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Doppler tracking of spacecraft with multi-frequency links

Comoretto, G.; Iess, L.; Bertotti, B.

We discuss the use of multi-frequency microwave links in Doppler tracking of interplanetary spacecraft for scientific purposes, especially in relation to the measurement and the elimination of the contribution due to the plasma in the solar wind and the ionosphere. We show how the two contributions in the up- and the down-link can be separately me…

ROSAT-pointed observations of two gamma-ray burst error boxes.

Hurley, K.; Motch, C.; Kouveliotou, C. +3 more

We present ROSAT observations of two gamma-ray burst error boxes and of one possible optical transient source. No point sources were detected and a comparison is made with previous observations of the same objects (Boer et al. 1988, 1991). We interpret the data in the context of gamma-ray burst models that invoke galactic neutron stars. Although r…

Radio emission from Jupiter observed by ULYSSES before and after encounter

Lecacheux, A.; Barrow, C. H.

The polarization and the occurrence probability of the radio emission from Jupiter at 940 and 52 kHz are compared before and after encounter. It is found that, after encounter, the right-hand polarized Main Component of the broad-band kilometric emission (bKOM) is not present while the left-hand polarized Intermittent Component is considerably enh…