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Table 1

Comparison between standard phase referencing, single source self-calibration and MSSC calibration techniques.

Phase referencing Single source self-calibration MSSC
Source ID P (μJy/bm) I (μJy) N (μJy/bm) S / N P (μJy/bm) I (μJy) N (μJy/bm) S / N P (μJy/bm) I (μJy) N (μJy/bm) S/N

123608+621036 41.8 50.8 6.3 6.6 45 65.6 6.3 7.1 63.5 78.8 5.6 11.4
123618+621541 61 75.2 9.7 6.3 63.7 75 9.9 6.4 75.3 90.0 9.7 7.8
123620+620844 60 60 6.9 8.7 37.6 49 6.1 6.2 83.4 (76.5) 83.4 (82.1) 9.7 (6.8) 8.6 (11.3)
123622+620654 42.8 68.7 6.4 6.7 N-D N-D 5.91 - 40.8 56.5 5.9 6.9
123624+621643 97.1 131.3 9.7 10.0 126.9 130.6 9.9 12.8 131.3 156.8 9.8 13.4
123641+621833 37.2 60.8 5.7 6.6 48.3 59.8 5.5 8.8 53.6 58.4 5.8 9.3
123642+621331 88.2 101.6 5.9 14.8 85.9 (96.3) 106.2 (115.5) 9.7 (6.8) 8.9 (14.2) 72.9 (113.2) 153.1 (141.2) 9.6 (6.0) 7.6 (18.9)
123644+621133 195 197.1 9.7 20.1 155.1 168.7 9.9 15.7 262.1 256.0 9.7 27.0
123646+621405 76 115.2 9.6 7.9 68.7 100.5 9.6 7.2 114.1 135.0 9.5 12.0
123653+621444 45.9 53.3 5.3 8.6 49.3 56.2 5.6 8.8 58.3 62.9 5.4 10.8
123659+621833 824 1348 14.7 56.1 1284 1743.9 18.1 70.9 1284.9 1732.7 11.1 115.8
123700+620910 63 79.1 5.8 10.8 48.8 63.4 5.7 8.5 63.4 (77.4) 89.2 (91.1) 9.5 (5.7) 6.7 (13.6)
123709+620838 34.5* 41.7* 5.9* 5.8* 28.4* 34.1* 5.4* 5.2* 44.9 55.5 5.5 8.2
123714+621826 170.5 181.2 10.0 17.1 185.1 216.2 10.4 17.8 235.1 252.5 10.1 23.3
123715+620823 840.8 946.8 13.5 62.3 524.4 701 14.6 35.9 1242.6 1300.6 15.6 79.7
123716+621512 50.1 54.3 5.6 8.9 49.6 59.5 6.1 8.2 59.4 75.1 5.9 10.1
123717+621733 68.3 76.2 9.7 7.0 71.8 102.8 9.7 7.4 86.3 99.3 9.6 9.0
123721+621130 110.7 153 9.9 11.1 112 143.9 9.8 11.5 182.0 195.1 9.9 18.5
123726+621128 49 63.7 5.6 8.8 N-D N-D 6.43 - 57.3 66.5 5.6 10.2
123701+622109 55.6 80.4 5.6 10.0 57.7 73.1 5.7 10.1 64.0 77.8 5.6 11.4
Phase referencing SSSC MSSC

Detected with natural weighting 19 17 20
Detected with uniform weighting 9 10 12
Failed solutions (iteration 3) 7% 2%

Notes. Top panel: comparison of the peak flux density per beam or brightness (P) in μJy/beam (shortened to μJy/bm), integrated flux density (I), in μJy, rms noise (R), in μJy/beam, and the S/N of the peak brightness to the rms noise for three different calibration methods. The peak flux densities and integrated flux densities were determined using the AIPS task JMFIT and the noise was measured using the AIPS task IMSTAT. The phase referencing uses only the two designated calibrators J1241+602 and J1234+619. Single source self-calibration has an additional calibration step. Only the brightest detected source (J123659+621833) is used for self-calibration with a solution interval of 6 min and MSSC uses 9 sources in MSSC. All entries correspond to values with calibrated weights, apart from entries in bold which are detections with natural weighting. The * represents sources which did not reach the detection threshold of 6σ but their flux densities could be measured, whereas N-D (non-detection) indicates sources that did not reach the detection threshold and their flux densities could not be measured. Bottom panel: a summary of the total number sources that reached the 6σ detection threshold with each calibration technique along with the percentage of failed solutions during the last iteration of self-calibration.

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