SNEWS The Supernova Early Warning System

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SNEWS The Supernova Early Warning System
But star is transparent to n within ms after the
formation of the neutron star so n precede
photons by the time it takes the shock to
traverse the radius of the star, hours of advance
notice of the impending SN if you can see the n
Light from a core-collapse Supernova will not
escape from star until the shock wave breaks out
through the photosphere.
Many n experiments sensitive to n from nearby SN
(in our galaxy) (expected rates below for SN_at_8.5
kpc)
Super-Kamiokande (Japan) 50kton
Sudbury Neutrino Observatory (Canada) 1.7kton
H2O, 1kton D2O

• SNEWS is a coincidence network between these
  experiments own SN alarm triggers
• Goal eliminate possible false alarms which
  occur in an individual experiment due to local
  conditions
• A real SN will be observed simultaneously in
  all!
• Removing the need to have a shiftworker manually
  vette alarms allows automated, fast alert to take
  advantage of n lead time
• Will allow observation of the next nearby SN from
  times near zero
• HST Target of Opportunity time allocated, an
  example of a pre-prepared observing plan to
  exploit this information
• Bonus this existing collaboration between
  experiments allows the coordination of downtime
  between experiments, to help ensure someone
  somewhere is live for supernova at any given time
• Bonus 2 experiments can send Gold, no-doubt
  alarms, or silver alarms which might have some
  problems (during calibration or maintenance runs,
  for example).
• If a coincidence is formed due to Silver
  alarms, the alert does not go to the world, but
  back to the experiments so the operators can
  verify things (and upgrade to a Gold alarm if
  appropriate)
• This is some comfort to experimenters, after all
  Murphys Law says that the next SN will come when
  youre not ready for it

7000 inv. b decay, 410 on 16O, 300 elast.
scattering, 4o pointing
710 inv. b decay, 160 2H breakup, 45 elast.
scattering, 17o pointing
SSL sockets
Server 10s coincidence window
Coincidence server securely hosted by Brookhaven
National Lab
PGP signed email
AMANDA (South Pole) 1.6kt ice/PMT, 667
PMTs 16s singles rate increase In final SNEWS
test phase
Email alarms to astronomers and n experimenters
GCN alert (coming soon!)
Sign up yourself to receive an alert at
http//snews.bnl.gov/
(Mini-BooNE, KamLAND, Borexino, LIGO also
sensitive to nearby SN but not yet sending
alarms to SNEWS)
How to pin down SN location?
Given that the best n pointing information is
from elastic scattering, leaving a search field
of many square degrees at best, how will
observers find the new Supernova to take
advantage of the early alert and get observations
from the earliest possible epoch? One avenue is
high energy satellites with all-sky capability, a
n alert will let them prepare. Shock breakout
should produce a strong UV/X-ray transient.
SNEWS will tie into GCN soon in order to make
this easier. Another Amateur astronomers have
many eyes, wide angle instruments, and intimate
knowledge of the sky Sky Telescope and the
AAVSO have experience in coordinating amateur
efforts On Feb 14 2003, a carefully labeled test
message was sent
Looking for 1 SN/century, cannot tolerate more
false alarms than SNe False Alarms are
Poissonian, uncorrelated. If rate is at most
1/10days /expt, (for 2 of 4 coincidence), above
is the false coincidence rate
This Sky Telescope AstroAlert is being issued
as a test in support of the SuperNova Early
Warning System (SNEWS). We seek your assistance
in pinpointing the location of a possible
supernova explosion. Neutrino detectors give the
targets approximate coordinates (equinox 2000.0)
in the constellation Bootes, as follows
Right ascension 13h 38m Declination
8.1 degrees Uncertainty radius 13
degrees Expected magnitude unknown
Please check this region of the sky as soon as
possible using your naked eyes, binoculars, a
telescope, or a camera. You are looking for a
starlike point of light ...

• Vesta (mag 6.7) was at a stationary point in its
  retrograde loop in the given error box
• Not a regular star, not moving
• It worked, given the small statistics of those
  wishing to participate in a known test
• 90 responses, all over the world, wide variety
  of instruments
• 70 of people got the alert within 8 hours (a
  dozen right away)
• Given time of day and weather, many found Vesta,
  and had good search strategies
• Will do more such tests, for practice and to
  maintain interest

• Summary
• SNEWS operational, waiting for galactic supernova
• Four participating experiments at present
• Adding others as their SN n triggers mature
• Sign up for your own once-per-career galactic
  supernova email alert
• http//snews.bnl.gov
• What would you do with hours warning of a
  supernova?
• See astro-ph/0406214 (New J.Phys. 6, 114) for far
  more details about SNEWS than fit on a poster and
  references

2001 high rate test using artificially lowered
experimental thresholds confirms Poissonian,
uncorrelated nature of the alarms and coincidence
network All alarm data normally kept
confidential, internal to the SNEWS server
SNEWS supported by NSF grants 0303196 and
0302166