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J/A+A/601/A12       S5 0716+714 VLBI K- and Q-band variability      (Lee+, 2017)

Simultaneous dual-frequency radio observations of S5∼0716+714: A search for intraday variability with the Korean VLBI Network. Lee J.W., Sohn B.W., Byun D.-Y., Lee J.A., Kim S.S. <Astron. Astrophys. 601, A12 (2017)> =2017A&A...601A..12L (SIMBAD/NED BibCode)
ADC_Keywords: BL Lac objects ; Radio sources ; VLBI Keywords: galaxies: active - galaxies: BL Lacertae objects: individual: S5 0716+714 - galaxies: jets - radio continuum: galaxies Abstract: This study aims to search for the existence of intraday variability (IDV) of BL Lac object S5 0716+714 at high radio frequencies for which the interstellar scintillation effect is not significant. Using the 21-m radio telescope of the Korean VLBI Network (KVN), we present results of multi-epoch simultaneous dual-frequency radio observations. Single-dish observations of S5 0716+714 were simultaneously conducted at 21.7GHz (K-band) and 42.4GHz (Q-band), with a high cadence of 30-60min intervals. We observed four epochs between December 2009 and June 2010. Over the whole set of observation epochs, S5 0716+714 showed significant inter-month variations in flux density at both the K- and Q-bands, with modulation indices of approximately 19% for the K-band and approximately 36% for the Q-band. In all epochs, no clear intraday variability was detected at either frequency. The source shows monotonic flux density increase in epochs 1 and 3 and monotonic flux density decrease in epochs 2 and 4. In the flux density increasing phases, the flux densities at the Q-band increase more rapidly. In the decreasing phase, no significant flux density difference is seen at the two frequencies. The situation could be different close to flux density peaks that we did not witness in our observations. We find an inverted spectrum with mean spectral indices, {bar}α(Sν∝ν), of -0.57±0.13 in epoch 1 and -0.15±0.11 in epoch 3. On the other hand, we find relatively steep indices of +0.24±0.14 and +0.17±0.18 in epochs 2 and 4, respectively. We conclude that the frequency dependence of the variability and the change of the spectral index are caused by source-intrinsic effects rather than by any extrinsic scintillation effect. Description: File table1.dat contains the flux density and measurement errors of S5 0716+714 at the K-band and the Q-band over 4 epochs. Objects: --------------------------------------------------------------- RA (2000) DE Designation(s) --------------------------------------------------------------- 07 21 53.45 +71 20 36.4 S5 0716+714 = JVAS J0721+713 --------------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 29 603 Flux density and error of S5 0716+714
See also: J/A+A/327/61 : BV(RI)c photometry of S5 0716+714 (Ghisellini+ 1997) J/A+A/402/151 : S5 0716+714 UBVRI photometry (Raiteri+, 2003) J/AJ/129/1818 : Photometry of S5 0716+714 (Wu+, 2005) J/A+A/451/435 : BV(RI)c photometry of S5 0716+714 (Montagni+, 2006) J/AJ/133/1599 : B'V'R' photometry of S5 0716+714 (Wu+, 2007) J/AJ/136/1846 : BVRI light curves of S5 0716+714 (Zhang+, 2008) J/ApJS/185/511 : Optical microvariability of S5 0716+714 (Poon+, 2009) J/AZh/83/310 : BV(RI)c photometry of S5 0716+714 (Amirkhanyan+, 2006) J/AJ/143/108 : B'V'R' photometry of the BL Lac object S5 0716+714 (Wu+, 2012) J/A+A/558/A92 : S5 0716+714 microvariability observation (Bhatta+, 2013) J/ApJ/783/83 : BVRI photometry of S5 0716+714 (Liao+, 2014) J/ApJS/218/18 : 2004-2012 BVRI observations of blazar S5 0716+714 (Dai+, 2015) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 9 F9.3 d MJD Modified Julian Date 11- 14 F4.2 Jy SK Flux density at K-band (22GHz) 16- 19 F4.2 Jy e_SK Measurement flux density error at K-band 21- 24 F4.2 Jy SQ Flux density at Q-band (43GHz) 26- 29 F4.2 Jy e_SQ Measurement flux density error at Q-band
Acknowledgements: Jee Won Lee, jeewon78(at) KASI/Kyung Hee University, Republic of Korea
(End) J.W. Lee [KASI/Kyung Hee Univ., Korea], P. Vannier [CDS] 04-Mar-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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