Current Status of Amplitude Calibration in the EVN. --------------------------------------------------- The following table shows the median absolute amplitude error for EVN stations in for the first two sessions of 2007 (March and June). These results are derived from the pipeline amplitude self-calibration results of all EVN experiments recorded in 2007 which have been pipelined to date. The number in brackets after each entry is the number of experiments that were used to determine the median error for that entry. Station 6cm 18cm 6GHz K-band X-band Cm 0.31(10) 0.19(10) Ef 0.04(7) 0.04(16) 0.05(11) 0.07(1) 0.06(1) Hh 0.03(2) 0.04(3) 0.05(3) Jb 0.08(8) 0.10(17) 0.11(10) Mc 0.04(7) 0.06(15) 0.11(11) 0.07(1) Nt 0.05(8) 0.07(15) 0.06(11) 0.05(1) 0.12(1) On 0.06(8) 0.07(15) 0.09(4) 0.14(1) 0.15(1) Sh 0.06(3) 0.11(10) 0.09(1) Tr 0.03(8) 0.09(16) 0.08(9) Ur 0.06(4) 0.16(10) Wb 0.07(7) 0.06(17) 0.06(11) 0.13(1) Mh 0.12(1) --------------------------------------------------------------------- The blank entries indicates insufficient data. The numbers above are the median absolute error in the antenna gain amplitude (as calculated from pipeline amplitude self calibration). A value above 0.1 indicates a significant error which should be investigated. In addition to the absolute errors summarised here, the EVN pipeline provides details on every experiment processed at JIVE including the sign and time variability of the errors. Points of note: Results are similar to those reported previously, but some improvement is noticed especially at 6 cm. Cm still does not provide Tsys monitoring. Jb cal diode failed in a few occasions in the last year. The failures occurred at L- and C-band in the middle of a session and during e-EVN runs (RL001 and RT004). The problem is under investigation. C-band calibration seems to be good across the network. At L-band, RFI seems to be the major source of errors. Calibration at this frequency is quite variable with occasional experiments having quite large errors. However, most L-band experiments give good results at most stations. In general, 6 GHz calibration has shown neither considerable improvement nor worsening, though there is room for improvement. 22 GHz calibration in 2007 was reasonable. However, only 1 experiments have been analysed. ANTAB Scripts -------------------------------------- Stations continue to produce their own ANTAB files using the 'antabfs' scripts. An improved version of the antabfs script was released by Cormac Reynolds. A few bugs affecting the previous versions were corrected. There was an improvement of the usability of the script, such as clearer on-screen outputs and addition of new switches ("-help" and "-debug"). Also, new features have been included: - The logs for MkIV racks using external filters (e.g. 1 MHz) can now be parsed properly (see experiments ei009*). - AIPS ANTAB has a limit on the number of Tsys entries that it can accept. antabfs now automatically reduces the number of entries put in the ANTAB file to this limit. The excess entries are written as comments so can be restored if desired. - The script should run much faster for VLBA racks than it previously did. - The names of the RXG file(s) used to produce the ANTAB file are now included in the ANTAB file for reference. Giuseppe Cimo' for the Science Operation and Support Group (JIVE)