These web services are the back-end of the MWA triggering system, described in detail Hancock et al, 2019 (https://ui.adsabs.harvard.edu/link_gateway/2019PASA...36...46H/EPRINT_PDF)
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TriggerVCS - Trigger a set of voltage-capture observations with the MWA telescope, on one or more targets.
eg: http://mro.mwa128t.org/trigger/triggerobstriggervcs?source=Sun&exptime=180&nobs=3&project_id=C001&secure_key=IAmASecret
Parameters can be passed in the URL, as with the other services, but there are usually a lot of them, so POSTing them is preferred.
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- result['success'] - a Boolean, True if the observations were scheduled successfully, False if there was an error.
- result['errors'] - a dictionary, containing integer keys from 0-N, where each value is an error message. Normally empty.
- result['params'] - a dictionary containing all parameters passed to the web service, after parsing, and some extra parameters calculated by the web service (the name of the automatically chosen calibrator, etc).
- result['clear'] - the commands used to clear the schedule. It contains the keys/values:
- 'command': The full clear_schedule.py command line
- 'retcode': The integer return code from that command
- 'stderr': The output to STDERR from that command
- 'stdout': The output to STDOUT from that command
- result['schedule'] - the commands used to schedule the triggered observations. It contains the keys/values:
- 'command': A string containing all of the schedule_observation.py command lines
- 'retcode':The integer return code from the shell spawned to run those commands
- 'stderr': The output to STDERR from those commands
- 'stdout': The output to STDOUT from those commands
TriggerBuffer - Trigger a buffer-dump in the correlator to retro-actively save the last few minutes of data from the past, and keep voltage-capture going for a set time into the future.
Parameters can be passed in the URL, as with the other services, but there are usually a lot of them, so POSTing them is preferred.
Base parameters are:
- project_id: MWA project ID string, eg G0055, that would be interrupting the existing observations. Defaults to 'C001'.
- secure_key: The password associated with that project ID. No default.
- pretty: True if the returned JSON should be rendered to be more human-readable. Defaults to False if called from a script, True if called from a web browser.
- pretend: Boolean, integer, or string (eg 'y', 'n', etc) - if true, then do everything except clear out existing observations and schedule new ones. Defaults to True.
The rest of the observations provide the time/s to start and stop capture. All other observation details are inherited from whatever observation/s are currently in progress, or if there is no current observation, whatever the last observation used - this includes pointing direction/s and frequency settings. Note that all future observations (from the time called, through to the end of the 'obstime' provided) are deleted by the triggerbuffer() call, to prevent the telescope state from being (further) changed during the capture.
- start_time: The earliest time in GPS seconds for which data should be saved - if zero, or before the earliest buffer file available save all data. This value is inclusive, so .free files later that, or starting at this time, are included.
- obstime: How many seconds to keep capturing data for, after the buffer dump (from 'now' into the future, not including past data dumped from the buffers).
The structure returned is a JSON encoded dictionary, containing the following:
- result['success'] - a Boolean, True if the observations were scheduled successfully, False if there was an error.
- result['errors'] - a dictionary, containing integer keys from 0-N, where each value is an error message. Normally empty.
- result['params'] - a dictionary containing all parameters passed to the web service, after parsing, and some extra parameters calculated by the web service (the name of the automatically chosen calibrator, etc).
- result['clear'] - the commands used to clear the schedule. It contains the keys/values:
- 'command': The full clear_schedule.py command line
- 'retcode': The integer return code from that command
- 'stderr': The output to STDERR from that command
- 'stdout': The output to STDOUT from that command
- result['schedule'] - the commands used to schedule the triggered observations. It contains the keys/values:
- 'command': A string containing all of the schedule_observation.py command lines
- 'retcode':The integer return code from the shell spawned to run those commands
- 'stderr': The output to STDERR from those commands
- 'stdout': The output to STDOUT from those commands
- result['obsid_list'] - The observation IDs of all MWA observations covered by the buffer dump and subsequent voltage capture. Use these observation IDs to download the voltage capture files, and to determine the telescope setting/s during the time span including the captured data.