The ALMA TelCal subsystem

Dominique Broguière , Institut de RadioAstronomie Millimétrique (IRAM)

TelCal Phasing meeting – Grenoble -10/12/2012

TELCAL Phasing meeting - 10 December 2012 2

Presentation layout

• TelCal overview

• ALMA software architecture

• TELCAL software architecture

• Offline mode of TelCal

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TelCal overview (1/3)• TELCAL is the on-line calibration software for the ALMA array.

• On-line calibration groups all the operations needed to maintain the ALMA interferometer optimally tuned to successfully execute the planned observations.

• On-line calibration primarily deals with :– pointing and focus offset computations– delay measurements – solving of antenna positions– measurement of atmospheric absorption and of phase radiometric correction– monitoring of phase and amplitude on an astronomical calibrator source– bandpass and sideband ratio measurements– holography to compute the panel adjustment needed to improve surface rms

and monitor surface quality– pointingModel

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TelCal overview (2/3)

• TELCAL software has been developed since 2003.

• People involved in TELCAL :– Robert Lucas : lead until 31-07-2012 – Dominique Broguiere (IRAM) lead since 01-08-2012– Jean-Christophe Roche (IRAM)

Alexis Tejeda was working in TELCAL until June 2012, currently working in JAO

Juan Pardo was working on ATM library until end of 2011

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TelCal overview (3/3)• Programming languages :

– 70% C++ : calibration code and C++ Corba components– 13% python : offline scripts– 12% fortran90 : holography (gildas)– 5% java : Corba components

• SLOC (Source Lines Of Code) report for TELCAL– Calibration (Engines,TelCalSolvers, tpoint andTools modules) : 40000 lines– CORBA components (TelCalDataManager, TelCalPublisher, TelCalMaster,

and DCsimulator modules) : 10000 lines– Offline scripts (AsdmReader, Tasks and Standalone modules) : 11000 lines– ATM library : 22000 lines– Holography (Gildas) : 260000 lines (~ 15000 lines of fortran90 developed for

ALMA holography and ASDM-PDB filler, rest is frozen code) – Shared Simulator (SharedSimulator and SharedSimLib) : 10000 lines– Others (TelCalScripts module) : 1300 lines

Total : ~ 100000 lines

ALMA Software

TelCal and the other subsystems

TELCAL

CONTROL

CORRELATOR

EXECUTIVE

ARCHIVE

Results (ASDM)

Results (ASDM)

Start/stop

Metadata (ASDM)

Correlator data

Totalpower data CONTROL(DataCapturer)

Interfaces of TELCAL with other subsystems

TELCAL architecture : containers and components

Based on ACS (Alma Common Software) infrastructure and tools

• CORBA : enables software components written in several languages (C++, java, python) and running on different machines to work together

• Components are deployed in containers. This simplifies the management of components

• Interface of components described in IDL language • Events used for asynchronous exchanges• AudioVideo streams for binary data transfer (high rates).

New implementation (2012-2013) based on RTI DDS.

TELCAL MASTERCOMPONENT

TELCALPUBLISHER

ARCHIVE

TELCAL TOTALPOWER RECEIVER

(n components)

TELCAL DATAMANAGER(n components)

CORBA components of TELCAL

TOTALPOWER

DISTRIBUTOR

DATACAPTURER

CORRELATOR

DISTRIBUTOR

EXECUTIVE

DATACAPTURER

scripts

TELCALPARAMETER_TUNING

TELCALARRAY

CONTROL

TelCal modules

Architecture :

4 main packages :• TelCalMaster : starting and

stopping the subsytem• TelCalDataManager : receiving,

filtering and organizing all data streams

• TelCalResults : processing the calibration

• TelCalPublisher : publishing the results

ATM package

• Result of research by J. Cernicharo and J. Pardo in Madrid• Agreement to use and extend this for ALMA (TelCal and Offline subsystems).• Predicts atmospheric emission, absorption and path-length for all ALMA bands • Water vapor retrieval algorithms available

Offline mode of TelCal

Goal : Exeute the data reduction off-line using the

science data produced (the asdm dataset)

• Python interface of the C++ modules of TelCal (Engines and AsdmReader)

• Provide tools (plots) to test the validity of the calibration• Default mode for Holography, AntennaPositions and

PointingModel • Also available for the other calibrations: PhaseCal,

PhaseCurve, Pointing, Focus, BandPass, Atmosphere, Skydip

Offline mode : user interface

• TelCal within Casa : Casa tasks– Use the Casa formalism (XML wrapper interface).– Offline tasks

• asdmplot : Plot the data from an ASDM dataset (visibilities,totalpower, WVR data…)

• asdmlist : List the content of an ASDM dataset• tc_antpos : Process an antenna position calibration and plot

the result

– Online tasks• tc_atmosphere, tc_wvr• tc_delay , tc_bandpass, tc_sidebandratio• tc_focus, tc_pointing• tc_amplical, tc_phasecal, tc_phasecurve

Calibration examples

• Examples :– Atmosphere calibration– Pointing, Focus– Delay measurements, Antenna Positions– PhaseCal, Phase Curve– BandPass– Holography

See: Telescope Calibration User Guide from Robert Lucas

TotalPower pointing (cross scan)

Single-Dish pointingCross-scan

Totalpower data

Source: Saturn

Results :DV01 :(-0.73, -1.66) arcsec

PM03:(1.15,-1.69) arcsec

Red : measured pointsGreen : fitted curveBlue : fitted points

OSF: 06/07/2009