Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.mrao.cam.ac.uk/~bn204/publications/2010/2010-10-07-Summary.pdf Дата изменения: Fri Aug 10 20:18:03 2012 Дата индексирования: Tue Oct 2 14:12:44 2012 Кодировка: Поисковые слова: п п п п п п п п п п п п п п п п п п

EU FP6 ALMA Enhancement: Work Package 5 Highlights since last F2F & Plans
Nikolic & Richer
Cavendish Laborator y/Kavli Institute University of Cambridge

7 October 2010 ESO, Garching

(University of Cambridge)

October 2010

1/9


Overview
Completion of documentation of empirical algorithms Commissioning trip August 2009: check-out of WVR hardware Repor t on the WVR on-site check-out Memo on effects of dispersion High-site interferometry & data recorded in ASDM January 2010 First release of wvrgcal program to JAO February 2010 Commissioning trip March-June 2010 On-line plotting of PWV and cloud cover Systematic analysis of test data January-June 2010 Numerous improvements to wvrgcal

(University of Cambridge)

October 2010

2/9


Introduction to wvrgcal

The user-facing application that does WVR phase correction Fully compatible with official ALMA software:
Reads ALMA/CASA Measurement Sets Writes CASA Gain Calibration ("T"-Jones) tables Callable and scriptable from CASA

Build on top of:
LibAIR, the phase correction librar y CASA-Core and CASA libraries for input/output

Publicly available, installed on computers at the JAO and at NRAO/Charolttesville

(University of Cambridge)

October 2010

3/9


User documentation at JAO
http://wikis.alma.cl/bin/view/AIV/Application

(University of Cambridge)

October 2010

4/9


First application ­ February 2010
Cour tesy of Al Wooten

150

Phase of Corrected Data (deg)

100

50

0

02:41:16.8
(University of Cambridge)

02:52:48.0

Time

03:04:19.2

03:15:50.4

03:27:21.6
October 2010 5/9


More recent example (uid

A002 Xb9f5d X1)

(University of Cambridge)

October 2010

6/9


More recent example (uid

A002 Xb9f5d X1)

(University of Cambridge)

October 2010

6/9


Overview of test data web-page
http://www.mrao.cam.ac.uk/~bn204/temp/wvrres/

Plots of WVR and astronomical receiver total power signals Allan variances Cross correlation phase and amplitude on each baseline Correlation between WVR difference signal and the astronomical path Single channel phase correction plots

(University of Cambridge)

October 2010

7/9


Overview of wvrgcal tests
http://www.mrao.cam.ac.uk/~bn204/temp/wvrgcal- regress.html

List of all usable test observations and conditions List of tested versions of wvrgcal and options to it Matrix of results showing residual phase errors after application of WVR phase correction

(University of Cambridge)

October 2010

8/9


Plans
Test obser vation:
1 2 3 4 5

Longer baselines In better conditions More consistent (same time of day, same antennas, same script) More realistic (fast-switching, requires R8.0) Minimising other sources of errors (LLCs, software updates, all WVRs working) Pipeline analysis multiple-source obser vations Extract more information (e.g., record "optimal" coefficients on all baselines) Tune algorithms according to results of tests WVR-specific filter frequencies and bandwidths Implement empirical algorithms Make use of ground weather instruments
October 2010 9/9

Analysis of test observations
1 2

Completion of wvrgcal
1 2 3 4

(University of Cambridge)