High resolution in space and time

Olaf Wucknitz
LOFAR Transients Key Project Meeting, Meudon, December 2011

Transcript

1. High resolution in space and time Olaf Wucknitz wucknitz@astro.uni-bonn.de LOFAR TKP meeting, Meudon, 14–16 December 2011
2. High resolution in space and time • International LOFAR • High resolution in space • The Crab • Pulsar scattering • Jupiter • High resolution in time • Some technical issues titlepage introduction summary back forward −1 +1 fullscreen 1
3. International LOFAR (late 2011) titlepage introduction summary back forward −1 +1 fullscreen 2
4. High resolution in space: 3C196 at 30–80 MHz NL only, 35 ×22 beam NL+DE, 1. 5×0. 9 beam titlepage introduction summary back forward −1 +1 fullscreen 3
5. Sub-arcsec: HBA Images of 3C196 international Dutch resolution: 0. 35 11 titlepage introduction summary back forward −1 +1 fullscreen 4
6. Early HBA image of 3C147 titlepage introduction summary back forward −1 +1 fullscreen 5
7. Current project: 3C123 (HBA) NL only [ Olaf Wucknitz ] international [ Adam Deller ] titlepage introduction summary back forward −1 +1 fullscreen 6
8. Reminder: first long-baseline observations of the Crab • 12 h on 13/14 Feb 2011 L2011 23410 • 115–160 MHz • international stations: DE601, DE603, FR606 • NL stations: CS032, RS106,205,208,306,307,406,503 • problems DE601 failed 50 % of subbands bad in blocks of 30/31 significant ionospheric delays, differential Faraday rotation titlepage introduction summary back forward −1 +1 fullscreen 7
9. Image of the pulsar (HBA) BOTH: 0534+220 IPOL 123.828 MHZ 23410.ICL001.1 PLot file version 1 created 26-JUN-2011 20:14:37 Grey scale flux range= -0.018 8.566 JY/BEAM Cont peak flux = 8.5657E+00 JY/BEAM Levs = 8.566E-03 * (-2, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024) 0 2 4 6 8 DECLINATION (J2000) RIGHT ASCENSION (J2000) 05 34 32.4 32.3 32.2 32.1 32.0 31.9 31.8 31.7 31.6 22 00 55 54 53 52 51 50 49 titlepage introduction summary back forward −1 +1 fullscreen 8
10. Imaging the nebula (HBA) titlepage introduction summary back forward −1 +1 fullscreen 9
11. Crab with VLA at 5 GHz [ Bietenholz (2004) ] titlepage introduction summary back forward −1 +1 fullscreen 10
12. Direct comparison LOFAR (red) and 5 GHz VLA (green) titlepage introduction summary back forward −1 +1 fullscreen 11
13. Crab with LOFAR (HBA) titlepage introduction summary back forward −1 +1 fullscreen 12
14. Crab with VLA at 5 GHz (smoothed) titlepage introduction summary back forward −1 +1 fullscreen 13
15. Direct comparison (smoothed) LOFAR (red) and 5 GHz VLA (green) titlepage introduction summary back forward −1 +1 fullscreen 14
16. New observations of the Crab: preliminary LBA image titlepage introduction summary back forward −1 +1 fullscreen 15
17. Faraday dispersion function from Q and U (30 subbands) titlepage introduction summary back forward −1 +1 fullscreen 16
18. After subtraction of leakage peak (one CLEAN iteration) titlepage introduction summary back forward −1 +1 fullscreen 17
19. Pulsar scattering: geometry DS observer θ scattering screen pulsar D τ = 1 2 θ2D D = DDs D −Ds ≈ D titlepage introduction summary back forward −1 +1 fullscreen 18
20. Pulsar scattering: one/three screens 0 0.2 0.4 0.6 0.8 1 τ temporal profile -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 θ spatial profile -1 -0.5 0 0.5 1 0 0.1 0.2 0.3 0.4 0.5 0.6 θ τ -6 -4 -2 0 2 4 6 0 0.1 0.2 0.3 0.4 0.5 0.6 baseline length τ 0 0.2 0.4 0.6 0.8 1 τ temporal profile -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 θ spatial profile -1 -0.5 0 0.5 1 0 0.1 0.2 0.3 0.4 0.5 0.6 θ τ -6 -4 -2 0 2 4 6 0 0.1 0.2 0.3 0.4 0.5 0.6 baseline length τ titlepage introduction summary back forward −1 +1 fullscreen 19
21. Pulsar scattering: continuous medium 0 0.2 0.4 0.6 0.8 1 τ temporal profile -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 θ spatial profile -1 -0.5 0 0.5 1 0 0.1 0.2 0.3 0.4 0.5 0.6 θ τ -6 -4 -2 0 2 4 6 0 0.1 0.2 0.3 0.4 0.5 0.6 baseline length τ titlepage introduction summary back forward −1 +1 fullscreen 20
22. Jupiter: sources of decametric emission aurora Io [ Zarka (2004) ] titlepage introduction summary back forward −1 +1 fullscreen 21
23. Jupiter observations 8th July: DE604-DE602 RR titlepage introduction summary back forward −1 +1 fullscreen 22
24. Jupiter observations 8th July: DE604-DE602 LL titlepage introduction summary back forward −1 +1 fullscreen 23
25. Jupiter observations 6th August: RS503-DE604 RR titlepage introduction summary back forward −1 +1 fullscreen 24
26. Jupiter observations 6th August: RS503-DE604 LL titlepage introduction summary back forward −1 +1 fullscreen 25
27. Conversion to circular requires beam models • convert LOFAR X/Y to IAU X/Y • convert IAU X/Y to R/L • no good beam models available • own geometrical model (1.5 years old) • improved for individual station orientations titlepage introduction summary back forward −1 +1 fullscreen 26
28. Correlations at full time-resolution • Jupiter needs resolution of msec • same for pulsar scattering studies (or even better) • correlator output rate too low • alternative: record “raw voltages” of stations, fly’s eye correlate (multiply) later possible for couple of stations, reduced bandwidth • tried since July, many problems with data corruption • first successful test (Crab) 28 October • first successful Jupiter obs 24/25 November titlepage introduction summary back forward −1 +1 fullscreen 27
29. First full-resolution Jupiter observations • L35624, 24/25 November 2011 23:30–01:45 UTC • 61 subbands 18–30 MHz, 256 channels/SB (763 Hz) • correlations 6 stations: DE602, FR606, RS106, RS307, SE607, UK608 1 sec integration time • fly’s eye “raw voltages” integration time 1.3 msec only 3 stations: DE602, FR606, RS106 • nice bursts, analysis in progress titlepage introduction summary back forward −1 +1 fullscreen 28
30. Entire observation DE602-FR606, RR amplitudes titlepage introduction summary back forward −1 +1 fullscreen 29
31. Entire observation DE602-FR606, LL amplitudes titlepage introduction summary back forward −1 +1 fullscreen 30
32. Entire observation DE602-FR606, LL/RR amplitudes titlepage introduction summary back forward −1 +1 fullscreen 31
33. Zooming in (1) DE602-FR606, RR amplitudes titlepage introduction summary back forward −1 +1 fullscreen 32
34. Zooming in (2) DE602-FR606, RR amplitudes titlepage introduction summary back forward −1 +1 fullscreen 33
35. Zooming in (3) DE602-FR606, RR amplitudes titlepage introduction summary back forward −1 +1 fullscreen 34
36. Zooming in (4) DE602-FR606, RR amplitudes titlepage introduction summary back forward −1 +1 fullscreen 35
37. Zooming in (5) DE602-FR606, RR amplitudes titlepage introduction summary back forward −1 +1 fullscreen 36
38. Zooming in (5) FR606 auto, RR amplitudes titlepage introduction summary back forward −1 +1 fullscreen 37
39. Elsewhere: Zooming in (1) DE602-FR606, RR amp titlepage introduction summary back forward −1 +1 fullscreen 38
40. Elsewhere: Zooming in (2) DE602-FR606, RR amp titlepage introduction summary back forward −1 +1 fullscreen 39
41. Elsewhere: Zooming in (3) DE602-FR606, RR amp titlepage introduction summary back forward −1 +1 fullscreen 40
42. Elsewhere: Zooming in (3) DE602-FR606, RR phase titlepage introduction summary back forward −1 +1 fullscreen 41
43. Bispectrum / closure phase DE602-FR606-RS106 RR titlepage introduction summary back forward −1 +1 fullscreen 42
44. Last Sunday’s Jupiter observations • L37058, 11 December 2011 16:30-18:30 UTC • 61 subbands 18–30 MHz, 64 channels/SB (3.052 kHz) • correlations 6 stations: DE602, DE604, DE605, FR606, SE607, UK608 1 sec integration time • fly’s eye “raw voltages” integration time 0.328 msec not checked yet • nice bursts, Faraday fringes titlepage introduction summary back forward −1 +1 fullscreen 43
45. FR606-SE607 RR+LL titlepage introduction summary back forward −1 +1 fullscreen 44
46. FR606 auto RR+LL titlepage introduction summary back forward −1 +1 fullscreen 45
47. SE607 auto RR+LL titlepage introduction summary back forward −1 +1 fullscreen 46
48. DE602 auto RR+LL titlepage introduction summary back forward −1 +1 fullscreen 47
49. Planned analysis • electron bunches moving with ∼ 20000km/s • cyclotron frequency: 1 MHz per 1000 km 20 MHz/s motion ca. 0. 3 over 50 ms • fringe spacing for 1000 km baseline at 20 MHz: 3 ∆φ ∼ 36◦ over 1 MHz • corresponds to delay of 100 ns ( ionosphere) • corresponds to position shift of 6 • cannot distinguish motion from delay! • need external calibration • or several emitting regions near Jupiter • serious calibration difficulty! titlepage introduction summary back forward −1 +1 fullscreen 48
50. Technical issues • how to visualise big 2d fields? (zoom in) • cross-correlations have phases • closure phase consistent with point-source (amplitudes?) • unusual properties for full resolution (∆ν ·∆t = 1) closure phases zero no structure from elementary cells limited S/N 1 (wave noise) but only thermal phase noise for point-source titlepage introduction summary back forward −1 +1 fullscreen 49
51. RFI (ASTRON/JIVE daily image 2 Dec 2011) titlepage introduction summary back forward −1 +1 fullscreen 50
52. Aliens? Arecibo message from Wikipedia giant pulses from Charlotte Sobey titlepage introduction summary back forward −1 +1 fullscreen 51
53. Summary • long baselines work (even at 20 MHz) • no automatic pipeline • can correlate with full resolution (eventually!) • important for pulsar scattering and Jupiter • first successfull full-resolution Jupiter observations • good phases, but how to calibrate? • statistics different from averaged visibilities • planning correlations with LWA (New Mexico) • many technical problems on the way, strange RFI • commissioners should look at their data! titlepage introduction summary back forward −1 +1 fullscreen 52