Bibcode
Kidger, Mark; de Diego, Jose A.; Takalo, Leo; Nilsson, Kari; Tornikoski, Merja; Sillanpaa, Aimo; Zerbi, Filippo
Bibliographical reference
American Astronomical Society, 181st AAS Meeting, #11.02; Bulletin of the American Astronomical Society, Vol. 24, p.1134
Advertised on:
12
1992
Citations
1
Refereed citations
1
Description
We report the results of a multisite observing campaign of observations
of OJ287 in the visible, near infrared and submillimetric in Winter
1989-90. Simultaneous UBVRIK and white light data were obtained with
three telescopes in Tenerife and La Palma on three nights in
December-January, supported by follow-up observations in January and
March 1990. Each telescope used a different instrument and observing
method to take photometry with a resolution from one to a few minutes.
The results show widely differing behavior at different frequencies and
on different nights, in particular, a number of high amplitude
sinusoidal oscillations were seen on December 31 in K and in V, R &
I, but were not seen in simultaneous U and B observations. Similar
oscillations were also seen in K in mid-January. Periodicity searches of
the data show that two characteristic periods are repeated in different
data sets, with different instruments, at different frequencies and at
different epochs, these being of approximately 23 and 44 minutes period
respectively. Confirmatory submillimetric observations at 90GHz carried
out in March 1990 also show both of these periods. However, these
variations do not show the standard characteristics of a periodicity
(e.g.: constant period and amplitude) and are not even always present in
the light curve, even in our data. We suggest that talk of "periodic"
behavior in this object is specious, at best there may be
pseudo-periodicity similar to some classes of semi-regular variable
stars. The fact that the light curves in different colors, even of
similar wavelength such as B and V show considerable differences,
indicates that at least a two-component model and probably one with
three or more components is required. The variations show significant
time delays of around one third of a period even between V and R.