J/MNRAS/385/823 UBVRI light curves of OJ 287 (Zheng+, 2008)
Long-term optical spectra variability of BL Lacertae object OJ 287.
Zheng Y.G., Zhang X., Bi X.W., Hao J.M., Zhang H.J.
<Mon. Not. R. Astron. Soc., 385, 823-829 (2008)>
=2008MNRAS.385..823Z 2008MNRAS.385..823Z
ADC_Keywords: BL Lac objects ; Photometry, UBVRI
Keywords: galaxies: active - BL Lacertae objects: general -
BL Lacertae objects: individual: OJ 287 -
galaxies: fundamental parameters
Abstract:
Based on the long-term data in the literature, we present evidence for
long-term optical spectral index variability behaviour for BL Lacertae
object OJ 287. First we find that the optical spectral index
variability period of BL Lacertae object OJ 287 is in agreement with
the optical flux variability period of about 11.96yr. It is
considered that different processes induce optical variability, and
each process should have a definite signature in the spectral index,
thus leading to the periodicity of the spectral index. We also find
that the time lag between the optical spectral index and the optical
flux density is half of the optical flux variability period. This
result tends to support the argument that when the brightness of the
long-term variations increases, the optical spectra become bluer.
These variations can be explained by energy loss of the electrons
during the outburst. We show that the spectral index is different
during the flares compared with outside the flares; between the first
and second flare peaks of the superflares, the spectrum shapes are
different. Disparate processes possibly induce the two peaks of
OJ 287.
Description:
We have compiled all available U-, B-, V-, R- and I-band optical data
on OJ 287 from 1972 to 2006.
Objects:
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RA (2000) DE Designation(s)
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08 54 48.9 +20 06 31 OJ 287 = OHIO J 287
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tables1.dat 71 256 Compiled raw data of OJ 287 (0851+202),
magnitude values
flux.dat 71 21 Compiled raw data of OJ 287 (0851+202),
flux density values
refs.dat 68 28 References
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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)
Byte-by-byte Description of file: tables1.dat
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Bytes Format Units Label Explanations
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1- 7 I7 d JD Julian date
9- 13 F5.2 mag Umag U magnitude
15- 18 F4.2 mag e_Umag ? rms uncertainty on Umag
21- 25 F5.2 mag Bmag B magnitude
27- 30 F4.2 mag e_Bmag ? rms uncertainty on Bmag
33- 37 F5.2 mag Vmag V magnitude
39- 42 F4.2 mag e_Vmag ? rms uncertainty on Vmag
45- 49 F5.2 mag Rmag ? R magnitude
51- 54 F4.2 mag e_Rmag ? rms uncertainty on Rmag
57- 61 F5.2 mag Imag ? I magnitude
63- 66 F4.2 mag e_Imag ? rms uncertainty on Imag
70- 71 I2 --- Ref Reference, in refs.dat file
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Byte-by-byte Description of file: flux.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 I7 d JD Julian date
9- 13 F5.2 mJy UFlux Flux density in U band
15- 18 F4.2 mJy e_UFlux ? rms uncertainty on UFlux
21- 25 F5.2 mJy BFlux Flux density in B band
27- 30 F4.2 mJy e_BFlux ? rms uncertainty on BFlux
33- 37 F5.2 mJy VFlux Flux density in V band
39- 42 F4.2 mJy e_VFlux ? rms uncertainty on VFlux
45- 49 F5.2 mJy RFlux ? Flux density in R band
51- 54 F4.2 mJy e_RFlux ? rms uncertainty on RFlux
57- 61 F5.2 mJy IFlux ? Flux density in I band
63- 66 F4.2 mJy e_IFlux ? rms uncertainty on IFlux
70- 71 I2 --- Ref Reference, in refs.dat file
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Ref Reference number
4- 22 A19 --- BibCode BibCode
24- 42 A19 --- Aut Author's name
49- 68 A20 --- Com Comments
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 13-Apr-2009