The Scanning Polarimetric Imaging Radiometer (SPIRA) is a versatile fully polarimetric imager operating at 91 GHz. It is designed for measurements of polarimetric signatures of the Earth's surface and man-made objects. SPIRA combines a method for the measurement of the complete polarization state with a relatively fast high-resolution imager, which is suitable for a range of applications. The instrument measures all four Stokes parameters simultaneously and delivers images by mechanically scanning the scene with an elevation over azimuth scanner and an offset parabolic antenna. A two-channel heterodyne receiver is used for the reception of polarized radiation. The Stokes parameters are obtained by correlating two linear orthogonal-polarization components in a broadband analog adding correlator. In this paper, we present the design of the instrument and analyze its radiometric and polarimetric characteristics. The polarimetric calibration and a method for the characterization of the polarimetric calibration device are described. First polarimetric measurements are presented and discussed.

We present a design concept for a new state-of-the-art balloon borne atmospheric monitor that will allow enhanced limb sounding of the Earth's atmosphere within the millimetre and submillimetre wavelength spectral range. The instrument, called TELIS (TErahertz and submm LImb Sounder), is being developed by a consortium of major European institutes that includes the Space Research Organisation of the Netherlands (SRON), the Rutherford Appleton Laboratory (RAL) in the United Kingdom and the Deutschen Zentrum für Luft- und Raumfahrt (DLR) in Germany (lead institute). The TELIS will utilise state-of-the-art superconducting heterodyne technology and is designed to be a compact, lightweight instrument capable of providing broad spectral coverage, high spectral resolution and long flight duration (~24 hours duration during a single flight campaign). The combination of high sensitivity and extensive flight duration will allow evaluation of the diurnal variation of key atmospheric constituents such as OH, ClO, BrO together will longer lived constituents such as O3, HCL and N2O. Furthermore, the TELIS will share a common balloon platform to that of the MIPAS-B Fourier transform spectrometer, developed by the Institute of Meteorology and Climate research of the University of Karlsruhe, Germany. MIPAS-B will provide simultaneous and complementary spectral measurements over an extended spectral range. The combination of the TELIS and MIPAS instruments will provide atmospheric scientists with a very powerful observational tool and, in addition, will act as a prelude to future spaceborne instruments planned by the European Space Agency (ESA).

SPIRA is a polarimetric imaging radiometer at 91 GHz, intended for obtaining signatures of the brightness temperature distribution of the Earth surface in all four Stokes parameters. SPIRA will be transportable by two persons and be set up within hours. A radiometric sensitivity of less than 1 K will be achieved with a superheterodyne receiver at a bandwidth of 2 GHz, millisecond sampling time and post-measurement digital integration. The antenna has been designed with special attention paid to the minimization of measurement errors due to side lobes and cross-polarization. A scanning system makes maps in azimut and elevation, that are presented in the form of images. In this paper we present the concept as well as the current status of the SPIRA project.

We present a multi-wavelength study of a near-limb flare (S10E56) that occurred on June 27, 1993 around 11:15-12:40 UT. The flare was classified as 2N in H-alpha, and as GOES class M3.6. BATSE and Yohkoh observed the beginning of the flare, with impulsive flux evolution especially in the lower X-ray energy channels. Impulsive bursts were also seen in dm-waves (Nancay Radioheliograph) in the beginning of the flare, starting around 11:18 UT. The millimeter and centimeter radio flux (Metsahovi flare site and Bern full disk observations) indicate a long-duration, gradual type event. However, there seems to be evidence for a rising spectral slope at mm-waves after 11:25 UT. From 11:38 UT onwards metric type IV emission was detected over the east limb, moving outwards along a loop structure that is seen in the Yohkoh post-flare images. This metric emission coincides with intense radio emission at 8 mm and cm-wavelengths.

With the approval of funds for the development and construction of the new Solar Submm-wave Telescope, its design was reviewed, updated and manufacturers for the subsystems were selected. The principal characteristics of the system and the proposed research programs are described in this note.

In the present paper we report the results of a correlation analysis for 57 microwave impulsive bursts observed at six frequencies in which we have obtained a regression line between the peak frequency and the corresponding rise time of microwave impulsive bursts: {ie361-01} (with a correlation coefficient of - 0.43). This can be explained in the frame of a thermal model. The magnetic field decrease with height has to be much slower than in a dipole field in order to explain the weak dependence of f p on t r . This decrease of magnetic field with height in burst sources is based on the relationship between f p and t r found by assuming a thermal flare model with a collisionless conduction front.