We describe the construction and discuss the performance of a d.c. amplifier which was installed at the 34-cm telescope of Vainu Bappu Observatory in 1987 January and since then extensively used for variable star photometry.

The response of the equatorial geomagnetic field to the passage of over 170 spacecraft-observed and well-established sector boundaries during the period 1962-1972 has been studied. It is shown from superposed epoch analysis ...

For Newtonian dynamics to hold over galactic scales, large amounts of dark matter (DM) are required which would dominate cosmic structures. Accounting for the strong obser- vational evidence that the universe is accelerating ...

Gravitational waves from mergers of black holes and neutron stars are now being detected by LIGO. Here we look at a new source of gravitational waves, i.e., a class of dark matter objects whose properties were earlier ...

The nature of dark matter (DM) and dark energy (DE) which is supposed to constitute about 95% of the energy density of the uni-verse is still a mystery. There is no shortage of ideas regarding the nature of both. While ...

Multilayer X-ray mirrors consist of a coating of a large number of alternate layers of high Z and low Z materials with a typical thickness of 10–100 Å , on a suitable substrate. Such coatings play an important role in ...

This report describes the concept of the electronics design and implementation of PMT pulse counting , rotation of Half wave plate, chopper spinning and shutter control and host computer communication.

The High Altitude GAmma-Ray (HAGAR) experiment is the highest altitude atmospheric Cherenkov sampling array, set up at 4300 m amsl in the Himalayas (Northern India). It constitutes 7 telescopes, each one with seven 90 ...