Summary of Data Quality Observations of 4/12/95 ------------------------------------------------ Bob Sault, Robin Wark * Overall the results were good, and are quite similar to the results of the 1/11/95 run. * There was a large amount of data flagged in this run (15-20%). This appears to be a combination of the automatic flagger, poor phase stability and the source being tracked until it set. * Phase stability at times was very poor, with 50 degrees phase variation between integrations at 6cm. Indeed it is possible to see the phase variation/atmospheric disturbance progressing over time along the array. This does not seem to have affected the overall results. * Investigations resulting from previous DQO observations shows that there are spikes in the leakage (7%) at 1326 and 1440 MHz, with a corresponding dip in the total intensity gain. Note that 1326 MHz is within the normal continuum band. * The polarised flux of 0823 is consistent with a rotation measure of 400 +/- 10 rad/m/m. At 1344 MHz this represents about 140 degrees of rotation over a bandwidth of 100 MHz. The linearly polarised flux is approx 20cm 3 mJy 13cm 25 mJy 6cm 50 mJy 3cm 25 mJy Array: 6C Fields: Calibrator 0823-500 Offset Calibrator 0823_a Blank Field 0823_b Frequencies: 1344 2368 4800 8640 MHz The offset calibrator field was offset in RA,DEC from 0823-500 by 0,-420 arcsec at 1344 MHz 0,-420 arcsec at 2368 MHz 0,-120 arcsec at 4800 MHz 0,-120 arcsec at 8640 MHz See the end of this document for an explanation of terms and the filenaming convention. ------------------------------------------------------------------------ Flagging statistics after ATLOD ------------------------------- File XX% YY% XY% YX% ---- --- --- --- --- 0823-500.1344 2.3% 2.1% 2.3% 2.0% 0823-500.2368 0.6% 0.4% 0.4% 0.6% 0823-500.4800 1.2% 1.4% 1.2% 1.4% 0823-500.8640 0.9% 0.4% 0.5% 0.8% 0823_a.1344 0.1% 0.1% 0.1% 0.1% 0823_a.2368 0.0% 0.0% 0.0% 0.0% 0823_a.4800 0.0% 0.2% 0.2% 0.0% 0823_a.8640 0.4% 0.1% 0.2% 0.4% 0823_b.1344 0.1% 0.0% 0.0% 0.0% 0823_b.2368 0.1% 0.1% 0.0% 0.1% 0823_b.4800 0.1% 0.1% 0.1% 0.1% 0823_b.8640 0.0% 0.0% 0.0% 0.0% ---------------------------------------------- Closure phase statistics for the point sources File Th.Phase Sigmas ---- -------- ------ 0823-500.1344 0.040 16.00 0823-500.2368 0.035 5.49 0823-500.4800 0.072 1.35 0823-500.8640 0.176 1.60 0823_a.1344 0.035 14.94 0823_a.2368 0.042 3.14 0823_a.4800 0.061 1.34 0823_a.8640 0.178 1.79 --------------------------------------- Post-reduction flagging statistics ---------------------------------- File XX% YY% XY% YX% ---- --- --- --- --- 0823-500.1344-cal 21.8% 21.8% 21.8% 21.8% 0823-500.2368-cal 8.6% 8.6% 8.6% 8.6% 0823-500.4800-cal 11.3% 11.3% 11.3% 11.3% 0823-500.8640-cal 12.6% 12.6% 12.6% 12.6% 0823_a.1344-cal 13.5% 13.5% 13.5% 13.5% 0823_a.2368-cal 0.8% 0.8% 0.8% 0.8% 0823_a.4800-cal 20.2% 20.2% 20.2% 20.2% 0823_a.8640-cal 24.1% 24.1% 24.1% 24.1% 0823_b.1344-cal 8.9% 8.9% 8.9% 8.9% 0823_b.2368-cal 4.8% 4.8% 4.8% 4.8% 0823_b.4800-cal 4.8% 4.8% 4.8% 4.8% 0823_b.8640-cal 18.0% 18.0% 18.0% 18.0% ======================================================================== File Th. RMS Sigmas D.R. Pk Val ---- ------- ------ ---- ------ 0823-500.1344-low.icln 2.82E-04 7.92 2436 5.440 0823-500.1344-low.qmap 2.82E-04 2.49 5 0.003 0823-500.1344-low.umap 2.82E-04 1.81 4 0.002 0823-500.1344-low.vmap 2.82E-04 2.05 6 0.003 0823-500.2368-low.icln 4.21E-04 3.06 4297 5.548 0823-500.2368-low.qmap 4.21E-04 2.80 13 0.016 0823-500.2368-low.umap 4.21E-04 2.45 14 0.014 0823-500.2368-low.vmap 4.21E-04 2.10 4 0.004 0823-500.4800-low.icln 4.47E-04 1.97 3495 3.085 0823-500.4800-low.qmap 4.47E-04 7.13 17 0.054 0823-500.4800-low.umap 4.47E-04 1.09 4 0.002 0823-500.4800-low.vmap 4.47E-04 1.16 4 0.002 0823-500.8640-low.icln 5.78E-04 0.63 3970 1.439 0823-500.8640-low.qmap 5.78E-04 2.33 14 0.018 0823-500.8640-low.umap 5.78E-04 0.99 5 0.003 0823-500.8640-low.vmap 5.78E-04 1.14 4 0.002 0823-500.1344-full.icln 1.07E-04 14.42 3527 5.436 0823-500.1344-full.qmap 1.07E-04 3.43 5 0.002 0823-500.1344-full.umap 1.07E-04 2.74 5 0.002 0823-500.1344-full.vmap 1.07E-04 3.87 5 0.002 0823-500.2368-full.icln 1.10E-04 5.72 8824 5.547 0823-500.2368-full.qmap 1.10E-04 5.21 27 0.015 0823-500.2368-full.umap 1.10E-04 4.90 28 0.015 0823-500.2368-full.vmap 1.10E-04 4.11 5 0.002 0823-500.4800-full.icln 9.73E-05 4.01 7894 3.084 0823-500.4800-full.qmap 9.73E-05 17.34 32 0.055 0823-500.4800-full.umap 9.73E-05 1.36 5 0.001 0823-500.4800-full.vmap 9.73E-05 1.28 5 0.001 0823-500.8640-full.icln 1.13E-04 1.86 6830 1.435 0823-500.8640-full.qmap 1.13E-04 6.36 26 0.019 0823-500.8640-full.umap 1.13E-04 1.45 17 0.003 0823-500.8640-full.vmap 1.13E-04 1.17 5 0.001 0823_a.1344-full.icln 1.05E-04 14.67 3125 4.813 0823_a.1344-full.qmap 1.05E-04 4.47 15 0.007 0823_a.1344-full.umap 1.05E-04 4.02 5 0.002 0823_a.1344-full.vmap 1.05E-04 2.22 8 0.002 0823_a.2368-full.icln 1.06E-04 10.15 3834 4.143 0823_a.2368-full.qmap 1.06E-04 32.51 20 0.069 0823_a.2368-full.umap 1.06E-04 27.90 8 0.024 0823_a.2368-full.vmap 1.06E-04 20.73 14 0.031 0823_a.4800-full.icln 9.95E-05 4.51 6402 2.870 0823_a.4800-full.qmap 9.95E-05 18.32 30 0.054 0823_a.4800-full.umap 9.95E-05 1.79 4 0.001 0823_a.4800-full.vmap 9.95E-05 1.36 5 0.001 0823_a.8640-full.icln 1.21E-04 1.53 6251 1.152 0823_a.8640-full.qmap 1.21E-04 11.26 22 0.030 0823_a.8640-full.umap 1.21E-04 4.60 6 0.003 0823_a.8640-full.vmap 1.21E-04 6.33 8 0.006 0823_b.1344-full.imap 1.01E-04 5.61 6 0.003 0823_b.1344-full.qmap 1.01E-04 1.19 5 0.001 0823_b.1344-full.umap 1.01E-04 1.24 4 0.001 0823_b.1344-full.vmap 1.01E-04 0.96 5 0.000 0823_b.2368-full.imap 1.08E-04 1.92 7 0.002 0823_b.2368-full.qmap 1.08E-04 0.97 5 0.000 0823_b.2368-full.umap 1.08E-04 0.99 5 0.000 0823_b.2368-full.vmap 1.08E-04 0.95 5 0.000 0823_b.4800-full.imap 9.46E-05 1.21 7 0.001 0823_b.4800-full.qmap 9.46E-05 1.10 4 0.000 0823_b.4800-full.umap 9.46E-05 1.08 5 0.000 0823_b.4800-full.vmap 9.46E-05 1.08 4 0.000 0823_b.8640-full.imap 1.18E-04 1.11 5 0.001 0823_b.8640-full.qmap 1.18E-04 1.16 4 0.001 0823_b.8640-full.umap 1.18E-04 1.09 5 0.001 0823_b.8640-full.vmap 1.18E-04 1.07 5 0.001 ======================================================================== Explanation of Terms: --------------------- XX%,YY%,XY%,YY% Percentage of XX, XY, YX and YY correlations flagged (excluding on-line flagging and shadowing). Th.Phase The theoretical closure phase (in degrees) based on thermal noise arguments (for the 5-minute time averaging used). Th. RMS The theoretical RMS in an image based on thermal noise arguments. Sigmas The factor by which the relevant meausre exceeds either of the above two theoretical levels. Ideally this should be 1. D.R. Dynamic range of an image, defined as the ratio of the peak absolute value divided by the RMS. For the CLEANed Stokes-I images of the calibrators, the RMS is evaluated outside the inner quarter of the image. Otherwise the RMS is evaluated over the entire image. Pk Val Peak value in an image in Jy. Explanation of File names: -------------------------- File names are of the form FIELD.FREQ Raw visibility data, giving the field name and observing frequency. FIELD.FREQ-cal Calibrated/flagged visibility data. FIELD.FREQ-low.TYPE Low resolution image, imaging the entire primary beam. TYPE gives the Stokes parameter and whether the image is CLEANed ("cln") or a dirty image ("map"). FIELD.FREQ-full.TYPE Full resolution image, but imaging only a subportion of the primary beam. TYPE is as above.