Hi Mark,
It seems that I used the wrong calibrators. I'm trying on G018 now, another source which had fewer problems in the 5GHz data, so presumably I should use 0023-263 as the phase calibrator and 1934-638 as still the bandpass calibrator?
I did flagging and calibration again following the link webpage but the dirty image looks like this, which I think might be problematic:

- g018_imap.png (127.72 KiB) Viewed 4829 times
Checking the calibration table and calibrated dataset:
1. uvplt of 1934-638 (axis=real,imag; options=equal,nobase)

- 1934-638_uvplt.png (11.25 KiB) Viewed 4829 times
2. varplt of 0023-263 (yaxis=chi): Does this look like a good parallactic angle coverage, as suggested in the webpage?

- 0023-263_parallactic_angle_coverage.png (7.28 KiB) Viewed 4829 times
3. uvflux of 0023-263: to check if the secondary data fits a point souce:
--------------------------------------------------------------------------------
Pol----Theoretic-----Vector Average----------RMS--------Average----RMS Amp---Number
-----------RMS------------(real,imag)---------Scatter---------Amp-------Scatter----Corrs
------ --- -------- -------------------- ------- --------- -------- ------
I.......8.0E-02....2.939E+00..-4.305E-03...3.0E-01...2.967E+00....1.26E-01..12488424
Q......8.0E-02....-1.432E-03...2.059E-04...8.7E-02....1.035E-01....6.63E-02..12488424
U......8.0E-02.....2.697E-03...3.254E-04...9.3E-02....1.066E-01....7.67E-02..12488424
V......8.0E-02....-7.737E-06...1.815E-04...8.3E-02....1.001E-01....6.06E-02..12488424
--------------------------------------------------------------------------------
4. uvplt of 0023-263 (axis=real,imag; options=equal,nobase):

5. gpplt of 0023-263 (yaxis=phase; options=xygains):

6. gpnorm (vis=0023-263; cal=1934-638): got an error message...
GpNorm: version 1.0 28-Sep-09
### Informational: Bandpass tables present
### Fatal Error: GPNORM does not work correctly in this case
I am not sure if the calibration process went wrong from the above plots and the error in gpnorm might reflect some problem in the data? Problem might also come from flagging for which I only used pgflag (this time it worked and didn't take forever

) in between mfcal and gpcal of both calibrators and after gpcopy and gpaver of the source...
Thanks again!
Tai-An