Near infrared intraday variability of Mrk 421

Free access article

Issue		A&A Volume 422, Number 2, August I 2004


Page(s)		505 - 508
Section		Extragalactic astronomy
DOI		http://dx.doi.org/10.1051/0004-6361:20040306

A&A 422, 505-508 (2004)
DOI: 10.1051/0004-6361:20040306

Research Note

Near infrared intraday variability of Mrk 421

A. C. Gupta¹, D. P. K. Banerjee², N. M. Ashok² and U. C. Joshi²

¹ Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211 019, India
e-mail: agupta@mri.ernet.in
² Astronomy and Astrophysics Division, Physical Research Laboratory, Navrangpura, Ahmedabad 380 009, India
e-mail: [orion;ashok;joshi]@prl.ernet.in

(Received 20 February 2004 / Accepted 2 April 2004 )

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/ $\gamma$ -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.

Key words: BL Lacertae objects: individual: Mrk 421 -- BL Lacertae objects: general -- infrared: general

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