COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 2857 Konkoly Observatory Budapest 31 January 1986 HU ISSN 0374 - 0676 PHOTOMETRY OF COMPARISON STARS As part of a photometric program to check the fluctuation of selected known variable stars in the H-Beta photometric system, comparison stars have been observed for constancy. Observations were made in the Johnson UBV passbands, as well as with H-Beta narrow and wide interference filters. The broadband filters provide a well-defined measure of comparison for the H-Beta measurements of the variable stars. All observations were performed on the No. 4 16-inch telescope at Kitt Peak National Observatory in 1983 and 1984. Observations and reductions of UBV data were done using techniques and formulae presented by Hardie (1962). Standard stars were chosen from the equatorial network of Landolt (1973). Additional extinction stars were selected from the list of Priser (1966) for the reduction of program stars at high northern declinations. Standard stars and H-Beta observation and reduction techniques were taken from the work of Crawford and Mander (1966). Secondary faint standards were selected from photometry of the prominent open clusters Praesepe (Crawford and Barnes 1969a), Coma ( ,1969b), and IC 4665 ( ,1972). Approximately 12 H-Beta standards and 16 UBV standards were observed on a typical complete night. Table I presents the available photometric data for the comparison stars, and includes the corresponding variable star. A description of each of the data columns is given under the table. All variables are short period eclipsing binaries (Algol-type), except for the dwarf Cepheid VZ Cnc. Previous photometric data for the comparison stars was located in the SKYMAP Catalog Version 3.1 (McLaughlin 1983) for only two stars, and is presented for comparison in Table II. Table I-A : Derived Magnitudes for Comparison Stars ID HD SAO RA (2000) DEC V B-V U-B Beta 1002 25679 76440 4 05 29 2 52 47 8.422 0.417 0.192 2.797 2002 25488 76419 4 03 58 27 42 34 8.801 0.376 0.060 2.758 2005 - 131124 4 20 16 - 6 10 04 9.469 0.580 0.068 2.637 1009 46536 114066 6 34 17 9 05 00 8.701 -0.061 -0.205 2.791 2009 46199 114019 6 32 17 8 49 06 6.977 0.285 0.123 2.745 1016 85030 61706 9 50 00 33 36 07 7.940 0.458 0.136 2.645 1017 89369 178651 10 18 23 -22 45 22 8.288 0.265 0.185 2.818 2017 89473 178673 10 19 05 -23 10 53 8.533 0.437 0.015 2.666 1020 115390 157833 13 17 07 -17 54 09 9.417 0.467 -0.034 2.629 2020 114945 157804 13 14 03 -17 25 36 9.584 0.592 0.071 2.597 1023 139549 16777 15 35 07 64 05 40 9.112 0.403 -0.060 2.675 2023 - 16752 15 30 17 64 00 46 9.440 0.319 -0.005 2.733 1024 152761 30134 16 52 29 52 55 47 8.465 0.268 0.090 2.794 2024 154199 30200 17 01 14 52 36 17 6.894 0.074 0.051 2.898 1026 180401 124450 19 16 07 9 19 41 7.689 0.156 -0.276 2.690 3026 181122 124497 19 18 53 9 37 05 6.294 1.053 0.880 2.549 1028 181361 104720 19 19 26 19 43 07 8.175 0.063 -0.106 2.782 2028 181523 104723 19 20 02 19 23 20 8.517 0.139 0.106 2.891 2029 182256 87134 19 22 47 25 19 34 8.612 0.436 0.038 2.666 1030 73295 97982 8 37 58 10 02 53 9.412 0.101 0.131 2.896 2030 73411 116986 8 38 38 9 23 59 8.805 0.327 0.075 2.737 Description of Columns: ID : Star Identification, internal HD : Henry Draper Number SAO : Smithsonian Astrophysical Observatory number RA,DEC : Epoch 2000 coordinates V B-V U-H : Standard Johnson magnitudes derived from mean of observations Beta : Standard H-Beta magnitudes from mean of observations Table I-B : Derived Magnitudes for Comparison Stars ID Sv Nv Sbv Nbv Sub Nub Sbt Nbt Nts Var 1002 0.008 13 0.004 13 0.012 13 0.008 13 2 RW Tau 2002 0.005 12 0.004 12 0.011 12 0.010 12 2 RW Tau 2005 0.007 2 0.002 2 0.041 2 0.021 2 1 TZ Eri 1009 0.003 11 0.004 11 0.010 11 0.008 11 1 RW Mon 2009 0.003 12 0.004 12 0.008 12 0.004 11 2 RW Mon 1016 0.005 11 0.001 11 0.002 11 0.005 11 1 T LMi 1017 0.008 14 0.005 14 0.006 14 0.004 14 4 VY Hya 2017 0.006 21 0.004 21 0.004 21 0.004 21 4 VY Hya 1020 0.005 11 0.007 10 0.004 11 0.012 11 1 UW Vir 2020 0.007 12 0.005 12 0.005 12 0.013 12 1 UW Vir 1023 0.004 17 0.005 18 0.008 17 0.008 18 2 TW Dra 2023 0.006 10 0.004 10 0.009 10 0.013 10 2 TW Dra 1024 0.003 27 0.003 27 0.003 27 0.004 27 4 AI Dra 2024 0.004 28 0.003 28 0.004 28 0.004 27 4 AI Dra 1026 0.009 9 0.007 9 0.008 8 0.008 9 2 V342 Aql 3026 0.004 4 0.003 4 0.002 4 0.009 4 1 V342 Aql 1028 0.005 6 0.003 6 0.005 6 0.007 6 1 U Sge 2028 0.011 2 0.005 2 0.004 2 0.004 2 1 U Sge 2029 0.000 2 0.003 2 0.003 2 0.005 2 1 Z Vul 1030 0.008 13 0.003 13 0.003 13 0.011 13 2 VZ Cnc 2030 0.006 20 0.003 20 0.002 20 0.006 20 2 VZ Cnc Description of Columns: ID : Star identification, internal S : Mean standard deviation of each of the 4 derived magnitude/color fields N : Number of values of each of the derived fields used for mean Nts : Number of nights each star was observed Var : Associated variable star for which these stars served as comparisons Table II : Previous Photoelectric Photometry ID V B-V U-B ---------------------------- 2024 6.82 0.09 0.07 3026 6.32 1.05 0.89 The author thanks Dr. C.C. Wu and Dr. P. Perry of Computer Sciences Corporation for assistance in funding these observations, the staff of Kitt Peak National Observatory for their assistance, and Dr. C. Sturch and E. Medeiros for several helpful discussions. STEVEN F. MCLAUGHLIN * Astronomy Programs Computer Sciences Corporation 8728 Colesville Rd. Silver Spring, MD 20910 USA References: Crawford, D.L. and Mander, J. (1966). Astron.J. 71, 114. [BIBCODE 1966AJ.....71..114C ] Crawford, D.L. and Barnes, J.V. (1969a). Astron.J. 74, 818. [BIBCODE 1969AJ.....74..818C ] Crawford, D.L. and Barnes, J.V. (1969b). Astron.J. 74, 407. [BIBCODE 1969AJ.....74..407C ] Crawford, D.L. and Barnes, J.V. (1972). Astron.J. 77, 862. [BIBCODE 1972AJ.....77..862C ] Hardie, R.H. (1962). in Astronomical Techniques, W.A. Hiltner, ed. (U. of Chicago Press), p. 178. [BIBCODE 1964aste.book..178H ] Landolt, A.U. (1973). Astron.J. 78, 959. [BIBCODE 1973AJ.....78..959L ] McLaughlin, S.F. (1983). Astron.J. 88, 1633. [BIBCODE 1983AJ.....88.1633M ] Priser, J.B. (1966). Publ. Astron. Soc. Pac. 78, 474. [BIBCODE 1966PASP...78..474P ] * Visiting Astronomer, Kitt Peak National Observatory, National Optical Astronomy Observatories, operated by the Association of Universities for Research in Astronomy, Inc. under contract with the National Science Foundation