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.