Blazar Times - No. 56 - August 2003
The Blazar Times
A Research Newsletter Dedicated to the BL Lac and Blazar Phenomena
No. 56 - August 2003 Editor: Travis A. Rector (


Campaign Announcement 1

Journal Abstracts 1

Abstract Guidelines 3

Campaign Announcement

Multiwavelength campaigns on AO 0235+16 and 3C 66A

The Whole Earth Blazar Telescope (WEBT, collaboration announces the forthcoming two multiwavelength observing campaigns on AO 0235+16 and 3C 66A.

The first campaign, on AO 0235+16, aims at the study of the long-term variability of the source in the radio and optical bands, and also at higher energies (an XMM proposal has just been approved). In particular, the continuous monitoring will allow to check the predicted periodicity of the main radio (and optical) outbursts. The campaign will last from July 2003 to April 2004; the Campaign Manager is Claudia M. Raiteri.

Details about the campaign can be found at

The second campaign, on 3C 66A, will last from September to December 2003 and will be coordinated by Markus Böttcher. The accent here is more on intensive radio/optical monitoring to be put in correlation with high-energy observations by RXTE and by TeV detectors.

Details about the campaign can be found at

Astronomers who are willing to contribute to these campaigns with observations at any wavelength are kindly invited to contact the Campaign Managers and the WEBT President (,,

Journal Abstracts

Coordinated Multiwavelength Observations of BL Lacertae in 2000

M. Böttcher1, A. P. Marscher2, M. Ravasio3, M. Villata4, C. M. Raiteri4, H. D. Aller5, M. F. Aller5, H. Teräsranta6, O. Mang7, G. Tagliaferri3, F. Aharonian8, H. Krawczynski9, O. M. Kurtanidze10,11,12, M. G. Nikolashvili10, M. A. Ibrahimov13,14, I. E. Papadakis15,16, K. Tsinganos15, K. Sadakane17, N. Okada17, L. O. Takalo18, A. Sillanpää18, G. Tosti19, S. Ciprini19, A. Frasca20, E. Marilli20, R. Robb21, J. C. Noble22, S. G. Jorstad22, V. A. Hagen-Thorn35, V. M. Larionov23, R. Nesci24, M. Maesano24, R. D. Schwartz25, J. Basler25, P. W. Gorham26, H. Iwamatsu27, T. Kato27, C. Pullen28, E. Benítez29, J. A. de Diego29, M. Moilanen30, A. Oksanen30, D. Rodriguez31, A. C. Sadun32, M. Kelly32, M. T. Carini33, H. R. Miller34, S. Catalano20, D. Dultzin-Hacyan29, J. H. Fan35, G. Ghisellini3, R. Ishioka27, H. Karttunen18, P. Keinänen18, N. A. Kudryavtseva23, M. Lainela18, L. Lanteri4, E. G. Larionova23, K. Matsumoto27, J. R. Mattox36, I. McHardy38, F. Montagni24, G. Nucciarelli19, L. Ostorero37, J. Papamastorakis15,16, M. Pasanen18, G. Sobrito4, and M. Uemura27

1 Department of Physics and Astronomy, Clippinger 339, Ohio University, Athens, OH 45701, USA
2 Department of Astronomy, Boston University, 725 Commonwealth Ave., Boston, MA 02215, USA
3 Osservatorio Astronomico di Brera, Via Bianchi 46, I-23807 Merate, Italy
4 Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy
5 Department of Astronomy, University of Michigan, 810 Dennison Building, Ann Arbor, MI 48109-1090, USA
6 Metsähovi Radio Observatory, Helsinki University of Technology, Metsähovintie 114, 02540 Kylmälä, Finland
7 Institut für Experimentelle und Angewandte Physik, Universität Kiel, Leibnitzstraß e 15 - 19, D-24118 Kiel, Germany
8 Max-Planck-Institut für Kernphysik, Postfach 10 39 80, D-69029 Heidelberg, Germany
9 Physics Department, Washington University, 1 Brookings Drive CB 1105, St. Louis, MO 63130, USA
10 Abastumani Observatory, 383762 Abastumani, Georgia
11 Astrophysikalisches Institute Potsdam, An der Sternwarte 16, D- 14482 Potsdam, Germany
12 Landessternwarte Heidelberg-Königstuhl, Königstuhl 12, D-69117 Heidelberg, Germany
13 Ulugh Beg Astronomical Institute, Academy of Sciences of Uzbekistan, 33 Astronomical Str., Tashkent 700052, Uzbekistan
14 Isaac Newton Institute of Chile, Uzbekistan Branch
15 Physics Department, University of Crete, 710 03 Heraklion, Crete, Greece
16 IESL, Foundation for Research and Technology-Hellas, 711 10 Heraklion, Crete, Greece
17 Astronomical Institute, Osaka Kyoiku University, Kashiwara-shi, Osaka, 582-8582 Japan
18 Tuorla Observatory, 21500 Piikkiö, Finland
19 Osservatorio Astronomico, Università di Perugia, Via B.\ Bonfigli, I-06126 Perugia, Italy
20 Osservatorio Astrofisico di Catania, Viale A. Doria 6, I-95125 Catania, Italy
21 Department of Physics and Astronomy, University of Victoria, British Columbia, Canada
22 Institute for Astrophysical Research, Boston University, 725 Commonwealth Ave., Boston, MA 02215, USA
23 Astronomical Institute, St.-Petersburg State University, Bibliotechnaya Pl. 2, Petrodvoretz, 198504 St.-Petersburg, Russia
24 Dipartimento di Fisica, Università La Sapienza, Piazzale A.\ Moro 2, I-00185 Roma, Italy
25 Department of Physics and Astronomy, University of Missouri-St. Louis, 8001 Natural Bridge Road, St. Louis, MO 63121, USA
26 Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
27 Department of Astronomy, Faculty of Science, Kyoto University, Kyoto, Japan
28 Clarke and Coyote Astrophysical Observatory, PO Box 930, Wilton, CA 95693, USA
29 Instituto de Astronomía, UNAM, Apdo. Postal 70-264, 04510 México DF, Mexico
30 Nyrölä Observatory, Jyväskylän Sirius ry, Kyllikinkatu 1, 40950 Jyväskylä, Finland
31 Guadarrama Observatory, C/ San Pablo 5, Villalba 28409, Madrid, Spain
32 Department of Physics, University of Colorado at Denver, PO Box 173364, Denver, CO 80217-3364, USA
33 Department of Physics and Astronomy, Western Kentucky University, 1 Big Red Way, Bowling Green, KY 42104, USA
34 Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, USA
35 Center for Astrophysics, Guangzhou University, Guangzhou 510400, China
36 Department of Chemistry, Physics, & Astronomy, Francis Marion University, PO Box 100547, Florence, SC 29501-0547, USA
37 Dipartimento di Fisica Generale, Università di Torino, Via P. Giuria 1, I-10125 Torino, Italy
38 Department of Physics and Astronomy, University of Southampton, Highfield, Southampton, SO17 1BJ, Great Britain

BL Lacertae was the target of an extensive multiwavelength monitoring campaign in the second half of 2000. Simultaneous or quasi-simultaneous observations were taken at radio (UMRAO and Metsähovi) and optical (WEBT collaboration) frequencies, in X-rays (BeppoSAX and RXTE), and at VHE gamma-rays (HEGRA). The WEBT optical campaign achieved an unprecedented time coverage, virtually continuous over several 10 - 20 hour segments. It revealed intraday variability on time scales of ~ 1.5 hours and evidence for spectral hardening associated with increasing optical flux. During the campaign, BL Lacertae underwent a major transition from a rather quiescent state prior to September 2000, to a flaring state for the rest of the year. This was also evident in the X-ray activity of the source. BeppoSAX observations on July 26/27 revealed a rather low X-ray flux and a hard spectrum, while a BeppoSAX pointing on Oct. 31 - Nov. 2, 2000, indicated significant variability on time scales of ~  a few hours, and provided evidence for the synchrotron spectrum extending out to ~ 10 keV during that time. During the July 26/27 observation, there is a tantalizing, though not statistically significant, indication of a time delay of ~ 4 - 5 hr between the BeppoSAX and the R-band light curve. Also, a low-significance detection of a time delay of 15 d between the 14.5 GHz and the 22 GHz radio light curves is reported. Several independent methods to estimate the co-moving magnetic field in the source are presented, suggesting a value of ~ 2  eB2/7 G, where eB is the magnetic-field equipartition factor w.r.t. the electron energy density in the jet.

Accepted for publication in ApJ

For preprints contact:

For preprints via WWW: ~ mboett/mw_bllac2000.html

High Energy g-rays From FR I Jets

. Stawarz1, M. Sikora2  and M. Ostrowski3

1 Obserwatorium Astronomiczne, Uniwersytet Jagiello\'nski, ul. Orla 171, 30-244 Kraków, Poland
2 Centrum Astronomiczne im. M. Kopernika, ul. Bartycka 18, 00-716 Warszawa, Poland; also at Stanford Linear Accelerator Center, Stanford, CA 94309-4349 USA
3 Obserwatorium Astronomiczne, Uniwersytet Jagiello\'nski, ul. Orla 171, 30-244 Kraków, Poland; also at Stanford Linear Accelerator Center, Stanford, CA 94309-4349 USA

Thanks to Hubble and Chandra telescopes, some of the large scale jets in extragalactic radio sources are now being observed at optical and X-ray frequencies. For the FR I objects the synchrotron nature of this emission is surely established, although a lot of uncertainties - connected for example with the particle acceleration processes involved - remain. In this paper we study production of high energy g-rays in FR I kiloparsec-scale jets by inverse-Compton emission of the synchrotron-emitting electrons. We consider different origin of seed photons contributing to the inverse-Compton scattering, including nuclear jet radiation as well as ambient, stellar and circumstellar emission of the host galaxies. We discuss how future detections or non-detections of the evaluated g-ray fluxes can provide constraints on the unknown large scale jet parameters, i.e. the magnetic field intensity and the jet Doppler factor. For the nearby sources Centaurus A and M 87, we find measurable fluxes of TeV photons resulting from synchrotron self-Compton process and from comptonisation of the galactic photon fields, respectively. In the case of Centaurus A, we also find a relatively strong emission component due to comptonisation of the nuclear blazar photons, which could be easily observed by GLAST at energy ~ 10 GeV, providing important test for the unification of FR I sources with BL Lac objects.

Accepted by ApJ, 597 (2003); astro-ph/0306251

For preprints contact:

Abstract Guidelines

Abstracts for ``The Blazar Times" are solicited for papers that have been recently accepted for publication by a refereed journal, and for recent Ph.D. theses. Please do not submit an abstract before it has been accepted, nor after it is published. Abstracts from papers which are not refereed (e.g., conference proceedings) are not accepted.

The subject matter should pertain directly to the BL Lac and/or blazar phenomenon in general. Both observational and theoretical abstracts are appropriate. Abstracts from papers dealing with other classes of AGN will generally not be included unless they explicitly discuss their relevance to the blazar phenomenon; however exceptions to this rule will be considered.

A monthly call for abstracts will be issued and abstracts received by the last day of the month will usually appear in the following month's newsletter. Announcements of general interest to the BL Lac and blazar communities may also be submitted for posting in the newsletter. These might include (but are not restricted to) the following: (i) Job Openings directed toward blazar researchers, (ii) announcements of Upcoming Meetings, (iii) announcements of Upcoming Observing Campaigns for which participation is solicited from the community at large, (iv) reviews of New Books, and (v) General Announcements that provide or request research-related information.

To subscribe, please send your name and email address to:

Contributions and all other correspondence relevant to the newsletter should also be sent to the above address. Please note that I respect the privacy of subscribers; therefore I will not distribute under any circumstance the subscriber email list.

To contribute, please use the appropriate LaTeX abstract and thesis templates, which can be obtained from ``The Blazar Times" web page at: 

Abstracts which are not in this template format cannot be accepted. Both templates are stand-alone LaTeX documents; and I ask that you compile them with LaTeX to check for any errors before submitting. This will save me tremendous efforts in solving any problems; and will assure that your abstract will appear in the newsletter as you had intended. Important: If you use any specially defined characters be sure to include their definitions as well.

File translated from TEX by TTH, version 2.25.
On 29 Jul 2003, 15:55.