Talk presented at the Physics Department
of the University of Rome "La Sapienza" on April 6, 2006


Radio Astronomy

at Torun


dr Kazimierz Borkowski
Centre for Astronomy, N.Copernicus University, Torun, Poland


n Introduction
        Torun, the University and the Observatory
        Radio astronomy
        Our equipment

n Current projects and research areas
        Very Long Baseline Interferometry (VLBI)
        Spectral observations
        Solar observations
        Pulsars
        Polarimetry
        OCRA project
        Cosmology
        80-100 m telescope project



Introduction



Toruñ
        population: ~210 000 (on decline)

  Nicolaus Copernicus University
        workers:   4100 (2000 scientists)
        students: 42000 (externals: half)
        faculties: 14
        specialties: >100
    Faculty of Physics Astronomy and Informatics
      Torun Centre for Astronomy (TCfA)
        Department of Radio Astronomy
                workers: 25 (7 scientists)
                PhD students: 6


View of the TRAO from 32-m telescope (click to get full resolution)

(or see this aerial view photo)



Astronomy in radio domain






l Our equipment
         32 m radio telescope (RT32; in use since 1994)
        15 m radio telescope
        23 m interferometer (127 MHz)
        VLBA terminal (with tape recorder)
        VLBI disk recorder Mark5A (1 Gb/s)
        hydrogen maser (stability: 10-15)
        GPS receiver
        radio astronomy receivers (1, 1.3-1.8, 5, 6, 12, 30 GHz)
        16384-channel digital spectrograph
        pulsar machine (64-channels, 3 MHz each)


Photo by F. Nowakowski    



l Solar observations
        Frequency: 127 MHz
        Time range: 1958 - present
        Instrument: 10 l interferometer; Dicke type receiver
        Results: regular monthly publications

This is edited version of image posted in G. Gawronska site          

World longest series of observations at metre wavelengths

 

l Pulsar observations
        Frequency: L-band (l = 21 cm; mostly)
        Instrument: RT32 + pulsar machine
        Type: long-term timing of some 50 pulsars

Image taken from A. Wolszczan site      

 

l Spectral observations
        Frequency: L-band (18 cm) & M-band (5 cm)
        Instruments: RT32 + 16384-channel autocorrelator
          and also VLBI (EVN) + Merlin, Nancay and Bonn
        Science: maser lines of hydroxyl (OH)
          and methanol (CH3OH)


Examples of methanol line sources

 

l OCRA - array of 1 cm receivers (with JBO)

        Frequency: 30 GHz (1 cm)
        Instruments: RT32 + OCRA-p/OCRA-f
        Aim: All sky survey


OCRA-p (currently in use)




 

l VLBI

        Method, results and accessibility:
Independent simultaneous observations
Recording on magnetic tapes or disks (Mark5A)
Disks assembled into 8-packs: up to 3.2 TByte capacity
Signal: Gaussian with 0 mean
Nyquist sampling at 2 Df (rates up to 1 Gsamples/s)
1- or 2-bit samples
All stations data combined with a dedicated correlator
Proposals accepted according to referees ranking
Result: maps or reduced data for the PI only
After a year the results are released for all interested
        Science: extragalactic sources, spectral lines (stars),
          supernovae and pulsars (occasionally)
        Observations: three 4-week sessions a year
        Frequencies/bands: L (21, 18 cm), C (6 cm) & M (5 cm)
        Instruments: EVN + MERLIN + VLBA + Halca and
          correlators (JIVE, Bonn, Socorro, Mitaka and Penticton)

 

EVN (European VLBI Network)


Low-resolution copy of a poster recently prepared in the TCfA
that presents our involvement in EVN activities 

Courtesy of TCfA  


Example map of a quasar

obtained from observations with the 8-m space antenna (VSOP) plus Effelsberg, Noto, Torun and Hartebeesthoek ground radio telescopes


 

e-VLBI - the future of VLBI

All telescopes connected by optical fibres
Transmission speeds up to 10 Gbits/s (bandwidth up to 5 GHz!)
On-line correlation and immediate results (maps)


The spectrum of IRC+10420 at 1612 MHz as observed during the EVN e-VLBI observations. The total velocity width of the emission shows that the shell is expanding at about 40 km/s

First observations
(from press release)

    20-hour long observations, performed in September 2004 using the EVN, involved radio telescopes in the UK, Sweden, the Netherlands, Poland and Puerto Rico. The maximum separation of the antennas was 8200 km, giving a resolution of at least 20 milliarcseconds (mas); this is about 5 times better than the Hubble Space Telescope.
    Each telescope was connected to its country's National Research and Education Network (NREN), and the data routed at 32 Mbits/second per telescope through GÉANT, the pan-European research network, to SURFnet, the Dutch network.


Present e-VLBI status

Introduced: Europe (EVN); tests: USA, Japan, Australia
1 Gbit/second connections from: Onsala, Jodrell Bank, Cambdridge, Westerbork, Medicina and Torun.
Practically usable speed: 128 Mb/s
Tomorrow (Friday): Test of transfers (Medicina, Torun, Jodrell Bank)
20 April: 24-hour science experiment

 

l 80-100 m telescope project

        Type: Offset paraboloid, altitude-only steerable
        Frequency: 5 - 22 GHz
        Stage: feasibility study