In this paper a logic circuit for digital clocks is discussed. Using high frequency radio time signals, it corrects errors upto Plus Minus 30 seconds with an accuracy of a millisecond. The circuit also monitors the clock errors, using the time display unit of the clock itself, and carries out synchronization even in relatively noisy reception conditions.

An analysis of 40 hours of data, collected at Gulmarg during 1987 and 1988, indicates absence of a significant d.c. or episodic periodic signal from 4U0115+63 (Cassiopeia gamma-1). We place an upper limit (at 99% confidence level) of 1.9x10(-11) photons cm-2 s-1 on the flux of a steady signal from this x-ray binary pulsar at primary energies greater-than-or-equal-to 3 TeV. This is consistent with the negative results reported recently by the Whipple group for the period 1985 -1988 but not with the detections claimed previously by Crimean and Durham groups.

Detailed Monte Carlo simulations have been carried out to determine at Gulmarg altitude (congruent-to 2740 m ASL), lateral and angular distributions of atmospheric Cerenkov radiation produced by gamma-ray primaries in the energy range 0.1-5 TeV and zenith angle range 0-degrees-45-degrees. This paper also describes the important changes in the lateral distribution properties of the Cerenkov radiation and its related effects on the threshold detection energy for oblique shower cases. We use the results of these simulations, along with an experimentally determined value for the intensity of light of the night sky at our location, to get an independent estimate of the threshold primary energy for the Gulmarg gamma-ray telescope.

A 15 minute-long episode of pulsed gamma-ray emission has been detected from Her X-1 on 1988 June 12. The observed pulsation period of (1.23762 +/- 0.00015) s is statistically indistinguishable from the contemporary X-ray period. The 35d phase for the episode is 0.02, showing that it has occurred near the expected onset time of the 'HIGH-ON' state in the X-ray flux. The 1.7d orbital phase for the burst is 0.66. The time-averaged flux has been estimated to be (4.7 +/- 1.2) x 10(-10) cm-2 s-1 at energies greater-than-or-equal-to 3 TeV.

We report here a possible detection of TeV gamma rays from the magnetic white dwarf binary system AM Herculis, with a phase-averaged flux of (5.6 +/- 2.1) x 10(-11) photons cm-2 s-1 at energies above 2 x 10(12) eV. The gamma-ray light curve exhibits two broad emission peaks at magnetic phases around (0.1 +/- 0.2) and (0.6 +/- 0.2) and closely matches in shape the phase modulation of circularly polarized light emitted by the source.