Alec Habig, UMD,for the SNEWS group

SNEWS – The Supernova Early Warning System

Light from a core-collapse Supernovawill not escape from star until theshock wave breaks out through the photosphere.

But star is transparent to within ms after the formation of the neutron star

so 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

Many experiments sensitive to from nearby SN (in our galaxy)

(expected rates below for SN@8.5 kpc)

Super-Kamiokande (Japan) 50kton Sudbury Neutrino Observatory

(Canada) 1.7kton H2O, 1kton D2O

(Mini-BooNE, KamLAND, Borexino, LIGO also sensitive to nearby SN but not yet sending alarms to SNEWS)

7000 inv. decay, 410 on 16O, 300 elast. scattering, 4o pointing 710 inv. decay, 160 2H breakup,

45 elast. scattering, 17o pointing

Server10s coincidence

window

Email alarmsto astronomers

and experimenters

SSL sockets

PGP signed email

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 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 Murphy’s Law says that the next SN will come when you’re not ready for it

SN 1987A was seen

by previous expts.

SNEWS supported by NSF grants#0303196 and #0302166

Coincidence server securely hosted byBrookhaven National Lab

Given that the best 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 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:

This Sky & Telescope AstroAlert is being issued [as a test] in support of the SuperNova Early Warning System (SNEWS). We seek your assistance in pinpointingthe location of a possible supernova explosion. Neutrino detectors give the target‘sapproximate 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 oflight ...

•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

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

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

Summary•SNEWS operational, waiting for galactic supernova•Four participating experiments at present

•Adding others as their SN 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

How to pin down SN location?

Sign up yourself to receive an alert at: http://snews.bnl.gov/

LVD (Italy) 1ktonLiquid scint ~300 e

<Ee> ~ 12 MeV

<Ee> ~ 15 MeV

<E> ~ 18 MeV

AMANDA(South Pole) 1.6kt ice/PMT, 667 PMTs~16 singles rate increase

In final SNEWS test phase

GCN alert(coming soon!)