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J/MNRAS/449/2750  V and R lightcurves of BL Lac object PKS 0537-441  (Li+, 2015)

Colour variation of the BL Lacertae object PKS 0537-441. Li X., Zhang L., Luo Y., Wang L., Zhou L. <Mon. Not. R. Astron. Soc., 449, 2750-2758 (2015)> =2015MNRAS.449.2750L (SIMBAD/NED BibCode)
ADC_Keywords: BL Lac objects ; Photometry, VRI ; Colors ; QSOs Keywords: galaxies: active - BL Lacertae objects: general - BL Lacertae objects: individual: PKS 0537-441 - galaxies: fundamental parameters Abstract: We present the colour indices V-R of BL Lacertae object PKS 0537-441 on the basis of the photometric data monitored by the Rapid Eye Mounting (REM) telescope located at the ESO Cerro La Silla observatory (Chile). Nearly 700 quasi-simultaneous data groups were collected during the period from 2004 to 2010. Our colour analysis shows the existence of at least two variability mechanisms: one is the long-term chromatic mechanism in which the variation traces a 0.04±0.01 slope in the V-R versus V plot, the other is the chromatic mechanism implying the spectral changes during the flares and on intraday time-scales. A general bluer-when-brighter trend is confirmed in both ascent and descent states during the flares and in the 2010 February flare interval, while a much stronger bluer-when-brighter chromatism is observed in both faint and bright states on intraday time-scales. The discrete correlation function analysis reveals the existence of a time-lag of 13+5.8-1.2 d between colour indices and magnitudes during the period MJD 54404-54453, whereas no measurable time-lag during other periods is found. Our results suggest that geometric effects may be responsible for the long-term achromatic mechanism, while the intrinsic shock-in-jet mechanism may produce the chromatic variability during the flares and on intraday time-scales. Description: We have collected the long-term optical photometric data of PKS 0537-441 during the period 2004-2010 from the NIR/optical photometric data collection presented by Impiombato et al. (2011, J/ApJS/192/12). These data were obtained from the REM telescope located at the ESO Cerro La Silla observatory (Chile). The telescope has a Ritchey-Chretien configuration with a 60 cm f/2.2 primary and two stable Nasmyth f/8 focal stations. By means of a dichroic placed before telescope focal plane, the telescope simultaneously feeds two instruments: an NIR camera (REMIR; see Tosti et al. 2004SPIE.5492..689T) and an optical imaging camera (ROSS; see Conconi et al. 2004SPIE.5492.1602C). The REMIR camera works with a NIR(z', J, H and K) filter set and a Rockwell Hawaii I 512x512 CCD, while the ROSS camera is equipped with a Johnson-Cousins VRI filters and hosts a back-illuminated 1024x1024 Marconi 47-10 CCD. Objects: ---------------------------------------------------------- RA (ICRS) DE Designation(s) ---------------------------------------------------------- 05 38 50.36 -44 05 08.9 PKS 0537-441 = QSO B0537-441 ---------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 62 683 The quasi-simultaneous magnitudes and the corresponding colour index
See also: J/MNRAS/277/1477 : A catalogue of BL Lacertae objects (Padovani+ 1995) J/ApJS/192/12 : Photometry of the blazar PKS 0537-441 (Impiombato+, 2011) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 11 F11.5 d MJD-V Modified Julian Date of the observation in the V-band 13- 18 F6.3 mag Vmag Observed magnitude in the Johnson V-band 20- 24 F5.3 mag e_Vmag Uncertainty in Vmag 26- 36 F11.5 d MJD-R Modified Julian Date of the observation in the R-band 38- 43 F6.3 mag Rmag Observed magnitude in the Cousins R-band 45- 49 F5.3 mag e_Rmag Uncertainty in Rmag 51- 56 F6.3 mag V-R Corresponding colour index V-R 58- 62 F5.3 mag e_V-R Uncertainty in V-R
History: From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 11-Dec-2017
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