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:

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:

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.

SNEWS 2.0