alert_packet

This package provides information about, and utilties for working with, LSST alerts in Apache Avro format. In particular, it includes:

• Alert schemas;
• Examples of alert contents;
• Utilities code for working with alerts.

Refer to DMTN-093 for more information on the LSST alert format.

Schemas

Alert schemas are located in the schema directory.

Schemas are filed according to their version number, following a MAJOR.MINOR scheme. We maintain FORWARD_TRANSITIVE compatibility within a major version, per the Confluent compatibility model. The latest version of the schema may always be found in schema/latest.txt.

Example Alert Contents

Example alert contents are provided in the sample_data directories included with the corresponding schema.

Utility Code

All code is written in Python, and uses the fastavro library. Simulation code also requires NumPy. Both of these may be installed using standard tooling (pip, Conda, etc).

Although this package contains multiple versions of the alert schema, this library code is only written and tested using the latest version (schema/latest) at present. Future versions of this package should offer wider compatibility.

Installation

Using pip

The name of the package is lsst-alert-packet:

$ pip install lsst-alert-packet

Using EUPS

This package may be managed using EUPS. Assuming EUPS is available on your system, simply:

$ git clone https://github.com/lsst/alert_packet.git
$ setup -r alert_packet

Library

The lsst.alert.packet Python package provides a suite of routines for working with alerts in the Avro format.

Command Line

validateAvroRoundTrip.py demonstrates round-tripping a simple alert through the Avro system. Sample data is provided in the schema/latest/sample_data/alert.json file, or an alternative may be provided on the command line. Optionally, the path to binary data files to be included in the packet as “postage stamp” images may be provided. If the --print flag is given, the alert contents are printed to screen for sanity checking. The command will print a brief summary of the size of the data in various formats. Thus:

$ validateAvroRoundTrip.py --input-data=./schema/latest/sample_data/alert.json --cutout-template=./examples/stamp-678.fits --cutout-difference=./examples/stamp-679.fits

simulateAlerts.py writes simulated alert packets to disk in Avro format. The resultant data is schema compliant, but the simulations are not intended to be realistic: packets are populated with pseudorandom numbers. The number of visits per year (equivalent to the number of previous DIASources observed for each alert) and the number of alerts to simulate may be specified on the command line. Thus:

$ simulateAlerts.py --visits-per-year=100 --num-alerts=10 ./output_file.avro