2MASS (twomass.psc)
Description
(paragraph adapted from the The Two Micron All Sky Survey)
The Two Micron All Sky Survey (2MASS) project is designed to close the gap between our current technical capability and our knowledge of the near-infrared sky. In addition to providing a context for the interpretation of results obtained at infrared and other wavelengths, 2MASS is providing direct answers to immediate questions on the large-scale structure of the Milky Way and the Local Universe. The optimal use of the next generation of infrared space missions, such as HST/NICMOS, the Space Infrared Telescope Facility (SIRTF), and the Next Generation Space Telescope (NGST), as well as powerful ground-based facilities, such as Keck I, Keck II, and Gemini, require a new census with vastly improved sensitivity and astrometric accuracy than that previously available.
To achieve these goals, 2MASS has uniformly scanned the entire sky in three near-infrared bands to detect and characterize point sources brighter than about 1 mJy in each band, with signal-to-noise ratio (SNR) greater than 10, using a pixel size of 2.0". This has achieved an 80,000-fold improvement in sensitivity relative to earlier surveys.
2MASS used two highly-automated 1.3-m telescopes, one at Mt. Hopkins, AZ, and one at CTIO, Chile. Each telescope was equipped with a three-channel camera, each channel consisting of a 256×256 array of HgCdTe detectors, capable of observing the sky simultaneously at J (1.25 microns), H (1.65 microns), and Ks (2.17 microns).
The University of Massachusetts (UMass) was responsible for the overall management of the project, and for developing the infrared cameras and on-site computing systems at both facilities. The Infrared Processing and Analysis Center (IPAC) is responsible for all data processing through the Production Pipeline, and construction and distribution of the data products. The 2MASS project involves the participation of members of the Science Team from several different institutions. The 2MASS project is funding by the National Aeronautics and Space Administration (NASA) and the National Science Foundation (NSF).
Attribution
If you have used 2MASS data in your research from this site, please use the following acknowledgement:
This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.
Database access and other data services are provided by the Associação Laboratório Interinstitucional de e-Astronomia (LIneA) with the financial support from INCT do e-Universo (Processo n.º 465376/2014-2).
Columns
| Name | Type | UCD | Unit | Description |
|---|---|---|---|---|
| ra | double |
pos.eq.ra meta.main |
deg |
J2000 right ascension with respect to the ICRS |
| decl | double |
pos.eq.dec meta.main |
deg |
J2000 declination with respect to the ICRS |
| err_maj | float | phys.angSize.smajAxis | arsec |
Semi-major axis length of the one sigma position uncertainty ellipse |
| err_min | float | phys.angSize.sminAxis | arsec |
Semi-minor axis length of the one sigma position uncertainty ellipse |
| err_ang | short |
pos.posAng instr.skyLevel |
deg |
Position angle on the sky of the semi-major axis of the position uncertainty ellipse (East of North) |
| designation | char |
meta.id meta.main |
Sexagesimal, equatorial position-based source name in the form: hhmmssss+ddmmsss[ABC...]. |
|
| j_m | float |
meta.ref phys.size.radius em.IR.J |
mag |
Default J-band magnitude, or if the source is not detected in the J-band, the 95% confidence upper limit derived from a 4" radius aperture measurement taken at the position of the source on the Atlas Image. |
| j_cmsig | float |
stat.error phot.mag em.IR.J |
mag |
Corrected photometric uncertainty for the default J-band magnitude. If rd_flg[1]="2", this is the measurement error from the profile-fitting procedure, corrected to be consistent with observed repeatability statistics. |
| j_msigcom | float |
meta.code.error phot.mag em.IR.J |
mag |
Combined, or total photometric uncertainty for the default J-band magnitude. |
| j_snr | float |
phot.flux phys.flux em.IR.J |
J-band "scan" signal-to-noise ratio. This value is given by the ratio of the J-band flux to the characteristic J-band scan noise. |
|
| h_m | float |
meta.ref phys.size.radius em.IR.H |
mag |
Default H-band magnitude, or if the source is not detected in the H-band, the 95% confidence upper limit derived from a 4" radius aperture measurement taken at the position of the source on the Atlas Image. |
| h_cmsig | float |
stat.error phot.mag em.IR.H |
mag |
Corrected photometric uncertainty for the default H-band magnitude. If rd_flg[2]="2", this is the measurement error from the profile-fitting procedure, corrected to be consistent with observed repeatability statistics. |
| h_msigcom | float |
meta.code.error phot.mag em.IR.H |
mag |
Combined, or total photometric uncertainty for the default H-band magnitude. |
| h_snr | float |
phot.flux phys.flux em.IR.H |
H-band "scan" signal-to-noise ratio. This value is given by the ratio of the H-band flux to the characteristic H-band scan noise. |
|
| k_m | float |
meta.ref phys.size.radius obs.image |
mag |
Default K_s-band magnitude, or if the source is not detected in the Ks-band, the 95% confidence upper limit derived from a 4" radius aperture measurement taken at the position of the source on the Atlas Image. |
| k_cmsig | float |
stat.error phot.mag |
mag |
Corrected photometric uncertainty for the default K_s-band magnitude. If rd_flg[3]="2", this is the measurement error from the profile-fitting procedure, corrected to be consistent with observed repeatability statistics. |
| k_msigcom | float |
meta.code.error phot.mag |
mag |
Combined, or total photometric uncertainty for the default K_s-band magnitude. |
| k_snr | float |
phot.flux phys.flux instr.det.noise |
K_s-band ""scan"" signal-to-noise ratio. This value is given by the ratio of the K_s-band flux to the characteristic K_s-band scan noise. |
|
| ph_qual | char |
meta.code.qual phot |
Photometric quality flag. |
|
| rd_flg | char | meta.code |
Read flag. |
|
| bl_flg | char | meta.code |
Blend flag. |
|
| cc_flg | char |
meta.code instr.obsty phys.current |
Minor Planet Flag. Indicates if this source is associated with the predicted position of a known minor planet, comet, planet or planetary satellite. |
|
| ndet | char |
pos.frame obs.field instr.sensitivity |
Frame detection statistics. |
|
| prox | float | arsec |
Proximity |
|
| pxpa | short | pos.posAng | deg |
The position angle on the sky of the vector from the source to the nearest neighbor in the PSC, in degrees East of North. |
| pxcntr | int |
meta.ref stat.value src |
The pts_key value of the nearest source in the PSC. |
|
| gal_contam | short |
meta.ref src |
Extended source ""contamination"" flag. |
|
| mp_flg | short |
meta.code instr.obsty |
Minor Planet Flag. Indicates if this source is associated with the predicted position of a known minor planet, comet, planet or planetary satellite. |
|
| pts_key | int |
meta.id meta.main meta.ref |
A unique identification number for the PSC source. |
|
| hemis | char |
meta.code instr.obsty src |
Hemisphere code for the 2MASS Observatory from which this source was observed. |
|
| date | char |
meta.ref time obs |
yyyy-mm-dd |
The observation reference date for this source expressed in ISO standard format. |
| scan | short |
meta.id src |
The nightly scan number in which the source was detected. |
|
| glon | float | pos.galactic.lon | deg |
Galactic longitude. |
| glat | float | pos.galactic.lat | deg |
Galactic latitude. |
| x_scan | float |
instr.tel.focalLength stat.mean |
arcsec |
Mean cross-scan focal plane position of the source in the Universal scan (U-scan) coordinate system. |
| jdate | double |
time.epoch time time.duration |
day |
The Julian Date of the source measurement accurate to +30 seconds. |
| j_psfchi | float |
stat.fit.chi2 obs.exposure em.IR.J |
Reduced chi-squared goodness-of-fit value for the J-band profile-fit photometry made on the 1.3 s ""Read_2"" exposures |
|
| h_psfchi | float |
stat.fit.chi2 obs.exposure em.IR.H |
Reduced chi-squared goodness-of-fit value for the H-band profile-fit photometry made on the 1.3 s ""Read_2"" exposures. |
|
| k_psfchi | float |
stat.fit.chi2 obs.exposure em.IR.H |
Reduced chi-squared goodness-of-fit value for the K_s-band profile-fit photometry made on the 1.3 s ""Read_2"" exposures. |
|
| j_m_stdap | float |
phot.mag instr.fov em.IR.J |
mag |
J-band ""standard"" aperture magnitude. |
| j_msig_stdap | float |
stat.error instr.fov em.IR.J |
mag |
Uncertainty in the J-band standard aperture magnitude. If there was more than one 1.3 s ""Read_2"" frame available for aperture photometry |
| h_m_stdap | float |
phot.mag instr.fov em.IR.H |
mag |
H-band ""standard"" aperture magnitude. |
| h_msig_stdap | float |
stat.error instr.fov em.IR.H |
mag |
Uncertainty in the H-band standard aperture magnitude. |
| k_m_stdap | float |
phot.mag instr.fov |
mag |
K_s-band ""standard"" aperture magnitude. |
| k_msig_stdap | float |
stat.error instr.fov phot.mag |
mag |
Uncertainty in the K_s-band standard aperture magnitude. |
| dist_edge_ns | int |
meta.ref pos.distance |
arsec |
The distance from the source to the nearest North or South scan edge. |
| dist_edge_ew | int |
meta.ref pos.distance |
arsec |
The distance from the source to the nearest East or West scan edge. |
| dist_edge_flg | char | phys.atmol.transProb |
Two character flag that specifies to which scan edges a source lies closest, and to which edges the dist_edge_ns and dist_edge_ew values refer. |
|
| dup_src | short |
meta.ref src |
Duplicate source flag. |
|
| use_src | short |
meta.ref src |
Use source flag. |
|
| a | char |
meta.table em.opt |
Catalog identifier of an optical source from either the Tycho 2 or USNO-A2.0 catalog that falls within approximately 5AA of the 2MASS source position. |
|
| dist_opt | float | pos.distance | arcsec |
Distance separating 2MASS source position and associated optical source within approximately 5AA. |
| phi_opt | short | pos.posAng | deg |
Position angle on the sky of the vector from the the associated optical source to the 2MASS source position, in degrees East of North. |
| b_m_opt | float |
meta.ref phot.mag em.IR.60-100um |
mag |
Blue magnitude of associated optical source. |
| vr_m_opt | float |
meta.ref phot.mag em.opt.R |
mag |
Visual or red magnitude of the associated optical source. |
| nopt_mchs | short | meta.number |
The number of USNO-A2.0 or Tycho 2 optical sources found within a radius of approximately 5AA of the 2MASS position. |
|
| ext_key | int |
meta.number phys.size.radius em.opt |
Unique identification number of the record in the XSC that corresponds to this point source. |
|
| scan_key | int |
meta.ref phys.size.radius meta.table |
Unique identification number of the record in the Scan Information Table that corresponds to the survey scan in which this source was detected. |
|
| coadd_key | int |
meta.record obs.image meta.table |
Unique identification number of the record in the Atlas Image Information Table that corresponds to Image in which the position of this source falls. |
|
| coadd | short |
meta.number obs.sequence obs.image |
Sequence number of the Atlas Image in which the position of this source falls. |