p1978 did polarization measurements on pulsars
using lbw.
Problems with the cal deflections:
The following problems were reported in jun07:
The cal deflection in the two polarizations were not
correlating. This could be caused if two diodes were being used rather
than 1. The measurement dates were:
The data was in file: P1978.J1911+1758_north.wapp1.53485.0003.
11 cal cycles (about .5 seconds) were averaged together.
The top plot shows the spectral band passes for the 4 stoked
parameters. The solid line in cal on + Tsys, the dashed line is calOff
+ Tsys. No bandpass correction has been done. White is I, red is
Q, green is U, and Blue is V.
The bottom plot has the stokes parameters of the cal deflection
(calOn-calOff). This should be 100 % polarized if a single diode was
used. Both U and V are zero. There is a small amount of power in Q.
This is because the polA,PolB band passes have not been calibrated
properly... The plot shows that two diodes were used.
This has 3 seconds of cal on followed by 3 seconds of cal off.
The first page shows the calOn and calOff stokes values. The
dashed lines are cal Off.
The 2nd page shows the stokes parameters for the cal deflection.
The bandpass has been corrected using calon-caloff. The phase ramp from
the iflo has also been corrected.
The power in Stokes U is equal to the power in stokes I. This
is to be expected for a single diode feeding both polarizations:
Conclusions:
Two diodes were used for the wapp cal deflections on
25apr05.
Spider scan data taken on the same day with the interim
correlator used a single diode.
The hardware was functioning properly. The problem must have been
that the gui did not configure the cal type correctly before taking the
data.
The wapp pulsar headers do not have the cal type used for the
measurement (hcorcal,hcal, etc..).
The cima.log file shows that the hcorcal was the cal that was
requested but it does not show if this value was actually sent to the
system (no vwsend line).