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GCN Circular 27107

GRB 200216A: Swift/BAT detection and arcminute localization from GUANO
2020-02-16T21:19:11Z (4 years ago)
Jamie A. Kennea at PSU/Swift-XRT <>
James DeLaunay (PSU), Aaron Tohuvavohu (U Toronto), and Jamie Kennea (PSU) report:

Swift/BAT did not trigger on GRB 200216A.

The Fermi/GBM Flight-Position notice, distributed at T0+24 seconds, from 
the Fermi/GBM detected GRB 200216A (GCN. 27096) triggered the Swift 
Mission Operations Center operated Gamma-ray Urgent Archiver for Novel 
Opportunities (GUANO; Tohuvavohu et al. 2020, in prep).

The GUANO is a fully autonomous, extremely low latency, spacecraft 
commanding pipeline designed for targeted recovery of BAT event mode data 
around the times of compelling astrophysical events to enable more 
sensitive GRB searches.

Upon trigger by the Fermi notice, GUANO sent a command to the Swift Burst 
Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from 
[-50,+150] seconds around the time of GRB 200216A.

All the requested event mode data was delivered to the ground.

In a ground analysis of the data, using the normal BAT imaging technique, 
we detect GRB 200216A with a SNR of 7.5.

With a more sophisticated maximum likelihood analysis (DeLaunay et al., 
2020 in prep.) on the event-mode data we detect GRB 200216A more 
confidently, with a square root of the test statistic (sqrt(TS)) of 15.4. 
The sqrt(TS) behaves similarly to SNR.

The BAT ground-calculated position is
RA, Dec = 311.4378, -11.6580 deg which is
   RA(J2000)  = 311d 26' 16.08"
   Dec(J2000) = -11d 39' 28.8"
with an uncertainty of 3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 40%.

This arcminute location is consistent with the localization region 
distributed by the Fermi/GBM team (GCN. 27096).

No XRT or UVOT follow-up will take place due to the source's proximity to 
the sun (1.2 hours). We encourage follow-up from instruments capable of 
observing near the sun.
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