J/A+AS/145/365 BVI photometry of NGC 7790 (Gupta+, 2000) ================================================================================ A complete photometric study of the open cluster NGC 7790 containing Cepheid variables. Gupta A.C., Subramaniam A., Sagar R., Griffiths W.K. =2000A&AS..145..365G ================================================================================ ADC_Keywords: Clusters, open ; Photometry, CCD ; Photometry, Cousins Keywords: Galaxy: open clusters: individual: NGC 7790 - stars: evolution - HR diagram Abstract: CCD photometry of the northern open star cluster NGC 7790 has been carried out in BVI photometric passbands down to V~21mag for 1150 stars of which for ~700 stars, the data is obtained for the first time. We derive the most reliable parameters for this cluster using all the available photometric, spectroscopic and proper motion data. The interstellar extinction over the cluster area is uniform and normal with E(B-V)=0.51+/-0.03mag. We determine a distance of 3.3+/-0.23Kpc to the cluster. The theoretical isochrone fittings to the Cepheid variables as well as the evolved part of the main-sequence near turn-off point indicate that the cluster is 120+/-20Myr old. We estimate the cluster radius to be 3.7' using radial stellar density profile. Both the distance and age determined using period luminosity/age relations for the Cepheid variables are consistent with their membership of the cluster. This unique opportunity has therefore been used to refine the zero-point of the period-luminosity relation for the Galactic Cepheids. Objects: ------------------------------------------------ RA (2000) DE Designation(s) ------------------------------------------------ 23 58 24 +61 13.0 NGC 7790 = C 2355+609 ------------------------------------------------ File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 67 1156 Relative (X, Y) pixel positions and CCD BVI magnitudes of stars measured in the field of NGC 7790 are presented. table1.tex 82 1272 LaTeX version of table 1 -------------------------------------------------------------------------------- See also: V/28 : Proper motions and UBV phot. in 4 open clusters (Frolov 1980) J/PASP/104/553 : CCD Standard Fields (Odewahn+ 1992) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 2- 5 I4 --- Seq Sequential number (1) 7- 12 F6.2 pix Xpos X position (2) 14- 19 F6.2 pix Ypos Y position (2) 21- 26 F6.3 mag Vmag V magnitude 28- 33 F6.3 mag B-V ? B-V colour index 35- 40 F6.3 mag V-I V-I Cousins colour index 42- 68 A27 --- Names Other identifications, separated by commas (3) -------------------------------------------------------------------------------- Note (1): Numbers are the same as Phelps & Janes (1994ApJS...90...31P) Numbers staring from 5001 is new detection of stars in this cluster Note (2): The coordinate system is that of the database given by Phelps & Janes (1994ApJS...90...31P). The center of the cluster is located at RA = 23h 54min 12s, DE = +60{deg} 57' (1950.0) 1 pix = 0.74". North is up, and east is to the left. Note (3): Other identifications: F: Frolov, 1977IzPul.195...80F, Cat. I: Iyeshima et al., 1994, Ann. Rep. Nishi - Harima Astron. Obs. 4, 18 O: Odewahn et al., 1992PASP..104..553O, Cat. P: Pedreros et al., 1984ApJ...286..563P R: Romeo et al., 1989MNRAS.240..459R -------------------------------------------------------------------------------- Acknowledgements: Alok Chandra Gupta ================================================================================ (End) Patricia Bauer [CDS] 05-Dec-2000