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J/AJ/138/845       BVRI observations of 235 bright quasars   (Ojha+, 2009)

Photometric observations of selected, optically bright quasars for Space Interferometry Mission and other future celestial reference frames. Ojha R., Zacharias N., Hennessy G.S., Gaume R.A., Johnston K.J. <Astron. J., 138, 845-857 (2009)> =2009AJ....138..845O
ADC_Keywords: QSOs ; Photometry, UBVRI ; Photometry, CCD Keywords: astrometry - galaxies: photometry - quasars: general - reference systems Abstract: Photometric observations of 235 extragalactic objects that are potential targets for the Space Interferometry Mission (SIM) are presented. Mean B, V, R, I magnitudes at the 5% level are obtained at 1-4 epochs between 2005 and 2007 using the 1m telescopes at Cerro Tololo Inter-American Observatory and the Naval Observatory Flagstaff Station. Of the 134 sources that have V magnitudes in the Veron & Veron-Cetty catalog (Cat. VII/248), a difference of over 1.0mag is found for the observed-catalog magnitudes for about 36% of the common sources, and 10 sources show over 3mag difference. Our first set of observations presented here form the basis of a long-term photometric variability study of the selected reference frame sources to assist in mission target selection and to support QSO multicolor photometric variability studies in general. Description: With the ultimate goal of selecting suitable, compact, optically bright QSOs for a future astrometric celestial reference frame that will be established by a mission like SIM, 242 extragalactic sources preferably brighter than 16th visual magnitude and with no noticeable asymmetric structure on the Digitized Sky Survey images as compared to nearby stellar objects were chosen by visual inspection from the Veron-Cetty catalog (Veron-Cetty & Veron, 2006, Cat. VII/248, hereafter VCV06). Photometric observations of these sources were carried out in the Johnson B, V, R, and I bands and results for 214 of these sources are presented along with an additional 21 sources which were observed as part of related observing programs. Objects in the northern hemisphere were primarily observed with the Naval Observatory Flagstaff Station (NOFS) 1.0m Ritchey-Chretien reflector, using a 2k CCD camera during four observing runs between 2005 and 2007. Objects in the southern hemisphere were observed with the Cerro Tololo Inter-American Observatory (CTIO) Small and Moderate Aperture Research Telescope System (SMARTS) 1.0m in Chile. The 4kx4k pixel camera Y4KCam was used and four successful observing runs were carried out from 2005 through 2007. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 101 390 Magnitudes of Space Interferometry Mission (SIM) candidate quasars
See also: VII/248 : Quasars and Active Galactic Nuclei (12th Ed.) (Veron+ 2006) VII/258 : Quasars and Active Galactic Nuclei (13th Ed.) (Veron+ 2010) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Name Source J2000.0 name (HHMM+DDd) 10- 15 F6.3 mag <Bmag> ? Mean B band magnitude 17- 22 F6.3 mag <Vmag> ? Mean V band magnitude 24- 29 F6.3 mag <Rmag> ? Mean R band magnitude 31- 36 F6.3 mag <Imag> ? Mean I band magnitude 38- 42 F5.3 mag e_<Bmag> ? Standard deviation in <Bmag> 44- 48 F5.3 mag e_<Vmag> ? Standard deviation in <Vmag> 50- 54 F5.3 mag e_<Rmag> ? Standard deviation in <Rmag> 56- 60 F5.3 mag e_<Imag> ? Standard deviation in <Imag> 62- 67 F6.3 mag B-V ? The (B-V) color index 69- 74 F6.3 mag V-R ? The (V-R) color index 76- 81 F6.3 mag R-I ? The (R-I) color index 83- 88 F6.3 mag V-I ? The (V-I) color index 90 I1 --- o_<Bmag> Number of observations in <Bmag> 92 I1 --- o_<Vmag> Number of observations in <Vmag> 94- 95 I2 --- o_<Rmag> Number of observations in <Rmag> 97 I1 --- o_<Imag> Number of observations in <Imag> 99-101 A3 --- Epoch Epoch label (1)
Note (1): Observation summary: -------------------------------- Label Telescope Epoch Nights -------------------------------- n51 = NOFS 2005.28 4 n52 = NOFS 2005.66 3 n53 = NOFS 2006.15 3 n54 = NOFS 2007.53 3 c02 = CTIO 2005.86 4 c03 = CTIO 2006.29 4 c05 = CTIO 2006.92 12 c06 = CTIO 2007.15 5 --------------------------------
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 16-Jan-2012
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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