TD1 - TD1 Stellar Ultraviolet Fluxes Catalog
The TD1 Catalog of Stellar Ultraviolet Fluxes represents results from the sky-scan experiment on the TD1 satellite of the European Space Research Organization (ESRO), now part of ESA. It lists the absolute fluxes, in four passbands, for 31,215 stars:
Passband Center: 274.0nm 236.5nm 196.5nm 156.5nm Effective Width: 31.0nm 33.0nm 33.0nm 33.0nmThe stars have been selected subject to the constraint that the signal-to-noise ratio should be at least 10.0 in any one of the four passbands.
Null values of a flux field and an error field indicate there are no valid data for the star. This usually arises with close pairs of stars whose spectra overlap. Five standard flux error values are greater than 99.99, and were too large for the format of the flux field in the original table. Thus, the flux error values which were greater than 99.99 are given as 99.99.
Many of the fainter stars of spectral type later than A5 do not have significant signals in all of the spectrophotometric channels (particularly the 1565A channel). Consequently, after the removal of the background, they can randomly give rise to small negative values of flux. Those negative values were not suppressed, but are given together with their error, as they can be significant when considered as part of a statistical sample.
Although the sky coverage is essentially complete, the catalog does not contain the fluxes for all stars that fall within the limit of the sensitivity of the instrument. If any star expected to be present is missing, then its signal is probably blended with that of a nearby star, in which case the data have been discarded.
Catalogue of stellar ultraviolet fluxes (TD1): A compilation of absolute stellar fluxes measured by the Sky Survey Telescope (S2/68) aboard the ESRO satellite TD-1 Thompson G.I., Nandy K., Jamar C., Monfils A. Houziaux L., Carnochan D.J., Wilson R. <The Science Research Council, U.K. (1978)>
The TD1 Catalog object designation (this does not appear in the printed catalog).
The Henry Draper Catalog number of the star.
This parameter is a flag which is set to 1 to indicate that the object is in the Ultraviolet Bright Star (UVBS) Spectrophotometric Catalog (Jamar et al. 1976, CDS Catalog <III/39>), else is set to 0. The full spectral information for 1356 bright stars has been published in the UBVS Spectrophotometric Catalog.
The Durchmusterung (BD/CD/CPD) designation of the star.
The S2/68 Catalog number of the star.
The Right Ascension of the star in the selected equinox. This was given in 1950 equatorial coordinates in radians to a precision of 1 microradian (0.2 arcseconds) in the original catalog.
The Declination of the star in the selected equinox. This was given in 1950 equatorial coordinates in radians to a precision of 1 microradian (0.2 arcseconds) in the original catalog.
The Galactic Longitude of the star.
The Galactic Latitude of the star.
The flux F(lambda) of the star in the 2740 Angstrom (274 nm) band, in erg/cm^s/s/A. The fluxes F(lambda), and errors, sigma(lambda), can be transformed to the visual magnitude scale using the absolute calibration of Haynes & Latham (=1975ApJ...197..593H):
m(lambda) = -2.5 log10 F(lambda) - 21.175 sigma_m(lambda) = 1.086 sigma(lambda)/F(lambda)Also, the following other related parameters can be calculated:
F(nu) = 3.336x10^-19 lambda^2 F(lambda) m(nu) = -2.5 log10 F(lambda) - 5 log10 lambda - 18.724 sigma_m(nu) = 1.086 sigma(lambda)/F(lambda) where F(lambda) is in units of erg.cm^-2s^-1A^-1 (mW/m^2/(0.1nm)) lambda is in Angstroms, and F(nu) is in units of erg.cm^-2s^-1Hz^-1 = mW/m^2/Hz = 10^23 Jy
The standard error of the flux in the 2740A band, in erg/cm^2/s/A.
The flux F(lambda) of the star in the 2365 Angstrom (236.5 nm) band, in erg/cm^s/s/A. See the help for the flux_2740_a parameter for more information about the TD1 fluxes.
The standard error of the flux in the 2365A band, in erg/cm^2/s/A.
The flux F(lambda) of the star in the 1965 Angstrom (196.5 nm) band, in erg/cm^s/s/A. See the help for the flux_2740_a parameter for more information about the TD1 fluxes.
The standard error of the flux in the 1965A band, in erg/cm^2/s/A.
The flux F(lambda) of the star in the 1565 Angstrom (156.5 nm) band, in erg/cm^s/s/A. See the help for the flux_2740_a parameter for more information about the TD1 fluxes.
The standard error of the flux in the 1565A band, in erg/cm^2/s/A.
The HEASARC Browse object classification, based on the value of the spect_type parameter.