CDROM/AJ/V107/P0230 M79 (Alcaino+ 1994) ================================================================================ BVRI CCD Photometry of the Globular Cluster NGC 1904 (M79) Gonzalo Alcaino, William Liller, Franklin Alvarado, & Erich Wenderoth <1994, AJ, 107, 230> =1994AJ....107..230A ================================================================================ Abstract: We present BVRI photometry of three overlapping fields in the globular cluster NGC 1904 (M79), observed with a CCD camera and the 2.2 m Max-Planck-Institute telescope at ESO/La Silla. We critically compare our photometry using the INVENTORY data reduction code with results derived by other investigators using different codes. These comparisons convince us that all modern codes give results reliable to at least +/- 0.3 mag at all levels, as long as the fields are not overly crowded. Specifically, our results for NGC 1904 (M79) are as follows: V(TO) = 19.60 +/- 0.10 (estimated external error), with turnoff colors at B-V = 0.40, V-R = 0.27, V-I = 0.57, and B-I = 0.97, all with estimated external errors of +/- 0.06. By fitting the four resulting ridge lines to the theoretical isochrones of VandenBerg & Bell [ApJS, 58, 561 (1985)] interpolated to [Fe/H] = -1.60, Y = 0.20, and [O/Fe] = 0.00, we derive an average value for the age of 16 Gyr, where we have adopted E(B-V) = 0.01. File Summary: -------------------------------------------------------------------------------- File Name Lrecl Records Explanations -------------------------------------------------------------------------------- table6.dat 69 750 CCD coordinates, magnitudes, and colors for 750 stars in NGC 1904 -------------------------------------------------------------------------------- Byte-by-byte Description of file: table6.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 I4 --- Star Star number 5- 6 A2 --- n_Star *Additional note for Star 7-12 F6.1 pix X X CCD coordinate 13-20 F8.1 pix Y Y CCD coordinate 21-29 F9.3 mag V V magnitude 30-37 F8.3 mag B-V []? B-V color 38-45 F8.3 mag V-R []? V-R color 46-53 F8.3 mag R-I []? R-I color 54-61 F8.3 mag V-I []? V-I color 62-69 F8.3 mag B-I []? B-I color -------------------------------------------------------------------------------- Notes for file: table6.dat -------------------------------------------------------------------------------- n_Star: Two variables reported by Sawyer-Hogg (1973, Pub. David Dunlop Obs. (University of Toronto Press, Toronto), Vol. 3, No. 6) lie in the observed area, and are marked "V2" (Star 437) and "V4" (Star 470). Also, the 6 standard stars are labelled "B" (Star 311), "C" (Star 714), "D" (Star 385), "E" (Star 303), "F" (Star 289), and "G" (Star 405). Table 4 of the printed paper details the observations of the standards. -------------------------------------------------------------------------------- ================================================================================ (End) Lee Brotzman [ADS] 21-May-1994