29a. Working Group on Absolute Spectrophotometry

Extract

Two new and independent determinations of the absolute spectral energy distribution in αLyr have been completed during the last three years. The first of these by Hayes has been published in part (Wolff, Kuhi and Hayes, 1968). It was done at the Lick Observatory using the Crossley reflector and two ribbon-filament standard lamps. His published results are based on the old practical temperature scale which is based on a melting point for gold of 1336·16K. The new scale has been adjusted to agree as well as possible with the thermodynamic temperature scale and is based on 1337·59K for the melting point of gold. Hayes’ results have been adjusted to this new scale and are shown in Table 1. The numbers listed are — 2·5 log f_v + const, when f_v is the flux from αLyr in ergs s^-1 cm^-2 Hz^-1. The results are normalized to 0·000 at λ5556.

The new calibration by Oke and Schild was carried out on Palomar Mountain. A four inch reflecting telescope was built and mounted with the prime focus scanner which was built for the 200-inch telescope. Three light sources were used (1) a ribbon-filament standard lamp calibrated with an accuracy of 2 % by the National Bureau of Standards was used from λ3300 to λ8000.