J/A+A/591/A21 Optical flux behaviour of Fermi blazars (Marchesini+, 2016)
Optical flux behaviour of a sample of Fermi blazars.
Marchesini E.J., Andruchow I., Cellone S.A., Combi J.A., Zibecchi L.,
Marti J., Romero G.E., Munoz-Arjonilla A.J., Luque-Escamilla P.,
Sanchez-Sutil J.R.
<Astron. Astrophys. 591, A21 (2016)>
=2016A&A...591A..21M 2016A&A...591A..21M (SIMBAD/NED BibCode)
ADC_Keywords: BL Lac objects ; Photometry
Keywords: BL Lacertae objects: general
Abstract:
We aim at investigating the time-behaviour of a sample of gamma-ray
blazars. We present the results from a 13 month-long optical
photometry monitoring campaign of the blazars PKS0048-097,
PKS0754+100, [HB89] 0827+243, PKS0851+202, PKS1253-055, PKS1510-089,
PKS1749+096, PKS2230+114 and PKS2251+158. We analyse the variability of
each object, focusing on different time-scales (long term, short term,
and microvariability), in an attempt to achieve a statistical
comparison of the results. After applying a geometric model to explain
the variability results, we found that it is possible that a slight
change in the direction of the jet generates the variations detected
in some objects during this campaign.
Description:
Optical variability results for a sample of 9 BL Lacs (PKS 0048-097,
PKS 0754+100, [HB89] 0827+243, PKS 0851+202, PKS 1253-055,
PKS 1510-089, PKS 1749+096, PKS 2230+114, and PKS 2251+158) are
presented. Column 1 gives the object name with the date, while the
following columns give, respectively for bands V and R: the
observational error, Sigma, obtained from the standard deviation of
the control-comparison differential light-curve for each filter; the
variability results; the confidence parameter from the F-test, F; the
gamma corrective factor Gamma as described in "Howell S.B., Warnock
III A. & Mitchell K.J., 1988AJ.....95..247H 1988AJ.....95..247H"; the number of points in
the light curves; and the corresponding critical value, Ft for n=N-1
degrees of freedom, assuming a 99% confidence level.
Optical differential photometry results for a sample of 9 BL Lacs
(PKS0048-097, PKS0754+100, [HB89]0827+243, PKS0851+202,
PKS1253-055, PKS 1510-089, PKS 1749+096, PKS 2230+114, and
PKS 2251+158) are presented. The file contains 9 columns: Column 1
gives the object name, column 2 the observed band, column 3 enumerates
the number of observations taken, column 4 shows the Heliocentric
Julian Date in days, column 5 the differential Heliocentric Julian
Date (counting from the last integer date), column 6 the differential
magnitude (i.e. the instrumental magnitude of the science object minus
the instrumental magnitude of the comparison star, both on the same
frame), column 7 its error, column 8 the differential control
magnitude (i.e. i.e. the instrumental magnitude of the control object
minus the instrumental magnitude of the comparison star, both on the
same frame), and column 9 its error.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sample.dat 61 9 Sample
table2.dat 91 30 Statistical results for the differential light
curves
phot.dat 71 481 BV differential photometry for the 9 BL Lacs
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Byte-by-byte Description of file: sample.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Blazar name
17- 28 A12 --- Type Type of source
31- 32 I2 h RAh Right ascension (J2000)
34- 35 I2 min RAm Right ascension (J2000)
37- 40 F4.1 s RAs Right ascension (J2000)
42 A1 --- DE- Declination sign (J2000)
43- 44 I2 deg DEd Declination (J2000)
46- 47 I2 arcmin DEm Declination (J2000)
49- 50 I2 arcsec DEs Declination (J2000)
52- 55 F4.1 mag Vmag Visual magnitude (as found in NED)
57- 61 F5.3 --- z Redshift (as found in NED)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Blazar name
17- 26 A10 --- Date Observation UT date or "All nights"
29- 33 F5.3 mag sigmaV V-band observational error (1)
35- 39 F5.3 mag sigmaR R-band observational error (1)
41- 42 A2 --- VarV [V NV] V-band variability flag
44- 45 A2 --- VarR [V NV] R-band variability flag
48- 54 F7.2 --- FV V-band confidence parameter from the F-test (2)
57- 63 F7.2 --- FR R-band confidence parameter from the F-test (2)
65- 68 F4.2 --- GammaV V-band gamma corrective factor (3)
70- 73 F4.2 --- GammaR R-band gamma corrective factor (3)
75- 76 I2 --- NV Number of points in the V light curves
78- 79 I2 --- NR Number of points in the R light curves
81- 85 F5.2 --- FtV V-band Ft critical value (2)
87- 91 F5.2 --- FtR R-band Ft critical value (2)
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Note (1): Observational error, Sigma, obtained from the standard deviation of
the control-comparison differential light-curve.
Note (2): For each light curve, we estimated the F parameter, defined as the
ratio of the variance of the object-comparison light curve (σ2o-c)
to the variance of the control-comparison light curve (σ2k-c).
If F=(σo-c)2/(σk-c)2≥Fnα, the object is said
to be variable, being Fnα a critical value. This critical value is
calculated for a set of n=N-1 degrees of freedom, where N is the number of
points in the light-curve, while α is chosen to determine the desired
level of confidence. If α=0.01, then the F test has a 99%
confidence level.
Note (3): gamma corrective factor as described in "Howell S.B., Warnock
III A. & Mitchell K.J., 1988AJ.....95..247H 1988AJ.....95..247H".
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Byte-by-byte Description of file: phot.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Blazar name
17 A1 --- Band [RV] Observed band
19- 20 I2 --- Seq Sequential number of observations within
the source and the band
22- 36 F15.7 d HJD Heliocentric Julian Date
38- 45 F8.6 d dHJD Differential Heliocentric Julian Date
(counting from the last integer date)
47- 52 F6.3 mag dmag Differential magnitude (1)
54- 58 F5.3 mag e_dmag rms uncertainty on dmag
60- 65 F6.3 mag dmagC Differential control magnitude (2)
67- 71 F5.3 mag e_dmagC ? rms uncertainty on dmagC
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Note (1): i.e. the instrumental magnitude of the science object minus the
instrumental magnitude of the comparison star, both on the same frame.
Note (2): i.e. the instrumental magnitude of the control object minus the
instrumental magnitude of the comparison star, both on the same frame.
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Acknowledgements:
Ezequiel Marchesini, razielezu(at)gmail.com
(End) Patricia Vannier [CDS] 18-Apr-2016