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152 Chapter 6. EVN and MERLIN observations Table 6.3: EVN array used in the observations. Antenna Code Location Diameter DPFU (a) Tsys (b) [m] [K Jy −1 ] [K] Effelsberg EB Germany 100 1.47 27 Jodrell Bank JB U.K. 25 0.11 40 Cambridge CM U.K. 32 0.21 38 Westerbork WB Netherlands 14×25 1.0 67 Medicina MC Italy 32 0.15 53 Noto NT Italy 32 0.16 47 Shanghai SH China 25 0.088 40 Toruń TR Poland 32 0.15 31 Onsala85 ON Sweden 25 0.043 45 (a) Degrees per flux unit. (b) Best value during the experiment. The data were processed at the EVN MkIV correlator at the Joint Institute for VLBI in Europe (JIVE), in Dwingeloo, The Netherlands. The correlator integration time was of 4 s. A first post-processing analysis was also carried out at JIVE. The data were processed using aips. A first a priori visibility amplitude calibration was performed using antenna gains and system temperatures measured at each antenna. The fringe fitting (fring) of the residual delays and fringe rates was performed for all the radio sources. No fringes were found for 1RXS J042201.0+485610 and 4C 61.02. Fringes for many baselines were missing for 1RXS J001442.2+580201, 1RXS J062148.1+174736 and TXS 0422+496. To improve the fringe detection on all baselines for 1RXS J001442.2+580201 and 1RXS J062148.1+174736 we used the delay, rate, and phase solutions from their corresponding phase-reference calibrators (J0007+5706, 1 ◦ 18 ′ separation, and J0630+1738, 1 ◦ 59 ′ separation, see Table 6.1) and interpolated them to the target sources using the aips task clcal. We fringe-fitted the target sources again using narrower search windows and obtained solutions for all baselines. A similar attempt on 1RXS J042201.0+485610 (with respect to TXS 0422+486 and NRAO 150) was unfruitful. Effelsberg was used as reference antenna throughout the aips data reduction process. We then averaged the data in frequency and exported them to be imaged and self-calibrated in difmap. The a priori visibility amplitude calibration was not suffi-
6.2. Observations and data reduction 153 cient to reliably image the weakest radio sources. We improved that by first imaging in difmap the calibrator sources J0007+5706, J0147+5840, and J0630+1738, with appropriate amplitude self-calibration. We deduced correction factors for each antenna, these being consistent for the three radio sources within 2%. The factors were: EB:0.98, JB:1.10, CM:0.78, WB:1.18, MC:0.87, NT:1.12, SH:1.03, TR:0.98 and ON:0.97. We corrected the amplitude calibration back in aips using the task sncor (optype ’mula’) for all the radio sources and exported the data again into difmap, where the final imaging was performed after editing and averaging of the visibilities in 32 s blocks. 6.2.3 Combining EVN and MERLIN The EVN and MERLIN arrays have one common baseline, between JB and CM, which allows to combine both data sets and map them together. Combining data sets from both arrays allows us to reach (u, v) resolution ranges from 0.04 Mλ (MK2- Tabley) to 140 Mλ (NT-SH) at 5 GHz. We processed the data within aips in order to combine both arrays. The B1950.0 (u, v) coordinates of the MERLIN data had to be corrected to the ones of the EVN for the same reference system (J2000.0) with uvfix. Then, the MERLIN data were self-calibrated with the EVN images (see below), and the phase solutions were limited to the longest MERLIN baselines. The MERLIN data were imaged and the peak-of-brightness of both data sets were checked to be similar. As a next step, the EVN data were averaged in frequency to correspond to the MERLIN data. The aips headers of both data sets were modified conveniently to match together, and the weighting of both data sets was also modified to be equal with wtmod. Finally, both data sets were concatenated (using dbcon) and exported to difmap to be imaged with different data weighting in (u, v) distance (tapering) after time averaging in 32 s bins. 6.2.4 Flux density measurements at the 100 m antenna in Effelsberg To complement the amplitude calibration and obtain additional information on the radio sources, we interleaved cross-scans (in azimuth and elevation) with the 100 m Effelsberg antenna to measure the radio source flux densities (A. Kraus, private
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UNIVERSITAT DE BARCELONA Departamen
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Per a la meva neboda Blanca, que va
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feina no presentada en aquesta tesi
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desfogar-nos conjuntament, per la s
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From the scientifical point of view
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Gràcies a la meva germana Nàdia,
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ii CONTENTS I Discovery and study o
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iv CONTENTS II A search for new mic
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vi CONTENTS
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viii Resum de la tesi d’Eddington
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xiv Resum de la tesi un comportamen
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xvi Resum de la tesi MilliARC SEC 4
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xxxii BIBLIOGRAFIA
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28 BIBLIOGRAPHY Lewin, W. H. G., va
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30 BIBLIOGRAPHY
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Chapter 2 Multiwavelength approach
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2.3. An interesting target in the s
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2.4. The radio counterpart: NVSS J1
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2.7. The γ-ray counterpart: 3EG J1
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2.7. The γ-ray counterpart: 3EG J1
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Figure 2.23: Scenario where the mul
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2.9. Conclusions 87 8. We have carr
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Bibliography Blandford, R. D., & K
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BIBLIOGRAPHY 91 Merck, M., Bertsch,
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Chapter 3 LS 5039 as a runaway micr
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3.1. Positions and proper motions 9
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3.1. Positions and proper motions 9
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3.3. The past trajectory of LS 5039
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