VS02v Results
Submitted checklist.txt and checklist.tex is also available		   [Summary | AIPS | Difmap ]
Analyst: William Scott
Date Prepared: 24-02-2000
 

Summary
 
Observation code : VS02v    AIPS Version : 15Apr99   
Date of Observation : 1999/147    Difmap Version : 2.3c 
Source Name : J1107-44    vsop_difmap used : Yes 
Calibration Source(s) : J1127-18         
Ground telescopes : AT, Ho, Se  Model Fitted to data : Yes 
Tracking Station(s) : UZ, RZ    Image made : Yes 
Correlator : Penticton         

 
Abstract
Model
Flux (Jy)
Radius (mas)
Theta (deg)
Major (mas)
Axial ratio
Phi (deg)
TB (10^12 K)
2.27978 0.250073 151.711 0.655456 0.606314 74.1351 0.4271
(*) Quoted Brightness temperatures assume Gaussian components and are in the local (z=0) frame.


AIPS Data Reduction Notes
 
Task
Adverbs
CL
in
SN
in
CL
out
SN
out
Comments
FITLD DIGICOR=DELCOR=-1
 
 
 
 
 Output file name = VS02v.FITLD 
MSORT
 
 
 
 
 Input file name = VS02v.FITLD, Output file name = VS02v.UVSRT 
INDXR
 
 
 
 
 Created NX(1) 
ANTAB
 
 
 
 
 Used Tsys values of 92,96K for Halca. For the AT, used nominal values (as far as I could tell, all 6 telescopes observed). For Ho, assumed that the "tsys"'s in the tsys file were actually SEFDs. Output sent to TY(1) and GC(1). 
APCAL
 
1 
 
 
 Input: Ty(1) + GC(1) 
CLCAL OPCODE = CALP
INTERPOL = 'AMBG'
REFANT 1 (AT)
1 
1 
2 
 
  
TBOUT INEXT = 'AN'
 
 
 
 
  
TBIN
 
 
 
 
 Changed MNTSTA entries in the AN table. Changed Halca from 3 to 2, changed Hobart from 2 to 0, and change Hart from 1 to 0 (although the latter change is irrelevant, since there was no Hart data). 
TBIN
 
 
 
2 
 Read in DQA1 delay and rate solutions. 
CLCAL OPCODE = CALP
INTERPOL = 'AMBG'
REFANT 1 (AT)
2 
2 
3 
 
  
FRING DOCALIB 1
GAINUSE 3
REFANT 1 (AT)
SEARCH 4,5
SOLINT 3
APARM(1)=2
APARM(7)=2 (SNR=2)
APARM(9)=1
DPARM(1)=3 (include baseline
   stacking)
DPARM(2)=100 (100ns delay
   window!)
DPARM(3)=50 (50mHz rate
   window)
DPARM(4)=0.5 (0.5 sec integration
   time)
DPARM(6)=1 (don't average
   in frequency)
BCHAN 0, ECHAN 0
TIMER 0 11 0 0 to 0 11 30
   0, then
TIMER 0 13 0 0 to o 13 30 0
3 
 
 
3 
 Got good solutions for all antennas, although Halca solutions were a little rattier during the TIMER starting at 0 13 0 0. Rate solutions were very small...so can reduce rate window more. Can reduce the delay window slightly as well to get more SNR. Will increase the solint to 4 to try to get more consistency in the Halca solns. 
FRING as above, except:
SOLINT 4
DPARM(2)=60 (60ns delay
   window!)
DPARM(3)=20 (20mHz rate
   window)
TIMER 0
3 
 
 
3 (nuked old test SN table 3s) 
 Solutions looked great. 
SNEDT
 
3 
 
4 
  
CLCAL OPCODE='CALP'
INTERPOL = 'AMBG'
SMOTYPE = ''
REFANT 1
3 
4 
4 
 
  
TACOP
4 
 
5 
 
  
CLCOR OPCODE = 'GAIN'
ANTENNAS = 5 (Ho)
CLCORPRM = 1.25
5 
 
5 
 
 Compared near-crossing points. Compared UV points for Se-Ho at 12:58 and Se-Halca at 11:10. Assuming Halca calibration is ok, need to multiply Ho by 1.25 to obtain similar amplitudes. Similarly, compared the Halca-AT and Halca-Ho UV tracks. The latter UV tracks are lower by about 1.25. After applying this correction, now Se seems a little lowish compared to the other data, but I'll let amp self-cal take care of this. 
CLCOR OPCODE = 'GAIN'
ANTENNAS = 0
CLCORPRM = 1.34
5 
 
5 
 
 Using the calibrator source J1127-18 to try to establish an absolute amplitude scale proved fruitless. The source appeared highly variable (by about a factor of 2) at 8GHz over the timespan of a year, while the 2 GHz flux remained constant. For both 2 and 8 GHz, there were no observations within a year of the Halca observations. No AT light curves were available for the calibrator. The PLS data for the calibrator was about 3 years old. All of these observations of the calibrator were within the ballpark of the Halca radplot. For the target source, the only data I could find was the AT light curve. The last data point was over a year ago. However, J1107-44 appeared reasonably constant before that. Need to multiply the zero spacing flux by 1.8 to coincide with the AT data (even after the Ho correction). Multiply all antennas by 1.8**0.5, since other than this scaling factor (and the minor Ho correction), all the data in the radplot looked self-consistent. 
TACOP
5 
 
6 
 
  
CLCOR OPCODE = 'GAIN'
ANTENNAS = see below
CLCORPRM = see below
6 
 
6 
 
 Applied the corrections I got from Difmap with gscale. If I let Difmap apply these corrections, I lose some of the data due to not having 4 co-observing antennas (even though gscale applies a GLOBAL amplitude scaling! Corrections were: IF1: AT 0.92, Sh 1.06, Ho 0.87, Halca 0.98 IF2: AT 0.92, Sh 1.13, Ho 0.88, Halca 1.12 
CLCOR OPCODE = 'GAIN'
ANTENNAS = 0
CLCORPRM = 1.08
6 
 
6 
 
 When cleaning the (post initial CLCORed) data in Difmap, I could not clean out enough small spacing flux, without making the clean component model fits to the rest of the visibilites bad. Hence, I ran gscale anyhow (allowing the low-spacing flux to be dragged down), then compensated with CLCOR by multiplying all visibilities by 1.08**2 ~ 1.17. 
SPLIT SOURCES 'J1107-44','J1127-18'
BCHAN 0, ECHAN 0
DOCALIB 1
GAINUSE 4
APARM(1)=2 (average each
   IF separately)
APARM(2)=0.5
APARM(4)=1
4 
 
 
 
 Input file: VS02V.UVSRT, Output files: J1107-44.noCLCO, J1127-18.FITS 
SPLIT SOURCES 'J1107-44'
BCHAN 0, ECHAN 0
DOCALIB 1
GAINUSE 5
APARM(1)=2 (average each
   IF separately)
APARM(2)=0.5
APARM(4)=1
5 
 
 
 
 Input file: VS02V.UVSRT, Output files: J1107-44.CLCOR1 
SPLIT SOURCES 'J1107-44'
BCHAN 0, ECHAN 0
DOCALIB 1
GAINUSE 6
APARM(1)=2 (average each
   IF separately)
APARM(2)=0.5
APARM(4)=1
6 
 
 
 
 Input file: VS02V.UVSRT, Output files: J1107-44.CLCOR2 
FITTP
 
 
 
 
 Input files: J1107-44.noCLCO, J1127-18.FITS Output files: J1107-44.noCLCOR.FITS, J1127-18.noCLCOR.FITS 
FITTP
 
 
 
 
 Input files: J1107-44.CLCOR1 Output files: J1107-44.CLCOR1.FITS 
FITTP
 
 
 
 
 Input files: J1107-44.CLCOR2 Output files: J1107-44.CLCOR2.FITS amplitude 

AIPS Input Files
ANTAB.TXT
INDXR.TXT		 Comments
- None -

AIPS Output Files
DTSUM_0.LIS
DTSUM_1.LIS
LISTR.LIS
PRTAN.LIS
POSSM01_AP_1.PS
POSSM02_AP_1.PS
POSSM03_AP_1.PS
SN_APCAL_AMP_1.PS		 SN_APCAL_AMP_2.PS
SN_CALIB_DEL_1.PS
SN_CALIB_DEL_2.PS
SN_CALIB_PHA_1.PS
SN_CALIB_PHA_2.PS
SN_CALIB_RAT_1.PS
SN_CALIB_RAT_2.PS
SN_CALIB_SNR_1.PS		 SN_CALIB_SNR_2.PS
UVPLT_UV.PS
UVPLT_UVD.PS
UVPLT_UVPA.PS
VPLOT_AP_1.PS
VPLOT_AP_2.PS
WEIGHTS.PS


Difmap Data Reduction Notes
Phase selfcal applied? Yes
Global amplitude selfcal (gscal) applied? No
Amplitude selfcal on non-global timescales used? No
Modelfit made and saved? Yes
Image Made and saved? Yes
Comments on Difmap processing
Imaged the source once, then model-fit the core to an elliptical Gaussian. Then, used this as a starting model for a second round of clean/self-cal. Used phase-self-cal down to a solint of 2 minutes. Did not run gscale, since these correction factors were already applied with CLCOR. Final image is resolved, with additional non-core components to the North and South-west.

Image
Ampl, Phase vs (u,v) Distance
PS (43 kb)
GIF (7 kb)
 Ampl, Phase vs Time
PS (143 kb)
GIF 1, 2		 (u,v) Coverage
PS (23 kb)
GIF (5 kb)
Closure Phase vs Time
PS (109 kb)
GIF 1		 Clean Image
PS (40 kb)
GIF (58 kb)
Modelfit
Ampl, Phase vs (u,v) Distance
PS (43 kb)
GIF (7 kb)
 Ampl, Phase vs Time
PS (142 kb)
GIF 1, 2		 (u,v) Coverage
PS (23 kb)
GIF (5 kb)
Closure Phase vs Time
PS (108 kb)
GIF 1		 Image with model components
PS (42 kb)
GIF (7 kb)

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

Model
Flux (Jy)
Radius (mas)
Theta (deg)
Major (mas)
Axial ratio
Phi (deg)
TB (10^12 K)
2.27978 0.250073 151.711 0.655456 0.606314 74.1351 0.4271
(*) Quoted Brightness temperatures assume Gaussian components and are in the local (z=0) frame.


Last updated on Tue Aug 22 06:53:09 GMT 2000
by db_results.pl version 0.2.0.