# 14.4.6 sdssdr9_original_valid

SDSS DR9 Catalogue, primary object only, extracted from photoObj fits files.
Reference paper: Ahn et al. (2012)
Original catalogue: http://data.sdss3.org/sas/dr9/boss/photoObj/

Columns description:

sdssdr9_oid : Unique Numeric Identifier (long)

Incremental unique numeric identifier (increasing with declination). This is the only field which was not in the original SDSS DR9 catalogue, but was added for cross-match purposes.

obj_id : Unique SDSS identifier (string)

A number identifying an object in the image catalog for DR9. It is a bit-encoded integer of run, rerun, camcol, field, object.
The bits are assigned in objid as follows:

• 63 0, unassigned

• 59$-$62 skyVersion resolved sky version

• 48$-$58 rerun, number of pipeline rerun

• 32$-$47 run, run number

• 29$-$31 camcol, camera column (1-6)

• 28 0, unassigned

• 16$-$27 field, field number within run

• 0$-$15 id, object number within field

thing_id : Unique identifier from global resolve (long)

Each unique source in the SDSS catalog is identified by the thing_id. Each source may have been observed more than once in multiple runs, and might therefore have multiple detections listed in the catalog. Only one detection is considered primary.

ra : RA (double, Angle[deg])

J2000 Right Ascension (from r-band, or best other band if r-band if too faint or saturated in r).

dec : DEC (double, Angle[deg])

J2000 Declination (from r-band, or best other band if r-band if too faint or saturated in r).

ra_error : Reference error in RAcosDEC (double, Angle[arcsec])

Error in RA*cos(DEC)

dec_error : Reference error in DEC (double, Angle[arcsec])

Error in DEC.

mjd : Date of observation (double, Time[day])

Modified Julian Date, used to indicate the date that a given piece of SDSS data (image or spectrum) was taken.

u_mag : PSF magnitude in the u band (double, Magnitude[mag])

For isolated stars, which are well-described by the point spread function (PSF), the optimal measure of the total flux is determined by fitting a PSF model to the object.

u_mag_error : error on PSF magnitude in the u band (double, Magnitude[mag])

PSF magnitude error.

g_mag : PSF magnitude in the g band (double, Magnitude[mag])

For isolated stars, which are well-described by the point spread function (PSF), the optimal measure of the total flux is determined by fitting a PSF model to the object.

g_mag_error : error on PSF magnitude in the g band (double, Magnitude[mag])

PSF magnitude error.

r_mag : PSF magnitude in the r band (double, Magnitude[mag])

For isolated stars, which are well-described by the point spread function (PSF), the optimal measure of the total flux is determined by fitting a PSF model to the object.

r_mag_error : error on PSF magnitude in the r band (double, Magnitude[mag])

PSF magnitude error.

i_mag : PSF magnitude in the i band (double, Magnitude[mag])

For isolated stars, which are well-described by the point spread function (PSF), the optimal measure of the total flux is determined by fitting a PSF model to the object.

i_mag_error : error on PSF magnitude in the i band (double, Magnitude[mag])

PSF magnitude error.

z_mag : PSF magnitude in the z band (double, Magnitude[mag])

For isolated stars, which are well-described by the point spread function (PSF), the optimal measure of the total flux is determined by fitting a PSF model to the object.

z_mag_error : error on PSF magnitude in the z band (double, Magnitude[mag])

PSF magnitude error.

objc_type : type classification of the object (int)

Distinguishes stars (type=6) and galaxies (type=3) based on their morphology. It is quantified on the basis of the difference between the PSF and model magnitudes.

clean_flag : clean photometry flag for point sources (int)

Clean photometry flag for point sources (1=clean, 0=unclean).