The CaII HK photometric system
Basic Reference
Anthony-Twarog B.J., Laird J.B., Payne D., Twarog B.A. (1991) Astron. J. 101, 1902
Abstract
A fifth filter (fwhm = 90 Å) centered on CaII H and K has been developed
for use with the standard uvby system. The filter, called Ca, is designed
primarily for applications to metal-poor dwrafs and red giants, regions where
the uvby metallicity index, m1, loses some sensitivity. An index, hk,
is defined by replacing v in m1 by Ca. The effects of interstellar extinction on the index are modeled and demonstrated to be modest and relatively insensitive
to spectral type. Observations of V, (b-y), and hk for 163 primary standards
are dtailed and transformed to the standard V and (b-y) system. A
qualitative analysis using only the primary standards indicates that
hk is more sensitive than m1 over the regions of interest by about
a factor of 3.
Content
Access to the data and references
Asiago Database on Photometric System (ADPS)
Indices and Parameters
V, b-y, hk
hk = (Ca - b) - (b - y) is intended to be a metallicity index.
Filters
Ca : narrow band filter, with half width of 90 Å
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commentsto epaunzen@physics.muni.cz
epaunzen@physics.muni.cz
Last update: 13 September 2002