= [wiki:TestCaseData]/2009-10-14_1934-638_commissioning_data =

== Description ==
Investigation of bandpass variations using the long observations of 1934-638 done during scientific commissioning.

This data set has an unusual fault - the time stamps on some records are incremented by 86400 seconds (instead of 0 or 1). This causes miriad to complain about the visibilities being out of time order; this is not the problem, the problem is the timestamps are off by 1 day.
To hack out the problem records, run {{{uvflag}}} with these selections:

{{{
   select=visibility(91993,93432)
   select=visibility(83353,84792)
   select=visibility(63361,64800)
   select=visibility(56161,57600)
   select=visibility(44581,44640)
   select=visibility(8581,8640)
}}}

Initial calibration was to take a small section of the data (2009-04-11_18:42 to 19:06) to compute the bandpass correction (with mfcal). This bandpass correction was applied to all the data on either side of this time range.  No time-variable was bandpass applied.

=== 6 cm Data ===
The first interesting feature (after taking out the median amplitude and phase of the spectrum at each time step) is that there is a clear systematic change in phase gradient (ie astronomical phase as a function of channel number) with time, that has larger amplitude and varies faster on longer baselines.

=== 3 cm Data ===
The 3 cm data exhibits the same systematic change in phase gradient and is of similar magnitude.

=== Data Set(s) ===
{{{
2009-04-11_1103.CX168
2009-04-11_1115.CX168
2009-04-11_1219.CX168
2009-04-11_1340.CX168
2009-04-11_1500.CX168
2009-04-11_1621.CX168
2009-04-11_1741.CX168
2009-04-11_1901.CX168
2009-04-11_2022.CX168
2009-04-11_2142.CX168
2009-04-11_2303.CX168
2009-04-12_0018.CX168
2009-04-12_0139.CX168
2009-04-12_0300.CX168
2009-04-12_0421.CX168
2009-04-12_0442.CX168
2009-04-12_0602.CX168
2009-04-12_0721.CX168
2009-04-12_0824.CX168
2009-04-12_0825.CX168
2009-04-12_0835.CX168
}}}

== Tickets ==
N/A (so far)

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