# 14.4.5 ppmxl_original_valid

PPMXL Catalogue
Reference papers:
PPMXL: Roeser et al. (2010)
PPMX: Röser et al. (2008a)
Original Catalogue:
VO access: http://vo.uni-hd.de/ppmxl

Columns description:

ppmxl_oid : Unique Numeric Identifier (long)

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

ipix : source Id in original catalog (long)

Identifier (Q3C ipix of the USNO-B 1.0 object)

ra : RA, ICRS, epoch J2000.0 (double, Angle[deg])

J2000 right ascension with respect to the ICRS, epoch 2000.0

dec : DEC, ICRS, epoch J2000.0 (double, Angle[deg])

J2000 declination with respect to the ICRS, epoch 2000.0.

ra_error_epra : mean error at mean epoch in RAcosDEC (double, Angle[mas])

Mean error in RA*cos(DEC) at mean epoch.

dec_error_epde : mean error at mean epoch in DEC (double, Angle[mas])

Mean error in DEC at mean epoch.

pmra : proper motion in RAcosDEC (double, Angular Velocity[mas/year])

Proper motion in RA*cos(DEC).

pmde : proper motion in DEC (double, Angular Velocity[mas/year])

Proper motion in Declination.

pmra_error : mean error in proper motion in RAcosDEC (double, Angular Velocity[mas/year])

Mean error in proper motion in RA*cos(DEC).

pmde_error : mean error in proper motion in DEC (double, Angular Velocity[mas/year])

Mean error in proper motion in DEC.

n_epochs : number of epochs used for proper motions (short)

Number of catalogs (epoch) used for proper motions.
May be blank (null) for stars coming from ARIHIP or Tycho-2 via PPMX (i.e. bit#1 is set in ”fl”).

epra : Mean RA Epoch (double, Time[Julian Years])

Mean Epoch for RA.

epde : Mean DEC Epoch (double, Time[Julian Years])

Mean Epoch for DEC.

b1mag : USNO B mag first epoch (double, Magnitude[mag])

B mag from USNO-B, first epoch.

Magnitudes from USNO-B should be used with care, photometric calibration may be severely off for some plates.
For objects from PPMX (bit#1 set in ”fl”), these magnitudes have a special meaning:
————————————————————
Column [PPMX] Content
————————————————————
b1mag [Cmag] Catalogue magnitude from source
b2mag [Bmag] Johnson B magnitude
r1mag [Rmag] calculated Ru (UCAC) magnitude from source
r2mag — (always empty)
imag [Vmag] Johnson V magnitude

b2mag : USNO B mag second epoch (double, Magnitude[mag])

B mag from USNO-B, second epoch.

Magnitudes from USNO-B should be used with care, photometric calibration may be severely off for some plates.
For objects from PPMX (bit#1 set in ”fl”), these magnitudes have a special meaning:
————————————————————
Column [PPMX] Content
————————————————————
b1mag [Cmag] Catalogue magnitude from source
b2mag [Bmag] Johnson B magnitude
r1mag [Rmag] calculated Ru (UCAC) magnitude from source
r2mag — (always empty)
imag [Vmag] Johnson V magnitude

r1mag : USNO R mag first epoch (double, Magnitude[mag])

R mag from USNO-B, first epoch.

Magnitudes from USNO-B should be used with care, photometric calibration may be severely off for some plates.
For objects from PPMX (bit#1 set in ”fl”), these magnitudes have a special meaning:
————————————————————
Column [PPMX] Content
————————————————————
b1mag [Cmag] Catalogue magnitude from source
b2mag [Bmag] Johnson B magnitude
r1mag [Rmag] calculated Ru (UCAC) magnitude from source
r2mag — (always empty)
imag [Vmag] Johnson V magnitude

r2mag : USNO R mag second epoch (double, Magnitude[mag])

R mag from USNO-B, second epoch.

Magnitudes from USNO-B should be used with care, photometric calibration may be severely off for some plates.
For objects from PPMX (bit#1 set in ”fl”), these magnitudes have a special meaning:
————————————————————
Column [PPMX] Content
————————————————————
b1mag [Cmag] Catalogue magnitude from source
b2mag [Bmag] Johnson B magnitude
r1mag [Rmag] calculated Ru (UCAC) magnitude from source
r2mag — (always empty)
imag [Vmag] Johnson V magnitude

imag : USNO I mag (double, Magnitude[mag])

I mag from USNO-B.

Magnitudes from USNO-B should be used with care, photometric calibration may be severely off for some plates.
For objects from PPMX (bit#1 set in ”fl”), these magnitudes have a special meaning:
————————————————————
Column [PPMX] Content
————————————————————
b1mag [Cmag] Catalogue magnitude from source
b2mag [Bmag] Johnson B magnitude
r1mag [Rmag] calculated Ru (UCAC) magnitude from source
r2mag — (always empty)
imag [Vmag] Johnson V magnitude

flags : flags (short)

The flag is a bitwise or number ($\Sigma 2^{i}$) where each bit number (i) has the meaning:
#0 (1) = if set, one of the coordinates had an excessively large chi square.
#1 (2) = Row is from PPMX. These objects are mostly Tycho stars that were masked out of USNO-B. When this bit is set, the USNO magnitudes (b1mag through imag) have special meanings.
#2 (4) = Row is from PPMX and replaces a single row from USNO-B. This is done when the astrometry from PPMX was better (in terms of error estimates) than the astrometry of the corresponding PPMXL object.
#3 (8) = Row replaces multiple USNO-B1.0 objects. When PPMX contains an object that has more than one counterpart in PPMXL, all such counterparts are discarded on the assumption that they should have been matched in USNO-B1.0 or result from erroneous matches. For these rows, bit#1 is always 1.