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J/A+A/469/503 VRIJHK observations of PKS 2155-304 (Dolcini+, 2007)
The following files can be converted to FITS (extension .fit .fgz or .fiZ)
tablea1.dat
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Query from: http://vizier.cds.unistra.fr/viz-bin/VizieR?-source=J/A+A/469/503
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Beginning of ReadMe :J/A+A/469/503 VRIJHK observations of PKS 2155-304 (Dolcini+, 2007)
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REM near-IR and optical multiband observations of PKS 2155-304 in 2005.
Dolcini A., Farfanelli F., Ciprini S., Treves A., Covino S., Tosti G.,
Pian E., Sbarufatti B., Molinari E., Chincarini G., Zerbi F.M., Conconi P.,
Nicastro L., Palazzi E., Testa V., Vitali F., Antonelli L.A., Danziger J.,
Tagliaferri G., Meurs E., Vergani S., Fernandez-Soto A., Distefano E.,
Cutispoto G., D'Alessio F.
<Astron. Astrophys. 469, 503 (2007)>
=2007A&A...469..503D
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ADC_Keywords: BL Lac objects ; Photometry, UBVRI ; Photometry, infrared
Keywords: galaxies: active - galaxies: BL Lacertae objects: PKS 2155-304
Abstract:
Spectral variability is the main tool for constraining emission models
of BL Lac objects. By means of systematic observations of the BL Lac
prototype PKS 2155-304 in the infrared-optical band, we explore
variability on the scales of months, days and hours. We made our
observations with the robotic 60cm telescope REM located at La Silla,
Chile. VRIJHK filters were used. PKS 2155-304 was observed from May
to December 2005. The wavelength interval explored, the total number
of photometric points and the short integration time render our
photometry substantially superior to previous ones for this source.
On the basis of the intensity and colour we distinguish three
different states of the source, each of duration of months, which
include all those described in the literature. In particular, we
report the highest state ever detected in the H band. The source
varied by a factor of 4 in this band, much more than in the V band
(a factor of about 2). The source softened with increasing intensity,
contrary to the general pattern observed in the UV-X-ray bands. On
five nights of November we had nearly continuous monitoring for 2-3
hours. A variability episode with a time scale of tau approx 24h is
well documented, a much more rapid flare with tau=1-2h, is also
apparent, but is supported by relatively few points. The overall
spectral energy distribution of PKS 2155-304 is commonly described
by a synchrotron-self-Compton model. The optical infrared emission is
however in excess of the expectation of the model, in its original
formulation. This can be explained by a variation of the frequency of
the synchrotron peak, which is not unprecedented in BL Lacs.
Description:
The table reported is the complete log of observations of the campaign
made with the REM telescope during 2005. For each photometric point we
report the filter (column 1), the Modified Julian Date (MJD, column
2), the integration time in seconds (column 3), the flux density in
mJy (column 4) and the correspondent standard deviation (column 5).
Objects:
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RA (2000) DE Designation(s)
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21 58 52.1 -30 13 32 PKS 2155-304 = QSO B2155-3027
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