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.

Position: HOUR, MINUTE, SECOND, DSIGN, DECDEG, DECMIN, DECSEC

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".

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.

• SSC information