SuperNova Early Warning System
Overview
The SuperNova Early Warning System, or SNEWS, is a network of neutrino and dark matter detectors sensitive to the 1-100 MeV neutrinos produced by a nearby core-collapse supernova. The network provides the astronomical community with a high-confidence early warning of a supernova hours to days before the optical emission can be detected. It provides timing and pointing information about the supernova for optical follow-up.
Further information about SNEWS and its successor network, SNEWS 2.0, can be found here:
Antonioli et al., SNEWS: The Supernova Early Warning System *, New J. Phys. 6:114, 2004.
Al Kharusi et al., SNEWS 2.0: a next-generation supernova early warning system for multi-messenger astronomy, New J. PHys. 23:3, 2021.
In the following sections, we describe the interaction between IceCube, the original SNEWS network, and SNEWS 2.0.
SNEWS
The SNDAQ Virtual Machine
A virtual machine (VM) hosted at WIPAC handles communications between IceCube
and the SNEWS server, hosted at Brookhaven National Laboratory. To get access
to the VM, contact the IceCube Help Desk to
be added to the list of users. Once your are added, you can log into the
machine through the cobalt
nodes:
$> ssh yourname@pub.icecube.wisc.edu
$> ssh cobalt
$> ssh sndaq
$> sudo su - sndaq
Alerts from i3Live
If SNDAQ measures a test statistic which fulfills the criteria for sending an
alert to SNEWS, it forwards the information vie i3Live and i3Live publishes the
SNEWS alert information via zmq
. The script
sndaq@sndaq:~$/I3LiveListener/startI3LiveListener.py
runs continuously and checks the published i3Live tables for SNEWS alerts. The
snippet below shows part of the program, which handles the zmq
connection
to i3Live:
context = zmq.Context()
socket = context.socket(zmq.SUB)
socket.connect("tcp://live:7010")
socket.setsockopt(zmq.SUBSCRIBE, '')
I3Live also publishes test alerts every 6 hours. If it receives a SNEWS alert or a test alert, it decides whether or not to send test alerts to the SNEWS
sndaq@sndaq:~$/I3LiveListener/make_alerts_html.py
SNEWS monitoring webpages are available in the SNDAQ section of i3Live. The shell scripot
sndaq@sndaq:~$/I3LiveListener/checkI3LiveListener.sh
polls to see if startI3LiveListener.py is running. If not, it automatically restarts the script.
Communication between the VM and the SNEWS server is handled by the third-party
library coincode
library maintained by Alec Habig.
SNEWS Monitoring Shifts
Experiments collaborating with SNEWS will shifts monitoring the SNEWS alert servers. In IceCube this is the responsibility of members of the Supernova Working Group, not winterovers or the monitoring shiftes. The following outlines the steps for completing a monitoring shift, though some information has been excluded in accordance with the SNEWS Collaboration’s privacy policy.
First, a shifter must obtain login credentials for:
sndaq
virtual machine: contact the IceCube Helpdesk *.Brookhaven National Lab (BNL) SSH Portal
ssh.bnl.gov
: contact Brett Viren.INFN Bologna Portal,
lnxbo.bo.infn.it
: contact Pietro Antonioli.BNL and INFN machines hosting SNEWS alert servers: contact Kate Scholberg or Alec Habig.
SNEWS Working Group Pages: contact Kate Scholberg or Alec Habig.
The primary SNEWS server is hosted by BNL and a backup is hosted by INFN Bologna. There is an online application to obtain credentials for BNL, but it may take time ot process. Allot at least 3 weeks to obtain BNL credentials. To obtain credentials for INFN Bologna, a paper form must be submitted with a passport/ID card photocopy. Additionally, shifters must read and agree to follow the SNEWS privacy policy.
SNEWS monitoring shifts last one week, during which a shifter must ping the
primary and backup SNEWS servers using an IceCube machine twice a day. To ping
the SNEWS servers from IceCube, log into the sndaq
virtual machine.
Then execute the following command in the directory /home/sndaq/coinccode
:
sndaq@sndaq:~$ ./shifter_cping
This is equivalent to running
sndaq@sndaq:~$ ./cping all 0 0 0 6
where the arguments to cping
are
cping [server] [DDMMYY] [HHMMSS] [nanoseconds] [xperiment]
with IceCube being experiment 6. After sending a ping from the IceCube system, shifters must confirm it has been recieved by the SNEWS alert servers. Log into the systems at BNL and INFN Bologna and then to the SNEWS alert servers as follows:
user@your_pc:~$ ssh user@ssh.bnl.gov
user@ssh.bnl.gov:~$ ssh primary_server@primary_server_domain
user@your_pc:~$ ssh user@lnxbo.bo.infn.it
user@lnxbo:~$ ssh second_server@second_server_domain
Note that the names and domains of the machines hosting the SNEWS servers are placeholders. A SNEWS shifter manual available to the private SNEWS working group details how to check and record that the SNEWS servers are running. Contact Kate Scholberg or Alec Habig to obtain the credentials for the SNEWS alert servers and working group pages.