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 (18:42 to 19:06) to compute the bandpass correction (with mfcal). No time-variable was bandpass applied.

The first interesting feature (after applying the bandpass correction and 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.

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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