Changes between Version 4 and Version 5 of Changes/gpcal

Timestamp:

08/17/07 14:40:03 (17 years ago)

Author:

MarkWieringa

Comment:

--

Changes/gpcal

@@ -12 +12 @@
 Research:
  * check whether gpcal reads xyphase from input uv data.
- At present this is in a variable? ''No, xyphase from syscal record can be applied in atlod and is stored in a uv variable (xyphase), but is not read by the calibration tasks.''
+ At present this is in a variable? 
+    * ''No, xyphase from RPFITS syscal records can be applied in atlod and is stored in a uv variable (xyphase), but is not read by the calibration tasks.''
  * Study how miriad stores calibration tables and how we can extend these to store additional variation in frequency for complex antenna gains and leakages.
+    * see MiriadCalibrationTables for some reverse engineered formats and possible extensions.
  * It's unclear to what extent the wide band at high freq (eg 20GHz) is an analogue of the 20cm situation, vis-a-vis calibration (particularly phase winding across band).
+   * ''Phase winding is directly proportional to the relative bandwidth, so across a 2 GHz band at 20 GHz the phase winding due to atmospheric delay would be 10% of the phase variation. For conditions where phase winding causes decorrelation of the vector averaged visibility over the band, we are likely to need selfcalibration on very short timescales. Correcting just the average phase would leave time variable phase slopes across the band in the data. Thus a delay correction should be applied instead. Mfcal can already solve for a time variable delay term on a calibrator, there is no task to do this on a general field yet.''