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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 (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) 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: ----------------------------------------------------- RA (2000) DE Designation(s) ----------------------------------------------------- 08 54 48.87 +20 06 30.6 OJ 287 = QSO J0854+2006 ----------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file photom.dat 230 37 Photometry of blazar OJ287
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
Bytes Format Units Label Explanations
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
Acknowledgements: Mark Kidger, mkidger(at)
(End) Patricia Vannier [CDS] 18-Dec-2017
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