Data Overview

Pub/Sub

Pub/Sub is an asynchronous, publish–subscribe messaging service. The Pitt-Google broker publishes alerts and value-added data to multiple topics, listed below. You can subscribe to one or more of these topics, and then pull and process the message stream(s). See the Pub/Sub Streams tutorial for more information.

Current Streams

Topic

Description

ztf-loop

Use this stream for testing. Recent ZTF alerts are published to this topic at a constant rate of 1 per second, day and night.

ztf-alerts

Full ZTF alert stream.

ztf-alerts_pure

ZTF alert stream filtered for purity.

ztf-exgalac_trans

ZTF alert stream filtered for likely extragalactic transients.

ztf-salt2

Salt2 fits + alert contents of ZTF alerts that passed quality cuts and the likely-extragalactic-transients filter.

ztf-alert_avros

Notification stream from the ztf-alert_avros Cloud Storage bucket indicating that a new alert packet is in file storage. These messages contain no data, only attributes. The file name is in the attribute “objectId”, and the bucket name is in the attribute “bucketId”.

Note on Costs

You do not need to setup billing to complete our tutorials. The Google Cloud services pricing structure includes a Free Tier, and the usage incurred from our tutorials stays well within these limits.

You cannot be charged unless you explicitly enable billing for your project and setup a billing account.

For users who wish to process volumes of data larger than the Free Tier quotas, Google’s pricing structure is “pay-as-you-go” and you only pay for what you actually use. See the links below for more information.

Some pricing examples (as of Aug. 2021):

Service

Activity

Free Tier quota

Price beyond Free Tier

BigQuery

querying data

1 TB per month

$5.00 per TB

Pub/Sub

message delivery

10 GB per month

$40 per TB

For more information, see: