J. Ticha

Peculiar Pair of Distant Periodic Comets C/2002 A1 and C/2002 A2 (LINEAR)

Distant comets C/2002 A1 and C/2002 A2 make up a peculiar pair that moves about the Sun in virtually identical, somewhat unstable orbits, extending currently between about 4.7 and 29 AU from the Sun. The two objects, observed since late 2001, are unquestionably of common origin. Analysis of their relative motion indicates that their parent body split nontidally most probably between mid-1977 and early 1979 at a heliocentric distance of 22.5 ± 0.1 AU and about 2.5 AU below the ecliptic, with a separation velocity of 2.7 ± 0.2 m s-1. The motion of C/2002 A2, the secondary component that trails behind the primary, is found to be affected by a nongravitational deceleration of (13.4 ± 1.5) × 10-5 units of solar gravitational acceleration relative to C/2002 A1, which is in a range of decelerations that companions of split comets are usually subjected to. C/2002 A2 was somewhat less condensed and, interestingly, brighter than C/2002 A1.

European Observation Network: first experience with BACODINE triggers

We present preliminary results obtained with the European Observation Network. This network consists of 9 observatories in the Czech Republic, Germany and Bulgaria and has been involved in the BACODINE activities since April 1, 1994. We also discuss related problems such as the background of unknown variable stars and suggest a strategy for work in this area.

Searches for optical counterparts to GRBs: EON and AIO

The recent results of the searches for optical counterparts provided by the programs operated by the Astronomical Institute Ondřejov (AIO) and under collaboration of several European observatories (European Observation Network, EON) are outlined and discussed, as well as new projects and approaches in development and/or in preparation. Most of the results have been obtained within the framework of the GRO/BATSE/BACODINE programs. We also briefly mention and discuss new results obtained in archival searches for optical activity inside the error boxes of precisely positioned GRBs.

CONFIRMATION OF COMETARY FEATURES OF NEWLY DISCOVERED BODIES

The majority of new ground-based discoveries of comets comes from large surveys devoted, predominantly, to Near Earth Asteroids. The first step in distinguishing these newly discovered members of the population of cometary bodies consists in confirmatory astrometric observations along with detection of their cometary features. Although both amateur and professional stations take part in such confirmatory observations, only some of them do a preliminary analysis of the cometary activity of a particular newly discovered body. A timely recognition of cometary features of a particular body having an unusual orbit can help in planning further observing campaigns. A main goals of the Kleť Observatory NEO astrometric follow-up programme consists of an analysis of possible cometary activity of newly discovered unusual bodies. Here, we describe several examples (comets C/1999 S4 (LINEAR) and so on). We also mention an extension of our programme to fainter objects after the completion of a new 1-m telescope at the Kleť Observatory.