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J/A+A/548/A107      U,V photometry in M2 (NGC 7089)            (Lardo+, 2012)
Carbon and nitrogen abundances of stellar populations in the
globular cluster M2.
    Lardo C., Pancino E., Mucciarelli A., Milone, A.P.
   <Astron. Astrophys. 548, A107 (2012)>
   =2012A&A...548A.107L
ADC_Keywords: Clusters, globular ; Photometry, UBV

Keywords: stars: abundances - globular clusters: individual: M 2


Description:
    We present U, V photometry of the globular cluster M2. Stars within
    1' and outside of 4' from the cluster center are excluded from the CMD
    to reduce blending effects and the field star contamination,
    respectively. We imposed on all stars the selection limits of CHI<2.0
    and -1<SHARP<1 on DAOPHOT II photometric parameters. To select a
    sample of well-measured stars we have followed the procedure given in
    Lardo et al. (2012A&A...541A.141L), Sect. 5.1. M2 photometry displays
    an anomalous branch beyond the red edge of the main body of the RGB.
    The difference in color between stars belonging to this structure and
    normal RGB stars is quite large (of the order of 0.2-0.3mags, well
    above the typical measurement errors) and extends down to the SGB
    region. There may be a second group of stars that are 0.3mags redder
    with respect to this sequence and can possibly be more, anomalous RGB
    stars.

    The observations were carried out during the nights of 2010 July 15 at
    the Telescopio Nazionale Galileo (TNG) located in La Palma, Canary
    Islands (Spain), with he DOLORES camera. The DOLORES camera offers a
    field of view of 8.6'x8.6' with a 0.252"/pix scale. We obtained images
    of the cluster in the standard Johnson U and V filters for a total of
    540s shifted in 3 single exposures in each filter. The seeing
    condition were average during (∼1.2-1.3") during the observing night.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1.dat        60     3022   Photometry of M2: selected sample


See also:
  J/AJ/117/2868  : BV photometry in M2 (NGC 7089) (Lee+, 1999)
  J/ApJS/182/509 : Blue stragglers in M2 (Dalessandro+, 2009)


Byte-by-byte Description of file: table1.dat

   Bytes Format Units   Label     Explanations

   1-  5  I5    ---     ID        [164/21800] Star Identifier (1)
   7- 17  F11.7 deg     RAdeg     Right ascension (J2000)
  20- 29  F10.7 deg     DEdeg     Declination (J2000)
  32- 37  F6.3  mag     Vmag      The V band magnitude
  40- 44  F5.3  mag     e_Vmag    Formal DAOPHOT errors associated to V magnitude
  47- 52  F6.3  mag     U-V       The U-V color index
  56- 60  F5.3  mag     e_Umag    Formal DAOPHOT errors associated to U magnitude

Note (1): We identify stars with the DAOPHOT ID number.



Acknowledgements:
    Carmela Lardo, carmela.lardo2(at)unibo.it
(End)                                        Patricia Vannier [CDS]  01-Oct-2012