J/A+A/610/A74 OJ 287 far-infrared photometry (Kidger+, 2018)
Far-infrared photometry of OJ 287 with the Herschel Space Observatory.
Kidger M., Zola S., Valtonen M., Laehteenmaeki A., Jaervelae E.,
Tornikoski M., Tammi J., Liakos A., Poyner G.
<Astron. Astrophys. 610, A74 (2018)>
=2018A&A...610A..74K 2018A&A...610A..74K (SIMBAD/NED BibCode)
ADC_Keywords: BL Lac objects ; Photometry, UBVRI ; Photometry, infrared ;
Photometry, millimetric/submm
Keywords: galaxies - BL Lacertae objects: individual: OJ 287
Abstract:
The blazar OJ 287 has shown a ≈12 year quasi-periodicity over more
than a century, in addition to the common properties of violent
variability in all frequency ranges. It is the strongest known
candidate to have a binary singularity in its central engine.
We aim to better understand the different emission components by
searching for correlated variability in the flux over four decades of
frequency measurements.
We combined data at frequencies from the millimetric to the visible to
characterise the multifrequency light curve in April and May 2010.
This includes the only photometric observations of OJ 287 made with
the Herschel Space Observatory: five epochs of data obtained over 33
days at 250, 350, and 500um with Herschel-SPIRE.
Although we find that the variability at 37GHz on timescales of a few
weeks correlates with the visible to near-IR spectral energy
distribution (SED), there is a small degree of reddening in the
continuum at lower flux levels that is revealed by the decreasing rate
of decline in the light curve at lower frequencies. However, we see no
clear evidence that a rapid flare detected in the light curve during
our monitoring in the visible to near-IR light curve is seen either in
the Herschel data or at 37GHz, suggesting a low-frequency cut-off in
the spectrum of such flares.
We see only marginal evidence of variability in the observations with
Herschel over a month, although this may be principally due to the
poor sampling. The spectral energy distribution between 37 GHz and the
visible can be characterised by two components of approximately
constant spectral index: a visible to far-IR component of spectral
index α=-0.95, and a far-IR to millimetric spectral index of
α=0.43. There is no evidence of an excess of emission that would
be consistent with the 60um dust bump found in many active galactic
nuclei.
Description:
A search was made using the Herschel Science Archive (HSA) for
calibration observations of OJ 287 made in standard photometric
observing modes. A total of five photometric observations were found,
all taken with the SPIRE photometer (Griffin 2010), each giving
simultaneous photometry at 250, 350, and 500um. The observations
were made on four Operational Days (ODs) between 2010/04/20 and
2010/05/23.
We have three sources of visible monitoring data for this period. Our
first source is the data in R only from the database of long-term
monitoring maintained at the Astronomical Observatory of the
Jagiellonian University (Cracow, Poland). This consists of 27
observations obtained from 19 nights of photometry in R, taken between
April 1 and May 28, 2010.
Additionally, very high-quality data are publicly available from the
SMARTS telescope (Bonning et al. 2012ApJ...756...13B 2012ApJ...756...13B) in B, V, and R.
26 sets of BVR photometry are available between April 1 and May 31,
2010.
The SMARTS monitoring programme also obtains high-quality data in the
J and K bands in the near-infrared. Three nights have visible, but no
infrared photometry, hence J and K data are available on 23 nights in
April and May 2010.
The 37GHz observations were made with the 13.7m diameter
Metsahovi radio telescope, which is a radome-enclosed
paraboloid antenna situated in Finland.
Objects:
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RA (2000) DE Designation(s)
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08 54 48.87 +20 06 30.6 OJ 287 = QSO J0854+2006
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
photom.dat 230 37 Photometry of blazar OJ287
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See also:
J/A+AS/129/569 : BVRI photometry of OJ 287 (Jia Guibin+ 1998)
J/AJ/132/1256 : eim BATC photometry of OJ 287 (Wu+, 2006)
J/MNRAS/385/823 : UBVRI light curves of OJ 287 (Zheng+, 2008)
J/MNRAS/402/2087 : Optical polarization of OJ 287 in 2005-09 (Villforth+, 2010)
J/AJ/141/65 : BATC ceimo light curves of OJ 287 (Dai+, 2011)
J/ApJ/764/5 : BR photometry of 2012 precursor flare in OJ287
(Pihajoki+, 2013)
J/ApJ/835/275 : OJ 287 flux + polarization during 2016 outburst
(Rakshit+, 2017)
J/A+A/597/A80 : GMVA 86GHz images of OJ 287 (Hodgson+, 2017)
Byte-by-byte Description of file: photom.dat
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Bytes Format Units Label Explanations
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1- 9 F9.3 d MJD-37 [55303.2/55356.3]? Observation MJD for 37GHz
11- 14 F4.2 Jy F37GHz ? Metsahovi 37GHz flux
16- 19 F4.2 Jy e_F37GHz ? rms uncertainty on F37GHz
21- 29 A9 --- Obs-37 Observatory from which 37GHz data where
obtained
31- 39 F9.3 d MJD-500 [55307.2/55340.1]? Observation MJD for
500, 350 and 250um
41- 44 F4.2 Jy F500um ? Herschel 500um flux
46- 49 F4.2 Jy e_F500um ? rms uncertainty on F500um
51- 54 F4.2 Jy F350um ? Herschel 350um flux
56- 59 F4.2 Jy e_F350um ? rms uncertainty on F350um
61- 64 F4.2 Jy F250um ? Herschel 250um flux
66- 69 F4.2 Jy e_F250um ? rms uncertainty on F250um
71- 78 A8 --- Obs-500 Observatory from which 250-500um data where
obtained
80- 88 F9.3 d MJD-K [55282.6/55348.5]? Observation MJD for K-band
90- 95 F6.3 mag Kmag ? SMARTS K magnitude
97-101 F5.3 mag e_Kmag ? rms uncertainty on Kmag
103-108 A6 --- Obs-K Observatory from which K-band data where
obtained
110-118 F9.3 d MJD-J [55282.6/55348.5]? Observation MJD for J-band
120-125 F6.3 mag Jmag ? SMARTS J magnitude
127-131 F5.3 mag e_Jmag ? rms uncertainty on Jmag
133-138 A6 --- Obs-J Observatory from which J-band data where
obtained
140-148 F9.3 d MJD-R [55288.2/55349.5] Observation MJD for R-band
150-155 F6.3 mag Rmag [14.014/15.094] R magnitude
157-161 F5.3 mag e_Rmag rms uncertainty on Rmag
163-171 A9 --- Obs-R Observatory from which R-band data where
obtained
173-181 F9.3 --- MJD-V [55282.6/55348.5]? Observation MJD for V-band
183-188 F6.3 mag Vmag ? V magnitude
190-194 F5.3 mag e_Vmag ? rms uncertainty on Vmag
196-201 A6 --- Obs-V Observatory from which V-band data where
obtained
203-211 F9.3 d MJD-B [55282.6/55348.5]? Observation MJD for B-band
212-217 F6.3 mag Bmag ? SMARTS B magnitude
219-223 F5.3 mag e_Bmag ? rms uncertainty on Bmag
225-230 A6 --- Obs-B Observatory from which B-band data where
obtained
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Acknowledgements:
Mark Kidger, mkidger(at)sciops.esa.int
(End) Patricia Vannier [CDS] 18-Dec-2017