Appendix B—Extended Source Catalog Parameters

Table 1 gives a complete list of the catalog parameters relevant to the 2MASS extended source catalog. The parameters represent a subset of information derived from the extended source database. The catalog was designed to be accessed using an on-line database engine (e.g., "catscan") which allows the user to choose smaller subsets from the field parameters given in Table 1 (e.g., positions coordinates and default fluxes).

"Default" magnitudes are used as a convenience measure to database engine for indexing and computing colors. The default measurements refer to the mags derived from the K-band fiducial 20 mag/sq.arsec circular isophotal apertures. However, the user is not obliged to use them, they are merely a convenience. The recommend flux measurements to use, in fact, are those from the elliptical isophotal apertures (e.g., <jhk>_m_k20fe).

"Fiducial" apertures are determined for each type of total and isophotal photometry.

They are used to make flux measurements for each type of photometry with the same aperture size in all three bands. The fiducial band for the total Kron photometry and 20mag/sq.arcsec isophotal photometry is the K band, and for the 21mag/sqarcsec isophotal photometry it is the J band.

Magnitude colors are calculated using the [jhk]_m default mags and sigmas for the extended sources and the optical mags [br]_m_opt in the associated point source catalog.

The system flux includes the flux from this extended source and anything else in the immediate area, including stars and neighboring galaxies that "touch" the source.

For each mag there is an associated confusion flag. The code definitions are as follows:

 

 

 

 

TABLE 1

Extended Source Catalog Parameter Fields

Parameter Name

Description of Parameter

ra

right ascension (J2000 decimal deg) based on peak pixel

dec

declination (J2000 decimal deg) based on peak pixel

glon

galactic longitude (decimal deg) based on peak pixel

glat

galactic latitude (decimal deg) based on peak pixel

r_3sig

3-s K isophotal semi-major axis

<band>_ba

<band> minor/major axis ratio fit to the 3-s isophote

<band>_phi

<band> angle to 3-s major axis (E of N)

<band>_m

<band> selected "default" magnitude

<band>_msig

<band> "default" mag uncertainty

<band>_flg

<band> confusion flag for "default" magnitude

j_mtype

source of J "default" mag (0=j_m_k20fe; 1=j_m_j21fe)

h_mtype

source of H "default" mag (0=h_m_k20fe; 1=h_m_j21fe)

k_mtype

source of K "default" mag (0=k_m_k20fe; 1=k_m_j21fe)

j_h

default J-H mag color

j_h_sig

s for J-H mag color

h_k

default H-K mag color

h_k_sig

s for H-K mag color

j_k

default J-K mag color

j_k_sig

s for J-K mag color

b_r

B-R mag color of associated optical source

r_k

default R-K mag color (using associated optical source)

b_k

default B-K mag color

r_j

default R-J mag color

b_j

default B-J mag color

<band>_m_7

<band> 7 arcsec radius circular aperture magnitude

<band>_msig_7

<band> 1-s uncertainty in 7 arcsec circular ap. mag

<band>_flg_7

<band> confusion flag for 7 arcsec circular ap. mag

<band>_peak

<band> peak pixel brightness

<band>_5surf

<band> central surface brightness (r<=5)

id_flg

type/galaxy ID flag (0=non-catalog; 1=catalog; 2=LCSB)

id_cat

matched galaxy's catalog name

density

coadd log(density per sq.deg.) of stars with k<14 mag

<band>_bisym_rat

<band> bi-symmetric flux ratio

<band>_sc_sh

<band> shape (score)

<band>_sc_wsh

<band> wsh (score) (LCSB: PSNR - peak raw SNR)

e_score

extended weight-average flag (1.0=fuzziest; 2.0=pointlike)

g_score

galaxy weight-average flag (1.0=fuzziest; 2.0=pointlike)

hemis

hemisphere (N/S) of observation

date

observation date

scan

scan number (unique within date)

coadd

3-digit coadd number (unique within scan)

id

source ID number (unique within scan; coadd)

x_coadd

x (cross-scan) position (coadd coord.)

y_coadd

y (in-scan) position (coadd coord.)

<band>_r_e

<band> Kron elliptical aperture semi-major axis

<band>_m_e

<band> Kron elliptical aperture magnitude

<band>_msig_e

<band> 1-s uncertainty in Kron elliptical mag

<band>_flg_e

<band> confusion flag for Kron elliptical mag

r_fe

K fiducial Kron elliptical aperture semi-major axis

<band>_m_fe

<band> fiducial Kron elliptical aperture magnitude

<band>_msig_fe

<band> 1- s uncertainty in fiducial Kron ell. mag

<band>_flg_fe

<band> confusion flag for fiducial Kron ell. mag

<band>_r_c

<band> Kron circular aperture radius

<band>_m_c

<band> Kron circular aperture magnitude

<band>_msig_c

<band> 1- s uncertainty in Kron circular mag

<band>_flg_c

<band> confusion flag for Kron circular mag

r_fc

K fiducial Kron circular aperture radius

<band>_m_fc

<band> fiducial Kron circular magnitude

<band>_msig_fc

<band> 1- s uncertainty in fiducial Kron circ. mag

<band>_flg_fc

<band> confusion flag for fiducial Kron circ. mag

<band>_r_i20e

<band> 20mag/sq." isophotal elliptical ap. semi-major axis

<band>_m_i20e

<band> 20mag/sq." isophotal elliptical ap. magnitude

<band>_msig_i20e

<band> 1-s uncertainty in 20mag/sq." iso. ell. mag

<band>_flg_i20e

<band> confusion flag for 20mag/sq." iso. ell. mag

r_k20fe

20mag/sq." isophotal K fiducial ell. ap. semi-major axis

<band>_m_k20fe

<band> 20mag/sq." isophotal fiducial ell. ap. magnitude

<band>_msig_k20fe

<band> 1-s uncertainty in 20mag/sq." iso.fid.ell.mag

<band>_flg_k20fe

<band> confusion flag for 20mag/sq." iso. fid. ell. mag

<band>_r_i20c

<band> 20mag/sq." isophotal circular aperture radius

<band>_m_i20c

<band> 20mag/sq." isophotal circular ap. magnitude

<band>_msig_i20c

<band> 1-s uncertainty in 20mag/sq." iso. circ. mag

<band>_flg_i20c

<band> confusion flag for 20mag/sq." iso. circ. mag

r_k20fc

20mag/sq." isophotal K fiducial circular ap. radius

<band>_m_k20fc

<band> 20mag/sq." isophotal fiducial circ. ap. mag

<band>_msig_k20fc

<band> 1-s uncertainty in 20mag/sq." iso.fid.circ. mag

<band>_flg_k20fc

<band> confusion flag for 20mag/sq." iso. fid. circ. mag

<band>_r_i21e

<band> 21mag/sq." isophotal elliptical ap. semi-major axis

<band>_m_i21e

<band> 21mag/sq." isophotal elliptical ap. magnitude

<band>_msig_i21e

<band> 1-s uncertainty in 21mag/sq." iso. ell. mag

<band>_flg_i21e

<band> confusion flag for 21mag/sq." iso. ell. mag

r_j21fe

21mag/sq." isophotal J fiducial ell. ap. semi-major axis

<band>_m_j21fe

<band> 21mag/sq." isophotal fiducial ell. ap. magnitude

<band>_msig_j21fe

<band> 1-s uncertainty in 21mag/sq." iso.fid.ell.mag

<band>_flg_j21fe

<band> confusion flag for 21mag/sq." iso. fid. ell. mag

<band>_r_i21c

<band> 21mag/sq." isophotal circular aperture radius

<band>_m_i21c

<band> 21mag/sq." isophotal circular ap. magnitude

<band>_msig_i21c

<band> 1-s uncertainty in 21mag/sq." iso. circ. mag

<band>_flg_i21c

<band> confusion flag for 21mag/sq." iso. circ. mag

r_j21fc

21mag/sq." isophotal J fiducial circular ap. radius

<band>_m_j21fc

<band> 21mag/sq." isophotal fiducial circ. ap. mag

<band>_msig_j21fc

<band> 1-s uncertainty in 21mag/sq." iso.fid.circ.mag

<band>_flg_j21fc

<band> confusion flag for 21mag/sq." iso. fid. circ. mag

<band>_m_5

<band> 5 arcsec radius circular aperture magnitude

<band>_msig_5

<band> 1-s uncertainty in 5 arcsec circular ap. mag

<band>_flg_5

<band> confusion flag for 5 arcsec circular ap. mag

<band>_m_10

<band> 10 arcsec radius circular aperture magnitude

<band>_msig_10

<band> 1-s uncertainty in 10 arcsec circular ap. mag

<band>_flg_10

<band> confusion flag for 10 arcsec circular ap. mag

<band>_m_15

<band> 15 arcsec radius circular aperture magnitude

<band>_msig_15

<band> 1-s uncertainty in 15 arcsec circular ap. mag

<band>_flg_15

<band> confusion flag for 15 arcsec circular ap. mag

<band>_m_20

<band> 20 arcsec radius circular aperture magnitude

<band>_msig_20

<band> 1-s uncertainty in 20 arcsec circular ap. mag

<band>_flg_20

<band> confusion flag for 20 arcsec circular ap. mag

<band>_m_25

<band> 25 arcsec radius circular aperture magnitude

<band>_msig_25

<band> 1-s uncertainty in 25 arcsec circular ap. mag

<band>_flg_25

<band> confusion flag for 25 arcsec circular ap. mag

<band>_m_30

<band> 30 arcsec radius circular aperture magnitude

<band>_msig_30

<band> 1-s uncertainty in 30 arcsec circular ap. mag

<band>_flg_30

<band> confusion flag for 30 arcsec circular ap. mag

<band>_m_40

<band> 40 arcsec radius circular aperture magnitude

<band>_msig_40

<band> 1-s uncertainty in 40 arcsec circular ap. mag

<band>_flg_40

<band> confusion flag for 40 arcsec circular ap. mag

<band>_m_50

<band> 50 arcsec radius circular aperture magnitude

<band>_msig_50

<band> 1-s uncertainty in 50 arcsec circular ap. mag

<band>_flg_50

<band> confusion flag for 50 arcsec circular ap. mag

<band>_m_60

<band> 60 arcsec radius circular aperture magnitude

<band>_msig_60

<band> 1-s uncertainty in 60 arcsec circular ap. mag

<band>_flg_60

<band> confusion flag for 60 arcsec circular ap. mag

<band>_m_70

<band> 70 arcsec radius circular aperture magnitude

<band>_msig_70

<band> 1-s uncertainty in 70 arcsec circular ap. mag

<band>_flg_70

<band> confusion flag for 70 arcsec circular ap. mag

<band>_m_sys

<band> system photometry magnitude

<band>_msig_sys

<band> 1-s uncertainty in system photometry mag

sys_flg

system flag: 0=no system; 1=nearby galaxy flux incl. in mag

contam_flg

contamination flag: 0=no stars; 1=stellar flux incl. in mag

<band>_5sig_ba

<band> minor/major axis ratio fit to the 5-s isophote

<band>_5sig_phi

<band> angle to 5-s major axis (E of N)

<band>_bisym_chi

<band> bi-symmetric cross-correlation chi

<band>_sc_1mm

<band> 1st moment (score) (LCSB: super blk 2;4;8 SNR)

<band>_sc_2mm

<band> 2nd moment (score) (LCSB: SNRMAX - super SNR max)

j_chif_ellf

J % chi-fraction for elliptical fit to 3-sig isophote

k_chif_ellf

K % chi-fraction for elliptical fit to 3-sig isophote

sup_chif_ellf

super-coadd % chi-fraction for ellip. fit to 3-sig isophote

<band>_sc_r23

<band> r23 (score) (LCSB: TSNR - integrated SNR for r=15)

<band>_back

<band> coadd median background

sup_ra

super-coadd centroid RA (J2000 decimal deg)

sup_dec

super-coadd centroid Dec (J2000 decimal deg)

sup_r_3sig

super-coadd 3-s isophotal semi-major axis radius

sup_ba

minor/major axis ratio fit to 3-sig. super-coadd isophote

sup_phi

super-coadd angle to major axis (E of N)

sup_r_3signorm

super-coadd 3-s radius normalized by shape radius

sup_mnsurfb

super-coadd mean surface brightness at 3-sig norm. radius

im_nx

size of postage stamp image in pixels

r_ngc

distance from nearest big galaxy

fg_flg

flux-growth convergence flag

blk_fac

LCSB blocking factor (1; 2; 4; 8)

ellfit_flg

ellipse fitting contamination flag

 

Notes.—<band> refers to the array band, j, h, or k. The "default" magnitudes, [jhk]_m, are the measurements at 20 mag/sq.arcsec with the K fiducial circular aperture ([jhk]_m_k20fc), indicated by [jhk]_mtype values of 0. If, however, the K band mag in this group is >14.0, all 3 [jhk]_m values will be the mags at 21 mag/sq.arcsec with the J fiducial circular aperture ([jhk]_m_j21fc) and the flags [jhk]_mtype are set to 1. Thus, the [jhk]_mtype flags will indicate the source of the "default" mags and sigmas as follows: 0: [jhk]_m_k20fe values, 1: [jhk]_m_j21fe values. The confusion flags [jhk]_flg* for each mag are defined in the text. If the integrated flux is negative, a mag value is calculated using the formula 99.0 - [zero_point - 2.5 log10(|flux|)]; the resulting mag range is between 75 and 99. The id_flg flag indicates the extended source catalog type as follows: 0 = extended source not found in another catalog, 1 = extended source found in galaxy catalog , and 2 = LCSB (Low Central Surface Brightness) source. Additional notes found in the text.