Issue |
Astron. Astrophys. Suppl. Ser.
Volume 130, Number 1, May II 1998
|
|
---|---|---|
Page(s) | 109 - 115 | |
DOI | https://doi.org/10.1051/aas:1998215 | |
Published online | 15 May 1998 |
monitoring of ON 231 during the great outburst in 1994-1997*
1
Cattedra di Astrofisica, Università di Perugia, Via A. Pascoli, I-06100 Perugia, Italy
2
Osservatorio Astronomico di Torino, Strada Osservatorio 20, I-10025 Pino Torinese, Italy
3
Istituto Astronomico, Università di Roma "La Sapienza", via G.M. Lancisi 29, I-00161 Roma, Italy
4
Osservatorio Astronomico di Brera, via Bianchi, 46, I-22055 Merate, Italy
5
Tuorla Observatory, Tuorla, FIN-21500 Piikkiö, Finland
Send offprint request to: emailtosti@pg.infn.it
Received:
5
August
1997
Accepted:
27
October
1997
We present the most continuous data base of optical multiband data ever
published on the BL Lacertae object ON 231 (W Com). The data have been
collected during an intensive and coordinated monitoring
campaign carried out in the period from March 1994 to March 1997.
During our campaign, the source brightness was at the highest level ever
observed.
The light curve shows a complex structure, characterized by the
presence of three major outbursts having the observed
maxima in March 1995, February 1996, and January 1997, when ON 231 reached its
historical maximum (
).
Variability on time scales from a few hours up to a month have frequently
been observed and the light curve seems to be
the superposition of many flares with different amplitudes and time scales.
The broad-band optical spectral energy distribution is characterized by a
spectral slope which correlates with the flux level. In
particular, the higher is the flux the flatter is the spectrum.
Key words: BL Lacertae objects: general; individual / ON231
© European Southern Observatory (ESO), 1998