Scheduling Strategy:
--------------------
The source list for each session satisfies the following requirements:

(1) A total of 30 sources are observed per session. 
(2) Roughly equal spacing in R.A. over 0-24h.
(3) No more than four low declination sources (dec < -10).
(4) No more than four circumpolar sources.
(5) No sources within 12 degrees of the Sun.


Observing Strategy 
------------------ 

Our observations are optimized for obtaining suitably high-dynamic
range, full-polarization images on a sample of ~250 sources at
specific intervals based on the angular speed of each invididual source. We have
adopted the following:

(1) One 24-hr VLBA observing session every 3 weeks (optimum time spacing).
(2) Dual-polarization, 512 Mbps, 4 IFs per polarization hand, 64 MHz total bandwidth.
(3) Scans on a given source are scheduled to have at least 6 antennas
    above 10 degrees elevation.
(4) Typically 9 scans per source, for a total on-source time of ~45 minutes. 
(5) UMRAO single-dish obs. of same sources within a few days of VLBA session.
(6) RATAN single-dish spectral observations whenever possible. 


Data Reduction Method
---------------------

Since several people are carrying out the data reduction, we rely
on standard scripts whenever possible. The major calibration steps are:

 (1) Load data into AIPS, excluding visibilities with weights < 70%.
 (2) Flag bad data according to observation log and elevated system temperatures. 
 (3) Remove correlator bias with ACCOR
 (4) Apply system temperature and opacity amplitude corrections. 
 (5) Apply parallactic angle correction.
 (6) Apply pulse-cal phase corrections (**not possible with 512 Mbps/8IFs).
 (7) Apply cross-hand phase corrections.
 (8) Apply bandpass amplitude corrections.
 (9) Align phases using short-solution interval point-source selfcal.
(10) Average data over 10 second intervals in DIFMAP.
(12) Produce I clean-component model & map in DIFMAP based on self-cal'd data.
(13) Perform amplitude and phase self-cal in AIPS using I model.
(14) Use CCEDT to produce sub-models from I models. 
(15) Determine polarization feed solutions from each source using LPCAL.
(16) Apply median LPCAL solutions to data with SPLIT.
(17) Perform another amplitude and phase self-cal in AIPS using I model.
(18) Export final calibrated data to DIFMAP for automated imaging in I,Q,U.
(19) Produce color fractional polarization plots with D. Homan's scripts.
(20) Re-calibrate to find V flux densities using D. Homan's procedures.


Electric Vector Calibration Method
----------------------------------

(1) Estimate approximate EVPA rotation corrections for each epoch  
from simultaneous UMRAO data on calibrators.

(2) Apply the corrections and check the phases of the dterms for
each IF, Antenna and hand for consistency between epochs.

(3) Throw out any dterm that appears to have
undergone an abrupt change during the period spanned by the epochs. 

(4) Pick one epoch as a "reference" epoch (BL111C was chosen)

(5) Starting with the first epoch (BL111A), find the best rotation correction
that minimizes the phase differences of all dterms between it and the
reference epoch. Repeat for all other epochs. This establishes the
relative rotation correction between epochs. 

(6) Using the UMRAO data, find a single rotation correction to all
epochs that minimizes the EVPA differences between UMRAO and the VLBA
data on calibrators. The establishes the absolute rotation correction to
the reference epoch. 

(7) For subsequent (new) epochs, exploit constancy of DTERM phases at
specific antennas to determine best EVPA rotation for the new epoch.