950.0 and epoch 1983.5. Hours (HOUR) and minutes (MINUTE) of right ascension are given as integers while seconds (SECOND) are rounded to integer deci-seconds. The declination is given as a character sign (DSIGN) followed by integer values of degrees (DECDEG), minutes (DECMIN) and seconds (DECSEC).
Position Angle: ANGLE
The position angle of the major axis of the SSC source error box expressed in degrees East of North.
Flux Density: FLUX(4)
Each of the four wavelengths has a NON-COLOR-CORRECTED flux density in units of Janskys (1 Jy = 1E-25 W m-2 Hz-1). Color correction for any spectral shape is possible. Quoted flux densities are the noise-weighted averages.
Flux Quality: FQUAL (4)
Each flux density measurement is designated high quality, moderate quality, or upper limit (FQUAL = 3, 2, or 1, respectively) based on the prescription discussed in Section III.C of the Explanatory Supplement.
Flux Density Uncertainty: RELUNC(4), TLSNR(4)
Each flux density measurement other than an upper limit has an associated uncertainty expressed in two ways; RELUNC is the uncertainty expressed as a 1 sigma value in units of 100x<n>/<F> (see Section III.C.2). TLSRN is ten times the local signal-to-noise ratio (see Section II.C) as determined from the reference or confirming grid, whichever is least.
Point Source Correlation Coefficient: CC(4)
As discussed in Section III.B of the Explanatory Supplement, SSC sources can have point source correlation coefficients between 70-100%. These are encoded as alphabetic characters with A = 100, B = 99, ..., Z=75-70, one value per band. The quoted correlation coefficients come from the reference or confirming grids, whichever is higher, for high-quality sources.
Flux Density Ratio: TRFLUX(4)
As discussed in Section III.B, SSC sources can have flux density ratios 0.5 < F(c)/F(r) < 2.0, where F(r) and F(c) are the flux densities for the reference and confirming observations, respectively. TRFLUX is the flux density ratio for high-quality sources expressed as 10 x F(c)/F(r).
Position differences: POSDRS12, POSDR12, POSDDS12, POSDD12, ...
The quoted positions of SSC sources are determined from a weighted average of the positions of the confirmed sources in each band with a high-quality flux density (see Section III.C.1). POSDRS12, POSDR12, POSDDS12, and POSDD12 give the sign and amplitude (in arcsec), of the difference in right ascension and declination, respectively, between the final band-merged position and the 12 micron confirmed source position. The succeeding 12 entries repeat the above format for 25, 60, and 100 micron confirmed source component.
Confusion: PNEARC(4)
In regions of high source density, the Pointed Observation source extraction process, as well as the Serendipitous Survey Confirmation and Band Merging processing, can result in degraded positions and incorrectly band-merged sources. PNEARC is 1-(number of confirmed sources in the confusion and band merge window). (See Section III.D.) Any value greater than zero is indicative of potential confusion in the processing and the resulting source information should be examined carefully, e.g., by inspection of the grids in question.
Positional Associations: NID, IDTYPE, CATNO, SOURCE, TYPE, RADIUS, POS, FIELD 1-3
The positional associations, formats, and definitions are done as per the format of the Point Source Catalog, with these exceptions:
  1. Positional associations are made with the PSC when SSC and PSC positions agree to within 60". The PSC catalog is assigned catalog number 41.
  2. The search box for associations with high precision stellar catalogs, 13 (SAO),15 (Bright Star catalog), and 24 (Two Micron Sky Survey with Improved Positions) is 28" x 180" rather than the 16" x 90" search box used for associations in the PSC.
  3. The search radius for associations with the Dearborn catalog is increased to 120".
Table 2. Format of Overlapping Fields File
Name Description Units Format
00 GRID0 Prime Ref. Grid   I5
05 SPARE 1 spare byte   1A1
06 GRID1 Overlapping Field #1, Ref. Grid   I5
11 SPARE 1 spare byte   1A1
12 AOVLP1 Overlapping Sky Coverage Arcmin2 I4
16-2 Repeat of 5-15 for Overlapping Field #2
17-27 Repeat of 5-15 for Overlapping Field #3
60-70 Repeat of 5-15 for Overlapping Field #5
71-79 SPARE 9 spare bytes   9A1
---- New Record ----
80-85 SPARE 6 spare bytes   6A1
86-96 Repeat of 5-15 for Overlapping Field #6

The quantities in the Overlapping Fields List are as follows:

Prime Reference Grid: GRID0
The grid against which other reference grids are checked for overlapping sky coverage.
First Overlapping Grid: GRID1
The number of the first reference grid with more than 5% overlap with GRID0.
Overlap Area: AOVLP1
Area of overlapping sky coverage between GRID0 and GRID1 in square arcminutes.

The format is repeated for each additional grid overlapping with GRID0. If more than 5 grids overlap with GRID0, they are listed in succeeding records, as necessary; the first six bytes of each of these additional records begins with a string of 6 spaces.