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J/MNRAS/416/2265    Variable stars in NGC 5024 (M53)     (Arellano Ferro+, 2011)

Exploring the variable stars in the globular cluster NGC 5024 (M53): new RR Lyrae and SX Phoenicis stars. Arellano Ferro A., Figuera Jaimes R., Giridhar S., Bramich D.M., Hernandez Santisteban J.V., Kuppuswamy K. <Mon. Not. R. Astron. Soc., 416, 2265-2284 (2011)> =2011MNRAS.416.2265A
ADC_Keywords: Clusters, globular ; Stars, variable ; Photometry Keywords: stars: variables: RR Lyrae - globular clusters: individual: NGC 5024 Abstract: We report CCD V and I time series photometry of the globular cluster NGC 5024 (M53). The technique of difference image analysis has been used which enables photometric precisions better than 10mmag for stars brighter than V∼18.5mag even in the crowded central regions of the cluster. The high photometric precision has resulted in the discovery of two new RR1 stars and 13 SX Phe stars. A detailed identification chart is given for all the variable stars in the field of our images of the cluster. Periodicities were calculated for all RR Lyrae and SX Phe stars and a critical comparison is made with previous determinations. Description: The observations employed in the present work were performed using the Johnson V and I filters on 2009 April 17, 18 and 19, on 2010 January 22 and 23, February 21 and 22, March 7 and 8, April 7 and 25, and May 6. A total of 177 epochs in the V filter and 184 in the I filter were obtained. The 2.0-m telescope of the Indian Astronomical Observatory (IAO), Hanle, India, located at 4500 m above sea level, was used. The estimated seeing was ∼1arcsec. The detector was a Thompson CCD of 2048x2048pixels with a pixel scale of 0.296arcsec/pix and a field of view of approximately 10.1x10.1arcmin2. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 91 71 General data for confirmed variables in NGC 5024 table3.dat 87 28 Fourier coefficients Ak for k=0,1,2,3,4, and phases φ(21, 31 and 41) for the 19 RR0-type and 9 RR1-type variables for which the Fourier decomposition fit was successful table6.dat 181 13 Frequencies and amplitudes of the newly found SX Phe stars table7.dat 42 5 Blue stragglers whose variability is to be confirmed table1.dat 79 30907 Time series V and I photometry for all the confirmed variables in our field of view
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 4 A4 --- VName Variable name (V1-V92) 7- 13 A7 --- Type Bailey's type 15- 17 A3 --- OType Other type 19- 27 F9.6 d Per ? Period, this work 28 A1 --- n_Per [a] a: adopted from Dekany & Kovacs 2009 (Cat. J/A+A/507/803) 30- 38 F9.3 d Tmax ? Date of maximum light (HJD-2400000) 41- 46 F6.4 d Per2 ? Period from Jeon et al, 2003AJ....125.3165J 48- 56 F9.7 d Per3 ? Period from Kopacki, 2000 Cat. J/A+A/358/547 58- 67 F10.7 d Per4 ? Period from Dekany & Kovacs, 2009 Cat. J/A+A/507/803 69- 70 I2 h RAh Right ascension (J2000) 72- 73 I2 min RAm Right ascension (J2000) 75- 79 F5.2 s RAs Right ascension (J2000) 81 A1 --- DE- Declination sign (J2000) 82- 83 I2 deg DEd Declination (J2000) 85- 86 I2 arcmin DEm Declination (J2000) 88- 91 F4.1 arcsec DEs Declination (J2000)
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 3 A3 --- Type [RR0/RR1] Variability type 5- 8 A4 --- VName Variable star ID (V1-V92) 10- 15 F6.3 mag A0 Fourier coefficient A0 (V mag) 17 I1 mmag e_A0 rms uncertainty on A0 19- 23 F5.3 mag A1 Fourier coefficient A1 (V mag) 25 I1 mmag e_A1 rms uncertainty on A1 27- 31 F5.3 mag A2 Fourier coefficient A2 (V mag) 33 I1 mmag e_A2 rms uncertainty on A2 35- 39 F5.3 mag A3 ?=- Fourier coefficient A3 (V mag) 41 I1 mmag e_A3 ? rms uncertainty on A3 43- 47 F5.3 mag A4 ?=- Fourier coefficient A4 (V mag) 49 I1 mmag e_A4 ? rms uncertainty on A4 51- 55 F5.3 rad phi21 Phase φ21 57- 59 I3 mrad e_phi21 rms uncertainty on phi21 61- 65 F5.3 rad phi31 ?=- Phase φ31 67- 69 I3 mrad e_phi31 ? rms uncertainty on phi31 71- 75 F5.3 rad phi41 ?=- Phase φ41 77- 80 I4 mrad e_phi41 ? rms uncertainty on phi41 82- 83 I2 --- N Number of harmonics used to fit the light curve of each variable 85- 87 F3.1 --- Dm ? Deviation parameter (see Section 4.3)
Byte-by-byte Description of file: table6.dat
Bytes Format Units Label Explanations
1- 4 A4 --- VName Variable name (V93-V105) 5 A1 --- n_VName [a] small amplitude (1) 7- 12 F6.3 mag Vmag V magnitude 14- 18 F5.3 mag V-I V-I colour index 20- 21 I2 h RAh Right ascension (J2000.0) 23- 24 I2 min RAm Right ascension (J2000.0) 26- 30 F5.2 s RAs Right ascension (J2000.0) 32 A1 --- DE- Declination sign (J2000.0) 33- 34 I2 deg DEd Declination (J2000.0) 36- 37 I2 arcmin DEm Declination (J2000.0) 39- 42 F4.1 arcsec DEs Declination (J2000.0) 44- 51 F8.5 d-1 Freq1 Frequency in mode "Mode1" 53- 54 I2 10-5d-1 e_Freq1 rms uncertainty on Freq1 56- 60 F5.3 mag A1 Amplitude in mode "Mode1" 62- 63 I2 mmag e_A1 rms uncertainty on A1 65- 71 F7.5 d Per1 Period in mode "Mode1" 73- 82 A10 --- Mode1 First mode identification (2) 84- 91 F8.5 d-1 Freq2 ? Frequency in mode "Mode2" 93- 94 I2 10-5d-1 e_Freq2 ? rms uncertainty on Freq2 96-100 F5.3 mag A2 ? Amplitude in mode "Mode2" 102-103 I2 mmag e_A2 ? rms uncertainty on A 105-111 F7.5 d Per2 ? Period in mode "Mode2" 113-131 A19 --- Mode2 Second mode identification (2) 133-140 F8.5 d-1 Freq3 ? Frequency in mode "Mode3" 142-143 I2 10-5d-1 e_Freq3 ? rms uncertainty on Freq 145-149 F5.3 mag A3 ? Amplitude in mode "Mode3" 151-152 I2 mmag e_A3 ? rms uncertainty on A 154-160 F7.5 d Per3 ? Period in mode "Mode3" 162-181 A20 --- Mode3 Third mode identification (2)
Note (1): a: Although clear variations are seen and a distinctive peak is seen in the frequency spectrum, the amplitude is very small. Note (2): Mode is F = Fundamental mode; 1O = First overtone; 2O = Second overtone.
Byte-by-byte Description of file: table7.dat
Bytes Format Units Label Explanations
1- 4 A4 --- VName Variable name (S1-S5) 7- 12 F6.3 mag Vmag V magnitude 14- 19 F6.3 mag V-I V-I colour index 21- 22 I2 h RAh Right ascension (J2000.0) 24- 25 I2 min RAm Right ascension (J2000.0) 27- 30 F4.1 s RAs Right ascension (J2000.0) 32 A1 --- DE- Declination sign (J2000.0) 33- 34 I2 deg DEd Declination (J2000.0) 36- 37 I2 arcmin DEm Declination (J2000.0) 39- 42 F4.1 arcsec DEs Declination (J2000.0)
Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 4 A4 --- VName Variable name (S1-S5, V1-V105) 6 A1 --- Band [VI] Observed band 8- 20 F13.5 d HJD Heliocentric Julian date 22- 27 F6.3 mag mag Standard magnitude, in Band 29- 34 F6.3 mag magi Instrumental magnitude, in Band 36- 40 F5.3 mag e_mag rms uncertainty on mag 42- 49 F8.3 s-1 fref Reference flux (in ADU/s) (1) 51- 55 F5.3 s-1 e_fref rms uncertainty on fref (in ADU/s) 57- 65 F9.3 s-1 fdiff Differential flux (in ADU/s) (1) 67- 72 F6.3 s-1 e_fdiff rms uncertainty on fdiff 74- 79 F6.4 --- p Photometric scalefactor (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.
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 10-Apr-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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