Hi,

I used two versions of miriad (20100204 and 20100218) to confirm if the 7 mm fix gives a sensible result (the latter has the updated version of atlod). The CABB dataset tested is from project C956; the observations took place on 2009 Aug 13/14 at 43 and 45 GHz. The target was the CSS source B1221-423, which is resolved into a number of components in lower-resolution data at 3 cm (Safouris et al. 2003, PASA, 20, 1). The primary, secondary, and bandpass calibrators were 1934-638, 1144-379, and 0420-014, respectively.

I followed exactly the same standard data reduction procedure each time (i.e. the procedure outlined in the ATCA users' guide). In atlod I used the options birdie, xycorr, rfiflag, opcorr and noauto. The data were manually flagged with blflag.

Here are some of my findings at 43 GHz; the output at 45 GHz is very similar. All the plots are in the file

http://www.astro.soton.ac.uk/~jb34g09/7mm_plots.tar.gz1. The bandpass calibration is nearly identical in both versions of miriad (plots 0420_X/Y_feb04/18). A quick check with uvflux after using mfcal:

--Feb 04--

UvFlux: version 1.0 24-Jun-99

Applying bandpass corrections to 0420-014.43000

Applying gain corrections to 0420-014.43000

--------------------------------------------------------------------------------

Source Pol Theoretic Vector Average RMS Average RMS Amp Number

RMS (real,imag) Scatter Amp Scatter Corrs

------ --- -------- -------------------- ------- --------- -------- ------

0420-014 I 1.8E-01 5.849E+00 -4.694E-04 1.5E-01 5.851E+00 1.45E-01 779875

Q 1.8E-01 2.079E-03 6.338E-04 1.4E-01 1.771E-01 9.73E-02 779875

U 1.8E-01 -5.133E-02 -9.015E-03 1.5E-01 1.885E-01 1.02E-01 779875

V 1.8E-01 -1.406E-02 -2.941E-02 1.7E-01 2.140E-01 1.12E-01 779875

--------------------------------------------------------------------------------

--Feb 18--

UvFlux: version 1.0 24-Jun-99

Applying bandpass corrections to 0420-014.43000

Applying gain corrections to 0420-014.43000

--------------------------------------------------------------------------------

Source Pol Theoretic Vector Average RMS Average RMS Amp Number

RMS (real,imag) Scatter Amp Scatter Corrs

------ --- -------- -------------------- ------- --------- -------- ------

0420-014 I 1.8E-01 5.849E+00 -4.344E-04 1.5E-01 5.851E+00 1.45E-01 776205

Q 1.8E-01 -2.099E-03 -7.817E-05 1.4E-01 1.770E-01 9.72E-02 776205

U 1.8E-01 5.146E-02 9.124E-03 1.5E-01 1.884E-01 1.02E-01 776205

V 1.8E-01 1.399E-02 2.921E-02 1.7E-01 2.141E-01 1.12E-01 776205

--------------------------------------------------------------------------------

so nothing has really changed except that the signs for Q/U/V have been flipped, as expected.

2. Here is some output for the secondary calibrator 1144-379. Again, nothing has changed significantly except that the signs have flipped for Q/U and the leakages.

--Feb 04 version of Miriad--

MFCAL: MfCal: version 1.1 17-Dec-09

MFCAL: Executed on: 10MAR02:10:04:36.0

MFCAL: Command line inputs follow:

MFCAL: vis=1144-379.43000

MFCAL: interval=0.1

MFCAL: options=nopassol

GPCAL: Gpcal: version 1.0 30-Apr-09

GPCAL: Executed on: 10MAR02:10:06:21.0

GPCAL: Command line inputs follow:

GPCAL: vis=1144-379.43000

GPCAL: options=qusolve,xyvary

GPCAL: interval=0.1

GPCAL: I flux density: 0.808

GPCAL: Percent Q: 5.846

GPCAL: Percent U: -3.893

GPCAL: Leakage terms:

GPCAL: Ant 1:Dx,Dy = ( 0.008,-0.001),

(-0.008, 0.001)

GPCAL: Ant 2:Dx,Dy = (-0.009,-0.005),

( 0.003,-0.003)

GPCAL: Ant 3:Dx,Dy = (-0.024,-0.002),

( 0.018, 0.001)

GPCAL: Ant 4:Dx,Dy = (-0.008, 0.002),

( 0.005, 0.004)

GPCAL: Ant 5:Dx,Dy = ( 0.022, 0.002),

(-0.026, 0.004)

GPCAL: Ant 6:Dx,Dy = (-0.001,-0.003),

(-0.004, 0.000)

GPBOOT: Miriad GpBoot: version 21-Jan-01

GPBOOT: Executed on: 10MAR02:10:06:23.0

GPBOOT: Command line inputs follow:

GPBOOT: cal=1934-638.43000

GPBOOT: vis=1144-379.43000

GPBOOT: select=+time(6:50,7:40)

GPBOOT: Secondary flux density scaled by: 1.051

UvFlux: version 1.0 24-Jun-99

Applying bandpass corrections to 1144-379.43000

Applying gain corrections to 1144-379.43000

Applying polarization leakage corrections to 1144-379.43000

--------------------------------------------------------------------------------

Source Pol Theoretic Vector Average RMS Average RMS Amp Number

RMS (real,imag) Scatter Amp Scatter Corrs

------ --- -------- -------------------- ------- --------- -------- ------

1144-379 I 2.0E-01 8.489E-01 2.226E-05 1.7E-01 8.663E-01 1.61E-0114039585

Q 2.0E-01 4.962E-02 -1.751E-05 1.6E-01 2.009E-01 1.24E-0114039585

U 2.0E-01 -3.304E-02 3.166E-05 1.6E-01 1.978E-01 1.23E-0114039585

V 2.0E-01 -4.240E-05 -2.351E-05 1.6E-01 1.955E-01 1.22E-0114039585

--------------------------------------------------------------------------------

--Feb 18 version of Miriad--

MFCAL: MfCal: version 1.1 17-Dec-09

MFCAL: Executed on: 10MAR02:11:09:04.0

MFCAL: Command line inputs follow:

MFCAL: vis=1144-379.43000

MFCAL: interval=0.1

MFCAL: options=nopassol

GPCAL: Gpcal: version 1.0 30-Apr-09

GPCAL: Executed on: 10MAR02:11:10:49.0

GPCAL: Command line inputs follow:

GPCAL: vis=1144-379.43000

GPCAL: options=qusolve,xyvary

GPCAL: interval=0.1

GPCAL: I flux density: 0.811

GPCAL: Percent Q: -5.845

GPCAL: Percent U: 3.891

GPCAL: Leakage terms:

GPCAL: Ant 1:Dx,Dy = (-0.007, 0.001),

( 0.009,-0.001)

GPCAL: Ant 2:Dx,Dy = ( 0.009, 0.005),

(-0.003, 0.003)

GPCAL: Ant 3:Dx,Dy = ( 0.023, 0.001),

(-0.020,-0.001)

GPCAL: Ant 4:Dx,Dy = ( 0.007,-0.002),

(-0.005,-0.005)

GPCAL: Ant 5:Dx,Dy = (-0.020,-0.001),

( 0.027,-0.004)

GPCAL: Ant 6:Dx,Dy = ( 0.001, 0.003),

( 0.004, 0.001)

GPBOOT: Miriad GpBoot: version 21-Jan-01

GPBOOT: Executed on: 10MAR02:11:10:50.0

GPBOOT: Command line inputs follow:

GPBOOT: cal=1934-638.43000

GPBOOT: vis=1144-379.43000

GPBOOT: select=+time(6:50,7:40)

GPBOOT: Secondary flux density scaled by: 1.047

UvFlux: version 1.0 24-Jun-99

Applying bandpass corrections to 1144-379.43000

Applying gain corrections to 1144-379.43000

Applying polarization leakage corrections to 1144-379.43000

--------------------------------------------------------------------------------

Source Pol Theoretic Vector Average RMS Average RMS Amp Number

RMS (real,imag) Scatter Amp Scatter Corrs

------ --- -------- -------------------- ------- --------- -------- ------

1144-379 I 2.0E-01 8.482E-01 1.410E-04 1.7E-01 8.661E-01 1.63E-0114129500

Q 2.0E-01 -4.957E-02 1.182E-05 1.6E-01 2.010E-01 1.24E-0114129500

U 2.0E-01 3.299E-02 1.703E-05 1.6E-01 1.990E-01 1.24E-0114129500

V 2.0E-01 -4.328E-05 2.766E-05 1.6E-01 1.951E-01 1.22E-0114129500

--------------------------------------------------------------------------------

In the Feb 18 version of miriad, the polarisation PA for 1144-379 is consistent with the value at 12 mm, which is encouraging. What is strange, however, is that the gain amplitudes are significantly different around the time 04:00 - 06:00 when the source transits (plots 1144_X/Y_feb04/18). The phase plots are identical, though.

3. After copying over the calibration tables to the target, the Q/U/V data are a lot noisier on some baselines in the later version of miriad (plots b1221_quv_feb04/18). The image quality is also significantly poorer for both Q and U (plots b1221-423_q/u_feb04/18). Apart from the flipped signs, the Q and U images obtained with the Feb 04 version of miriad look sensible given the images I already have of the source at 12 mm and 3 cm. This is not the case in the Feb 18 version. On the other hand, I cannot see any obvious problems for Stokes I; both versions of miriad give similar final images and flux densities.

Any ideas about what is going on?

Thanks,

Jess