The ALMA Observation Support Tool

Adam AvisonUK ALMA Regional Centre Node

Overview

• Introduction to the OST• Breaking the 4th wall• Simulation inputs• Breaking the 4th wall (reprise)• Output to users• ALMA cycle 0: An Education• ALMA cycle 0: How things went

ALMA: A very brief introduction

• When in full operation ALMA will consist of 66 dishes operating between ~90GHz and ~1THz, on the Chajnantor plateau, Chile.

• Full operation is expected sometime in 2013.

• As of 10 days ago ALMA began Cycle 0 observations with ~16 dishes.

ALMA Observation Support Tool

• The OST is a web based ALMA simulator. Accessible from any standard web browser.

• Designed for those who are not interferometry experts .

• Written by Ian Heywood (Oxford).

• http://almaost.jb.man.ac.uk

USER’S EMAILUSER’S EMAIL

USER @ HOME/OFFICE OST @ MANCHESTER

INPUT WEBFORMinc. LiveValidation

OUTPUT WEBPAGE

ADAM @ REST

SUBMISSION NOTIFICATION

SERVER SIDE CHECKS

OST ADMINOST ADMINSIMULATION

SIMULATION COMPLETE!

OST WORKFLOW

Python/CASA backendBrowser + e-mail Client

Breaking the 4th wall

- OST simulation of under illuminated Lunar surface

User Input.

• Array: Selects the array configuration. Currently has the two Cycle 0 configurations, the ACA and one called ALMA*.

• Sky Setup: • Source Model. Can select

from OST library or user Uploaded FITS file.

• Declination==Declination• Image peak For rescaling

input image peak value.• Observation Setup: Standard

observing characteristics e.g. Frequency, BW, resolution*, etc. etc.

User Input.• Corruption: User can select

from 3 PWV values. Good, Bad or Ugly.

Behind the scenes: Noise is calculated using eqn 1. Comparison to simdata fairly good.

• Imaging: Standard interferometric parameters. Image Weighting, CLEAN application and output file format (FITS or MS).

• E-mail Address: Possibly the most important parameter.

Breaking the 4th wall (reprise)

- OST Simulation of ‘Super’ M4R10 Galaxy

Cycle 0: The results• Over the ~95 Day call

period 2064 jobs we submitted and completed successfully. Excluding IH and AA == 1846 by users.

• 19.4 jobs per day (average).

• 261 jobs caught in LiveValidation or server side checks.

• ~60 jobs for unique users caused the OST to fail. With only 6 remaining unresolved at the end of call*.

• Mostly FITS file issues see later slide.

Daily OST usage: Solid blue line total number of successfully completed submissions. Dashed purple line total minus testing by OST admin. Solid Orange seven day running average. Vertical green denotes Cycle 0 proposal call, vertical red Cycle 0 deadline, vertical black separates months

Cycle 0: The results• OST seems to have been

well received internationally. A fun, though erroneous, statistic would be there are ~2 OST submission per Cycle 0 proposal submitted :D.

• The largest number of jobs came from the UK, then from the .com TLD (which is tricky to pin down).

• The largest number of unique users use the .com TLD followed by .uk and .jp.

• Both figures exclude AA and IH

Cycle 0: An Education• FITS Headers: ‘Flexible Image

Transport System’ or ‘Frustration Incarnate, Telephone Samaritans’.– 3 methods (at least) of defining WCS.– BITPIX values. (GIMP!)– Rotation, currently not handled by OST.

• Expect the unexpected: … and don’t expect all submitted jobs to make sense!

Future upgrades:

– Separate Hour Angle coverage.– Rotation handling.– Bigger library.– Some behind the scenes bits (mostly

already done!).– Enhanced mosaicking capability.