TITLE: GCN CIRCULAR
NUMBER: 34285
SUBJECT: GRB 230728A: NOT optical observations and possible host galaxy
DATE: 23/07/28 09:23:06 GMT
FROM: Dong Xu at NAOC/CAS <dxu(a)nao.cas.cn>
D. Xu, S.Y. Fu, S.Q. Jiang, Z.P. Zhu (NAOC), Z. Gray (NOT), report:
We observed the field of GRB 230728A detected by Swift (Salvaggio et al., GCN 34282) using the the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations started at 04:26:55 UT on 2023-07-28, i.e., ~ 1.61 hr after the Swift/BAT trigger, and 3x300 s Sloan r-filter images and 5x200 s Sloan z-filter images were obtained, respectively.
No optical source is detected within or at the border of the Swift/XRT error circle (radius ~1.9 arcsec, 90% containment, Salvaggio et al., GCN 34282) down to upper limits of r > 24.2 mag (5-sigma) and z > 23.0 mag (5-sigma).
We note that there exists a galaxy south-western, ~3.7 arcsec away from the center of the Swift/XRT error circle. This galaxy is present in SDSS with r ~ 22.39 mag, z ~ 22.99 mag, z_phot ~ 0.34, and in Legacy Survey with r ~ 22.14 mag, z ~ 22.04 mag, z_phot ~ 0.37, respectively. Preliminary photometry of the galaxy from the NOT data gives r ~ 22.4 mag and z ~ 23.0 mag, which are consistent with the above archival values, indicating that there is no prominent optical afterglow in this potential host galaxy.
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TITLE: GCN CIRCULAR
NUMBER: 34284
SUBJECT: IceCube-230724A: No counterparts from the Zwicky Transient Facility
DATE: 23/07/28 09:13:14 GMT
FROM: Sven Weimann at Ruhr University Bochum <swei(a)astro.rub.de>
Sven Weimann (Ruhr University Bochum), Simeon Reusch (DESY), Jannis Necker (DESY), Robert Stein (Caltech) and Anna Franckowiak (DESY/Ruhr University Bochum) report:
On behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations:
As part of the ZTF neutrino follow up program (Stein et al. 2022), we observed the localization region of the neutrino event IceCube-230724A (Santander et. al, GCN 34265) with the Palomar 48-inch telescope, equipped with the 47 square degree ZTF camera (Bellm et al. 2019, Graham et al. 2019). We started observations in the g- and r-band beginning at 2023-07-24 10:12 UTC, approximately 8.4 hours after event time. We covered 100.0% (0.5 sq deg) of the reported localization region. This estimate accounts for chip gaps. Each exposure was 300s with a typical depth of 21.0 mag.
The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC to search for potential counterparts (Masci et al. 2019). AMPEL (Nordin et al. 2019, Stein et al. 2021) was used to search the alerts database for candidates. We reject stellar sources (Tachibana and Miller 2018) and moving objects, and apply machine learning algorithms (Mahabal et al. 2019).
No candidate counterparts were detected.
Additional observations are planned as part of our standard neutrino follow-up procedure, and any candidates will be reported.
ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA; WIS, Israel; OKC, Sweden; JSI/UMd, USA; DESY, Germany; TANGO, Taiwan; UW Milwaukee, USA; LANL, USA; TCD, Ireland; IN2P3, France.
GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949.
Alert distribution service provided by DIRAC@UW (Patterson et al. 2019).
Alert database searches are done by AMPEL (Nordin et al. 2019).
Alert filtering is performed with the nuztf package (Stein et al. 2021, https://github.com/desy-multimessenger/nuztf).
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TITLE: GCN CIRCULAR
NUMBER: 34283
SUBJECT: GRB 230727A: AstroSat CZTI detection
DATE: 23/07/28 06:47:03 GMT
FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in>
B. Pari (IITB), P K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 230727A which was also detected by Fermi (Fermi GBM Team, GCN Circ. 34275) and Swift/BAT-GUANO (DeLaunay et al., GCN Circ. 34280).
The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-07-27 11:03:09.45 UTC. The measured peak count rate associated with the burst is 709.2 (+211.2, -56.0) counts/s above the background in the combined data of all quadrants, with a total of 1916 (+278, -290) counts. The local mean background count rate was 522.1 (+5.0, -7.7) counts/s. Using cumulative rates, we measure a T90 of 11.8 (+2.5, -1.6) s.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-07-27 11:03:08.85 UTC. The measured peak count rate associated with the burst is 343.3 (+76.9, -79.7) counts/s above the background in the combined data of all quadrants, with a total of 1231 (+419, -444) counts. The local mean background count rate was 1992.2 (+5.8, -7.1) counts/s. We measure a T90 of 11.3 (+3.7, -5.1) s from the cumulative Veto light curve.
CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.
CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb
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TITLE: GCN CIRCULAR
NUMBER: 34282
SUBJECT: GRB 230728A: Swift detection of a burst
DATE: 23/07/28 03:07:03 GMT
FROM: David Palmer at LANL <palmer(a)lanl.gov>
C. Salvaggio (INAF-OAB), P. D'Avanzo (INAF-OAB), S. Laha (GSFC/UMBC),
D. M. Palmer (LANL), T. M. Parsotan (GSFC/UMBC/CRESSTII) and
M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 02:50:03 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230728A (trigger=1181187). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 343.539, +28.151 which is
RA(J2000) = 22h 54m 09s
Dec(J2000) = +28d 09' 03"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). Due to a telemetry gap, BAT lightcurve information
is not immediately available.
The XRT began observing the field at 02:51:33.5 UT, 90.3 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source with an enhanced position: RA, Dec 343.51530,
28.17470 which is equivalent to:
RA(J2000) = 22h 54m 03.67s
Dec(J2000) = +28d 10' 28.9"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This
location is 113 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
https://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (6.29 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 7.2
(+2.52/-2.21) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 7.13e-10 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 99 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.079.
Burst Advocate for this burst is C. Salvaggio (chiara.salvaggio AT inaf.it).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)
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TITLE: GCN CIRCULAR
NUMBER: 34281
SUBJECT: Swift GRB230728.12: Global MASTER-Net observations report
DATE: 23/07/28 02:56:43 GMT
FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru>
V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko,
G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin
(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile
(Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),
D. Buckley
(South African Astronomical Observatory),
O.A. Gres, N.M. Budnev
(Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov
(Blagoveschensk Educational State University)
MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB230728.12 (trigger No 1181187,22h 54m 09.36s , +28d 09m 03.6s, R=0.05) errorbox 19 sec after notice time and 36 sec after trigger time at 2023-07-28 02:50:40 UT, with upper limit up to 17.2 mag. The observations began at zenith distance = 64 deg. The sun altitude is -33.9 deg.
The galactic latitude b = -28 deg., longitude l = 94 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2246027
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
42 | MASTER-SAAO | P/ | 10 | 16.3 |
42 | MASTER-SAAO | C | 10 | 17.2 |
61 | MASTER-SAAO | P/ | 10 | 16.4 |
61 | MASTER-SAAO | C | 10 | 17.2 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
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TITLE: GCN CIRCULAR
NUMBER: 34280
SUBJECT: GRB 230727A: Swift/BAT-GUANO detection of a burst
DATE: 23/07/28 01:05:25 GMT
FROM: Jimmy DeLaunay at University of Alabama <delauj2(a)gmail.com>
James DeLaunay (UAlabama), Gayathri Raman (PSU), Samuele Ronchini (PSU), Aaron Tohuvavohu (U Toronto), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report:
Swift/BAT did not localize GRB 230727A onboard (T0: 2023-07-27T11:03:06.85 UTC, Fermi Trig 712148591, GCN 34275).
The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).
Upon trigger by this 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 the burst. All the requested event mode data was delivered to the ground.
The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), detects the burst with a sqrt(TS) of 11 in a 2.048 s analysis time bin.
NITRATES results, independently, are ambiguous with respect to whether this burst originates from in or outside the BAT coded FOV, with a borderline DeltaLLHOut of 7.4.
The Fermi GBM localization (GCN 34275) has this burst significantly outside of the BAT coded FOV
See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.
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.
A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/
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TITLE: GCN CIRCULAR
NUMBER: 34279
SUBJECT: Fermi-LAT gamma-ray observations of IceCube-230725A
DATE: 23/07/28 00:11:45 GMT
FROM: Simone Garrappa at DESY <simone.garrappa(a)desy.de>
S. Garrappa (Weizmann Institute of Science), C. Bartolini (INFN Bari), S. Buson (Uni Wuerzburg) and J. Sinapius (DESY) on behalf of the Fermi-LAT collaboration:
We report an analysis of observations of the vicinity of the IC230725A high-energy neutrino event (GCN 34261) with all-sky survey data from the Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope. The IceCube event was detected on 2023-07-25 at 21:30:51.06 UT (T0) with J2000 position RA = 327.04 (+2.27, -2.03) deg, Decl. = 12.33 (+1.80, -1.36) deg (90% PSF containment). There is one Fermi 4FGL-DR3 cataloged gamma-ray (>100 MeV; The Fermi-LAT collaboration 2022, ApJS, 260, 53) source in the 90% IC230725A uncertainty localization region. This is 4FGL J2150.8+1118 associated with the BL Lac object NVSS J215051+111915, located at 1.2 deg from the IC230725A position. Based on a preliminary analysis of the LAT data over a month and day timescale prior T0, this object is not significantly detected at gamma rays.
We searched for intermediate (days to years) timescale emission from a new gamma-ray source. Preliminary analysis indicates no significant (> 5 sigma) new excess emission (> 100 MeV) at the IC230725A best-fit position. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC230725A best-fit position, the >100 MeV flux upper limit (95% confidence) is < 3.5e-10 ph cm^-2 s^-1 for ~15-years (2008-08-04 to 2023-07-25 UTC), and < 5.3e-9 (< 7.3e-8) ph cm^-2 s^-1 for a 1-month (1-day) integration time before T0.
Since Fermi normally operates in an all-sky scanning mode, regular monitoring of this region will continue. For these observations the Fermi-LAT contact persons are S. Garrappa (simone.garrappa at weizmann.ac.il), C. Bartolini (chiara.bartolini at ba.infn.it), S. Buson (sara.buson at uni-wuerzburg.de) and J. Sinapius (jonas.sinapius at desy.de).
The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.
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TITLE: GCN CIRCULAR
NUMBER: 34278
SUBJECT: Fermi-LAT gamma-ray observations of IceCube-230724A
DATE: 23/07/28 00:08:28 GMT
FROM: Simone Garrappa at DESY <simone.garrappa(a)desy.de>
C. Bartolini (INFN Bari), S. Garrappa (Weizmann Institute of Science), S. Buson (Uni Wuerzburg) and J. Sinapius (DESY) on behalf of the Fermi-LAT collaboration:
We report an analysis of observations of the vicinity of the IC230724A high-energy neutrino event (GCN 34265) with all-sky survey data from the Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope. The IceCube event was detected on 2023-07-24 at 01:49:13.38 UT (T0) with J2000 position RA = 32.52 (+0.58, -0.40) deg, Decl. = -1.87 (+0.23, -0.33) deg (90% PSF containment). There are no Fermi 4FGL-DR3 cataloged gamma-ray (>100 MeV; The Fermi-LAT collaboration 2022, ApJS, 260, 53) sources in the 90% IC230724A uncertainty localization region.
We searched for intermediate (days to years) timescale emission from a new gamma-ray source. Preliminary analysis indicates no significant (> 5 sigma) new excess emission (> 100 MeV) at the IC230724A best-fit position. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC230724A best-fit position, the >100 MeV flux upper limit (95% confidence) is < 7.0e-10 ph cm^-2 s^-1 for ~15-years (2008-08-04 to 2023-07-24 UTC), and < 5.8e-9 (< 1.1e-7) ph cm^-2 s^-1 for a 1-month (1-day) integration time before T0.
Since Fermi normally operates in an all-sky scanning mode, regular monitoring of this region will continue. For these observations the Fermi-LAT contact persons are C. Bartolini (chiara.bartolini at ba.infn.it), S. Garrappa (simone.garrappa at weizmann.ac.il), S. Buson (sara.buson at uni-wuerzburg.de) and J. Sinapius (jonas.sinapius at desy.de).
The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.
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TITLE: GCN CIRCULAR
NUMBER: 34277
SUBJECT: Fermi trigger No 712143685: Global MASTER-Net observations report
DATE: 23/07/27 23:16:06 GMT
FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru>
V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko,
G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin
(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile
(Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),
D. Buckley
(South African Astronomical Observatory),
O.A. Gres, N.M. Budnev
(Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov
(Blagoveschensk Educational State University)
MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB230727.40 (trigger No 712143685,08h 45m 55.92s , +67d 25m 58.8s, R=35.95) errorbox 46132 sec after notice time and 46164 sec after trigger time at 2023-07-27 22:30:45 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 83 deg. The sun altitude is -26.1 deg.
The galactic latitude b = 36 deg., longitude l = 148 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2245798
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
46255 | 2023-07-27 22:30:45 | MASTER-Tavrida | (12h 21m 30.58s , +42d 33m 27.5s) | C | 180 | 15.0 |
46444 | 2023-07-27 22:33:54 | MASTER-Tavrida | (12h 21m 35.57s , +42d 34m 12.3s) | C | 180 | 15.5 |
46632 | 2023-07-27 22:37:02 | MASTER-Tavrida | (12h 21m 29.13s , +42d 34m 57.1s) | C | 180 | 15.3 |
46836 | 2023-07-27 22:40:26 | MASTER-Tavrida | (07h 12m 38.43s , +71d 49m 39.5s) | C | 180 | 14.2 |
47032 | 2023-07-27 22:43:42 | MASTER-Tavrida | (08h 44m 07.94s , +76d 40m 35.0s) | C | 180 | 17.6 |
47225 | 2023-07-27 22:46:55 | MASTER-Tavrida | (08h 50m 09.42s , +74d 46m 02.6s) | C | 180 | 17.6 |
48071 | 2023-07-27 23:01:01 | MASTER-Tavrida | (08h 52m 20.39s , +76d 39m 48.2s) | C | 180 | 17.9 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
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TITLE: GCN CIRCULAR
NUMBER: 34276
SUBJECT: IceCube-230727A - IceCube observation of a high-energy neutrino candidate track-like event
DATE: 23/07/27 20:09:11 GMT
FROM: Erik Blaufuss at University of Maryland, College Park <blaufuss(a)umd.edu>
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
On 2023-07-27 at 16:05:39.63 UT IceCube detected a track-like event with a high probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_BRONZE alert stream. The average astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 3.384 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection.
After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/138198_44334860.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:
Date: 2023-07-27
Time: 16:05:39.63 UT
RA: 33.66 (+1.16, -0.77 deg 90% PSF containment) J2000
Dec: 7.63 (+0.70, -0.64 deg 90% PSF containment) J2000
We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino.
There are no Fermi 4FGL-DR3 or 3FHL catalog sources in the 90% uncertainty region. The nearest gamma-ray source in either catalog is 4FGL J0219.5+0724 at RA: 34.89 deg, Dec: 7.41 deg (1.25 deg away from the best-fit alert position).
The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu
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