CDROM/PASP/V106/P404 Photometry of Globulkar Cluster NGC 6535 (Sarajedini 1994) ================================================================================ CCD Photometry of the Galactic Globular Cluster NGC 6535 in the B and V Passbands Ata Sarajedini <1994, PASP, 106, 404> =1994PASP..106..404S ================================================================================ Abstract: The first CCD color-magnitude diagram (CMD) in B and V is presented for the Galactic globular cluster NGC 6535. From this CMD, which extends below the main-sequence turnoff, we draw the following conclusions: (1) The horizontal branch (HB) is predominantly blue in nature with no RR Lyrae variables known to be cluster members. Nonetheless, based on a comparison with clusters which have blue HBs and RR Lyraes (M15 and M79), we infer a mean HB magnitude of = 15.73 +/- 0.11 for NGC 6535. (2) Again, via a direct comparison with the blue HBs of M15 and M79, we derive a cluster reddening of E(B-V) = 0.44 +/- 0.02. (3) When combined with the apparent color of the red-giant branch at the level of the HB, (B-V)g = 1.18 +/- 0.02, the derived reddening yields a metal abundance of [Fe/H] = -1.85 +/- 0.10, similar to that of NGC 6397. (4) Application of the Delta(V(TO-HB)) and Delta((B-V)(SGB-TO)) cluster dating techniques reveals no perceptible age difference between NGC 6535 and NGC 6397. (5) A significant population of nine blue-straggler candidates is detected in NGC 6535. However, this is too few to facilitate a meaningful analysis of their radial distribution. File Summary: -------------------------------------------------------------------------------- File Name Lrecl Records Explanations -------------------------------------------------------------------------------- table2.dat 38 932 Photometry of NGC 6535 -------------------------------------------------------------------------------- Byte-by-byte Description of file: table3.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 I3 --- ID Star number 4-13 F10.2 pix X X CCD coordinate 14-22 F9.2 pix Y Y CCD coordinate 23-29 F7.2 mag V Visual magnitude 30-35 F6.2 mag B-V B-V color 36-38 I3 --- N Number of observations -------------------------------------------------------------------------------- ================================================================================ (End) Lee Brotzman [ADS] 21-May-1994