The y b1 b2 b3 photometric system
Basic Reference
Willstrop R.V. 1960, MNRAS 124, 17
Abstract
Observations at the Cambridge Observatories showed the broad-band V and B
photometric systems may be reproduced by observations in narrow bands about
200A broad centred at 5410A and at 4390A respectively. At the Royal
Observatory, Cape of Good Hope, measurements were made of the radiation
flux outside the Earth's atmosphere in four narrow (~200A) wavelength bands
from stars of known magnitude and colour index, by comparing bright stars with
an artificial star, composed of a calibrated lamp and blue filter. A 4-inch
refractor was used, with interference filters and a d.c. photometer. The resuls
are given in Table I. They are in good agreement with some other recent measurements. Systematic errors are discussed in detail.
Narrow-band visual magnitudes were measured for 221 stars, and compared with
broad-band visual magnitudes determined by Johnson, by Hogg and by Eggen, and
with early and recent Cape results. When linear colour equations are removed
the standard deviations of the residuals are between + 0m.014 and + 0m.036.
The internal random errors of the best individual series are believed to be
+ 0m.010 (narrow-band) +0m.007 (Johnson) and +0m.007 (cape.) It follows that
the large differences usually found between similar broad-band visual magnitudes
cannot be explained by differences of band-width and equivalent wave-length
combined with differences of stellar spectra.
There is good agreement between the present narrow-band colour indices and
gradients on the Greenwich system measured at Mt Stromlo. The relation between
absolute and Greenwich gradients was found to be phi = GG + 1.11, in excellent
agreement with the best previous results.
Content
Access to the data and references
Asiago Database on Photometric System (ADPS)
I. Census parameters for 167 photometric system
II. Band and reddening parameters
Indices and Parameters
y, b1-y, b2-y, b3-y
Filters
- y : interference filter
- Max transmission: 5410 Å
- b1 : interference filter
- Max transmission: 4600 Å
- b2 : interference filter
- Max transmission: 4390 Å
- b3 : interference filter
- Max transmission: 4220 Å
Photomultiplier
EMI
commentsto epaunzen@physics.muni.cz
epaunzen@physics.muni.cz
Last update: 21 May 1996