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J/A+A/548/A92       VrI light curves of NGC1904 variables        (Kains+, 2012)

Constraining the parameters of globular cluster NGC 1904 from its variable star population. Kains N., Bramich D.M., Figuera Jaimes R., Arellano Ferro A., Giridhar S., Kuppuswamy K. <Astron. Astrophys. 548, A92 (2012)> =2012A&A...548A..92K
ADC_Keywords: Clusters, globular ; Stars, variable ; Photometry, CCD Keywords: stars: variable: RR Lyrae - globular clusters: individual: NGC 1904 Abstract: We present the analysis of 11 nights of V and I time-series observations of the globular cluster NGC 1904 (M 79). Using this we searched for variable stars in this cluster and attempted to refine the periods of known variables, making use of a time baseline spanning almost 8 years. We use our data to derive the metallicity and distance of NGC 1904. We used difference imaging to reduce our data to obtain high-precision light curves of variable stars. We then estimated the cluster parameters by performing a Fourier decomposition of the light curves of RR Lyrae stars for which a good period estimate was possible. We also derive an estimate for the age of the cluster by fitting theoretical isochrones to our colour-magnitude diagram (CMD). Out of 13 stars previously classified as variables, we confirm that 10 are bona fide variables. We cannot detect variability in one other within the precision of our data, while there are two which are saturated in our data frames, but we do not find sufficient evidence in the literature to confirm their variability. We also detect a new RR Lyrae variable, giving a total number of confirmed variable stars in NGC 1904 of 11. Using the Fourier parameters, we find a cluster metallicity [Fe/H]ZW=-1.63±0.14, or [Fe/H]UVES=-1.57±0.18, and a distance of 13.3±0.4kpc (using RR0 variables) or 12.9kpc (using the one RR1 variable in our sample for which Fourier decomposition was possible). Description: V, I and r time-series photometry and difference imaging parameters for all confirmed variables in NGC 1904. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table43.dat 101 11 Data for all confirmed variable stars in NGC1904 table2.dat 81 2511 *V, I and r lightcurves
Note on table2.dat: r light curves were not used in the paper but are supplied as they might be of use for future work.
See also: J/MNRAS/413/1275 : VrI light curves of NGC6981 variables (Bramich+, 2011) Byte-by-byte Description of file: table43.dat
Bytes Format Units Label Explanations
1- 3 A3 --- VName Variable ID (VNN) 5- 6 I2 h RAh Right ascension (J2000) (1) 8- 9 I2 min RAm Right ascension (J2000) (1) 11- 15 F5.2 s RAs Right ascension (J2000) (1) 17 A1 --- DE- Declination sign (J2000) (1) 18- 19 I2 deg DEd Declination (J2000) (1) 21- 22 I2 arcmin DEm Declination (J2000) (1) 24- 27 F4.1 arcsec DEs Declination (J2000) (1) 29- 37 F9.4 d Ep ? Epoch (HJD-2450000) 39- 46 F8.6 d Per ? Period (2) 48- 56 F9.7 d Per1 ? Amigo et al. (2011, in RR Lyrae stars, Metal-poor stars and the Galaxy, ed. A. McWilliam, 127) period 58- 65 F8.6 d Per2 ? Rosino (1952MmSAI..23..101R) period 66- 70 F5.2 mag <Vmag> Intensity-weighted mean V magnitude 71 A1 --- n_<Vmag> [b] Note on <Vmag> (3) 73- 77 F5.2 mag <Imag> ? Intensity-weighted mean I magnitude 78 A1 --- n_<Imag> [b] Note on <Imag> (3) 80 A1 --- l_Vamp [~] Limit flag on Vamp 81- 84 F4.2 mag Vamp Amplitude in V band 86 A1 --- l_Iamp [~] Limit flag on Iamp 87- 90 F4.2 mag Iamp Amplitude in I band 92-100 A9 --- VType Variable type 101 A1 --- n_VType [a] Note on VType (1)
Note (1): Coordinates derived from our astrometric fit to the V-band reference image. Note (2): Periods are determined using phase dispersion minimisation (PDM) and the string length method (see text) Note (3): Notes as follows: a = potentially RRd, see text b = error-weighted mean magnitudes, rather than intensity-weighted magnitudes
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 3 A3 --- VName Variable ID (VNN), as in table4 5 A1 --- Filter [VIr] Observation filter 7- 19 F13.5 d HJD Heliocentric Julian date 21- 26 F6.3 mag mag.s Standard magnitude 28- 33 F6.3 mag mag.i Instrumental magnitude 35- 39 F5.3 mag e_mag.i Error on the magnitude 41- 49 F9.3 s-1 Fref Reference flux (in ADU/s) 51- 56 F6.3 s-1 e_Fref Error on the reference flux (in ADU/s) 58- 67 F10.3 s-1 DFlux Differential flux (in ADU/s) 69- 74 F6.3 s-1 e_DFlux Error on the differential flux (in ADU/s) 76- 81 F6.4 --- p Photometric scale factor
Acknowledgements: Noe Kains, nkains(at)
(End) Patricia Vannier [CDS] 16-Nov-2012
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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