IceCube-240105A
GCN Circular 35485
Subject
IceCube-240105A - IceCube observation of a high-energy neutrino candidate track-like event
Date
2024-01-05T15:22:16Z (a year ago)
From
Erik Blaufuss at University of Maryland, College Park <blaufuss@umd.edu>
Via
Web form
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
On 2024-01-05 at 12:27:42.57 UT IceCube detected a track-like event with a moderate 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 2.64 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/138821_46175426.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:
Date: 2024-01-05
Time: 12:27:42.57 UT
RA: 72.69 (+0.53, -0.33 deg 90% PSF containment) J2000
Dec: +11.42 (+0.20, -0.08 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.
One gamma-ray source listed in the 4FGL-DR4 Fermi-LAT catalog is located in the 90% uncertainty of the event. The source is 4FGL J0449.1+112 (associated with PKS 0446+11), located at RA = 72.28 deg and Dec = +11.36 deg (J2000), 0.4 deg away from the best-fit 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@icecube.wisc.edu
GCN Circular 35498
Subject
Update of IceCube-240105A - Corrected errors
Date
2024-01-08T16:26:08Z (a year ago)
From
Giacomo Sommani at Ruhr-Universität Bochum <gsommani@icecube.wisc.edu>
Via
Web form
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
The directional errors of the high-energy track-like event IceCube-240105A reported in GCN circular 35485 were incorrectly reported, as they were not taking into consideration ice systematics. All other information was correct. The corrected refined directional information is:
Date: 2024-01-05
Time: 12:27:42.57 UT
RA: 72.69 (+1.92, -1.85 deg 90% PSF containment) J2000
Dec: +11.42 (+0.50, -0.44 deg 90% PSF containment) J2000
In addition to the previously reported event in the 90% uncertainty region, one additional gamma-ray source listed in the 4FGL Fermi-LAT catalog is also found. The source is 4FGL J0458.0+1152, associated with a Blazar candidate, and located 1.8 deg away from the best-fit position. The source is also listed in the Fermi 3FHL catalog as 3FHL J0458.0+1151.
We apologize for the error.
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@icecube.wisc.edu
GCN Circular 35499
Subject
IceCube-240105A: JCMT SCUBA2 Detection of Two Bright Submillimeter Sources
Date
2024-01-08T17:04:31Z (a year ago)
From
Kuiyun Huang at CYCU <kuiyun@gmail.com>
Via
legacy email
K.Y. Huang and Y. Urata, on behalf of a large collaboration
SCUBA2 onboard JCMT captured images in 450um and 850um encompassing
the entire 90% PSF containment region of IceCube-240105A (GCN
Circ. #35485) on January 6, 2024. No sources with an rms of 7 mJy were
detected within the 90% PSF containment region of IceCube-240105A. However,
the 850μm map revealed the presence of two bright sources near the
periphery of the 90% PSF containment region. These sources are identified
as PKS 0446+11 and the flat spectrum radio quasar (or Blazar, hereafter
J0448+1127), previously cataloged in various publications.
SCUBA2 measured the peak flux for PKS 0446+11 as
1130 mJy at 850um
838 mJy at 450um
Combined with the ALMA calibrator source catalog, the light curve
peaked on November 5, 2023. The SCUBA2 measurement indicates a slight
fading from the peak.
The other source, J0448+1127, is located at 04:49:07.754 +11:21:31
with 13 arcsec error, 0.48 deg away from the IceCube's best-fit
position. Catalog matching indicates the source is FSRQ, with redshift
1.375 recorded in various catalogs. SCUBA2 measured the peak flux as
104 mJy at 850um. Although there are no suitable reference observations for
variability checking, the source may exhibit brightening based on
comparisons with the last observation by ALMA in 2021 with a similar
wavelength.
GCN Circular 35510
Subject
IceCube-240105A: Three candidates from the Zwicky Transient Facility
Date
2024-01-09T19:28:50Z (a year ago)
From
Jannis Necker at DESY <jannis.necker@desy.de>
Via
Web form
Jannis Necker (DESY), Simeon Reusch (DESY), Robert Stein (Caltech), Sven Weimann (Ruhr University Bochum) 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. 2023), we observed the localization region of the neutrino event Update of IceCube-240105A (Sommani et. al, GCN 35498) 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 2024-01-06 02:38 UTC, approximately 14.2 hours after event time. We covered 74.4% (2.6 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) . We are left with the following high-significance transient candidates by our pipeline, all lying within the 90.0% localization of the skymap.
+---------------------------------------------------------------------------------+
| ZTF Name | IAU Name | RA (deg) | DEC (deg) | Filter | Mag | MagErr |
+---------------------------------------------------------------------------------+
| ZTF23abtgfpu | AT2023ackx | 072.6719530 | +11.1938046 | r | 21.36 | 0.14 |
| ZTF23abtgghf | AT2023acky | 073.9142070 | +11.0765116 | r | 21.61 | 0.17 |
| ZTF24aaanwyg | AT2024ui | 073.3448656 | +11.8765801 | r | 20.34 | 0.06 |
+---------------------------------------------------------------------------------+
Amongst our candidates,
ZTF23abtgfpu and ZTF23abtgghf are probable supernovae based on their distance to the core of their respective host galaxy.
The nature of ZTF24aaanwyg is less clear.
We will resume our regular follow-up observation schedule to obtain more observations of these objects.
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 (Stein et al. 2021, https://github.com/desy-multimessenger/nuztf ).
GCN Circular 35512
Subject
IceCube-240105A: Upper limits from a search for additional neutrino events in IceCube
Date
2024-01-09T21:47:25Z (a year ago)
From
Jessie Thwaites at IceCube/U Wisc-Madison <thwaites@wisc.edu>
Via
Web form
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-240105A (https://gcn.nasa.gov/circulars/35498) in a time range of 1000 seconds centered on the alert event time (2024-01-05 12:19:22.57 UTC to 2024-01-05 12:36:02.57 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-240105A. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-240105A is 1.3e-01 GeV cm^-2 in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 2e+02 GeV and 1e+05 GeV.
A subsequent search was performed including 2 days of data centered on the alert event time (2024-01-04 12:27:42.57 UTC to 2024-01-06 12:27:42.57 UTC). In this case, we report a p-value of 1.00, consistent with no significant excess of track events. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-240105A ranges from 1.5e-01 to 1.6e-01 GeV cm^-2 in a 2 day time window.
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@icecube.wisc.edu.
[1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021)
GCN Circular 35517
Subject
Fermi-LAT detection of increased gamma-ray activity of blazar PKS 0446+11, located inside the IceCube-240105A error region
Date
2024-01-10T15:47:25Z (a year ago)
From
Sara Buson at Univ. of Wurzburg <sara.buson@gmail.com>
Via
Web form
J. Sinapius (DESY), S. Garrappa (Weizmann Institute of Science), S. Buson (Univ. of Wuerzburg), C. Bartolini (INFN Bari) and L. Pfeiffer (Univ. of Wuerzburg) on behalf of the Fermi-LAT collaboration
We report an analysis of observations of the vicinity of the IC240105A high-energy neutrino event (GCN 35498) 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 2024-01-05 at 12:27:42.57 UT (T0) with J2000 coordinates RA = 72.69 (+1.92, -1.85) deg, Decl. = +11.42 (+0.50, -0.44) deg (90% PSF containment). There are two known gamma-ray sources (>100 MeV; 4FGL-DR4, The Fermi-LAT collaboration 2023, arXiv:2307.12546) located within the 90% IC240105A localization region. These are 4FGL J0449.1+1121, associated with the FSRQ PKS 0446+11 at a redshift of 2.15 (Shaw et al. 2012, ApJ, 748, 49) and the blazar of uncertain type 4FGL J0458.0+1152 (a.k.a. NVSS J045804+115142). These sources are located at 0.4 deg and 1.9 deg from the neutrino best-fit position, respectively. Based on a preliminary analysis of the LAT data over the timescales of 1-day prior to T0, these objects are not significantly detected (> 5 sigma).
In a preliminary analysis of LAT data integrated over 1 month before T0, only 4FGL J0449.1+1121 is significantly detected (> 5 sigma). This gamma-ray source showed significantly increased activity in November 2023 (ATel #16332), where its flux reached 18 times the cataloged average flux reported in 4FGL-DR4. A preliminary light curve of the object is available at https://fermi.gsfc.nasa.gov/ssc/data/access/lat/LightCurveRepository/source.html?source_name=4FGL_J0449.1+1121.
Preliminary analysis indicates that 4FGL J0449.1+1121 has been brighter than its average state also in the weeks before T0, and likely in the descending phase of the flare reported on November 2023. In a preliminary analysis of LAT data integrated over one month prior T0, the observed flux (E>100 MeV) is (1.9 +/- 0.3) e-7 photons cm^-2 s^-1 (statistical uncertainty only). This is more than 3 times greater than the average flux reported in the 4FGL-DR4. We encourage multiwavelength observations of this source.
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 IC240105A best-fit position. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC240105A best-fit position, the >100 MeV flux upper limit (95% confidence) is <5.9e-10 ph cm^-2 s^-1 for ~15-years (2008-08-04 to 2023-01-05 UTC), and < 2.8e-8 (<2.8 e-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 person is 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.
GCN Circular 35548
Subject
IceCube-240105A: ZTF optical observation of blazar PKS 0446+11
Date
2024-01-16T20:09:30Z (a year ago)
From
Jannis Necker at DESY <jannis.necker@desy.de>
Via
Web form
Jannis Necker (DESY), Simeon Reusch (DESY), Robert Stein (Caltech), Sven Weimann (Ruhr University Bochum) and Anna Franckowiak (DESY/Ruhr University Bochum) report:
We observed the blazar PKS 0446+11 with the Palomar 48-inch telescope as part of our ZTF neutrino follow up campaign (Necker et. al, GCN 35510) of IceCube-240105A (Sommani et. al, GCN 35498).
The blazar is detected over 2000 days with clear signs of variability. It recently reached its peak brightness in g-band in November after a around one month long rise in both g- and r-band, which coincides with activities in gamma-rays (ATEL #16398) and radio (ATEL #16399). At 2024-01-06T06:16:01.001280, we measured the all-time peak r-band brightness (17.1mag) only around 17 hours after the detection of IceCube-240105A, coinciding with the recent activitiy in X-rays (ATEL #16397). The blazar has since faded in both bands to 19.5mag in g-band and 18.3mag in r-band.
The blazar was not selected as a candidate counterpart by our automatic follow-up pipeline because it got rejected as a star based on a metric derived from Pan-STARRS data (Tachibana & Miller, 2018, PASP 130 128001).
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 (Stein et al. 2021, https://github.com/desy-multimessenger/nuztf ).
GCN Circular 35584
Subject
IceCube-240105A: Detection of NIR flare of PKS 0446+11 with WINTER
Date
2024-01-19T22:13:46Z (a year ago)
From
Robert Stein at Caltech <rdstein@astro.caltech.edu>
Via
Web form
Robert Stein (Caltech), Danielle Frostig (MIT), Viraj Karambelkar (Caltech), Mansi Kasliwal (Caltech), Nathan Lourie (MIT), Geoffrey Mo (MIT), and Robert Simcoe (MIT) report, on behalf of the WINTER collaboration:
We observed the localization region of the neutrino event IceCube-240105A (Sommani et. al, GCN 35498) with the Palomar 1-m telescope, equipped with the 1 square degree WINTER camera (Lourie et al 2020). We started observations in the J-band beginning at 2024-01-06T05:22:36 UTC, approximately 16.9 hours after event time. As a result of the evolving neutrino localisation (GCN 35485, GCN 35498) and inclement weather, our observations took place over four nights (Jan 5th, 6th, 12th, 16th), with some overlap in coverage between visits. In total, we covered ~90% of the reported localization region at least once, and ~35% at least twice. This estimate does not account for chip gaps. Exposures had a median depth of 18.5 mag AB.
The images were processed through the WINTER data reduction pipeline implemented using mirar (Stein, Karambelkar et al in prep., https://github.com/winter-telescope/mirar), with image subtraction performed relative to reference images built from the UKIRT Hemisphere Survey (Dye et al. 2017). We extract sources with positive difference flux.
Three methods were used to identify time-varying sources in our data.
First, we apply loose image quality cuts to all 10,789 WINTER candidate sources, without requiring multiple detections, and this yields 1,607 candidates. Second, we separately cross-match all 10,789 WINTER detections to optical detections from the Zwicky Transient Facility (ZTF, Bellm et al 2019) with a radius of 3 arcseconds, and select sources that are detected by both WINTER and ZTF. We recover 12 candidates with a ZTF crossmatch. Third, we select sources detected at least twice by WINTER, and recover 56 candidates. There is some overlap in candidates between these three selection methods.
After visual scanning of all these candidates to reject subtraction artefacts, and removing probable stars with measured Gaia DR3 parallax and sources with matches in the Minor Planet Center, we recover one candidate counterpart in our observations. WNTR24aabfj, spatially coincident with blazar PKS 0446+11, passes all three candidate selection methods.
The blazar has already been flagged as a possible counterpart to IC240105A (GCN #35499, GCN #35517, GCN #35548, ATEL #16397, ATEL #16398, ATEL #16399, ATEL #16402, ATEL #16407, ATEL #16409), undergoing a substantial flare across the EM spectrum. Given that this is a variable source, we perform forced photometry directly on our WINTER science images to measure the flux of this source in our data. We detect the following AB magnitudes for this blazar in our data:
—----------------------------------------------------
| Date (UTC) | Mag (AB) | Mag Err | Filter |
—----------------------------------------------------
| 2024-01-06T05:22:36 | 15.10 | 0.04 | J |
| 2024-01-07T02:43:37 | 15.56 | 0.07 | J |
| 2024-01-17T02:38:36 | 15.83 | 0.06 | J |
—----------------------------------------------------
For comparison, the reference flux of this source in 2MASS J-band is 17.9 mag (AB), indicating a clear increase in NIR flux relative to this historical baseline. Even over the course of our WINTER observations, the source has faded by >0.7 magnitudes from peak across our three epochs.
Further observations of the field will continue.
WINTER (Widefield INfrared Transient ExploreR) is a partnership between MIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF AAG, the David and Lucille Packard Foundation, and the MIT Kavli Institute for Astrophysics and Space Research
Alert querying for coincident ZTF detections is done with AMPEL (Nordin et al. 2019) and nuztf (Stein et al. 2021, https://github.com/desy-multimessenger/nuztf ).