J/A+A/702/A140 The Blazar IRA Monitoring Program (Marchili+, 2025)
Twenty years of blazar monitoring with the INAF radio telescopes.
Marchili N., Righini S., Giroletti M., Raiteri C.M., Giri R.P.,
Carnerero M.I., Villata M., Bach U., Cassaro P., Liuzzo E., Buemi C.S.,
Leto P., Trigilio C., Umana G., Bonato M., Patricelli B., Stamerra A.
<Astron. Astrophys. 702, A140 (2025)>
=2025A&A...702A.140M 2025A&A...702A.140M (SIMBAD/NED BibCode)
ADC_Keywords: BL Lac objects ; QSOs ; Radio continuum
Keywords: radiation mechanisms: non-thermal -
astronomical databases miscellaneous - galaxies: active -
BL Lacertae objects: general - quasars: general -
radio continuum: galaxies
Abstract:
The extreme variability of blazars, in both timescale and amplitude,
is generally explained as the effect of a relativistic jet closely
aligned to the observer's line-of-sight. Due to causality arguments,
variability characteristics translate into spatial information about
the emitting region of blazars. Since radiation at different
wavelengths is emitted in different parts of the jet, multi-frequency
observations provide us with a virtual view of the structure of the
jet on different scales. Radio-gamma-ray correlations, moreover, are
essential to reveal where and how the high-energy radiation is
produced.
We present here the observations collected within the blazar radio
monitoring program that we are running at the Medicina and Noto
telescopes. It aims at investigating how the variability
characteristics and spectral energy distribution of blazars evolve in
time.
Since 2004, observation have been performed at 5, 8, 24, and 43GHz on
47 targets, with monthly cadence; the monitoring program is still
active at frequencies of 8 and 24GHz.
The database we built in more than twenty years of activity comprises
to date about 21000 flux density measurements. Some basic analysis
tools have been applied to the data to characterise the detected
variability and offer a first glance at the wealth of information that
such a program can provide about blazars.
Description:
Basic information and variability characteristics of the sources
included in the Blazar IRA Monitoring Program. For each source, we
specify the blazar type, the equatorial coordinates, the redshift,
and, for each of the monitored frequency, the number of epochs in
which the source was observed, the average flux densities, the
intrinsic modulation indices, the normalised structure function
calculated at a time lag of 1.5yr, the ratio between this structure
function value and the one calculated at a time lag of 3.0yr, and
finally the average spectral index between 8 and 24GHz.
Flux density measurements collected within the ROBIN (Radio
Observations of Blazars with INaf telescopes) programme between 2004
and 2024. For each data point we provide the observed source, the
modified Julian date, the Observed frequency, and the measured flux
density, with its uncertainty.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 112 47 Basic information about the sources included in
the Blazar IRA Monitoring programme
tablea2.dat 125 47 Basic characteristics of the monitored sources
in different bands
dataall.dat 51 20915 Flux density measurments collected within
the ROBIN programme
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Source name (HHMM+DDd)
12- 23 A12 --- AName Alternative name
27- 35 A9 --- Type Blazar type
38- 39 I2 h RAh Right ascension (J2000.0)
41- 42 I2 min RAm Right ascension (J2000.0)
44- 47 F4.1 s RAs Right ascension (J2000.0)
50 A1 --- DE- Declination sign (J2000.0)
51- 52 I2 deg DEd Declination (J2000.0)
54- 55 I2 arcmin DEm Declination (J2000.0)
57- 60 F4.1 arcsec DEs Declination (J2000.0)
63- 66 F4.2 --- z Redshift
69- 70 I2 --- N(5GHz) Number of datapoints at 5GHz
73- 77 F5.2 Jy S(5GHz) ? Average flux density at 5GHz
80- 82 I3 --- N(8GHz) Number of datapoints at 8GHz
85- 89 F5.2 Jy S(8GHz) Average flux density at 8GHz
92- 94 I3 --- N(24GHz) Number of datapoints at 24GHz
97-101 F5.2 Jy S(24GHz) Average flux density at 24GHz
104-105 I2 --- N(43GHz) Number of datapoints at 43GHz
108-112 F5.2 Jy S(43GHz) ? Average flux density at 43GHz
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Source name (HHMM+DDd)
12- 16 F5.2 % m(5GHz) ? Intrinsic modulation index at 5GHz
21- 25 F5.2 % SF'1.5(5GHz) ? Structure function at a time lag
of 1.5yr at 5GHz
31- 34 F4.2 --- SF'1.5/SF'3.0(5GHz) ? Fastness of the flux density
variations at 5GHz
40- 44 F5.2 % m(8GHz) Intrinsic modulation index at 8GHz
49- 53 F5.2 % SF'1.5(8GHz) Structure function at a time lag
of 1.5yr at 8GHz
59- 62 F4.2 --- SF'1.5/SF'3.0(8GHz) ? Fastness of the flux density
variations at 8GHz
68- 72 F5.2 % m(24GHz) Intrinsic modulation index at 24GHz
77- 81 F5.2 % SF'1.5(24GHz) Structure function at a time lag
of 1.5yr at 24GHz
87- 90 F4.2 --- SF'1.5/SF'3.0(24GHz) ? Fastness of the flux density
variations at 24GHz
96-100 F5.2 % m(43GHz) ? Intrinsic modulation index
at 43GHz
105-109 F5.2 % SF'1.5(43GHz) ? Structure function at a time lag
of 1.5yr at 43 GHz
115-118 F4.2 --- SF'1.5/SF'3.0(43GHz) ? Fastness of the flux density
variations at 43GHz
121-125 F5.2 --- alpha Spectral index between 8 and 24GHz
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Byte-by-byte Description of file: dataall.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Source name
12- 22 F11.5 d MJD Modified Julian date
26- 30 I5 MHz Freq Observed frequency (1)
37- 42 F6.3 Jy S Flux density
46- 51 F6.3 Jy e_S 1-sigma uncertainty on S
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Note (1): Observed frequencies ouls be 4835, 5000 5075, 5125, 6075, 8000, 8305,
8520, 20000, 22000, 22664, 23840, 24000, 24100, 24500, 24600, and 43000 MHz.
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Acknowledgements:
From Nicola Marchili, nicola.marchili(at)inaf.it
The Medicina and Noto radio telescopes are funded by the Ministry of
University and Research (MUR) and are operated as National Facilities
by the National Institute for Astrophysics (INAF). The Sardinia Radio
Telescope is funded by the Ministry of University and Research (MUR),
Italian Space Agency (ASI), and the Autonomous Region of Sardinia
(RAS) and is operated as National Facility by the National Institute
for Astrophysics (INAF). We acknowledge financial support from the
INAF Fundamental Research Funding Call 2023 (PI: Raiteri).
(End) Patricia Vannier [CDS] 05-Sep-2025