Summary
 

Observation code	:	VS08u		AIPS Version	:	12DEC00
Date of Observation	:	2001/155		Difmap Version	:	2.3c
Source Name	:	J0309-6058		vsop_difmap used	:	Yes
Calibration Source(s)	:	J0303-62, J0635-75
Ground telescopes	:	HA, HO, MP		Model Fitted to data	:	Yes
Tracking Station(s)	:	RZ		Image made	:	Yes
Correlator	:	Penticton

 

Abstract This is one of problematical experiments correlated after March 2001, same as vs01s, vs07p, vs09c, vs09p, which suffer significantly lower amplitude, about factor 10 or so, in AIPS comparing DQA1 plots provided by Penticton. We have not yet solved this problem. These data were first correlated with 32 channels/IF. I requested for vs08u to be re-correlated with 128ch/IF but no change in amplitude was observed either in AIPS or DQA1 from previous amplitudes in each system. Fringes were detected during most of the run for all baselines. Applying thses solutions without gain-tsys correction, VPLOT in AIPS with averaging all channels provided the amplitude about 5*10^(-5) Jy for HA-MP baselines around 2UT, while DQA1 amplitude was 8*10^(-4) Jy. Assuming DQA provided right amplitude, I multiply sqrt(80/5) = 4 for each antenna in AIPS by CLCOR prior to ANTAB, APCAL etc. to adjust amplitude to that of DQA1. Tsys information obtained during the experiment was available for HA and HO. Nominal information was applied for Halca and MP. HO was flagged by FG table generated by FITLD, but ASIP-FRING provided good solution for this antenna with FLAGVER=-1. However it turned out that HO was showing remakable low amplitude, about factor 10. I would not be surprized because there was a report in PI-letter on high error rate: "HO transport #3 showed high error rates and was dropped from correlation. This caused DATA VALID to be low for baselines including HO. Data is probably still ok though". I do not know what causes this problem. I multiply additional sqrt(10) for HO in AIPS by CLCOR to reproduce reasonable amplitude for HO-HA baseline which is to be comparable to MP-HA amplitude. However signal/noise ratio was so low for HO baselines and I ended up with flagging HO data in difmap. Except HO the data looked OK including amplitude as one gaussian-like structure, though no published image was available to compare. EBF 12-OCT-2005: Single gaussian fit is 0.784875v 0.0125572v 7.83403v 0.598912v 0.309109v 33.9491v 1 Two component fit is better and more compatible with image. Unclear which is core.

Model
Flux (Jy)	Radius (mas)	Theta (deg)	Major (mas)	Axial ratio	Phi (deg)	TB (10^12 K)
0.518894	0.160859	-143.100	0.228750	1.00000	49.0183	0.4839
0.276233	0.309379	35.9336	0.138115	1.00000	34.3361	0.7067
(*) Quoted Brightness temperatures assume Gaussian components and are in the local (z=0) frame.

AIPS Input Files

Comments - None -

Additional Files

Name	Description
VS08U.ANTAB

AIPS Output Files

PRTAN.LIS LISTR.LIS DTSUM_0.LIS DTSUM_1.LIS UVPLT_UV.PS UVPLT_UVD.PS UVPLT_UVPA.PS

SN_APCAL_AMP_1.PS SN_APCAL_AMP_2.PS SN_CALIB_DEL_1.PS SN_CALIB_DEL_2.PS SN_CALIB_RAT_1.PS SN_CALIB_RAT_2.PS SN_CALIB_SNR_1.PS

SN_CALIB_SNR_2.PS SN_CALIB_PHA_1.PS SN_CALIB_PHA_2.PS POSSM_AP1_01.PS POSSM_AP1_02.PS IMAGE.FITS

More details on the Images and Modelfits are found in this page.