GCN News and Events
The Swift-BAT/GUANO, IceCube, and GCN teams are pleased to announce the availability of new GCN notice types via the new GCN in JSON format. JSON format notices can be streamed via Kafka. These new notice types are not available via GCN Classic.
- Summary: GUANO is a ground-based analysis of data from Swift BAT, significantly enhancing the sensitivity and sky area covered as compared to Swift's onboard triggering.
- Occurence Rate: The Swift/BAT-GUANO notices occur at a rate of 50 times per year.
- Time Delay: The post-event processing and communication of alert is distributed to GCN within 10 minutes to 5 hours of detection, depending on data downlink method and space-to-ground communications resource availability.
- Notice Type: The new Swift/BAT-GUANO notice type (gcn.notices.swift.bat.guano) provides timestamps, sky locations, durations, and other supplementary information on gamma-ray transients discovered through this system, to enable prompt follow-up by observers and other instruments. The 'initial' notice distributed for any detection will not include localization information. In the majority of cases later 'update' notices will follow with a localization attached. ~1/4 of GUANO bursts will have arcminute-scale localizations, distributed in the form [RA, Dec, Error] the remainder will be more poorly localized and may be distributed as HEALPix maps.
IceCube LVK Neutrino Track Search: gcn.notices.icecube.lvk_nu_track_search
- Summary: IceCube is a is a cubic-kilometer Cherenkov particle detector deployed in the Antarctic ice beneath the Amundsen-Scott South Pole Station. IceCube detects neutrinos by observing the light produced by relativistic charged particles created by neutrino interactions in or near the instrumented volume of ice.
- Occurrence Rate: The LVK Nu Track Search notices are triggered by LIGO/Virgo/KAGRA alerts and occur at the same rate of these alerts, searching for neutrino signals from both significant and low significance LVK alerts.
- Time Delay: Neutrino searches are performed in a +/- 500 second time window about the LVK alert, and Nu Track search results are generally available within ~1000 seconds of the LVK GW event time.
- Notice Type: The new LVK Nu Track Search notice type (gcn.notices.icecube.lvk_nu_track_search) provides results from realtime searches for coincident neutrino signals from all LIGO/Virgo/KAGRA gravitational-wave alerts, using a realtime muon neutrino track-like event selection and the sky maps from gravitational wave detectors. Search results will include neutrino directions for observed coincident events with the aim to identify multi-messenger transient sources and seed electromagnetic followup up observations.
This September, we've added some new features to GCN Circulars:
- Cross References. Navigate the GCN Circulars archive faster with Circulars cross-references, arXiv preprints, DOIs, and other URLs displayed as hyperlinks.
- Bibliographies. Cite GCN Circulars by retrieving their SAO/NASA Astrophysics Data System (ADS) bibcodes and BibTeX records from the GCN Circulars archive. See the documentation for details.
- Archive Download. Download the entire GCN Circulars archive as a tarball. See the Advanced options section of the GCN Circulars archive.
Thanks to the feedback of some of our users, we have tracked down and fixed several reliability issues related to our Kafka brokers and clients. If you are consuming GCN Notices via Kafka in Python, then please take the actions noted below.
Daily Kafka outages have been resolved. The GCN Kafka brokers had been experiencing daily outages at around 00:00 UTC and lasting from about a minute to an hour. We traced the problem to a log collection agent that was using excessive memory. We resolved the issue by disabling the agent.
Python sample code has been updated. Our Python client sample code was missing some necessary error handling. Some errors that may occur in the
consumer.consume()loop are reported in the returned Kafka message. If you consume GCN Notices via Kafka in Python using the gcn-kafka-python client or confluent-kafka-python, then please be sure to update your code as follows.
If your client consume loop looks like this:
while True: for message in consumer.consume(timeout=1): value = message.value() # add your code to process the alert here
then add an
ifstatement to skip normal processing for errors, like this:
while True: for message in consumer.consume(timeout=1): if message.error(): print(message.error()) continue value = message.value() # add your code to process the alert here
New version of Python client. We have released version 0.3.3 of our official Python client, gcn-kafka-python. This version improves the reliability of authentication for long-lived connections. Please update to the latest version. If you are not using our official client but you are using confluent-kafka-python directly, then please update to the latest version of confluent-kafka-python (2.2.0 or newer).
Due to planned network maintenance at GSFC, the connections to GCN Classic will be offline on Saturday, May 6 from 8AM ET (12:00 UTC) and concluding no later than 3PM ET (19:00 UTC). This affects the following GCN services:
- GCN Classic Notices distribution via socket, VOEvent, and email
- GCN Classic Notices web site archive
- GCN Classic-to-Kafka connection and distribution of Notices via Kafka and email
- Forwarding of GCN Circulars submitted to email@example.com, however submission to firstname.lastname@example.org and the web form will be unaffected.
We are pleased to announce that on April 17, 2023, the General Coordinates Network will launch the most significant overhaul of GCN Circulars since its inception in 1997. The modernized GCN Circulars experience will be part of the new GCN web site. After the transition on April 17, you will be able to:
- Browse and search Circulars in our all-new archive.
- Sign up for and manage your own email subscriptions.
- Enroll yourself and your colleagues to submit Circulars with arXiv-style peer endorsements for new contributors.
- Submit Circulars with our new Web form, or continue to submit by email.
Here is what you need to know about preparing for the transition on April 17.
- If you use Circulars now, we will transfer your settings automatically.
- If you receive Circulars now, you will continue to receive them.
- If you submit Circulars now, you will still be able to submit from the same email addresses.
- Emails from Circulars will come from a new address, email@example.com.
- We will encourage you to submit Circulars to the new address, firstname.lastname@example.org, but we will still support the old address email@example.com.
- The new archive will include all past Circulars. We will freeze the old archive, https://gcn.gsfc.nasa.gov/gcn3_archive.html.
To introduce GCN users to the new GCN Circular system, we invite you to join one of our three public Zoom webinars:
GCN now distributes notices from the GECAM mission. Start streaming GECAM notices using GCN Classic over Kafka, have them delivered to your email inbox using self-service email subscriptions, or receive them as legacy notices using GCN Classic. To modify GCN Classic subscriptions, please contact us.
Have GCN Notices delivered to your email inbox by signing up and managing your subscriptions through this web site. To get started, sign in or sign up and then select "Email Notifications" from the account dropdown menu. Note that signing up here does not affect prior subscriptions on the old web site, https://gcn.gsfc.nasa.gov. To unsubscribe from the old web site, please contact us. See GCN Circular 32517.
All three classic GCN Notice formats (text, VOEvent, 160-byte binary packet) are now also available over Kafka. This new Kafka streaming service can be used as a drop-in replacement for GCN Classic socket and VOEvent subscribers, with an upcoming release serving email subscribers. See GCN Circular 32419.