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VI/19 UBV Photoelectric Sequences in SA 92-115 (Landolt 1973)
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UBV Photoelectric Sequences in SA 92-115
Landolt A.U.
<AJ, 78, 959 (1973)>
=1973AJ.....78..959L
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ADC_Keywords: Photometry, UBV ; Photometry, sequences ; Selected areas
Description:
The UBV system was originally defined by ten bright standard stars,
primarily in the northern sky. These stars are too bright to be used
with large telescopes and cannot be reached from southern observatories.
This catalog is a careful compilation of data on fainter stars in the
equatorial Selected Areas. They are intended as a new set of standards
which can be used to define the UBV system at fainter magnitudes in
both hemispheres. The stars range in V between 6.0 and 14.9 with most
between 9.0 and 13.0.
Introduction:
A discussion of modern broad-band photometric systems has been given by
Johnson and Morgan (1953). The stars upon which this system is based are
tabulated in Johnson and Morgan (1953), Johnson and Harris (1954) and
Johnson (1955,1963). The stars which define the system are nearly all
bright stars. The recent large body of southern hemisphere standards
(Moreno, Moreno, Stock, Torres and Wroblewski 1966) also consists of
bright stars. The stars now recommended for use as UBV standard stars
were redefined at the XIVth General Assembly of the IAU to be those
objects brighter than V = 5.0 mag between DE = +- 10 deg; however,
most of them are still brighter than desirable for the observing
techniques and photometers used by most astronomers.
There exist, scattered around the sky, photoelectric sequences of fainter
stars which are tied into the UBV system. Such sequences, more often
than not, are located in galactic or globular star clusters. However,
they really are not all on the same precise photometric system, as an
intercomparison of two or more observers' data on a given cluster many
times shows (see, for example, Landolt 1964); slight zero-point
differences and color equation problems occur. Many times, sequences are
defined only by one, two or three observations per star. Hence, one
ought not use these sequences for extension to fainter objets in extended
programs around the sky.
There has been much discussion, both privately and in the literature
(Blaauw 1955; Walker 1959; Stoy 1958, 1961; Greaves 1955), of the
desirability of a faint sequence of standard stars distributed over
the sky. Although a variety of useful photometric systems has been
established in recent years, the broad-band UBV system still has an
important future role in astronomical research. Particularly is this
true for the fainter objects to be observed with the big reflectors,
where a well defined, widely adopted standard photometric system can
be used to great advantage in the initial reconnaissance of faint
celestial objects.
An attempt is made in this paper to provide a homogeneous set of UBV
standard stars in the celestial equatorial Selected Areas. By doing so,
astronomers in both hemispheres will have access to faint standard stars
readily accessible to the largest telescopes. It is not claimed that
this system is a priori better than other fine photoelectric sequences
scattered in various regions about the celestial sphere. However, the
stars observed herein were thoroughly tied together completely around
the sky during many observing sessions from the same site, and using
the same type of equipment throughout the duration of the observing
program. Therefore, the system should be internally quite accurate
and consistent.
Many, but not all, of the stars in this catalog are included in later
catalogs: 2118 and 2183.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
gicfeige.dat 67 16 Photoelectric Photometry of Giclas, Feige Stars
gicnotes.dat 80 6 Giclas and Fiege Notes
selstars.dat 80 642 Selected Area Stars
selnotes.dat 80 57 Selected Area Notes
spectral.dat 18 608 Spectral Types
spnotes.dat 80 85 Spectral Type Notes
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Byte-by-byte Description of file: gicfeige.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- ID Star Identifications
10- 11 I2 h RAh Right Ascension (1975) hours
12- 13 I2 min RAm Right Ascension (1975) minutes
14- 15 I2 s RAs Right Ascension (1975) seconds
17 A1 --- DE- Declination (1975) sign
18- 19 I2 deg DEd Declination (1975) degrees
20- 21 I2 arcmin DEm Declination (1975) arcminutes
22- 23 I2 arcsec DEs Declination (1975) arcseconds
25- 29 F5.2 mag V V Magnitude
31- 35 F5.2 mag B-V (B-V) Color Index
37- 41 F5.2 mag U-B (U-B) Color Index
43- 44 I2 --- N Number of times star was observed
47 I1 --- M Number of nights star was observed
49- 53 F5.3 mag e_V V mean error
55- 59 F5.3 mag e_B-V (B-V) mean error
61- 65 F5.3 mag e_U-B (U-B) mean error
67 I1 --- rem ?Note number
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Byte-by-byte Description of file: gicnotes.dat
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Bytes Format Units Label Explanations
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1- 2 F2.0 --- rem *?Note number followed by period
5- 80 A76 --- note Note
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Note on rem:
If rem is blank, then note is the continuation from the previous record.
Byte-by-byte Description of file: selstars.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- area Selected Area Field
4 A1 --- hyphen [-]Hyphen
5- 8 I4 --- ID *Star I.D.
10- 11 I2 h RAh *Right Ascension (1975) hours
12- 13 I2 min RAm Right Ascension (1975) minutes
14- 15 I2 s RAs Right Ascension (1975) seconds
17 A1 --- DE- Declination (1975) sign
18- 19 I2 deg DEd *Declination (1975) degrees
20- 21 I2 arcmin DEm Declination (1975) arcminutes
22- 23 I2 arcsec DEs Declination (1975) arcseconds
25- 29 F5.2 mag V V magnitude
31- 35 F5.2 mag B-V (B-V) index
36 A1 --- u_B-V *Uncertainty flag on B-V
37- 41 F5.2 mag U-B (U-B) index
42 A1 --- u_U-B *Uncertainty flag on U-B
43- 44 I2 --- N Number of times star was observed
46- 47 I2 --- M Number of nights star was observed
49- 53 F5.3 mag e_V ? V mean error
55- 59 F5.3 mag e_B-V ? (B-V) mean error
60 A1 --- u_e_B-V *Uncertainty flag on e_B-V
61- 65 F5.3 mag e_U-B ? (U-B) mean error
66 A1 --- u_e_U-B *Uncertainty flag on e_U-B
67- 70 I4 --- BSD ?Bergedorfer Spektral Durchmusterung ID
72- 77 A6 --- Sp BSD spectral type
79- 80 I2 --- rem ?Note number
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Note on ID:
from Harvard Annals, Vol 101 Durchmusterung of Selected Areas
Note on RAh:
(precessed from l900)
Note on DEd:
(precessed from l900)
Note on u_*:
: = uncertain
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Byte-by-byte Description of file: selnotes.dat
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Bytes Format Units Label Explanations
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1- 3 F3.0 --- rem *?Note number followed by a period
5- 80 A76 --- note Note
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Note on rem:
If rem is blank, then note is the continuation from the previous record.
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Byte-by-byte Description of file: spectral.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- area Selected Area Field
4 A1 --- hyphen [-]Hyphen
5- 8 I4 --- ID *Star I.D.
10 A1 --- rem [*]Indicates special note on this star
12- 18 A7 --- Sp MK Spectral type
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Note on ID:
from Harvard Annals, Vol 101 Durchmusterung of Selected Areas
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Byte-by-byte Description of file: spnotes.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- area Selected Area Field
4 A1 --- hyphen [-]Hyphen
5- 8 I4 --- ID *Star I.D.
10- 80 A71 --- note Note
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Note on ID:
from Harvard Annals, Vol 101 Durchmusterung of Selected Areas
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References:
Blaauw A. (1955) . IAU Symposium No. 1, Coordination of Galactic Research
(Cambridge U. P., London), pp. 7 and 22.
Drilling J.S. and Landolt A.U. (1979). Astron. J. 84, 783. ADC Cat. 6019.
Greaves W.M.H. (1955). Trans. Int. Astron. Union 9, 353.
Johnson H.L. (1955). Ann. Astrophys. 18, 292.
Johnson H.L. (1963). In Basic Astronomical Data, edited by K. Aa. Strand
(U. Chicago P., Chicago), p. 204.
Johnson H.L., and Harris D. L. III (1954). Astrophys. J. 120, 196.
Johnson H.L., and Morgan W. W. (1953). Astrophys. J. 117, 313.
Landolt A.U. (1964). Astrophys. J. Suppl. Ser. 8, 352.
Landolt A.U. (1973). Astron. J. 78, 959. ADC Cat. 6019.
Landolt A.U. (1983). Astron. J. 88, 493. ADC Cat. 2118.
Landolt A.U. (1992). Astron. J. 104, 340. ADC Cat. 2183.
Moreno A. Gutierrez-, Moreno H., Stock J., Torres C., and Wroblewski H.
(1966). Publ. Dept. Astron., Universidad de Chile, No. 1.
Stoy R.H. (1958). Trans. Int. Astron. Union 10, 373.
Stoy R.H. (1961). Trans. Int. Astron. Union 11, 242.
Walker M.F. (1959). I.A.U. Symposium No. 7, Second Conference on
Coordination of Galactic Research (Cambridge U. P., London), p. 91.
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(End) Julie Anne Watko [SSDOO/ADC] 10-MAR-1996