Use of the complex dynamic cross-spectrum for indentifying sporadic radio emissions

Vladimir Kolyadin
LOFAR Transients Key Project Meeting, Meudon, December 2011

Transcript

1. The using of complex dynamic cross-spectra for identification of sporadic radio emission Vladimir L. Koliadin The Institute of Radio Astronomy of NASU, Kharkov, Ukraine W N S NS "West" "North" "South" 0.9km 0.9km 0.9km W N S NS "West" "North" "South" 0.9km 0.9km 0.9km 00 00 11 11 000 111 000 111 00 11 00 11 W2 W1 N2 N1 S1 S2
2. Very short baseline interferometry (VSBI) • Idea: we form local interferometers within the antenna system of UTR-2 • Goal: to get and use information about the phase difference between antennas • Background: the phase difference carries information about the direction of arrival
3. UTR-2 antenna system W N S NS "West" "North" "South" 0.9km 0.9km 0.9km
4. Some variants of local interferometers W N S NS "West" "North" "South" 0.9km 0.9km 0.9km W N S NS "West" "North" "South" 0.9km 0.9km 0.9km 0 0 1 1 000 111 000 111 000 111 000 111 W2 W1 N2 N1 S1 S2
5. DSPZ - Digital spectral analyzer (RI NASU) DSPZ u1 (t) u2 (t) P1 (f, t) P2 (f, t) Re ˙ R12 (f, t) Im ˙ R12 (f, t)
6. ˙ R(f, t) = P1 (f, t) ˙ R∗ 12 (f, t) ˙ R12 (f, t) P2 (f, t) = R11 (f, t) ˙ R∗ 12 (f, t) ˙ R12 (f, t) R22 (f, t)
7. ˙ S1i (f, t) = FFT(u1i (t)), t ∈ Ti ; ˙ S2i (f, t) = FFT(u2i (t)), t ∈ Ti ; ˙ Rmn (f, t) = 1 N K i=1 ˙ Smi (f, t) ˙ S∗ ni (f, t), m, n = 1, 2
8. Dynamic spectra: at DSPZ output • P1 (f, t) = R11 (f, t) - power dynamic spectrum of the 1st antenna • P2 (f, t) = R22 (f, t) - power dynamic spectrum of the 2nd antenna • A12 (f, t) = | ˙ R12 (f, t)| - cross-power dynamic spectrum • Φ12 (f, t) = arg ˙ R12 (f, t) - phase dynamic spectrum
9. Parameters of DSPZ Frequency range: 0 . . . 33MHz Frequency resolution: ∆f = 4kHz Frequency channels: K = 8192 Temporal resolution: ∆t = 0.001 . . . 0.1sec
10. False event: solar Type III burst (from sidelobes)
11. False event: phase dynamic spectrum
12. True event: solar Type III burst (in the main beam)
13. True event: phase dynamic spectrum
14. AD Leo flare star (ON + 2 OFF)
15. AD Leo - phase dynamic spectrum, ON
16. Test exoplanet (ON + OFF)
17. Test exoplanet (ON + OFF)
18. Saturn electrostatic discharges (SEDs): ON + OFF, 40s
19. Terrestrial lightning: Phase dynamic spectrum
20. SED: Phase dynamic spectrum
21. Two pairs of local interferometers 00 00 11 11 00 11 00 11 000 111 000 111 W2 W1 N2 N1 S1 S2 ments
22. Solar sporadic radio emission (30 sec): type IIIb-III
23. Multibase observations: Sun ments
24. Solar event: June 7, 2011: 4 bases, power - West ments
25. Solar event: June 7, 2011: 4 bases, correlation ments
26. Two solar bursts: 4 bases, power - West ments
27. Two solar bursts: 4 bases, correlation ments