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J/PASP/122/288     UBVIKC photometry in NGC 2309          (Piatti+, 2010)

NGC 2309: a relatively young open cluster projected onto a random stellar concentration. Piatti A.E., Claria J.J., Ahumada A.V. <Publ. Astron. Soc. Pac., 122, 288-298 (2010)> =2010PASP..122..288P
ADC_Keywords: Clusters, open ; Photometry, CCD ; Photometry, UBVRI Abstract: We have obtained CCD UBVIKC photometry down to V∼22.0 for the open cluster NGC 2309 and its surrounding field. Twenty three probable cluster members have been identified for the first time on the basis of sound photometric criteria. Because NGC 2309 is a relatively poor cluster projected onto a rich star field showing density fluctuations, the frequently used membership criteria based on stellar density profiles or proper motion measurements would not be enough to assess the star membership status if employed independently. We estimated a cluster radius of 7.9' and a radius at half the maximum of the cluster density profile of 1.7'. Based on the best fits of isochrones computed by the Geneva group to the cluster color-magnitude and color-color diagrams, previously shifted by the cluster reddening (E(B-V)=0.32) and distance (d=2.5kpc), we derived the cluster age (250Myr) and metallicity ([Fe/H]∼0.0). If an 8.5kpc distance from the Sun to the center of the Galaxy is assumed, then NGC 2309 is found to be located just in front of the Perseus spiral arm. Description: We obtained images for NGC 2309 on the night of 2000 December 25 with the UBVIKC filters and a 2048x2048 pixel Tektronix CCD attached to the Cerro Tololo Inter-American Observatory (CTIO, Chile) 0.9m telescope. Objects: --------------------------------------------------- RA (2000) DE Designation(s) --------------------------------------------------- 06 56.2 -07 12 NGC 2309 = Cl Collinder 122 --------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 80 2275 UBVI data of stars in the field of NGC 2309
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 4 I4 --- Seq [1/2275] Sequential number 6- 13 F8.3 pix Xpos X position (1) 15- 22 F8.3 pix Ypos Y position (1) 24- 29 F6.3 mag Vmag Johnson V magnitude 31- 35 F5.3 mag e_Vmag rms uncertainty on Vmag 37 I1 --- o_Vmag Number of observation for Vmag 39- 44 F6.3 mag U-B ?=99.999 Johnson U-B colour index 46- 50 F5.3 mag e_U-B ?=9.999 rms uncertainty on U-B (2) 52 I1 --- n_U-B Number of observation for U-B 54- 59 F6.3 mag B-V ?=99.999 Johnson B-V colour index 61- 65 F5.3 mag e_B-V ?=9.999 rms uncertainty on B-V (2) 67 I1 --- n_B-V Number of observation for B-V 69- 74 F6.3 mag V-Ic ?=99.999 Johnson-Cousins V-I colour index 76- 80 F5.3 mag e_V-Ic ?=9.999 rms uncertainty on V-Ic (2)
Note (1): (x,y) coordinates correspond to the reference system of Figure 1. North is up, and east is to the left. Note (2): Magnitude and color errors are the standard deviations of the mean or the observed photometric errors for stars with only one measurement.
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 06-Apr-2010
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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