Near infrared monitoring of a sample of blazars with the Carlos Sanchez Telescope.

Takalo, L. O.; Kidger, M.; Diego, J. A. de; Sillanpää, A.; Nilsson, K.

doi:10.1086/116219

Cited by 66 publications

(87 citation statements)

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“…However, the P ν of OJ 287 in past polarimetric monitorings in optical bands has not been systematically negative (see e.g. Takalo et al 1992), and, overall, the source exhibited preferentially a WDP behavior opposite to the one observed by us, namely decreasing polarization with increasing wavelength (Takalo 1994). One may argue that, since the accretion disk component is presumably more modestly variable than the beamed non-thermal one, it emerges during phases of quiescent synchrotron emission, so that a negative P ν value may be more often seen during low brightness states of the source, such as the one we have monitored in our campaign.…”

Section: Discussionmentioning

confidence: 99%

“…We selected 11 northern BL Lacs among the brightest and most polarized objects observed by Impey & Tapia (1988) and Takalo et al (1992). During the first night of the run, we performed a brief photopolarimetric "survey" with short integration times on all the sources, to determine which of them were the brightest and most polarized at the epoch of observation, to be intensively monitored in the two following nights: 3C 66A and PKS 0735+178 were chosen.…”

Section: Observationsmentioning

confidence: 99%

“…Also for this BL Lac object, we searched the literature for previous polarimetric data (Brindle et al 1986;Mead et al 1990;Puschell et al 1983;Sitko et al 1985;Smith et al 1987;Takalo 1991;Takalo et al 1992;Valtaoja et al 1991Valtaoja et al , 1993 and reported them in histograms along with our data (Fig. 6) as done in the case of 3C 66A.…”

Section: Pks 0735+178mentioning

confidence: 99%

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Multiband optical polarimetry of BL Lacertae objects with the Nordic Optical Telescope

Tommasi

Palazzi

Pian

et al. 2001

A&A

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Abstract. Optical polarization of seven selected BL Lac objects in UBV RI bands was studied with the Nordic Optical Telescope from December 10-14, 1999. Two of them, 3C 66A and PKS 0735+178, were monitored for 4 nights for a total integration time of 4.75 and 5.5 hours, respectively. Other objects (1 Jy 0138−097, H 0414+009, PKS 0823−223, OJ287 and BL Lac) were observed sparsely during the run. Apart from PKS 0823−223 (more polarized than observed in the past), the sources show levels of flux and polarization consistent with results at previous epochs. 3C 66A and PKS 0735+178 were intensively observed during December 11 and 12 and exhibited variability of polarization, both on internight and intranight time scales. Wavelength dependence of polarization has been investigated, as well as circular polarization. The results are discussed within the standard model for BL Lacs.

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Section: Discussionmentioning

confidence: 99%

Section: Observationsmentioning

confidence: 99%

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Multiband optical polarimetry of BL Lacertae objects with the Nordic Optical Telescope

Tommasi

Palazzi

Pian

et al. 2001

A&A

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“…For those sources in which the spectral dependence of the polarization parameters was studied, P ν < 0, which indicates that the spectral dependence is not due to the host galaxy light dilution (Takalo et al 1992, for example). These observations are part of an effort to continuously monitor AGNs, mainly blazars, at different wavelengths (radio, optical, NIR) and covering several time scales of variability.…”

Section: Final Remarksmentioning

confidence: 99%

Characterization of the optical polarimetric variability in a sample of blazars

et al. 2004

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Abstract. Brightness variations across the entire electromagnetic spectrum, occurring at several time scales, are known properties of blazars. The variability of the continuum emission may be related to the formation and propagation of shock waves in the relativistic jet. In this case we may expect variations also in the degree of polarization and its position angle. In order to effectively constrain such models, we begun in 2003 a program to monitor the optical polarimetry of a sample of blazars, of which we present here the first results.

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“…From this work, and also subsequent reports, we note that there have been very few studies of micro and short-term variability of Mrk 421 in the J band. The notable studies in this respect are those by Takalo et al (1992), Makino et al (1987) and Kidger et al (1999). The study by Takalo et al (1992) gives shortterm variability in 2 nearby slots (JD 2 448 272-2 448 280 and 2 448 324-2 448 335) with durations of 9 days and 12 days respectively.…”

Section: Introductionmentioning

confidence: 99%

Near infrared intraday variability of Mrk 421

Gupta¹,

Banerjee

Ashok

et al. 2004

A&A

103

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Abstract.We report results from our monitoring of the BL Lac object Mrk 421 in the near-IR J band. The observations, aimed at studying the intraday variability (IDV) of the object, were carried out systematically over an extended (and near-continuous) period of eight nights from the 1.2 m Mount Abu Infrared Telescope, India. There are limited studies for Mrk 421 in the J band for such an extended period. The observation epoch for this study (25 February-5 March 2003) was chosen to significantly overlap other concurrent studies of Mrk 421 in the X-ray/γ-ray regions being conducted using the Rossi X-ray timing explorer (RXTE) and the solar tower atmospheric Cherenkov effect experiment (STACEE). Hence these results could be useful for a multi-wavelength analysis of the variability behavior of Mrk 421. We find that Mrk 421 was quite active during the observed period and showed significant IDV and short term variability. A maximum variation of 0.89 mag is seen over the entirety of the observed period. Flaring activity, with typical brightness variations of ∼0.4, are also seen on several occasions. The extent of the variability observed by us is compared with the results of other similar studies of Mrk 421 in the J band.

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Near infrared monitoring of a sample of blazars with the Carlos Sanchez Telescope.

Cited by 66 publications

References 0 publications

Multiband optical polarimetry of BL Lacertae objects with the Nordic Optical Telescope

Multiband optical polarimetry of BL Lacertae objects with the Nordic Optical Telescope

Characterization of the optical polarimetric variability in a sample of blazars

Near infrared intraday variability of Mrk 421

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