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IRASSSC: Help

IRASSSC - IRAS Serendipitous Survey Catalog


Overview

The Infrared Astronomical Satellite (IRAS) Serendipitous Survey Catalog (SSC) is a catalog of 12, 25, 60 and 100 micron photometric observations of 43,866 point-like sources detected fortuitiously in the IRAS Pointed Observation program. The main objective was to take advantage of the longer-than-nominal integration time per source to extend the detection threshold relative to that of the IRAS Point Source Catalog (PSC); about three-fourths of the SSC sources do not appear in the PSC. From 1813 Pointed Observation fields, the effective sky coverage is 1108 square degrees. Relative to the PSC, the SSC is characterized by: enhanced sensitivity (by a factor of about 4) in all four wavelength bands; excellent reliability in uncrowded fields; uneven sky coverage and completeness; reduced positional accuracy; improved photometric accuracy; much greater depth in crowded fields at the expense of reliability and accuracy. More information about the SSC data processing, the catalog format, and an analysis are given in the Explanatory Supplement to the IRAS Serendipitous Survey Catalog.

Catalog Bibcode

1986SSC...C......0K

References

IRAS Serendipitous Survey Catalog
     Kleinmann S.G., Cutri R.M., Young E.T., Low F.J., Gillett F.C.
    <Joint IRAS Science W.G. (1986)>
    =1986SSC...C......0K

Provenance

This Browse table was created by the HEASARC in December 2006 based on CDS table II/126, the file sources.dat. More information, e.g., on counterparts in other catalogs to the SSC sources, is available in other files in the directory ftp://cdsarc.u-strasbg.fr/pub/cats/II/126/

Parameters

Name
The IRAS/SSC source name is constructed as for IRAS/PSC sources, and is derived from its position by combining the hours, minutes and tenths of minutes of (equinox 1950) right ascension and the sign, degrees and minutes of (equinox 1950) declination. In obtaining the minutes of right ascension and declination for the name, the positions were truncated. The letters 'A','B','C', etc., were appended to names of sources which were so close together that they would otherwise have had identical names.

RA
The Right Ascension of the IRAS/SSC source in the selected equinox. The RA was given in 1950.0 coordinates and for epoch 1983.5 to a precision of 0.1 seconds of time in the original table.

Dec
The Declination of the IRAS/SSC source in the selected equinox. This was given in 1950.0 coordinates and for epoch 1983.5 to a precision of 1 arcsecond in the original table.

LII
The Galactic Longitude of the IRAS/SSC source.

BII
The Galactic Latitude of the IRAS/SSC source.

PA_Error_Ellipse
The orientation of the source error box on the sky, expressed in terms of the position angle between the error box major axis and the local equatorial meridian. It is expressed in units of degrees east of the north direction.

Flux_12um
The non-color-corrected flux density at 12 microns (um), in units of Janskies, (1 Jy = 1.0E-26 W/m**2/Hz). The quoted value is the noise-weighted average of the combined individual source extractions, as defined in Section III.C.2 of the Explanatory Supplement to the IRAS/SSC.

Flux_25um
The non-color-corrected flux density at 25 microns (um), in units of Janskies, (1 Jy = 1.0E-26 W/m**2/Hz). The quoted value is the noise-weighted average of the combined individual source extractions, as defined in Section III.C.2 of the Explanatory Supplement to the IRAS/SSC.

Flux_60um
The non-color-corrected flux density at 60 microns (um), in units of Janskies, (1 Jy = 1.0E-26 W/m**2/Hz). The quoted value is the noise-weighted average of the combined individual source extractions, as defined in Section III.C.2 of the Explanatory Supplement to the IRAS/SSC.

Flux_100um
The non-color-corrected flux density at 100 microns (um), in units of Janskies, (1 Jy = 1.0E-26 W/m**2/Hz). The quoted value is the noise-weighted average of the combined individual source extractions, as defined in Section III.C.2 of the Explanatory Supplement to the IRAS/SSC.

Quality_Flag_12um
The quality flag for the 12-micron flux density, where 3 means high quality, 2 moderate quality, and 1 an upper limit, based on the prescription discussed in Section III.C of the Explanatory Supplement to the IRAS/SSC.

Quality_Flag_25um
The quality flag for the 25-micron flux density, where 3 means high quality, 2 moderate quality, and 1 an upper limit, based on the prescription discussed in Section III.C of the Explanatory Supplement to the IRAS/SSC.

Quality_Flag_60um
The quality flag for the 60-micron flux density, where 3 means high quality, 2 moderate quality, and 1 an upper limit, based on the prescription discussed in Section III.C of the Explanatory Supplement to the IRAS/SSC.

Quality_Flag_100um
The quality flag for the 100-micron flux density, where 3 means high quality, 2 moderate quality, and 1 an upper limit, based on the prescription discussed in Section III.C of the Explanatory Supplement to the IRAS/SSC.

Ref_Grid_Number
The identifying number for the reference grid (R) for the field in which the source was detected. (See Section III.A of the Explanatory Supplement to the IRAS/SSC for more details about the R and C (confirming) grids for the SSC fields: the R grid for a field is the one with the lower 60-um median noise).

Rel_Error_Flux_12um
The relative flux density uncertainty at 12 um, expressed as a percentage of the flux density. Each flux density measurement other than an upper limit has an associated uncertainty which is expressed as a 1-Sigma value in units of 100 x [Delta f(Nu)/f(Nu)] = percent.

Rel_Error_Flux_25um
The relative flux density uncertainty at 25 um, expressed as a percentage of the flux density. Each flux density measurement other than an upper limit has an associated uncertainty which is expressed as a 1-Sigma value in units of 100 x [Delta f(Nu)/f(Nu)] = percent.

Rel_Error_Flux_60um
The relative flux density uncertainty at 60 um, expressed as a percentage of the flux density. Each flux density measurement other than an upper limit has an associated uncertainty which is expressed as a 1-Sigma value in units of 100 x [Delta f(Nu)/f(Nu)] = percent.

Rel_Error_Flux_100um
The relative flux density uncertainty at 100 um, expressed as a percentage of the flux density. Each flux density measurement other than an upper limit has an associated uncertainty which is expressed as a 1-Sigma value in units of 100 x [Delta f(Nu)/f(Nu)] = percent.

Local_SNR_12um
The local signal-to-noise ratio (SNR) at 12 um (see Section II.C of the Explanatory Supplement to the IRAS/SSC) as determined from the reference or confirming grid, whichever is least. Notice that in the original CDS version of this catalog, the equivalent parameter given there (TLSNR) was 10 times the minimum signal-to-noise ratio.

Local_SNR_25um
The local signal-to-noise ratio (SNR) at 25 um (see Section II.C of the Explanatory Supplement to the IRAS/SSC) as determined from the reference or confirming grid, whichever is least. Notice that in the original CDS version of this catalog, the equivalent parameter given there (TLSNR) was 10 times the minimum signal-to-noise ratio.

Local_SNR_60um
The local signal-to-noise ratio (SNR) at 60 um (see Section II.C of the Explanatory Supplement to the IRAS/SSC) as determined from the reference or confirming grid, whichever is least. Notice that in the original CDS version of this catalog, the equivalent parameter given there (TLSNR) was 10 times the minimum signal-to-noise ratio.

Local_SNR_100um
The local signal-to-noise ratio (SNR) at 100 um (see Section II.C of the Explanatory Supplement to the IRAS/SSC) as determined from the reference or confirming grid, whichever is least. Notice that in the original CDS version of this catalog, the equivalent parameter given there (TLSNR) was 10 times the minimum signal-to-noise ratio.

Corr_Coeff_12um
The coded value of the point source correlation coefficient at 12 um. As discussed in Section III.B of the Explanatory Supplement to the IRAS/SSC, the correlation coefficients of SSC sources can have values between 70 - 100%, or can have been given no values (represented in this Browse table by blanks). The values are encoded as alphabetic characters with A = 100, B = 99 ... up to Z = 75 - 70. The values quoted come from the reference or confirming grids, whichever is higher, for high-quality sources.

Corr_Coeff_25um
The coded value of the point source correlation coefficient at 25 um. As discussed in Section III.B of the Explanatory Supplement to the IRAS/SSC, the correlation coefficients of SSC sources can have values between 70 - 100%, or can have been given no values (represented in this Browse table by blanks). The values are encoded as alphabetic characters with A = 100, B = 99 ... up to Z = 75 - 70. The values quoted come from the reference or confirming grids, whichever is higher, for high-quality sources.

Corr_Coeff_60um
The coded value of the point source correlation coefficient at 60 um. As discussed in Section III.B of the Explanatory Supplement to the IRAS/SSC, the correlation coefficients of SSC sources can have values between 70 - 100%, or can have been given no values (represented in this Browse table by blanks). The values are encoded as alphabetic characters with A = 100, B = 99 ... up to Z = 75 - 70. The values quoted come from the reference or confirming grids, whichever is higher, for high-quality sources.

Corr_Coeff_100um
The coded value of the point source correlation coefficient at 100 um. As discussed in Section III.B of the Explanatory Supplement to the IRAS/SSC, the correlation coefficients of SSC sources can have values between 70 - 100%, or can have been given no values (represented in this Browse table by blanks). The values are encoded as alphabetic characters with A = 100, B = 99 ... up to Z = 75 - 70. The values quoted come from the reference or confirming grids, whichever is higher, for high-quality sources.

Flux_Ratio_12um
The ratio of the confirming flux density F_c to the reference flux density F_r at 12 um, given for high-quality sources. As discussed in Section III.B of the Explanatory Supplement to the IRAS/SSC, SSC sources can have flux density ratios 0.5 < F_c/F_r < 2.0. Notice that in the original CDS version of this catalog, the equivalent parameter given there (TRFLUX ) was 10 times the ratio of F_c to F_r.

Flux_Ratio_25um
The ratio of the confirming flux density F_c to the reference flux density F_r at 25 um, given for high-quality sources. As discussed in Section III.B of the Explanatory Supplement to the IRAS/SSC, SSC sources can have flux density ratios 0.5 < F_c/F_r < 2.0. Notice that in the original CDS version of this catalog, the equivalent parameter given there (TRFLUX ) was 10 times the ratio of F_c to F_r.

Flux_Ratio_60um
The ratio of the confirming flux density F_c to the reference flux density F_r at 60 um, given for high-quality sources. As discussed in Section III.B of the Explanatory Supplement to the IRAS/SSC, SSC sources can have flux density ratios 0.5 < F_c/F_r < 2.0. Notice that in the original CDS version of this catalog, the equivalent parameter given there (TRFLUX ) was 10 times the ratio of F_c to F_r.

Flux_Ratio_100um
The ratio of the confirming flux density F_c to the reference flux density F_r at 100 um, given for high-quality sources. As discussed in Section III.B of the Explanatory Supplement to the IRAS/SSC, SSC sources can have flux density ratios 0.5 < F_c/F_r < 2.0. Notice that in the original CDS version of this catalog, the equivalent parameter given there (TRFLUX ) was 10 times the ratio of F_c to F_r.

Delta_RA_12um
The difference in Right Ascension, in arcseconds, between the final band-merged source position and the 12-um confirmed source position. The band-merged position is the weighted average of the the position of the confirmed source in each band having a high-quality flux density (see Section III.C.1 of the Explanatory Supplement to the IRAS/SSC).

Delta_Dec_12um
The difference in Declination, in arcseconds, between the final band-merged source position and the 12-um confirmed source position. The band-merged position is the weighted average of the the position of the confirmed source in each band having a high-quality flux density (see Section III.C.1 of the Explanatory Supplement to the IRAS/SSC).

Delta_RA_25um
The difference in Right Ascension, in arcseconds, between the final band-merged source position and the 25-um confirmed source position. The band-merged position is the weighted average of the the position of the confirmed source in each band having a high-quality flux density (see Section III.C.1 of the Explanatory Supplement to the IRAS/SSC).

Delta_Dec_25um
The difference in Declination, in arcseconds, between the final band-merged source position and the 25-um confirmed source position. The band-merged position is the weighted average of the the position of the confirmed source in each band having a high-quality flux density (see Section III.C.1 of the Explanatory Supplement to the IRAS/SSC).

Delta_RA_60um
The difference in Right Ascension, in arcseconds, between the final band-merged source position and the 60-um confirmed source position. The band-merged position is the weighted average of the the position of the confirmed source in each band having a high-quality flux density (see Section III.C.1 of the Explanatory Supplement to the IRAS/SSC).

Delta_Dec_60um
The difference in Declination, in arcseconds, between the final band-merged source position and the 60-um confirmed source position. The band-merged position is the weighted average of the the position of the confirmed source in each band having a high-quality flux density (see Section III.C.1 of the Explanatory Supplement to the IRAS/SSC).

Delta_RA_100um
The difference in Right Ascension, in arcseconds, between the final band-merged source position and the 100-um confirmed source position. The band-merged position is the weighted average of the the position of the confirmed source in each band having a high-quality flux density (see Section III.C.1 of the Explanatory Supplement to the IRAS/SSC).

Delta_Dec_100um
The difference in Declination, in arcseconds, between the final band-merged source position and the 100-um confirmed source position. The band-merged position is the weighted average of the the position of the confirmed source in each band having a high-quality flux density (see Section III.C.1 of the Explanatory Supplement to the IRAS/SSC).

Confusion_Flag_12um
The number of sources in the confusion window, at 12 um, less 1. 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. This parameter (called PNEARC in the original CDS version of this table) is (the number N of confirmed sources in the confusion and band merge window) - 1. 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. In the original documentation for this parameter (in both the Explanatory Supplement and the CDS files), PNEARC is defined as 1 - N rather than N - 1, which cannot be correct since its values are >= 0.

Confusion_Flag_25um
The number of sources in the confusion window, at 25 um, less 1. 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. This parameter (called PNEARC in the original CDS version of this table) is (the number N of confirmed sources in the confusion and band merge window) - 1. 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. In the original documentation for this parameter (in both the Explanatory Supplement and the CDS files), PNEARC is defined as 1 - N rather than N - 1, which cannot be correct since its values are >= 0.

Confusion_Flag_60um
The number of sources in the confusion window, at 60 um, less 1. 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. This parameter (called PNEARC in the original CDS version of this table) is (the number N of confirmed sources in the confusion and band merge window) - 1. 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. In the original documentation for this parameter (in both the Explanatory Supplement and the CDS files), PNEARC is defined as 1 - N rather than N - 1, which cannot be correct since its values are >= 0.

Confusion_Flag_100um
The number of sources in the confusion window, at 100 um, less 1. 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. This parameter (called PNEARC in the original CDS version of this table) is (the number N of confirmed sources in the confusion and band merge window) - 1. 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. In the original documentation for this parameter (in both the Explanatory Supplement and the CDS files), PNEARC is defined as 1 - N rather than N - 1, which cannot be correct since its values are >= 0.

Number_ID
Much of the utility of the IRAS catalogs comes from the association of infrared objects with sources known to exist from other astronomical catalogs. A large number of catalogs were searched for positional matches (in the same way as was done for the IRAS/PSC with the exceptions noted in Section III.F of the SSC Explanatory Supplement), and the total number of matches found is given by this parameter. For more information on these identifications, please refer to the file ftp://cdsarc.u-strasbg.fr/pub/cats/II/126/assoc.dat.gz

ID_Type
This parameter has values which range from 0 to 4, and gives information on whether an association was found in an extragalactic catalog (value of 1), a stellar catalog (2), other catalogs (3), or matches in multiple types of catalogs (4), or that no association at all was found (0).


Contact Person

Questions regarding the IRASSSC database table can be addressed to the HEASARC User Hotline.
If you have any problems, please consult the help page or mail ledas-help@star.le.ac.uk
 
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