Fink client

fink-client is a light package to manipulate catalogs and alerts issued from the fink broker programmatically. It is used in the context of 2 major Fink services: Livestream and Data Transfer.

Installation

fink_client requires a version of Python 3.9+.

Install with pip

pip install fink-client --upgrade

Use or develop in a controlled environment

For development, we recommend the use of a virtual environment:

git clone https://github.com/astrolabsoftware/fink-client.git
cd fink-client
python -m venv .fc_env
source .fc_env/bin/activate
pip install -r requirements.txt
pip install .

Registration

In order to connect and poll alerts from Fink, you need to get your credentials:

1. Subscribe to one or more Fink streams by filling this form.
2. After filling the form, we will send your credentials. Register them on your laptop by simply running:

fink_client_register -survey SURVEY -username USERNAME -group_id GROUP_ID -servers SERVERS ...

Note that SURVEY is among ztf or lsst. In case of doubt, run fink_client_register -h. You can also inspect the configuration file on disk:

cat ~/.finkclient/credentials.yml

Livestream usage

Once you have your credentials, you are ready to poll streams! You can easily access the documentation using -h or --help:

fink_consumer -h
usage: fink_consumer    [-h] -survey SURVEY [--display]
                        [--display_statistics] [-limit LIMIT]
                        [--available_topics] [--save]
                        [-outdir OUTDIR] [-schema SCHEMA]
                        [--dump_schema] [-start_at START_AT]

Kafka consumer to listen and archive Fink streams from the
Livestream service

options:
  -h, --help            show this help message and exit
  -survey SURVEY        Survey name among ztf or lsst. Note that
                        each survey will have its own configuration
                        file.
  --display             If specified, print on screen information
                        about incoming alert.
  --display_statistics  If specified, print on screen information
                        about queues, and exit.
  -limit LIMIT          If specified, download only `limit` alerts.
                        Default is None.
  --available_topics    If specified, print on screen information
                        about available topics.
  --save                If specified, save alert data on disk
                        (Avro). See also -outdir.
  -outdir OUTDIR        Folder to store incoming alerts if --save is
                        set. It must exist.
  -schema SCHEMA        Avro schema to decode the incoming alerts.
                        Default is None (version taken from each
                        alert)
  --dump_schema         If specified, save the schema on disk (json
                        file)
  -start_at START_AT    If specified, reset offsets to 0
                        (`earliest`) or empty queue (`latest`).

You can also look at an alert on the disk:

fink_alert_viewer -h
usage: fink_alert_viewer [-h] [-f F] [-s S]

Display cutouts and lightcurve from an alert

options:
  -h, --help  show this help message and exit
  -f F        Path to an alert data file (avro format)
  -s S        Survey name among ztf or lsst.

More information at docs/livestream.

Data Transfer usage

If you requested data using the Data Transfer service (ZTF or LSST), you can easily poll your stream using:

usage: fink_datatransfer [-h] -survey SURVEY [-topic TOPIC] [-limit LIMIT]
                            [-outdir OUTDIR] [-partitionby PARTITIONBY]
                            [-batchsize BATCHSIZE] [-nconsumers NCONSUMERS]
                            [-maxtimeout MAXTIMEOUT]
                            [-number_partitions NUMBER_PARTITIONS]
                            [--restart_from_beginning] [--dump_schema] [--verbose]

Kafka consumer to listen and archive Fink streams from the data transfer service

options:
  -h, --help            show this help message and exit
  -survey SURVEY        Survey name among ztf or lsst. Note that each survey will have its
                        own configuration file.
  -topic TOPIC          Topic name for the stream that contains the data.
  -limit LIMIT          If specified, download only `limit` alerts from the stream.
                        Default is None, that is download all alerts.
  -outdir OUTDIR        Folder to store incoming alerts. It will be created if it does not
                        exist.
  -partitionby PARTITIONBY
                        If specified, partition data when writing alerts on disk.
                        Available options: - `time`: year=YYYY/month=MM/day=DD (ztf and
                        lsst) - `finkclass`: finkclass=CLASS (ztf only) - `tnsclass`:
                        tnsclass=CLASS (ztf only) - `classId`: classId=CLASSID (ELASTiCC
                        only) Default is None, that is no partitioning is applied (all
                        parquet files in the `outdir` folder).
  -batchsize BATCHSIZE  Maximum number of alert within the `maxtimeout` (see conf).
                        Default is 1000 alerts.
  -nconsumers NCONSUMERS
                        Number of parallel consumer to use. Default (-1) is the number of
                        logical CPUs in the system.
  -maxtimeout MAXTIMEOUT
                        Overwrite the default timeout (in seconds) from user
                        configuration. Default is None.
  -number_partitions NUMBER_PARTITIONS
                        Number of partitions for the topic in the distant Kafka cluster.
                        Do not touch unless you know what your are doing. Default is 10
                        (Fink Kafka cluster)
  --restart_from_beginning
                        If specified, restart downloading from the 1st alert in the
                        stream. Default is False.
  --dump_schema         If specified, save the schema on disk (json file)
  --verbose             If specified, print on screen information about the consuming.

More information at docs/datatransfer.