VIRAC

OBSERVATIONS

THE FIRST ASTRONOMICAL TEST OBSERVATIONS OF THE VIRAC RT-32

For a more detailed information on the first astronomical test observations with the VIRAC 32 metre radiotelescope, see Ozolins et al. 1998 (in Latvian Journal of Physical and Technical Sciences, 1998, N6). See also the chronology of events.

Click on the images of this page to see them with explanations in full resolution.

How did it start?	The first light. In June 9, 1996 the RT-32 recorded the radio signals from the Sun. In September 15, 1996 for the first time the RT-32 detected the bright distant cosmic radio sources (Cas A and Cyg A).
	Test observations of Cas A, Crab nebula, Jupiter and other sources were made during September – November 1997.

A run of astronomical transit observations in 1998:

	A lunar transit. The brightness temperature is near 225 K.
	A transit of Cas A radiosource. The antenna temperature increased by 18.5 K.
	A transit of Tau A (the Crab Nebula) radiosource. The antenna temperature increased by 17 K.
	A transit of Cyg A radiosource. The antenna temperature increased by 14 K.
	The spatial representation of a series of consequentive Cyg A transits.
	A transit of the Vir A radiosource. The antenna temperature increased by 5 K.
	A transit of the planet Jupiter. The antenna temperature increased by 1 K.
	A false coloured radio map of the Sun obtained on November 28, 1998.

A run of astronomical transit observations in 1999:

	A grayscaled radio map of the Sun obtained on June 20, 1999.
	A grayscaled radio map of the Sun obtained on July 1, 1999.
	A false coloured radio map of the Sun obtained on July 2, 1999.
	A contour map of the Tau A obtained on July 2, 1999 (the angular scale of the map is in arcminutes).

Figures are made by D.Bezrukov.

Radio observations of the solar eclipse on August 11, 1999

We have started with a hope to explore the unique possibility of the solar eclipse to achive the angular resolution of a few arc seconds with the 32-meter radiotelescope.

Seclipse1.jpg (15097 bytes)
Figure1. Maximum phase of occultation and the trajectory of the Moon as seen at the VIRAC RT-32 site

Seclipse2.gif (14730 bytes)

Figure 2. The following Solar points of interest were tracked with the VIRAC RT-32 radiotelescope at 10.6 GHz frequency band:

1. First Sun-Moon contact 9:26 - 9:43 UT
2. Active region 8656 on the west solar limb 9:44 - 10:00, 10:26 - 11:00 UT
3. Most pronounced active region 8662 on the solar disc 10:01 - 10:25, 11:15 - 11:45 UT
4. Region of the quiet Sun 11:01 - 11:14 UT
5. Fourth Sun-Moon contact 11:46 - 12:20 UT

Figures are made by B.I.Ryabov.

Future layout:

The RT-32 is designed to make observations as a single-aperture antenna as well as a part of interferometer network.

After a set of the test astronomical observations with the 32 meter radio telescope the solar and low-frequency VLBI observations lie ahead. Both the radio mapping of the Sun and the tracking of the alone standing solar active regions are scheduled. The goal is to improve our understanding of a solar flare and the evolution of the large-scale coronal structures, such as coronal holes.

It is suggested to participate the Low Frequency VLBI Network which main directions of research are:

pre-lunched survey for Space VLBI mission RadioAstron;
investigations of scattering effects in different mediums (interstellar, interplanetary);
study of solar corona, far-out corona, solar wind;
radio spectroscopy of interstellar medium;
investigations of non-stationary solar radio sources;
radio images of nearest active stars;
measurements of pulsar proper motion.

The host as well as join projects for solar observations with the VIRAC RT-32 are welcome. Contact person: B.I. Ryabov.