Summary
 

Observation code	:	VS01s		AIPS Version	:	12DEC00
Date of Observation	:	2000/337		Difmap Version	:	2.3c
Source Name	:	J2225-04		vsop_difmap used	:	Yes
Calibration Source(s)	:	J2148+06, J2258-27
Ground telescopes	:	CE, HA, MP, KL,SH		Model Fitted to data	:	Yes
Tracking Station(s)	:	RZ, TZ		Image made	:	Yes
Correlator	:	Penticton

 

Abstract This is one of problematical experiments correlated after March 2001, same as vs07p, vs08u, vs09p, vs09c which suffer significantly lower amplitude, about factor 10 or so, in AIPS comparing DQA1 plots provided by Penticton. We have not yet solve 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. This vs01s was the second Penticton correlation made on 12 September 2001. Note that all Penticton data generated after 28 May 2001 has *NO* need for sqrt(2) modification (Rob Shank, private communication). However the DQA plots was based on the first correlation made on 23 March 2001. Fringes were detected during most of the run for all baselines except IF2 of HA in which there is no data because the station recorded RCP mode. Applying thses solutions without gain-tsys correction, VPLOT in AIPS with averaging all channels provided the amplitude for TARGET SOURCE about 3.8*10^(-4) for CE-SH baselines, while DQA1 amplitude was 4.2*10^(-3). There was addtional amplitude gap in CD baselines both in DQA and AIPS, which did not seem to be consistent with Tsys curve of CD. The timerange outside of 8:12-10:30 for CD-SH bseline is about 3.2*10^(-4). Assuming (DQA amplitude)*sqrt(2) provided right amplitude, I multiply sqrt(42*sqrt(2)/38) = 3.9536 for each antenna in AIPS by CLCOR to adjust amplitude to that of DQA1 prior to APCAL correction. Then adidional factor for CD was multiplied for the timerange. MP data has a problem. Only half of each IF has coherence as one can see POSSM plots. The PI-letter from Penticton said: MP recorded both channels with a 1st LO of 4824MHz LSB centered on 4816MHz. Were able to correlate lower 8MHz of this band with ch1(4800-4816MHz) from other stations and the upper 8MHz with ch2(4816-4832MHz). I tried to multiply some factor, derived from a scan of compact calibrator J2258-27, to make use of MP data, but later I ended up with flagging all MP baseline because of low signal/noise ration. (In fact this was a big loss. May be better to go back to this data to recover right amplitude of this dataset.) Tsys information obtained during the experiment was available for the GTRs except MP. Nominal information was applied for Halca and MP. The amplitude for target is about 3.4 Jy at 50 Mlambda and 2.8 Jy at 120 Jy while PLS showed 3.0 Jy at 5 Mlambda and 0.6 Jy at 120 Mlambda. For the calibrator J2258-27, 1.8 Jy at at 100 Mlambda while PLS showed 2.8Jy@5Mlambda and 2.2Jy@120Mlamdga. The image is well modelfitted with two compact gaussian. Source is well resolved with space baselines. Extended jet component at 8 mas in East are not seen from this data.

Model
Flux (Jy)	Radius (mas)	Theta (deg)	Major (mas)	Axial ratio	Phi (deg)	TB (10^12 K)
1.99033	0.158916	22.2179	0.382289	0.254434	15.9592	2.6121
1.38389	0.206086	-60.3916	0.179029	1.00000	-81.8699	2.1070
(*) Quoted Brightness temperatures assume Gaussian components and are in the local (z=0) frame.

AIPS Input Files

Comments - None -

Additional Files

Name	Description
VS01S.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_2.PS SN_APCAL_AMP_1.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 POSSM01_AP_1.PS POSSM01_AP_2.PS

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