S.V. Damle

High energy X-ray timing and spectral observations of SCO X-1, CYG X-1, GX 5-1, CYG X-3 and GX 1+4

Abstract A high energy X-ray astronomy payload with phoswich scintillation detectors was flown from Hyderabad, India on December 18, 1984. Five galactic X-ray sources, Sco X-1, Cyg X-1, Gx 5-1, Cyg X-3 and GX I+4 were observed. The timing data, with a high time resolution of 40 μs, were analysed for periodicities and quasi-periodic oscillations (QPOs). GX 1+4 was in a low luminosity state and showed pulsations with a period of 95.9 s. Its period derivative was calculated. Sco X-1 was found not to exhibit QPOs in 18–40 keV X-rays with a 90% confidence limit of 0.20 on amplitude. Spectra are presented for Sco X-1, Cyg X-1 and GX 5-1.

A high sensitivity phoswich scintillator X-ray telescope for hard X-ray (20 – 120 keV) astronomy from balloon platform

Abstract A large area (400 cm 2 ) low background X-ray telescope consisting of four collimated NaI/CsI scintillator phoswich detectors (each 100 cm 2 ) was built and successfully flown several times during 1980–1984. The phoswich configuration enables one to eliminate X-ray background produced by high energy atmospheric and cosmic gamma-rays. Combined with large area, small field of view (5° × 5°) and large exposure time that was possible due to an on-board telescope pointing programmer, for the 20 – 120 Kev energy range, 3σ sensitivity achieved was 5 × 10 −6 photon/cm 2 sec Kev for exposure time of 10 4 sec at observational altitude of 4 g/cm 2 . The Instrument characteristics, relevant details on pointing system, detector system, associated electronics and telemetry and in-flight performance in 1983 and 1984 are presented.

Present status and new trends in scientific ballooning in India

Abstract The efforts in scientific ballooning in India have always been focussed towards continuous upgrading of capabilities in all aspects of balloon flights - balloon material, balloon fabrication, launch techniques, heavy payload launch, telemetry, telecommand and other ground facilities - to meet the growing demands of the scientific community. A brief account of recent progress in several of these aspects and future plans for further improvements in scientific ballooning capability is presented.

Some special sub-systems for stratospheric balloon flights in India

Abstract During last few years several new sub-systems for balloon were developed and are being regularly used in the balloon flights. Some of these sub-systems are i) positive monitor for magnetic ballast release using an opto-electronic device ii) one-way pressure switch to terminate flight for runaway balloon iii) in-flight payload reel down system for atmospheric science experiment. The design, usage and performance of these and other sub-systems will be presented.

The observation of the galactic anticenter region by the balloon borne gamma-ray telescope Natalya-I

Abstract This paper presents the results of measurements of gamma radiation with energies above 5 MeV, from the galactic anticenter region. The balloon-borne gamma ray telescope “Natalya-I”, was launched on 6 November, 1980 from the Tata Institute of Fundamental Researchs Balloon Facility (Hyderabad, India) and reached ceiling altitude of 35 km. The results on the accelerator calibration of the telescope, using a “tagged” gamma ray beam are also presented.

Developments and advances in scientific balloon capability of the TIFR National Balloon Facility, Hyderabad

Abstract The Indian balloon group started development of plastic balloon technology in 1956, and today it is one of the leading balloon groups in the world. For the last 25 years, the TIFR scientific balloon group has been carrying out plastic balloon flights from TIFRs National Ballooning Facility (TNBF), Hyderabad. The TNBF undertakes design and fabrication of large zero pressure plastic balloons and provides full flight services: PCM Telemetry, Telecommand, tracking and dynamic launch of scientific payload weighing upto 1200 kg. The TNBF is responsible for all balloon flights as well as for the R & D in all aspects of scientific ballooning viz. balloon engineering, balloon material and other balloon subsystems like telemetry, telecommand, tracking and general flight control instrumentation. A continued effort in R & D in balloon film material has resulted in establishing a new balloon grade film codenamed ANTARIX. This balloon film has all the requisite low temperature characteristics essential for a good balloon film. For example, the cold brittle point of ANTARIX balloon film is −96°C. A number of balloon flights made with balloons made out of ANTARIX balloon film have been successful; this includes the recent balloon flight in April 1994 with a 1000 kg payload. Present capabilities include design, manufacture and launch of 430,000 cu.m. balloon to altitudes of 41.5 km with 500 kg scientific payload. Todate the TNBF has carried out 432 balloon flights for various disciplines of space sciences - primary cosmic ray studies, X-ray, Gamma-ray and Infrared Astronomies and Atmospheric Sciences. These balloon flights have provided very good scientific results. Recent developments and achievements in Scientific Ballooning in India are presented.

Recent trends in balloon flights from TIFR'S national balloon facility, hyderabad

Abstract The Tata Institute of Fundamental Research (TIFR), Bombay established the TIFR National Balloon Facility (TNBF) at Hyderabad near geomagnetic equator, in 1969. The TNBF undertakes design/fabrication of stratospheric balloons and is also responsible for balloon launch, tracking, data retrieval and recovery of scientific payload after the flight. It provides radio telemetry, telecommand, tracking and undertakes mechanical and electrical integration and test of the scientific payloads. The TNBF has also its own R&D programme in balloon engineering and support instrumentation. To-date 419 balloon flights have been carried out for space astronomy (x-ray, gamma-ray, infrared) and atmospheric sciences (ozone, aerosol, electric field and conductivity). In future several balloon flights are planned for the International Geosphere Biosphere Programme (IGBP) and for the space astronomy programme.

New balloon-borne telescope system tical - Mark II for hard X-ray astronomy

Abstract For the study of hard X-rays (18–150 KeV) from the celestial X-ray sources, NaI/CsI phoswich scintillator telescopes have been flown from Hyderabad during the last decade. The NaI(Tl)/CsI(Na) scintillator phoswich with Pulse Shape Discrimination technique reduces the non X-ray background by a factor 10 at balloon altitudes. The new telescope TICAL Mark-II with 1000sq.cm area [5 mm thick NaI(Tl) and 50 mm thick CsI(Na) phoswich] had a sensitivity to detect a minimum flux of 2.2 × 10−6 photons/sq.cm sec KeV in the energy range 18–150 KeV for 104 s exposure; this allows study of several bright active galactic nuclei. The telescope had a microprocessor-based tracking system to automatically follow celestial sources in elevation and azimuth according to a predetermined schedule. Several galactic X-ray sources, mostly binary pulsars, and the quasar 3C273 have been studied. The scintillator phoswich X-ray detector, the X-ray telescope and the electronic systems of the TICAL Mark II will be described.

Soviet-Indian research of cosmic radiation by high altitude balloons

The report presents some results on the cosmic radiation intensity research carried out with the high-altitude balloons for the period of 1977–1979. The intensity of gamma-radiation with the energy above 40 MeV was measured in two balloon flights at an altitude of 4–7 g/cm2 of residual atmosphere in the vicinity of the geomagnetic equator. A temporal analysis of the intensity to discover fluctuations with periods in the range of 4–60 min was made. Quasi-periodic fluctuations of gamma-radiation intensity with 5 min periods, amplitude ∼20% and duration of several hours were discovered. Possible mechanisms of such fluctuation appearance are discussed. The report gives the results of measuring downward, upward and horizontal electron fluxes in the vicinity of the equator. The obtained data and the data provided by satellites are compared. The report discusses the prospects of further joint Soviet-Indian research of cosmic gamma-radiation.

Gamma-radiation with Eγ > 5 MeV detected from Seyfert galaxy 3C120 and region with 1II = 190° and bII = 20°

Abstract A low mass wire spark chamber gamma ray telescope “Natalya-1” was launched on a balloon flight on November 6, 1980 from Hyderabad, India (Geomagnetic cut-off rigidity R ⋍ 16.8 GV ). The galactic anti-center region was observed during the balloon flight. We report here the detection of gamma rays, with energy, E γ > 5 MeV from the Seyfert galaxy 3C120 and from a region 1II = 190° and bII = 20°. The significance of the detection of gamma rays from 3C120 is also discussed.