The Ducati alpha photometric system
Basic Reference
Strauss F.M., Ducati J.R. 1981, A&A Suppl. 44, 337
Abstract
A set of 168 stars of spectral types B0 to G5, luminosity classes I to V with
well determined beta indices were observed with a pair of Halpha filters (37
and 208A bandwidth) to establish a common set of standard stars for Halpha and
Hbeta photometry. The new standard alpha indices were obtained simultaneously
from a weighted least squares solution of almost 2000 observations made on 54
nights over a two year period, by a methode described in the text. The average
r.m.s. accuracy of each standard alpha index is 0.002. A comparison is made
with other system. An application of alpha and beta photometry to the study
of supergiants showed that is possible to:
a) separate them from lower luminosity stars,
b) divide them into early and late types, and
c) derive color excesses.
Content
Access to the data and references
Asiago Database on Photometric System (ADPS)
Indices and Parameters
alpha
Filters
Definition of the Halpha filters:
- Narrow filter bandwidth : 37 Å
- Wide filter bandwidth : 208 Å
Photomultiplier
EMI 9658AR, extended S20 cathode
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commentsto epaunzen@physics.muni.cz
epaunzen@physics.muni.cz
Last update: 21 May 1996