101.1. Remote access to the Alert Retrieval Service

For the API Aspect of the Rubin Science Platform (RSP) at data.lsst.cloud.

Data Release: Prompt Products

Last verified to run: 2026-07-13

Learning objective: Retrieve a single alert packet.

LSST data products: Alert packets.

Credit: Originally developed by the Rubin Community Science team. Please consider acknowledging them if this tutorial is used for the preparation of journal articles, software releases, or other tutorials.

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Introduction

This tutorial demonstrates how to remotely retrieve a single LSST alert packet from an external python environment using the API Aspect of the RSP. It was tested and confirmed to work with the NOIRLab Astro DataLab.

Steps

1. Create a token.

Follow the instructions in the RSP user guide for Creating user tokens. The token must have a scope of read:image to access the Alert Retrieval Service.

2. Get the API endpoint.

All URL for data access via the RSP are available at data.lsst.cloud/api-aspect. The Alert Retrieval Service URL is listed under “Prompt”.

3. Install python packages, if needed.

This tutorial requires the requests, fastavro, and io python packages. The first two can be pip-installed and the latter is standard. These steps have been confirmed to work with, at minimum, python version 3.10, requests version 2.32.4, and fastavro version 1.12.0.

4. Python code for alert retrieval.

In the code block below, the requests package is used to create an authenticated access session using the token from step 1, and the URL from step 2. Then, the desired alertId number is passed and a response returned, and the content of the response is read with the fastavro.reader to return the packet in the Avro format.

import requests
import fastavro
import io

token = "<paste-your-token-here>"
url = "https://data.lsst.cloud/api/alerts"
alert_id = 170059317401616524
session = requests.Session()
session.headers["Authorization"] = f"Bearer {token}"
response = session.get(url, params={"ID": alert_id})
packet = fastavro.reader(io.BytesIO(response.content))

5. Interact with the alert contents.

From here, use the same python code as in 101.1. Alert retrieval service.