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J/MNRAS/424/2722    Variable stars in NGC 5024 (M53)         (Bramich+, 2012)

Investigation of variable star candidates in the globular cluster NGC 5024 (M53). Bramich D.M., Arellano Ferro A., Figuera Jaimes R., Giridhar S. <Mon. Not. R. Astron. Soc., 424, 2722-2732 (2012)> =2012MNRAS.424.2722B
ADC_Keywords: Clusters, globular ; Stars, variable ; Photometry Keywords: stars: variables: general, globular clusters: individual: NGC 5024 Abstract: We have performed a careful investigation of the 74 candidate variable stars presented by Safonova & Stalin (2011AJ....142..179S) . For this purpose we used our data base of imaging and light curves from Arellano Ferro et al. (J/MNRAS/416/2265 and J/MNRAS/420/1333). We find that two candidates are known variable stars, eight candidates were discovered first by Arellano Ferro et al. (J/MNRAS/416/2265), but would not have been known to Safonova & Stalin (2011AJ....142..179S) at the time of their paper submission, while four candidates are new variables. Three of the new variables are SX Phe type and one is a semiregular (SR) type red giant variable. We also tentatively confirm the presence of true variability in two other candidates, and we are unable to investigate another four candidates because they are not in our data base. However, we find that the remaining 54 candidate variable stars are spurious detections where systematic trends in the light curves have been mistaken for true variability. We believe that the erroneous detections are caused by the adoption of a very low detection threshold used to identify these candidates. Description: Time-series V and I photometry for all the SX Phe and long-period variables in NGC 5024 from the works of Arellano Ferro et al. (2011, Cat. J/MNRAS/416/2265), Arellano Ferro et al. (2012, Cat. J/MNRAS/420/1333) and this work. We list standard and instrumental magnitudes and their uncertainties corresponding to the variable star identification, filter, and epoch of mid-exposure. For completeness, we also list the reference flux, difference flux, and photometric scale factor, along with the uncertainties on the reference and difference fluxes. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file stars.dat 41 33 List of studied stars table2.dat 81 19580 Time series V and I photometry for all the SX Phe and long-period variables in NGC 5024
See also: J/AJ/116/1775 : BV photometry of M53 (Rey+, 1998) J/PAZh/23/454 : Identification and coordinates in M 53 (Evstigneeva+, 1997) J/A+A/358/547 : M53 variable stars V light curves (Kopacki, 2000) J/A+A/507/803 : VI photometry of new M53 variables (Dekany+, 2009) J/MNRAS/416/2265 : Variable stars in NGC 5024 (M53) (Arellano Ferro+, 2011) J/MNRAS/420/1333 : Variable stars in NGC 5024 (M53) (Arellano Ferro+, 2012) Byte-by-byte Description of file: stars.dat
Bytes Format Units Label Explanations
1- 4 A4 --- VName Variable star Name 6- 7 I2 h RAh Simbad Right ascension (J2000) 9- 10 I2 min RAm Simbad Right ascension (J2000) 12- 16 F5.2 s RAs Simbad Right ascension (J2000) 18 A1 --- DE- Simbad Declination sign (J2000) 19- 20 I2 deg DEd Simbad Declination (J2000) 22- 23 I2 arcmin DEm Simbad Declination (J2000) 25- 28 F4.1 arcsec DEs Simbad Declination (J2000) 30- 39 F10.7 d Per Period 41 A1 --- n_Per [abc*] Reference for period (1)
Note (1): References for period as follows: a = Arellano Ferro et al., 2011, Cat. J/MNRAS/416/2265 b = Period in "Mode 1", Arellano Perro et al., 2011, Cat. J/MNRAS/416/2265 * = Dekany & Kovacs, 2009 Cat. J/A+A/507/803 c = this paper
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 4 A4 --- VName Variable star ID 6 A1 --- Filter [VI] Observation filter 8- 20 F13.5 d HJD Heliocentric Julian date at mid-exposure 22- 27 F6.3 mag magst Standard magnitude 29- 34 F6.3 mag maginst Instrumental magnitude 36- 40 F5.3 mag e_maginst Magnitude uncertainty (standard or instrumental) 42- 50 F9.3 s-1 Fref Reference flux (in ADU/s unit) (1) 52- 56 F5.3 s-1 e_Fref Reference flux uncertainty (in ADU/s unit) 58- 66 F9.3 s-1 DFlux Difference flux (in ADU/s unit) (1) 68- 74 F7.3 s-1 e_DFlux Difference flux uncertainty (in ADU/s unit) 76- 81 F6.4 --- p Photometric scale factor (1)
Note (1): Light curves for each star were constructed by calculating the total flux ftot(t) in adu/s at each epoch t from ftot(t)=fref+fdiff(t)/p(t) where fref is the reference flux (adu/s), fdiff(t) is the differential flux (adu/s) and p(t) is the photometric scalefactor (the integral of the kernel solution) Conversion to instrumental magnitudes was achieved using mins(t)=25.0-2.5log(ftot(t)) where mins(t) is the instrumental magnitude of the star at time t. Uncertainties were propagated in the correct analytical fashion.
Acknowledgements: Daniel Bramich, dbramich(at)
(End) Daniel Bramich [ESO, Germany], Patricia Vannier [CDS] 31-Jan-2013
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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