M. M. Gogoshev

Properties of dust in comet P/Halley measured by the Vega-2 three-channel spectrometer

Optical properties of cometary dust exhibit no substantial variations at distances from 100 to 15 000 km from the nucleus. Dust ejection can be approximated by cos φ where φ is the angle with the sun-nucleus axis. Phase functions of dust scattering at 10 wavelengths from 328 nm to 1.4 µm are obtained and discussed. Dust reflectivity is nearly constant in the range 0.3 µm to 1.8 µm. Vega-2 in situ measurements are analysed and compared with optical data. Phase functions calculated for Mie and Fresnel spheres fail to reproduce adequately the obtained data. More promising seems to be the approximation of rough spheres. Dust density was evaluated as 0.3 g cm−3 from comparison of the in situ data with our measurements. Dust velocities are approximated by the expression V g/V d =1 + (ϱr/b)1/2 with b= 4 g µm cm−3 obtained in our measurements. Total dust production rate equals 10 tons−1 and Q d/Q g ≈0.3 on 1986 March 9.

Vega project — Three channel spectrophotometer for the Halley's comet investigation

Abstract A spectrometer for the Halleys Comet Investigation after the VEGA Project is described in the present work. It consists of a telescope and three spectral channels: UV (120 – 290 nm), resolution Δ λ / λ = 170; VIS (280 – 710 nm), resolution Δ λ / λ = 170; IR (950 – 1900 nm), resolution Δ λ / λ = 70. With the help of two-coordinate scanner, the secondary mirror of the telescope allows spatial scanning of the Comet with a frame 2°×1,5° with 105 different pixels.

VEGA three-channel spectrometer experiment: Spectroscopy of comet Halley in the visible and near-ultraviolet ranges

Abstract A total of 3600 spectra of Comet Halley in the 275–710 nm were obtained on March, 8, 9, 10 and 11, 1986, from the VEGA 2 spacecraft. The emissions of OH, NH, CN, C 3 , CH, C 2 , NH 2 and H 2 O + are identified. From the OH intensity in the (0,0) band: 1.1 Megarayleigh at 5400 km from the nucleus, it can be inferred that the OH production rate was (1.4 ± 0.5)×10 30 molecules s −1 . The NH, C 3 , CH and NH 2 bands became comparatively more intense at distances from the nucleus shorter than 3000km. At 06:40 U.T. when the instrument field of view was 6000×4500 km, two jets were observed. Spectra from the jets show significant differences with other spectra. Inside a jet NH, C 3 and NH 2 are comparatively more intense and the rotational distributions of OH, CN and C 2 are strongly distorted. This shows that part of the observed emissions probably comes from radicals directly produced in the excited state during the initial process of photolysis of the parent molecules.

Airglow atmospheric imager on board the ‘IK-Bulgaria-1300’ satellite

Abstract This paper shows the possibilities of the optical scanning imager for investigation of the structure of the auroral, SAR and tropical arcs and in this way to study the particle precipitation, neutral winds across the magnetic equator, drifts, electric fields and the current systems in the ionosphere.

Energy deposition in the polar ionosphere as determined by measurements aboard ‘INTERCOSMOS-BULGARIA-1300’ satellite

Abstract Data were obtained from the measurements of optical emissions, ion drift, DC magnetic field and energetic particles, on board INTERCOSMOS - BULGARIA - 1300 satellite. In two cases of night-time passes through auroral oval, an estimate has been made of the energy input by particle precipitation and Joule heating. In order to determine the Joule heating, the Pedersen currents flowing in the lower ionosphere were determined. In orbits 231 and 203 Pedersen currents of 0.94 Am −1 and 0.71 am −1 were observed. From these values estimates of Joule heating rates of2 × 10 −7 Wm −3 and8 × 10 −7 Wm −3 were obtained. The integral energy deposited by the precipitated particles was also estimated in the current systems regions. The possibility for identification of the auroral electrojet based only on satellite data is pointed out.

SAR-arcs and emissions in the main trough of the electron concentration

Abstract This paper presents a study of the problem of magnetospheric — ionospheric influences in regions near the plasmapause at different levels of geomagnetic activity. As a basic indicator of these influences, the optical emissions of the SAR-arcs type are examined. We analyze the optical emissions in the region of the main trough of the electron, concentration situated polarly of the SAR-arc region.

Observations in the South Atlantic geomagnetic anomaly with Intercosmos-Bulgaria-1300 during a geomagnetic storm

Abstract The region of South Atlantic Geomagnetic Anomaly (SAGA) was investigated by the Intercosmos-Bulgaria-1300 satellite, launched on August 7, 1981. On the basis of data obtained from 15 orbits during increased geomagnetic activity in August 1981, a map of the Anomaly was elaborated. Two centres of activity were identified. By means of the EMO-5 electrophotometer on board the Intercosmos-Bulgaria-1300 satellite, the atmosphere glow in lines λ 5577 A, λ 6300 A and λ 4278 A was studied.

Structure of the polar oval from simultaneous observations of the optical emissions and particle precipitations during the period of high solar activity 1981–1982

Abstract The observations on board the IC-Bulgaria-1300 satellite, obtained during the period 1981–1982, have been analysed. The optical emissions have been measured by the optical photometer EMO-5. The simultaneous precipitating electron and proton fluxes have been measured by the ANEPE spectrometer. The structure of the oval is studied as a function of the magnetic local time and the geomagnetic activity. Accurate criteria for both the separation into two basic zones of the oval, a diffuse and a discrete zone, and the separation of a zone of diffusive luminosity equatorward of the polar oval are proposed.

Optical investigations of magnetospheric-ionospheric coupling by using data from the Intercosmos-19 satellite

Abstract In this paper we present the main parameters measured by the ionospheric observatory “Intercosmos-19”. In particular data from the visible electrophotometer EMO-1 are shown. Some preliminary results related mainly to the behaviour and distribution of the red line emission at higher latitudes are also given.

VERTICAL DISTRIBUTION OF AIRGLOW EMISSIONS IN THE EQUATORIAL IONOSPHERE DURING MODERATE GEOMAGNETIC ACTIVITY

A four-channel electrophotometer was instaled on board a Centaur-II rocket to measure the vertical distribution of 5577 A, 6563 A, 6600 A, 3914 A airglow emissions. The rocket was launched on 31 October 1978 from Thumba, India, in moderate solar and geomagnetic activity conditions -Ap = 20, Kp =4, Dst = − 74, Rs = 98, F10.7 = 144. The pair of red filters showed no H emission, i.e. no particle dissipation. The green oxygen line emission is between 77 and 110 km, with maximum at 97 km. A slow intensity increase is observed at about 105 km. The illumination of 3900 A filter was interpreted as emission of 02 Herzbergs band. The intensity maximum coincided with that of 5577 A. Some atmospheric parameters within the interval 75–110 km are calculated using the experimental values and the Chapman mechanism of excitation.