A computer search for asteroid families

The improved proper elements of 4100 numbered asteroids have been searched for clusterings in a, e, i space using a computer technique based on the D-criterion. A list of 14 dynamical families each with more than 15 members is presented. Quantitative measurements of the density and dimensions in phase space of each family are presented

Activity of the Lyrid meteor stream

The activity of the Lyrid meteor stream is in most years fairly low with a visual rate at maximum (21-22 April) of 5-10 meteors per hour. Short bursts of very high Lyrid activity, with visual hourly rates of 100 or more, have sometimes been reported. These observations generally refer to faint visual meteors. The reported bursts of high activity have occurred in a very narrow interval of solar longitudes (deg 31.24 to 31.38 equinox 1950.0), while the recurrent or 'normal' maximum for bright meteors occurs at solar longitude deg 31.6, or slightly later. A mass separation of the meteors in the shower is thus indicated

Galileo dust data from the jovian system: 1997-1999

The dust detector system on board the Galileo spacecraft recorded dust impacts in circumjovian space during the craft's orbital mission about Jupiter. This is the eighth in a series of papers dedicated to presenting Galileo and Ulysses dust data. We present data from the Galileo dust instrument for the period January 1997-December 1999 when the spacecraft completed 21 revolutions about Jupiter. In this time interval data were obtained as high resolution realtime science data or recorded data during 449 days (representing 41% of the entire period), or via memory readouts during the remaining times. Because the data transmission rate of the spacecraft was very low, the complete data set (i.e. all parameters measured by the instrument during impact of a dust particle) of only 3% (7625) of all particles detected could be transmitted to Earth; the other particles were only counted. Together with the data of 2883 particles detected during, Galileo's interplanetary cruise and 53 53 particles detected in the jovian system in 1996, complete data of 15 861 particles detected by the Galileo dust instrument from 1989 to 1999 are now available. The majority of the detected particles were tiny grains (about 10 nm in radius), most of them originating from Jupiter's innermost Galilean moon Io. They were detected throughout the jovian system and the highest impact rates exceeded 100 min(-1) (C21 orbit; 01 July 1999). With the new data set the times of onset, cessation and a 180 degrees shift in the impact direction of the grains measured during 19 Galileo orbits about Jupiter are well reproduced by simulated 9 nm particles charged up to a potential of +3 V, confirming earlier results obtained for only two Galileo orbits (Horanyi, M., Grun, E., Heck, A., 1997. Modeling the Galileo dust measurements at Jupiter. Geophys. Res. Lett. 24, 2175-2178). Galileo has detected a large number of bigger particles mostly in the region between the Galilean moons. The average radius of 370 of these grains measured in the 1996-1999 period is about 2 mu m (assuming spherical grains with density 1 g cm(-3)) and the size distribution rises steeply towards smaller grains. The biggest detected particles have a radius of about 10 mu m. (c) 2006 Elsevier Ltd. All rights reserved

Galileo Dust Detection System V4.1

This data set contains the data from the Galileo dust detector system (GDDS) from start of mission through the end of mission. Included are the dust impact data, noise data, laboratory calibration data, and location and orientation of the spacecraft and instrument

Ulysses Dust Detection System V3.1

This data set contains the data from the Ulysses dust detector system (UDDS) from start of mission through the end of mission, 1990-2007. (As the dust detector was turned off after Nov. 30, 2007, this is the last date for which UDDS data is recorded.) Included are the dust impact data, noise data, laboratory calibration data, and location and orientation of the spacecraft and instrument