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J/A+A/497/371       UBVI photometry of NGC 3201              (Kravtsov+, 2009)

Multi-color photometry in wide field of the galactic globular cluster NGC 3201. Kravtsov V., Alcaino G., Marconi G., Alvarado F. <Astron. Astrophys., 497, 371-378 (2009)> =2009A&A...497..371K
ADC_Keywords: Clusters, globular ; Photometry, CCD ; Photometry, UBVRI Keywords: globular clusters: general - globular clusters: individual: NGC 3201 Abstract: This paper aims at further studying one of the nearby Galactic globular clusters (GCs), NGC 3201. It is known to experience notable irregular variability of reddening across its face. By relying on our previous studies and findings and by developing them, we focus on the brighter sequences of the color-magnitude diagram (CMD) and on the cluster's characteristics. We carried out and analyzed new multi-color photometry of NGC 3201 in UBVI reaching below the turnoff point in all passbands in a fairly large cluster field, about 14'x14'. To achieve more reliable results and conclusions, we reduced the negative impact of the irregularly varying reddening and contamination by field stars. With this aim we first estimated mean reddening in different zones of the studied cluster field and then took its variations into account, by reducing them to the same level. We estimated metallicity of NGC 3201 using a new metallicity indicator related to U-based CMDs, recently proposed by us. We find [Fe/H]zw=-1.54±0.12dex, which falls between extreme estimates of the cluster's metallicity obtained using different methods or indicators. Also, the location of the RGB bump on the branch corresponds to [Fe/H]zw=-1.46±0.15dex. We isolate 73 probable blue straggler (BS) candidates, the largest population found in NGC 3201 so far. They are more centrally concentrated than the lower red giants at the 99.2% level. Their position in the two-color diagram assumes that presumably none of them belongs to BSa of collisional origin. The luminosity function (LF) of the RGB and its features in the low part of the branch are examined and discussed. We also resolve some of the contradictory results of previous publications. Description: The observations were acquired on three nights, December 30/31/1997 and January 01/02, 02/03 1998, with the 1.3m Warsaw telescope, Las Campanas Observatory, using a set of UBVI filters. Objects: ----------------------------------------------- RA (2000) DE Designation(s) ----------------------------------------------- 10 17 36.8 -46 24 40 NGC 3201 = C 1015-461 ----------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file phot.dat 55 12487 Photometric data for 12487 stars in the globular cluster NGC 3201
See also: J/ApJS/90/83 : Binaries in NGC 3201 (Cote+, 1994) J/ApJ/454/788 : Radial velocities and BV photometry of NGC 3201 (Cote+ 1995) J/PAZh/22/269 : Giant branch and variable stars in NGC 3201 (Samus+, 1996) J/AJ/123/279 : VI Photometry and Variables in NGC 3201 (von Braun+, 2002) J/A+A/445/155 : XMM count-rates in M 55 and NGC 3201 (Webb+, 2006) Byte-by-byte Description of file: phot.dat
Bytes Format Units Label Explanations
1- 5 I5 --- Seq Sequential number 7- 12 F6.3 mag Vmag ?=- V magnitude 14- 19 F6.3 mag U-B ?=- U-B color index 21- 26 F6.3 mag B-V ?=- B-V color index 28- 33 F6.3 mag V-I ?=- V-I color index 35- 40 F6.1 pix Xpos x coordinate (1) 42- 47 F6.1 pix Ypos y coordinate (1) 49 I1 --- gr Grade of reddening (2) 51- 52 I2 --- BS ?=- Isolated blue straggler candidates (3) 54- 55 I2 --- ID ?=- Identification with known BS candidates (4)
Note (1): 1 pix = 0.417" Note (2): Grade of reddening code as follows: 1 = blue 2 = green 3 = yellow 4 = red Note (3): The number 99 indicates the isolated blue straggler candidates Note (4): The numbers in the column are the sequential numbers from Table 3 of Brewer et al. (1993AJ....105.2158B)
Table 1: Data on color and magnitude offsets applied to the CMDs of regions with different reddening. -------------------------------------------------------------------------------- Reddening Delta(B-V) Delta(V-I) Delta(B-I) DeltaV DeltaU -------------------------------------------------------------------------------- grade mag mag mag mag mag -------------------------------------------------------------------------------- blue 0.04 0.09 0.15 0.20 0.25 green 0.02 0.04 0.07 0.10 0.15 yellow 0.01 0.01 0.02 0.05 0.05 -------------------------------------------------------------------------------- The most probable colors and magnitudes (as estimated from CMDs with different colors) of the turnoff (TO) point in the reference "red" CMDs are as follows: V=18.35, U=19.05, B-V=0.70, V-I=0.94, B-I=1.64. Acknowledgements: Valery Kravtsov, vkravtsov(at)
(End) V. Kravtsov [Universidad Catolica del Norte], P. Vannier [CDS] 14-May-2009
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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