Рубрика: Новости

Astronomer’s Telegram #6414

V. M. Larionov (Astron. Inst. of St. Petersburg Univ.), G. A. Borman (Crimean Astrophysical Observatory), S. G. Jorstad (Boston Univ. and St. Petersburg Univ.)
on 24 Aug 2014; 09:38 UT

We perform optical photometric and polarimetric monitoring of selected gamma-ray blazars using 0.7-m AZT-8 telescope (Crimean Obs.,, Russia), LX-200 0.4-m telescope (St.Petersburg Univ., Russia) (see) and 1.8-m Perkins telescope (Lowell Obs., AZ, USA) (here), partly in the frames of WEBT/GASP project. Our recent observations of AO 0235+164 showed that this well-known blazar entered a phase of high activity, reaching R=16.6 in the night of 2014 Aug.24 (JD2456893.847), as compared to the quiescence level R~18-19 mag of previous seasons. The degree of polarization varies between 35% and 13% on the nightly scale.

Astronomer’s Telegram #6019

T. S. Konstantinova, A. A. Mokrushina (St. Petesburg Univ., Russia)
on 28 Mar 2014; 13:07 UT

We report on the renewed optical activity of the high-mass X-ray binary system SAX J2103.5+4545. The source was monitored with the 0.4-m LX-200 (St.Petersburg, Russia) telescope. In the night of 2014-03-27 the brightness of the optical counterpart reached R= 13.20+/-0.02, as compared to R= 13.60+/-0.02 in the night 2014-01-29. Last fourteen months, since December 2012, the system was in optical quiescent state. The previous optical activity observed from March 2013 (see ATel#4068) was followed by onset of X-ray activity of the source (ATel#4168) and also the IR brightening of the system and H-alpha line emission (ATel#4187). New spectral observations of the system are desirable for monitoring a recent disc formation around the Be star.

Astronomer’s Telegram #5921

V. M. Larionov, D. A. Morozova, E. N. Kopatskaya, D. A.Blinov (St. Petersburg University, Russia)
on 26 Feb 2014; 09:52 UT

We perform optical photometric and polarimetric monitoring of flat spectrum radio quasar (FSRQ) PKS 1222+21 (4C 21.35, z=0.432) using 16″ LX-200 telescope (St.Petersburg, Russia) and 70-cm AZT-8 (Crimea, Ukraine). During last month this quasar displays prominent activity. In the nights of 2014 February 24 and 25 it reached a level of R=13.86 and 13.80, correspondingly. These values can be compared to the quiescence level of R~15.7 recorded in 2012-2013. Our preliminary optical light curve is given here. Optical fractional polarization during the outburst is rather modest, on the level 2-5%. We notice that our analysis of the publicly available Fermi LAT data also shows enhanced activity in gamma-rays, see. Our observations are made in the frames of GASP-WEBT collaboration.

Astronomer’s Telegram #5597 V. M. Larionov and T. S. Konstantinova (Astron. Inst., St.-Petersburg State Univ., Russia), C. M. Raiteri and M. Villata (INAF, Osservatorio Astrofisico di Torino, Italy)

on 25 Nov 2013; 08:55 UT

We report on optical observations of BL Lacertae carried out at the Crimean and St.-Petersburg observatories in the framework of the GASP-WEBT collaboration.

Starting from early 2013, when the source was observed at its historical minimum levels (R about 15.2), BL Lacertae has shown an almost continuous brightening until November 23.9, when it reached R = 12.34. This is the maximum optical brightness level ever detected, a bit higher than that observed during the 1997 outburst (see e.g. Villata et al. 2004, A&A, 421, 103).

Astronomer’s Telegram #5423 V. M. Larionov, D. A. Morozova, N. V. Efimova (St. Petersburg Univ. and Pulkovo Observatory, Russia), D. A. Blinov (Univ. of Crete, Greece; St. Petersburg Univ., Russia), A. Di Paola (INAF — Osservatorio Astronomico di Roma, Monte Porzio, Italy)

on 26 Sep 2013; 18:53 UT

In addition to ATel#5411 and in reference to ATel#5412 and ATel#5418 we report that recently announced flare of the blazar 3C 454.3 seems to have culminated at 2013 September 25. Our optical (AZT-8, Crimea) and NIR (AZT-24, Campo Imperatore, Italy) photometric measurements taken this night yield, correspondingly, R=13.427 at JD2456561.336 and J=11.67 at JD2456561.259. Afterwards we see a clear decline (0.1 mag) in all bands. This outburst is accompanied by very high level of optical polarization: 33% during the nights of September 24 and 25. We notice that the positional angle of polarization is approximately perpendicular to the direction of the VLBA jet. The maximum level of Fermi gamma-ray flux is rather modest, 5.0E-6 ph cm^-2 s^-1. Figure shows the evolution of optical flux and polarization parameters, and also gamma-ray behaviour, during last month. It may be noted that previous outbursts of this blazar had multiple structure (Jorstad et al, 2013, ApJ, 773, 147), and a renewed activity may be expected within 2-3 weeks . We got also NIR spectrum of 3C454.3 during the night of September 25 and found that the flux in H_alpha is now (2.8+/-03)E-16 W m-2, that is markedly more than during moderately faint state of 2007, when it was in the range of [2.0-2.5] E-16 W m-2 (Raiteri et al, 2008, A&A, 491, 755) It may reflect a higher level of current BLR activity than that seen in 2007.