J/PASP/111/57 Galactic reddening maps (Hudson+, 1999)
A test for large-scale systematic errors in maps of galactic reddening
Hudson M.J.
<Publ. Astron. Soc. Pac. 111, 57 (1999)>
=1999PASP..111...57H 1999PASP..111...57H
ADC_Keywords: Reddening ; Galaxies, photometry ; Stars, variable
Abstract:
Accurate maps of Galactic reddening are important for a number of
applications, such as mapping the peculiar velocity field in the
nearby universe. Of particular concern are systematic errors which
vary slowly as a function of position on the sky, as these would
induce spurious bulk flow. We have compared the reddenings of Burstein
& Heiles (BH, 1982, Cat. J/AJ/87/1165) and those of Schlegel,
Finkbeiner, & Davis (1998ApJ...500..525S 1998ApJ...500..525S, SFD) to independent
estimates of the reddening, for Galactic latitudes |b|>10°. Our
primary source of Galactic reddening estimates comes from comparing
the difference between the observed B-V colors of early-type galaxies,
and the predicted B-V color determined from the B-V-Mg2 relation. We
have fitted a dipole to the residuals in order to look for large-scale
systematic deviations. There is marginal evidence for a dipolar
residual in the comparison between the SFD maps and the observed
early-type galaxy reddenings. If this is due to an error in the SFD
maps, then it can be corrected with a small (13%) multiplicative
dipole term. We argue, however, that this difference is more likely to
be due to a small (0.01mag) systematic error in the measured B-V
colors of the early-type galaxies. This interpretation is supported by
a smaller, independent data set (globular cluster and RR Lyrae stars),
which yields a result inconsistent with the early-type galaxy residual
dipole. BH reddenings are found to have no significant systematic
residuals, apart from the known problem in the region
230°<l<310°, -20°<b<20°.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 67 311 Early-type galaxies
table3.dat 26 86 RR Lyrae and Abt & Golson stars
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Galaxy name
13- 16 F4.2 mag B-V B-V colour index
18- 25 F8.4 deg GLON Galactic longitude
27- 34 F8.4 deg GLAT galactic latitude
36- 41 F6.4 mag Mg2 Mg2 index
43- 45 I3 --- Qual Quality flag
47- 52 F6.4 mag E(B-V)SFD Schlegel et al. (1998ApJ...500..525S 1998ApJ...500..525S)
reddening
54- 60 F7.4 mag E(B-V)BH Burstein & Heiles (1982, Cat. J/AJ/87/1165)
reddening
62 I1 --- Cluster [0/1] 0: field, 1: cluster/group
64- 67 I4 km/s sigma ?=-999 Cluster/group velocity dispersion
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 6 F6.2 deg GLON Galactic longitude
8- 13 F6.2 deg GLAT Galacitc latitude
15- 20 F6.3 mag E(B-V) Reddening
22- 26 F5.3 mag E(B-V)SFD Schlegel et al. (1998ApJ...500..525S 1998ApJ...500..525S) reddening
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History: From PASP electronic version
(End) James Marcout, Patricia Bauer [CDS] 15-Mar-1999