We studied the relationship between successive coronal mass ejections (CMEs) and a long-lived geomagnetic storm (LLGMS) by examining the 1998 May 4 event. Five successive CMEs from the same active region and four interplanetary shocks were found to be associated with this LLGMS. We investigated the effect of successive and interacting CMEs on the LLGMS.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present observational results from long term monitoring of giant pulses from two pulsars. One of the pulsars (PSR 0950+08) has been observed simultaneously at three different observatories, at different radio frequencies. There is evidence to suggest that the giant pulse phenomenon is intrinsic to the pulsar.

When radio waves propagate through a irregular medium, scattering by the random refractive index inhomogeneities can lead to a wide variety of phenomena, which include intensity scintillation. The observed scattering can be interpreted to gain information about the random medium and such inversion studies are valuable when the accessibility of the medium becomes difficult. This paper briefly describes the intensity scintillation of celestial radio sources caused by the turbulence in the solar wind and summarizes the salient features of the method employed in mapping the structure of disturbances leaving the Sun out to ∼1 AU.

Interplanetary scintillation measurements obtained inside 200 R⊙ using the Ooty Radio Telescope during August 1986 - April 1991 have been analysed to study the interplanetary disturbances (or events) and their occurrence rates at various phases of the solar cycle. The disturbances are identified by the increase in the level of scintillation compared with the expected value. In total, 735 events have been identified. The results show a rate of 0.49 events per day near solar maximum and a low rate of 0.16 events per day during minimum of activity. The results are compared with coronal mass ejection (CME) rates and transients rates obtained from the Doppler scintillation measurements.

The variable BL Lac objects OJ 287 and B2 (1308+326) have been observed using the Ooty Synthesis Radio Telescope (OSRT) at 327 MHz. Preliminary analysis of one of them, namely OJ 287 indicates that flux variations of ∼ 20% on a time scale of few hours to few days could be present, but this needs to be confirmed by a larger data base.