National Radio Astronomy Observatory Memo -------------------------------------------------------------------------------- Updated: 28 May 1993 To : VLBA users From : J.M. Wrobel Subject: Your recent VLBA project 1. WHERE ARE YOUR VLBA OBSERVING LOGS, CALIBRATION FILES, AND TAPE LOGS? Machine readable copies of VLBA observing logs, calibration files, and tape logs are (or soon will be) on UVAX1 at the Array Operations Center (AOC) in Socorro. These files will be in directory [nug.mmmyy] for Network projects and in directory [nug.vlba.mmmyy] for non-Network projects. 'mmmyy' is a code for the month and year of your observations (e.g., jun93). VLBA observing logs contain operator entered comments, and are called 'bbblog.vlba', where 'bbb' is your Network or VLBA project code (e.g., bw1a). Calibration files contain system temperatures, weather station data, and flagging data for all available VLBA antennas, and are called 'bbbcal.vlba', where 'bbb' is as above. VLBA tape logs contain lists of the VLBI tapes used for projects, and are called 'bbbtap.vlba', where 'bbb' is as above. VLBA operations will e-mail your observing logs, calibration files, and tape logs to the processor indicated on your project cover sheet. VLBA observing logs will be e-mailed to PIs whose addresses are known to VLBA operations. If you want your observing log but do not receive it via e-mail and are not able to gather it from UVAX1 (see item 3), then contact VLBA operations with either an e-mail address (Internet is preferred) or a request that a paper copy be sent. Communicate with VLBA operations by telephone at 505-835-7250 or 7251; or by e-mail to NRAO user VLBAOPS. The following list gives the appropriate e-mail addresses for user VLBAOPS in various mail systems: Internet vlbaops@nrao.edu Bitnet use Internet address SPAN east::"vlbaops@nrao.edu" SPAN (alternate) 6913::"vlbaops@nrao.edu" Calibration files are often very large, and in the past some PIs have complained when these were automatically e-mailed to them. Thus if you want your calibration file and are not able to gather it from UVAX1 (see item 3), then contact VLBA operations with a request that an e-mailed or a paper-mailed version be sent to you. The contents of the [nug.mmmyy] and [nug.vlba.mmmyy] areas will be backed up and removed from disk after one year has elapsed. 2. IF THE VLA WAS ALSO INVOLVED IN YOUR VLBI PROJECT... A VLA observing log, including VLBI tape information, will be sent to you by VLA operations. This will be done by e-mail if possible, and by paper mail otherwise. If e-mailing is possible, machine-readable copies will also be sent to the NUG account for archive purposes and to the processor indicated on your project cover sheet. A VLA calibration file called 'bbbcal.y' will appear in the same UVAX1 subdirectory you find your VLBA calibration files. An explanatory memo will be appended to the end of your VLA calibration file. I will make one attempt to e-mail the calibration file to the PI. If this fails, then I will assume that the PI will gather the VLA calibration file from UVAX1 (see item 3). A PI can also specifically request that I send a paper-mailed version of the calibration file. Such requests can be made by e-mail to NRAO user JWROBEL or by phoning me at 505-835-7392. 3. ACCESSING YOUR LOGS AND CALIBRATION INFORMATION ON UVAX1 3.1. Get the NUG Password To access the log and calibration files described above, you must log in to UVAX1 as user NUG. This NUG account is password protected. For the password, contact an active NUG user or one of the following people: Analysts 1-505-835-7238, AOC office (e-mail to NRAO user ANALYSTS or NUG) or -7239 or -7359 Phil Diamond 1-505-835-7365, AOC office (e-mail to NRAO user PDIAMOND) Craig Walker 1-505-835-7247, AOC office (e-mail to NRAO user CWALKER) Joan Wrobel 1-505-835-7392, AOC office (e-mail to NRAO user JWROBEL) Anton Zensus 1-505-835-7348, AOC office (e-mail to NRAO user AZENSUS) Walter Alef 49-228-525220, Bonn processor. The password should NOT be transmitted in an e-mail message. E-mail user names are given for AOC people so you can contact them by either phone or e-mail if you experience trouble accessing UVAX1. E-mail addresses for NRAO were given in item 1 for user VLBAOPS. 3.2. Dial In Call 505-835-7010. To the 'SOCORRO DDS:' prompt, respond 'MAX' ( is a carriage return). More than one may be required. To the 'Xt_command:' prompt, respond 'C UVAX1'. To the 'username:' prompt, respond 'NUG'. Give the password when requested. 3.3. Span Type 'SET HOST EAST' (or 'SET HOST 6913'). To the 'username:' prompt, respond with '146.88.1.6!'. To the next 'username:' prompt, respond with 'NUG'. Give the password when requested. 3.4. Internet You can use ftp to examine and transfer files in the NUG area over the Internet. The Internet address of UVAX1 is UVAX1.AOC.NRAO.EDU or 146.88.1.6. Use the standard ftp procedure, which requires the login name and password, to access the NUG area. You can also use UVAX1's Internet address to telnet in to the NUG account; a password will be required. 4. VLBA ZENITH SENSITIVITIES AND GAIN CURVES The information in this section is taken from updates to VLBA Test Memorandum 40 by Craig Walker. Users wanting full details should refer to that document. 4.1. VLBA Zenith Sensitivities Consult the Tcal and zenith sensitivity tables below to determine the appropriate sensitivity to use for your project. Note that the tabulated sensitivity is based on the assumed Tcal. In some cases, that Tcal is clearly wrong. However, as long as the measured Tsys is based on the same Tcal, your VLBI data can be calibrated correctly with the listed sensitivity. Systematic 7 mm results are not yet available. Until they are, please contact Anton Zensus regarding parameters at this wavelength. For wavelengths between 20 and 4 cm, the zenith sensitivities tablulated below are accurate to between 2 and 5 %, with the 6 and 4 cm data being the best. The 13 cm results are somewhat more variable, probably because of effects of the dichroic plate. For 2 and 1 cm, the accuracy is worse because the calibrators are weaker and weather effects are stronger; those results are probably good to 10 % with some antennas being better. Zenith sensitivity errors may be 20 % at 90 cm and somewhat lower at 50 cm. Tcal (K) ========================================================================= *1* *1* *2* Ant Pol 90cm 50cm 20cm 13cm 13cmSX 6cm 4cm 4cmSX 3cm 2cm 1cm ------------------------------------------------------------------------- SC RCP: 7.70 4.00 0.80 1.26 1.26 2.39 3.48 3.48 ---- 2.71 14.21 LCP: 6.90 4.00 0.94 1.34 1.34 2.39 3.44 3.44 ---- 2.78 13.96 HN RCP: 8.00 4.69 1.83 1.20 1.20 1.40 2.59 2.59 ---- 3.20 11.42 LCP: 9.00 4.60 1.75 1.48 1.48 1.30 2.77 2.77 ---- 2.91 11.44 NL RCP: 9.00 5.20 1.74 1.02 1.02 3.47 4.03 4.03 ---- 3.03 10.27 LCP: 9.00 5.50 1.84 1.12 1.12 3.79 4.08 4.08 ---- 2.93 9.43 FD RCP: 11.70 5.60 3.34 2.82 2.82 3.34 3.89 3.89 ---- 3.85 8.06 LCP: 11.10 6.00 3.43 2.00 2.00 3.26 3.81 3.81 ---- 3.92 7.74 LA RCP: 8.90 5.70 3.60 0.92 0.92 3.43 3.72 3.72 ---- 3.73 7.26 LCP: 9.30 5.70 3.69 1.28 1.28 3.40 3.82 3.82 ---- 3.96 7.41 PT RCP: 22.60 10.00 2.70 2.42 2.42 2.89 3.52 3.52 4.12 1.90 7.85 LCP: 25.20 10.30 2.59 2.62 2.62 3.07 3.96 3.96 3.86 1.66 10.10 KP RCP: 10.20 6.90 3.07 1.42 1.42 2.63 3.71 3.71 ---- 2.95 23.33 LCP: 10.00 6.70 3.06 1.52 1.52 2.37 3.48 3.48 ---- 2.70 23.98 OV RCP: 7.00 4.00 2.81 1.52 1.52 1.09 3.42 3.42 ---- 4.30 11.90 LCP: 6.50 4.00 2.81 1.32 1.32 1.20 3.69 3.69 ---- 3.98 17.20 BR RCP: 7.20 4.00 2.87 1.04 1.04 1.86 3.78 3.78 ---- 3.61 3.57 LCP: 7.10 4.00 2.64 1.02 1.02 1.79 3.80 3.80 ---- 3.79 3.74 MK RCP: 5.30 4.20 3.39 4.14 4.14 1.40 4.13 4.13 ---- 3.92 3.43 LCP: 5.30 4.20 3.56 6.16 6.16 1.30 3.79 3.79 ---- 3.49 3.09 ========================================================================= See notes to zenith sensitivity table. Zenith Sensitivity (K/Jy) ========================================================================= *1* *1* *2* Ant Pol 90cm 50cm 20cm 13cm 13cmSX 6cm 4cm 4cmSX 3cm 2cm 1cm ------------------------------------------------------------------------- SC RCP: 0.110 0.087 0.094 0.077 0.064 0.135 0.112 0.107 ---- ----- 0.100 LCP: 0.109 0.091 0.119 0.077 0.064 0.130 0.119 0.116 ---- ----- 0.110 HN RCP: 0.089 0.055 0.093 0.091 0.075 0.121 0.094 0.087 ---- 0.105 0.084 LCP: 0.103 0.053 0.089 0.101 0.085 0.123 0.100 0.091 ---- 0.105 0.080 NL RCP: 0.075 0.043 0.084 0.085 0.068 0.125 0.110 0.109 ---- 0.117 0.093 LCP: 0.078 0.055 0.091 0.096 0.078 0.100 0.114 0.109 ---- 0.117 0.096 FD RCP: 0.098 0.085 0.100 0.109 0.091 0.119 0.126 0.121 ---- 0.109 0.061 LCP: 0.094 0.093 0.101 0.105 0.087 0.126 0.117 0.110 ---- 0.110 0.059 LA RCP: 0.069 0.069 0.091 0.080 0.068 0.146 0.119 0.114 ---- 0.148 0.101 LCP: 0.073 0.073 0.123 0.093 0.080 0.137 0.121 0.117 ---- 0.137 0.100 PT RCP: 0.151 0.068 0.117 0.091 0.078 0.135 0.132 0.114 0.130 0.094 0.116 LCP: 0.189 0.071 0.110 0.105 0.094 0.146 0.123 0.109 0.166 0.101 0.116 KP RCP: 0.084 0.080 0.100 0.078 0.064 0.139 0.125 0.112 ---- 0.121 0.101 LCP: 0.089 0.084 0.101 0.080 0.066 0.134 0.126 0.119 ---- 0.114 0.107 OV RCP: 0.109 0.085 0.087 0.098 0.078 0.121 0.103 0.100 ---- 0.100 0.078 LCP: 0.105 0.093 0.107 0.112 0.080 0.126 0.100 0.096 ---- 0.098 0.100 BR RCP: 0.098 0.085 0.100 0.082 0.069 0.123 0.110 0.109 ---- 0.105 0.084 LCP: 0.107 0.087 0.098 0.098 0.082 0.117 0.119 0.114 ---- 0.098 0.082 MK RCP: 0.077 0.103 0.098 0.249 0.247 0.144 0.128 0.126 ---- 0.112 0.096 LCP: 0.080 0.094 0.101 0.249 0.249 0.142 0.125 0.119 ---- 0.110 0.089 ========================================================================= Notes: *1* The appended 'SX' means that 13cm and 4cm were observed simultaneously. *2* PT has the only planned 3 cm receiver. 4.2. VLBA Gain Curves Post-observing amplitude adjustments might be necessary for an antenna's position depdendent gain (the 'gain curve') and for the atmospheric opacity above an antenna. Optimal schemes for doing the latter adjustments are being developed. The VLBA antenna gain curves can be assumed to be flat at most wavelengths. However, at 2 cm, 1 cm, and 7 mm, the gain curves are NOT flat; we are currently in the process of systematically quantifying the gain curves at these wavelengths, and we plan to notify the user community once gain curves are available in tabulated form and/or as polynomial fits. (document ends)