National Radio Astronomy Observatory                           Memo
-------------------------------------------------------------------
 Updated: 2007 August 1
 To     : VLBA users
 From   : Peggy Perley(pperley@aoc.nrao.edu)
 Subject: Your recent VLBA program


1. AUTOMATED CALIBRATION TRANSFER FOR VLBA CORRELATOR OUTPUT

Your data includes automated calibration transfer tables for data
from the VLBA correlator.  These transfer tables of calibration 
information includes data from the 10 VLBA antennas, as well as selected
information from the High Sensitivity Array antennas (VLA, Green Bank,
Effelsberg and Arecibo) which currently provide VLBA-style monitor data.
Significant changes to AIPS have been required to introduce calibration
transfer. To take advantage of new tools and current updates, it is
highly recommended that users download the latest version of AIPS 
(currently 31DEC06), available from http://www.aoc.nrao.edu/aips. Help
files for a number of AIPS tasks have been updated to reflect the new 
calibration procedures. 

The calibration-transfer process relieves observers of the burden of
creating and inputting calibration files for VLBA and HSA antennas.
Instead, this information is now provided as tables attached to the
FITS data sets output by the VLBA correlator.  The ancillary data
include antenna gain (GC table), system temperature (TY table), pulse
calibration (PC table), flags (FG table), and weather (WX table).
Wise observers will not modify these original tables, as processing
errors might then force the data to be reloaded using FITLD.
Skeptical observers can simply delete the appropriate tables created
by FITLD and generate their tables in the old manner using fetched
files (see section 2).  Please send comments to cwalker@nrao.edu, and
send bug reports to daip@nrao.edu, with a copy to cwalker@nrao.edu.

1.1 Important Messages for VLBA Users

Users are advised to check http://www.vlba.nrao.edu/astro/messages/
for additional information tha may affect their data.

2. VLBA/VLA FILE SUMMARY SHOULD YOU NEED OR WISH TO FETCH FILES

2.1. Anonymous FTP

The session
    ftp ftp.aoc.nrao.edu      ! or 146.88.1.10
    Name: anonymous
    Password: <your e-mail address>
    ftp> cd pub
    ftp> get vlba_gains.key
    ftp> quit
fetches file `vlba_gains.key' containing VLBA zenith sensitivities and
gain curves, with an explanatory preamble.  This file is *not* needed
if you receive a distribution tape from the VLBA correlator with GC
tables attached.

2.2. File Server vlbiobs

2.2.1. What Files Might You Want?

If `mmmyy' is a code for the month and year of the beginning of your
program (e.g., oct05) and `pppppp' is your program code (e.g.,
bw999x), then the following files are stored in directory
/home/vlbiobs/astronomy/mmmyy/pppppp:
  + pppppplog.vlba:  VLBA observing log containing comments entered
    by the array operator.  File is automatically e-mailed to
    observers whose addresses are known to VLBA operations.
  + ppppppcal.vlba.gz:  Gzipped VLBA calibration file containing
    system temperatures, flagging information, pulse cal and weather 
    station data, scan summaries, and VLBA tape recorder information
    for all available VLBA antennas (plus the VLA).  File is *not*
    needed if you receive a distribution tape from the VLBA 
    correlator with TY, FG, PC, and WX tables attached.
  + pppppptsm.XX.ps.gz:  Gzipped PostScript plots of selected data
    from file ppppppcal.vlba.gz for each available antenna with 
    station code XX = SC, HN, NL, FD, LA, PT, KP, OV, BR, MK, or Y.
  + pppppplog.y:  VLA observing log containing comments entered
    by the array operator, if VLA was used.  File is automatically 
    e-mailed to observers whose addresses are known to VLA operations.
  + ppppppcal.y.gz:  Gzipped VLA calibration file containing
    calibration information for all VLA polarizations and IFs,
    if VLA was used.  File starts with an explanatory preamble.
    File *is* needed even if you receive a distribution tape from 
    the VLBA correlator with TY, FG, PC, and WX tables attached.
  + pppppptap.vlba:  VLBA tape log made for programs not correlated
    in Socorro.  File lists VLBI tapes used.

2.2.2. Browse the File Server VLBIOBS

Operations staff have devised a web browser to navigate the file
server, as well as view and retrieve its text and PostScript files,
gzipped or not.  This browser can be reached from
http://www.vlba.nrao.edu/astro/obscor, then click on "Browse the
VLBIOBS File Server".

(document ends)