RADIOASTROPHYSICAL DEPARTMENT  INSTITUTE OF SOLAR-TERRESTRIAL PHYSICS RAS SB  
Russian Foundation for Basic Research
 

SSRT - Possibilities of observing

The principle of operation and characteristics of the SSRT offer the prospect of recordings of solar events of all scales:

  • spatial - from the radio diameter (35') to structural details in the active region atmosphere (15"),

  • temporal - from evolutionary day-to-day changes to fast processes during flares (14 ms),

  • energy scales - from low-contrast features to the flare flash phase.

The SSRT is characterized by a relatively low level of the beam's sidelobes (design level - 22%). Unlike aperture synthesis instruments, this makes it possible to use radio maps, even not subjected to the "cleaning" procedure. Thesidelobes become critical in observations of bright objects, such as intense radio sources in active regions. Investigations of the SSRT 5.7 GHz radio maps in conjunction with images obtained in other emission ranges, suggested the following conclsions:

The SSRT provides observations of processes in the upper chromosphere - lower corona. Comparison with images obtained at 17 GHz (Nobeyama Radioheliograph - upper chromosphere), in soft X-rays (space-borne Yohkoh telescope - upper corona), and in ultraviolet emission (SOHO/EIT - upper chromosphere - lower corona) shows that the observations in these ranges successfully supplement but not duplicate each other.

The SSRT sensitivity in the projected two-dimensional mode is about 10% of the quiet Sun level (16,000 K at 5.7 GHz), which make it possible to record, in addition to active regions, a traditional object of research for the SSRT, also a number of low-contrast objects:

  • SSRT ensures an assure registration of filaments and protuberances (brigthnes temperature is of order 8000 K);

  • On SSRT radiomaps there are identified bright points known from observing in soft X-rays. The best correlation is observed between bright points on SSRT radio images and images obtained in ultraviolet emission in Fe 171 Å and Fe 195 Å lines (SOHO EIT);

  • In some cases the SSRT radiomaps reveal a separate regions of low latidude coronal holes.

Solar images obtained at the SSRT on 27 april 1997 (on the left, 01:57 UT,SSRT) and orbital telescope of ultraviolet emission at SOHO EIT (on the right, 01:21 UT)

Solar images obtained in line Ha;(on the left, 16:11 UT, Big Bear observatory) and in the microwave emission (on the right, 04:04 UT, SSRT) 4 march 1997