observing modes from a software viewpoint robert lucas and philippe salomé (ssr)

Observing ModesObserving Modesfrom a Software viewpointfrom a Software viewpoint

Robert LucasRobert Lucasand Philippe Salomé and Philippe Salomé (SSR)(SSR)

ESAC Meeting - Garching - 2006-sep-06 2

Observing Modes

• Observing modes are pre-defined ways to use ALMA to obtain science and calibration data.

• Use of standard modes individually tested for accuracy and efficiency makes operation easier for ALMA observers and for ALMA staff.

• Choice, definition of standard modes and their order of implementation and commissioning is an important element of observatory development.

• A sequential implementation of Observing Modes is very important for software deployment and testing, once the basic computing structures are in place.


Observing Modes of two kinds

• Observer Modes:– Open to the general

science observer– Aimed at obtaining

general science data– Examples:

• Single-field mapping with interferometry

• OTF single-dish maps• Full mapping of sky area

with long, short, zero spacings

• Observatory Modes:– For the observatory staff– Aimed at obtaining array

calibration data used by science projects

– Examples:• Measure antenna precise

positions• Measure pointing models• Check antenna surface

accuracy with holography


How do we define Observing Modes?

• Basic modes defined by the hardware, e.g. :– Correlators: ACA/Baseline, correlation and autocorrelation, or autocorrelation only, polarizations, resolution, bandwidths…– Continuum detectors: integration time– Local oscillators: Frequency switching, side band separation/rejection– Nutator: beam switching– Antenna: OTF scanning, individual pointings …– WVR receivers: apply mode (model, empirical)…Note: These are not independent as e.g. some switching choices may restrict correlator configuration

• Definitions of simple modes are based on the science goal, with sub-modes defined when there are hardware options, mainly dictated by the calibration strategy– Example: a single dish continuum map may use OTF scanning with or without beam switching; a line map may use spatial referencing or frequency switching.

• For many science goals a combination of simple modes are needed:– Example: extended source mapping will need short spacing, total power, long spacing data, that are obtained sequentially using basic simple modes.

• Simple Modes– Produce a single science result obtained in a rather simple way

• Example: single field interferometry map– For the general user– Aimed at producing science data– Simple:

• , • OTF total power map

– Complex: • simultaneous measurement of short spacings and zero spacing maps• combined extended object map (including both single-dish and short/zero spacings, or multi-configuration data)


The structure of a Project

• One ObsUnitSet is aimed at a science result (e.g., one image)

• One ObsUnitSet applies a simple observing mode

• A ObsUnitSet may need one ore more SchedBlocks to be observed (e.g. several configurations

• There can also be several ObsUnitSets in a project, as several science results may be required, with (may be) different modes.

• A complex observing mode uses several simple modes

• Thus there can be several ObsUnitSets in an ObsUnitSet (hierarchy of observing modes).


Standard Observer Mode: Simple/Complex

Example:1. Simple Standard Mode: single field interferometer map

• One ObsUnitSet, one or a few SB, which may be repeated2. Complex Standard Mode: extended object map

Uses the hierarchy of ObsUnitSets: • One ObsUnitSet for an interferometer map

– interferometer pointed mosaic• One ObsUnitSet for an interferometer map

– ACA single-dish and short-spacing map• Top Level ObsUnitSet produces final combined map• This complexity affects the OT, scheduling, pipeline, but

not Control, Quick Look, or On-line calibration


Standard Observer Mode Contents

• Parameters (defaults when possible) to be defined in the Observing Tool:– Observing parameters

• Area to be mapped• Spectral definition from science point of view• Quality parameters (sensitivity, dynamic range…) resulting in scheduling

constraints– Pipeline parameters and options

• Should be minimal, we leave to standard observing mode heuristics what can be decided in an automated way

– SB definition policy, as specific rules for each mode may be needed• Standard Mode observing script:

– One per simple mode and per kind of SB generated in that mode– Actually controls the observations

• Standard mode data reduction script (pipeline heuristics)• And naturally user documentation.


Observing Tool Snapshot


An example SchedBlock

• The contents of the Scheduling Block are stored in an xml file.

• This contains all the information needed to schedule it, and execute it; in particular the reference to a standard mode script that will perform the actual observing on the telescope.


Observing Script

Commands (in Control Command Language) in order to:– Recover user’s input parameters (SB content)– Frequency setup, correlator setup commands, using the SB content

as input– Real time choices (e.g. which calibrators)– Perform calibrations as needed:

• Some calibrations are in Observing Mode SB script: pointing, focus, amplitude, phase,…

– With script logic to decide when to calibrate• More expensive calibrations, e.g. BandPass calibration

– Check if calibration exists already (query Calibration Data Base)– Perform calibration if needed

– Recover calibration results from on-line calibration (TelCal)– Observing cycles; stop when conditions met (e.g. time elapsed).


Example of script (holography)


Example ExecBlock (ASDM)Holography ASDM

Two of 24 tables, mostly in xml format:

Pointing table, TotalPower table are

stored in binary format for efficiency.


Tentative list of Simple Observer Modes (1)

1. Pointed interferometer mosaic map2. On-the-fly interferometer mosaic map3. Pointed single-dish map

1. Position switched spectral/continuum2. Beam switched spectral/continuum3. Frequency switched spectral

4. On-the-fly single-dish map1. Position switched spectral/continuum2. Beam switched spectral/continuum3. Frequency switched spectral


Tentative list of Simple Observer Modes (2)

5. Simultaneous pointed interferometer / single dish mosaic map1. Position switched spectral/continuum2. Beam switched spectral/continuum3. Frequency switched spectral

6. Simultaneous on-the-fly interferometer / single dish mosaic map1. Position switched spectral/continuum2. Beam switched spectral/continuum3. Frequency switched spectral

These are the ACA modes of course; more complexity may be actually involved…


Observatory Modes

1. Transmitter holography2. Astronomical holography3. Optical pointing model4. Radio pointing model5. Antenna position measurements6. Axes offset measurement7. Focus model (using holography)8. Delays9. Receiver band pointing offsets10. Beam shape determination11. Primary feed illumination (size and offsets)12. Primary amplitude calibration (standard flux calibrators)13. … any other, found necessary during commissioning


Observing Mode Development

• Start with simple observer modes– How many standard observer modes?– If too many, gets too complicated for user– If too few, they get complicated– E.g.

• single field interferometry and pointed mosaic are probably one mode.• Position switch and frequency switch in Single-dish are two modes.

• Observatory Modes are needed first– Optical pointing, Holography

• In CIPT the modes are developed both– at the instrument level (control, correlator subsystems)– at the observatory level (end-to-end approach) in function-based teams.

• They are the object of Integrated User Tests (e.g. optical pointing at the ATF).


Modes for Commissioning

This sets in practice an order of priorities, according to needs for antenna acceptance and commissioning plan, e.g.:1. Single Dish Holography2. Optical Pointing3. Single Dish with Total Power detectors only

– No nutator, then nutator– Focus checking, beam maps– Radio Pointing model determination

4. Single Dish with Correlator – Position, Beam, Frequency switching

5. Interferometry– Baseline measurement– Interferometer holography


Observer Modes Implementation

• We need to work on the science modes in parallel with the commissioning – we need ultimately to commission the science modes one

after the other• Work first on single-field interferometry

– using hardware simulation at the array level, for an end-to end approach (OT to Off-line data reduction) before the whole hardware is available

• Further work will soon involve single-dish modes.• Naturally the order of priority of implementation and

testing of observer modes is a science issue.


Present Status: Observatory Modes

• Optical Pointing implemented, and tested March 2006.– A report on the integrated user testing is available– Actually bad weather did not allow a full science checking

at the time• Transmitter Holography implemented (still to be

tested; hw expected in 2007-Sep. at ATF)– Control software ready and tested in simulation– Data reduction identical to that used in Antenna Evaluation– Data format now converted to new ALMA Science Data

Model (ASDM).


Present Status: Single Field Interferometry

• Implemented in simulation, waiting for hardware to be ready at ATF – While first fringes should be reached soon, the end-to-end software will not be

used (or desired) to obtain them. Real tests of end-to-end software with hardware will start only at that point.

• Next Stage (end of October) should include, in simulation mode:– a target source– several phase calibrations, with on-line phase interpolation between them– Main development areas:

• Validate the ASDM: from DataCapture to Off-Line Filler• LO phase and delay tracking• Shift Log prototype implementation

– Secondary development areas:• Usage of standard mode scripts• Feedback of on-line calibration results• Performance validation of ASDM• Quick-Look display of Calibration results


Next Observer Modes

• Need to define priorities for Single-Dish– Should have simple single dish modes to test the antennas

(2007/2008)– Should also aim particularly towards the main science modes for

ACA single-dish (science input needed):• Relative priorities of simple and combined switching modes.

• Pointed Mosaics – Really a variation of the single field interferometry, but more

complex for OT and pipeline• OTF Mosaics

– Probably not for Early Science– When we can do this end-to-end we’re in a good shape.

observing modes from a software viewpoint robert lucas and philippe salomé (ssr)

Documents

basic modes

basic simple modes

modesobserving modes

spacingsobservatory

kindsobserver modes

different modes

combination of simple

use of standard modes