J/A+A/423/935 BVRI photometry of OQ 530 (Massaro+, 2004)
VLBI imaging and optical variability of the BL Lac object OQ 530 (B1418+546).
Massaro E., Mantovani F., Fanti R., Maesano M., Montagni F., Nesci R.
Sclavi S., Tosti G., Venturi T.
<Astron. Astrophys. 423, 935 (2004)>
=2004A&A...423..935M 2004A&A...423..935M
ADC_Keywords: BL Lac objects ; Photometry, CCD ; Photometry, UBVRI ; VLBI
Keywords: galaxies: active - galaxies: BL Lacertae objects: individual: OQ 530 -
galaxies: jets
Abstract:
Results of VLBI and optical observations are presented for the BL Lac
object OQ 530 (B1418+546), whose long-term optical variability is
characterised by a decreasing mean luminosity trend. EVN images at
1.6GHz and 5GHz of OQ 530 show a very bright core with a much weaker
jet extending to about 35-40mas. The radio flux density from the core
in June 2001 was much higher than that measured in February 1999. A
similar increase was also found from nearly simultaneous optical
photometry, while the total flux density of the jet remained
unchanged. The structure of the jet shows several knots which move
outward with an apparent superluminal motion with a
betaapp≥3.5h-1.
The region within about 3mas from the core contains a component not
well resolved in our images and emerging from it in the jet direction.
That component was also detected in images taken from 1990 to 1997 and
it seems to be a rather stable structural feature.
Using nearly simultaneous optical and radio data, we can describe the
SED of the synchrotron peak with a simple formula, approximating a
power law at low frequencies and a log-parabola at the high ones,
whose maximum lies in the range 3.5-5x1013Hz, and the extrapolation
in the X-ray range give a flux comparable to that observed with
BeppoSAX.
Description:
Table A1 contains all the data of our photometric monitoring OQ 530 in
the four bands B, V (Johnson) and R, I (Cousins) from 1994 to 2001.
Objects:
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RA (2000) DE Designation(s)
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14 19 46.6 +54 23 15 OQ 530 = QSO B1418+546
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 66 840 B,V,R,I photometric data of OQ 530
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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- 10 A10 "DD-MM-YYYY" Obs.date Observation date
12- 13 I2 h Obs.h Hour of observation (UT)
15- 16 I2 min Obs.m Minute of observation (UT)
18- 29 F12.4 d JD Observation time in Julian days
31- 35 F5.2 mag mag measured magnitude of OQ 530
37- 40 F4.2 mag e_mag Error (1 standard deviation) of magnitude
42 A1 --- Band [BVRI] photometric band
44- 45 A2 --- Tel telescope used for the measurement (1)
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Note (1): Telescope used for the measurement:
VA: Vallinfreda
GR: Greve
MP: TRC70 Monte Porzio
PG: AIT Perugia
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Acknowledgements: Enrico Massaro
History:
* 01-Jun-2004: recevied from the author
* 17-Oct-2004: JD indicated as > 2499000 in a few 1995 measurements
have been corrected to 2449000.
(End) Patricia Vannier [CDS] 01-Jun-2004