J/ApJS/257/41 V and R -band light curves of BZCAT blazars (Kalita+, 2021)
Optical variability of a newly discovered blazar sample from the BZCAT catalog.
Kalita N., Gupta A.C., Gu M.
<Astrophys. J. Suppl. Ser., 257, 41 (2021)>
=2021ApJS..257...41K 2021ApJS..257...41K
ADC_Keywords: Active gal. nuclei; BL Lac objects; QSOs; Photometry, UBVRI;
X-ray sources; Redshifts
Keywords: Blazars
Abstract:
In an optical monitoring program to characterize the variability
properties of blazars, we observed 10 sources from the Roma-BZCAT
catalog for 26 nights in V and R bands during 2014 October to
2015 June with two telescopes located in India. The sample includes
mainly newly discovered BL Lacertae objects (BL Lacs) for which the
redshift of some sources is not yet known. We present the results of
flux and color variations of the sample on intraday and short
timescales obtained by using the power-enhanced F-test and the
nested-ANOVA tests, along with their spectral behavior. We find
significant intraday variability in the single flat-spectrum radio
quasar in our sample, having an amplitude of variation ∼12%. Although
a few of the BL Lacs showed probable variation in some nights, none of
them passed the variability tests at 99.9% significance level. We find
that 78% of the sample showed significant negative color-magnitude
correlations, i.e., a redder-when-brighter spectral evolution. Those
that do not show strong or clear chromatism predominantly exhibit a
redder-when-brighter trend. Unlike on hourly timescales, the high-
synchrotron-peaked blazars in the sample (BZGJ0656+4237,
BZGJ0152+0147, and BZBJ1728+5013) show strong flux variation on
timescales of days to months, where again we detect a decreasing trend
of the spectral slope with brightness. We observe a global steepening
of the optical spectrum with increasing flux on the intranight
timescale for the entire blazar sample. The nonvariability in the BL
Lacs in our sample might be caused by the distinct contribution from
the disk as well as from other components in the studied energy range.
Description:
The observations were carried out with two telescopes:
the 1.04m Sampurnanad Telescope (ST), and the 1.3m Devasthal Fast
Optical Telescope (DFOT), located at the Aryabhatta Research Institute
of observational sciencES (ARIES), Nainital, India, between
2014 October and 2015 October for a total of 26 nights. Both of these
telescopes are equipped with CCD detectors and with the standard
Johnson UBV and Cousins RI filter system.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 79 10 Basic parameters of the Roma-BZCAT catalog blazars
studied in our sample
fig1v.dat 85 447 Differential V-band magnitude light curves
fig1r.dat 85 569 Differential R-band magnitude light curves
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See also:
VII/274 : The Roma BZCAT - 5th edition (Massaro+, 2015)
J/A+A/327/61 : BV(RI)c photometry of S5 0716+714 (Ghisellini+ 1997)
J/A+A/333/231 : O-M stars model atmospheres (Bessell+ 1998)
J/ApJ/537/101 : Optical Study for blazars. I. (Fan+, 2000)
J/A+A/495/691 : Multifrequency cat. of blazars, Roma-BZCAT (Massaro+, 2009)
J/ApJ/716/30 : SED of Fermi bright blazars (Abdo+, 2010)
J/ApJ/744/177 : VLBA 5GHz observations of Fermi/LAT AGNs (Linford+, 2012)
J/MNRAS/421/1861 : OJ287 polarization and VLBI jet direction (Valtonen+, 2012)
J/A+A/560/A23 : Radio properties of faint BL Lacs (Liuzzo+, 2013)
J/A+A/570/A126 : XShooter spectrum of 4 BL Lacs (Landoni+, 2014)
J/ApJS/226/20 : X-ray, opt. & radio SEDs of Fermi blazars (Fan+, 2016)
J/A+A/608/A68 : TeV BL Lacs multi-lambda fluxes (Fallah Ramazani+, 2017)
J/ApJS/229/21 : VRI monitoring of the QSO 3C 273 in 2005-2016 (Xiong+, 2017)
J/ApJ/880/155 : RI photometry of blazars S5 0716+714 and 3C 273 (Liu+, 2019)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- Name Source name, BZCAT catalog
(<[MGL2009] BZ{BQ} JHHMM+DDMM> or
<[MML2015] 5BZG JHHMM+DDMM> in Simbad)
15- 28 A14 --- OName Other name from the Fermi-AGN catalog
30- 31 I2 h RAh Hour of right ascension (J2000)
33- 34 I2 min RAm Minute of right ascension (J2000)
36- 39 F4.1 s RAs Second of right ascension (J2000)
41 A1 --- DE- Sign of declination (J2000)
42- 43 I2 deg DEd Degree of declination (J2000)
45- 46 I2 arcmin DEm Arcminute of declination (J2000)
48- 51 F4.1 arcsec DEs Arcsecond of declination (J2000)
53- 57 F5.3 --- z [0.041/0.158]? Redshift
59- 62 F4.1 mag Rmag [11.1/15.7] Apparent R-band magnitude from BZCAT
64- 69 A6 --- Class Object class
71- 73 A3 --- Type Source type based on SED (1)
75- 79 F5.2 10-15W/m2 Fx [0.44/63.1]? 0.1-2.4keV X-ray flux
in units of 10-12erg/cm2/s
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Note (1): Blazars are divided based on the peak frequency of the synchrotron
hump νsyncpeak in the SEDs of a large sample of Fermi-LAT
blazars into the following:
LSP = low-synchrotron-peaked blazars with νsyncpeak≤1014Hz,
ISP = intermediate-synchrotron-peaked blazars with
1014<νsyncpeak<1015Hz, and
HSP = high-synchrotron-peaked blazars with νsyncpeak≥1015Hz.
See Section 1.
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Byte-by-byte Description of file: fig1v.dat
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Bytes Format Units Label Explanations
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1- 13 E13.7 d JD Julian Date of observation
15- 28 E14.7 mag dVmag1 [-0.55/1.25] Differential V band magnitude,
source-reference star
30- 42 E13.7 mag e_dVmag1 [0.002/0.031] Uncertainty in dVmag1
44- 57 E14.7 mag dVmag2 [-0.76/2.27] Differential V band magnitude,
comparison star 1 - reference star
59- 71 E13.7 mag e_dVmag2 [0.0027/0.042] Uncertainty in dVmag2
73- 85 A13 --- Name Source name as in Table 2
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Byte-by-byte Description of file: fig1r.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 E13.7 d JD Julian Date of observation
15- 28 E14.7 mag dRmag1 [-0.33/0.91] Differential R band magnitude,
source-reference star
30- 42 E13.7 mag e_dRmag1 [0.0018/0.031] Uncertainty in dRmag1
44- 57 E14.7 mag dRmag2 [-0.54/1.95] Differential R band magnitude,
comparison star 1 - reference star
59- 71 E13.7 mag e_dRmag2 [0.0024/0.043] Uncertainty in dRmag2
73- 85 A13 --- Name Source name as in Table 2
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 28-Feb-2022