Ts.N. Gogosheva

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.

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.

Near infrared observations of comet Halley from Vega 2

Abstract Spatial distribution of the continuum radiation in the range of 0.95–1.9 μ m presumes total dust production rate of the comet of 10 ρ tonne s −1 ( ρ is the dust material density) and its angular distribution proportional cos ϕ . Observations of the water vapor band at 1.38 μ m reveal strong jets, their time shift from the dust jet measured in situ is consistent with gas velocity of 0.82±0.1 km s −1 and dust velocity of 0.55±0.08 km s −1 . The OH vibrational-rotational bands observed are excided directly via photolysis of water vapor. Water vapor production rate deduced from the H 2 O band and OH band intensities is 8×10 29 s −1 . Intensity of the CN(0,0) band result in the CN column density of 9×10 12 cm −2 , i.e. larger by a factor of 3 than given by the violet band.

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.

Experimental determination of the main F-layer parameters on a global scale using data from a remote optical probe onboard the satellite Interkosmos-Bulgaria-1300

Abstract The optical complex of the satellite Interkosmos-Bulgaria-1300 includes the UV-spectrometer “Photon-1”, and the scanning spectrometer EMO-5 operating in the visible spectrum. Using the intensities of the OI 1356 and 6300 nm emission as measured by these two spectrometers, a theoretical evaluation of the two main F-layer parameters has been made: hmF, the height of the F2-maximum and NmF, the electron density at this height, together with the constant Ao characterizing the Ne(h) distribution in the IRI. The MSIS and CIRA-72 models are used for determining the distribution of the neutral component. If we had used CIRA-72, lower NmF values and higher hmF values had been obtained than with MSIS. The results obtained show that the method is very sensitive to the assumed neutral model, particularly when determining hmF. This work demonstrates the possibility of probing the F-region near its peak on a global scale using comperatively cheap and easily available optical methods.

Electrophotometrical studies of equatorial and tropical arcs on board the Salyut-6 orbital station☆

The results from the electrophotometric investigation of the equatorial and tropical ionospheric arcs on board the orbital station “Salyut-6”, carried out with Bulgarian photometer “Duga”, intended for measurements of the self-radiation of the Earths upper atmosphere in the lines λ = 6300 A, λ = 5577 A, λ = 4278 A and λ = 6563 A, are analyzed. From the obtained results of the intensity of the measured emissions is established by calculation that the cause of these arcs is the plasma drift downwards, which leads to intensification of the dissociative recombination of the ions O2+ and of the radiative recombination of O+.