II/118 UBVRI standards around Celestial Equator (Landolt 1983)
UBVRI Photometric Standards around the Celestial Equator
Landolt A.U.
<Astron. J. 88, 439 (1983)>
=1983AJ.....88..439L 1983AJ.....88..439L (SIMBAD/NED Reference)
ADC_Keywords: Photometry, UBVRI ; Stars, standard ; Stars, equatorial
Description:
The catalog contains UBVRI photoelectric observations of 223 stars,
mostly in an approximately 2-degree zone centered on the celestial
equator. The catalog is intended to provide a uniform set of new
standards, available to various sizes of telescopes in both
hemispheres, on an internally consistent, homogeneous system. Most of
the stars are in Selected Areas 92-115 and fall in the magnitude range
of about 7 to 12.5 in V and color range -0.3 to +2.0 in B-V. The data
include equatorial coordinates, photoelectric magnitudes and colors,
numbers of observations, and computed internal errors.
See the complete description by Wayne H. Warren Jr., either in
plain ascii (file adc.doc) or in LaTeX format (file adc.tex)
Remark:
Fainter standards have been observed (Landolt A.U., 1992, AJ 104, 340)
and collected as catalogue II/183
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
adc.doc 79 336 Documentation (ascii) by W.H.Warren Jr
adc.tex 79 300 Documentation (LaTeX) by W.H.Warren Jr
adc.sty 78 68 Style file used to process adc.tex
main 125 223 The Data
appendix 132 251 Notes & Remarks (Appendix I)
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Byte-by-byte Description of file: main
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Star identification (1)
13- 14 I2 h RAh Hours RA, Equinox=1985, Epoch=1985
16- 17 I2 min RAm Minutes RA, equinox and epoch 1985.0
19- 20 I2 s RAs Seconds RA, equinox and epoch 1985.0
22 A1 --- DE- Sign Dec, equinox and epoch 1985.0
23- 24 I2 deg DEd Degrees Dec, equinox and epoch 1985.0
26- 27 I2 arcmin DEm Minutes Dec, equinox and epoch 1985.0
29- 30 I2 arcsec DEs Seconds Dec, equinox and epoch 1985.0
32- 37 F6.3 mag Vmag Weighted V magnitude in the UBVRI system
39- 44 F6.3 mag B-V Weighted B-V color in the UBVRI system
46- 51 F6.3 mag U-B Weighted U-B color in the UBVRI system
53- 58 F6.3 mag V-R Weighted V-R color in the UBVRI system
60- 65 F6.3 mag R-I Weighted R-I color in the UBVRI system
67- 72 F6.3 mag V-I Weighted V-I color in the UBVRI system
74- 75 I2 --- Obs Number of observations used
to compute weighted means
77- 78 I2 --- Nights Number of nights on which the star
was observed
81- 86 F6.4 mag e_Vmag Mean error of mean V magnitude (2)
88- 93 F6.4 mag e_B-V Mean error of mean B-V color (2)
95-100 F6.4 mag e_U-B Mean error of mean U-B color (2)
102-107 F6.4 mag e_V-R Mean error of mean V-R color (2)
109-114 F6.4 mag e_R-I Mean error of mean R-I color (2)
116-121 F6.4 mag e_V-I Mean error of mean V-I color (2)
123-125 A3 --- Notes Number(s) of notes (3)
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Note (1):
BD = Bonner Durchmusterung;
F = Feige;
G = Giclas et al. numbers in Lowell Obs. Bulletin proper-motion lists;
GD = Giclas et al. White Dwarfs
HD = The Henry Draper Catalogue
SA = Selected Areas
Note (2): the mean error is computed for the mean value, i.e.
mean error = sqrt(sum(x_i - )/(n*(n-1)))
(the individual mean error is sqrt(n) times larger)
Note (3): the numbers correspond to
1. Additional information for this star appears in Appendix I.
2. BD -15 115 is the planetary nebula NGC 246 (118 -74 1). W. Liller
reminded me that if indeed this object is usable as a standard,
an observer should use the same size diaphragm that I used,
namely a 27 arc sec diameter.
3. Although the mean error in V is at the 2 sigma level, the V, B-V,
and U-B almost precisely reproduce earlier measures (Landolt 1973),
including mean errors. It is usable as a standard.
4. HD 46056 has a companion at PA about 340, sep. about 9";
V = 11.468, B-V = +1.040, U-B = -0.070, V-R = +0.105, R-I = +0.252,
V-I = +0.359.
5. Variable.
6. HD 79097 is a possible variable; the mean error of a single
observation in V indicates a 3.3 sigma variation.
7. HD 118246 is a possible variable; the mean error of a single
observation in V indicates a 3.1 sigma variation.
8. SA 106 1024 is a possible variable; the mean error of a single
observation in V indicates a 3.5 sigma variation.
Historical Notes:
* From the "Selected Astronomical Catalogs" Vol. 1 CD-ROM (1992),
directory /photom/landolt
* Introduction from ADC
(End) Francois Ochsenbein [CDS] 18-Jan-1995