TITLE: GCN CIRCULAR
NUMBER: 34295
SUBJECT: GRB 230723B: MITSuME Ishigaki optical observation
DATE: 23/07/30 08:54:50 GMT
FROM: Natsuki Hayatsu H. at Ishigakijima Astronomical Observatory <natsuki.h.hayatsu(a)gmail.com>
N. H. Hayatsu, H. Hanayama (NAOJ), M. Sasada, I. Takahashi, M. Niwano, S. Sato, S. Hayatsu, N. Higuchi, H. Takei, H. Seki, Y. Yatsu (Tokyo Tech), K. L. Murata (Kyoto U) and N. Kawai (Riken) report on behalf of the MITSuME collaboration:
report:
We observed the field of GRB 230723B (Page et al. GCN Circular #34234, Campana et al. #34236, Page et al. #34238, Lipunov et al. #34239, Siegle et al. #34240, Agui Fernandez et al. #34241, Adami et al. #34247, Osborne et al. #34248, Mangan et al. #34249, Quadri et al. #34250, Agui Fernandez et al. #34251, Leonini et al. #34252, Ruocco et al. #34253, Pavoni et al. #34254, Lopresti et al. #34259, Anderson et al. #34267, Sanada et al. #34268, and Agui Fernandez et al. #34271) with the optical three color (g', Rc, and Ic) CCD cameras attached to the 105 cm Murikabushi telescope of Ishigakijima Astronomical Observatory, Okinawa, Japan.
The observation with a series of 60 sec exposures started at 2023-07-23 12:21:20.29 UT (2328 seconds after the Swift/BAT detection). In the stacked image at 3193 seconds after the burst, we detected an object of g'=20.5+/-0.2, Rc=19.4+/-0.1, and Ic=19.6+/-0.1 at the coordinate reported by Agui Fernandez et al. #34251. We also report the g’-, Rc- and Ic-band 5-sigma upper limits of the stacked images.
TT0+[sec] | MID-UT | T-EXP[sec] | candidate magnitudes | 5-sigma limits
------------------------------------------------------------------------------------------------
3193 | 2023-07-23 12:35:45 | 1080 | g'=20.5+/-0.2, Rc=19.4+/-0.1, Ic=19.6+/-0.1 | g'>20.6, Rc>21.2, Ic>20.1
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used PS1 catalog for flux calibration. The conversion from PS1 r and i band to our Rc and Ic band is by the equation of Tonry et al. (2012), Table. 6. The magnitudes are expressed in the AB system. The images were processed through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 34294
SUBJECT: IceCube-230727A: No candidates from the Zwicky Transient Facility
DATE: 23/07/29 15:47:21 GMT
FROM: Jannis Necker at DESY <jannis.necker(a)desy.de>
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. 2022), we observed the localization region of the neutrino event IceCube-230727A (Blaufuss et. al, GCN 34276) 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 2023-07-28 09:54 UTC, approximately 17.8 hours after event time. We covered 72.1% (1.7 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.
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).
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 34293
SUBJECT: LIGO/Virgo/KAGRA S230729z: Identification of a GW compact binary merger candidate
DATE: 23/07/29 11:17:18 GMT
FROM: Angélique Lartaux at IJCLab <angelique.lartaux(a)ijclab.in2p3.fr>
The LIGO Scientific Collaboration, the Virgo Collaboration, and the
KAGRA Collaboration report:
We identified the compact binary merger candidate S230729z during
real-time processing of data from LIGO Hanford Observatory (H1) and
LIGO Livingston Observatory (L1) at 2023-07-29 08:23:17.201 UTC (GPS
time: 1374654215.201). The candidate was found by the GstLAL
[1], MBTA [2], and PyCBC Live [3] analysis pipelines.
S230729z is an event of interest because its false alarm rate, as
estimated by the online analysis, is 3.4e-09 Hz, or about one in 9
years. The event's properties can be found at this URL:
https://gracedb.ligo.org/superevents/S230729z
The classification of the GW signal, in order of descending
probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS
(<1%).
Assuming the candidate is astrophysical in origin, the probability
that the lighter compact object is consistent with a neutron star mass
(HasNS) is <1%. [4] Using the masses and spins inferred from the
signal, the probability of matter outside the final compact object
(HasRemnant) is <1%. [4] Both HasNS and HasRemnant consider the
support of several neutron star equations of state. The probability
that either of the binary components lies between 3 and 5 solar masses
(HasMassgap) is 6%.
Two sky maps are available at this time and can be retrieved from the
GraceDB event page:
* bayestar.multiorder.fits,0, an initial localization generated by
BAYESTAR [5], distributed via GCN notice about 35 seconds after the
candidate event time.
* bayestar.multiorder.fits,1, an initial localization generated by
BAYESTAR [5], distributed via GCN notice about 5 minutes after the
candidate event time.
The preferred sky map at this time is bayestar.multiorder.fits,1. For
the bayestar.multiorder.fits,1 sky map, the 90% credible region is
1428 deg2. Marginalized over the whole sky, the a posteriori
luminosity distance estimate is 1546 +/- 472 Mpc (a posteriori mean
+/- standard deviation).
For further information about analysis methodology and the contents of
this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide
https://emfollow.docs.ligo.org/userguide/.
[1] Tsukada et al. arXiv:2305.06286 (2023) and Ewing et al.
arXiv:2305.05625 (2023)
[2] Aubin et al. CQG 38, 095004 (2021)
[3] Dal Canton et al. ApJ 923, 254 (2021)
[4] Chatterjee et al. ApJ 896, 54 (2020)
[5] Singer & Price PRD 93, 024013 (2016)
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 34292
SUBJECT: IceCube-230727A: Upper limits from a search for additional neutrino events in IceCube
DATE: 23/07/29 04:24:42 GMT
FROM: Jessie Thwaites at IceCube/U Wisc-Madison <thwaites(a)wisc.edu>
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-230727A (https://gcn.nasa.gov/circulars/34276) in a time range of 1000 seconds centered on the alert event time (2023-07-27 15:57:19.630 UTC to 2023-07-27 16:13:59.630 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-230727A. 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-230727A 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 3e+02 GeV and 1e+05 GeV.
A subsequent search was performed including 2 days of data centered on the alert event time (2023-07-26 16:05:39.630 UTC to 2023-07-28 16:05:39.630 UTC). In this case, we report a p-value of 0.10, 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-230727A is 1.5e-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(a)icecube.wisc.edu<mailto:roc@icecube.wisc.edu>.
[1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021)
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 34291
SUBJECT: GRB 230728A: BOOTES-1 optical upper limit
DATE: 23/07/28 19:11:16 GMT
FROM: Youdong HU at IAA-CSIC <huyoudong072(a)hotmail.com>
Y.-D. Hu, E. Fernandez-Garcia, A. J. Castro-Tirado, M.D. Caballero-Garcia, R. Sanchez-Ramirez, I. Perez-Garcia and S. Guziy (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco and A. Reina (Univ. de Malaga) and F. Rendon (IAA-CSIC and INTA-CEDEA) on behalf of a larger collaboration, report:
Following the detection of GRB 230728A by Swift (Salvaggio et al., GCNC 34282), the 0.3m BOOTES-1B robotic telescope in Mazagon (Huelva, Spain) automatically responded to this burst on Jul. 28 at 02:50:54 UT (i.e. ~51 s after trigger). In the co-added frame (60 x 10 s, clear filter), no source is detected within the enhanced XRT position (Evans et al., GCNC 34286) down to 19.9 mag.
This non-detection is consistent with the upper limits reported by MASTER (Lipunov et al. GCNC 34281), NOT (Xu et al. GCNC 34285), UVOT (Oates et al. GCNC 34288) and LCOGT (Strausbaugh et al. GCNC 34289).
We thank the staff at INTA-CEDEA for their excellent support.
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 34290
SUBJECT: GRB 230728A: Fermi GBM Observation
DATE: 23/07/28 18:51:37 GMT
FROM: Sarah Dalessi at UAH <sd0104(a)uah.edu>
S. Dalessi (UAH) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 02:50:05.24 UT on 28 July 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230728A (trigger 712205410/230728118).
which was also detected by Swift BAT (Salvaggio et al. 2023, GCN 34282) and Swift XRT (Evans et al. 2023, GCN 34286).
The Fermi GBM on-ground location is consistent with the Swift XRT position.
The angle from the Fermi LAT boresight is 66 degrees.
The GBM light curve consists of multiple peaks with a duration (T90)
of about 19 s (50-300 keV). The time-averaged spectrum
from T0-6.1 to T0+12.3 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.2 +/- 0.2 and the cutoff energy,
parameterized as Epeak, is 95 +/- 15 keV.
The event fluence (10-1000 keV) in this time interval is
(1.7 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-2.6 s in the 10-1000 keV band is 3.1 +/- 0.2 ph/s/cm^2.
A Band function fits the spectrum equally well
with Epeak= 78 +/- 20 keV, alpha = -1.1 +/- 0.3 and beta = -2.4 +/- 0.4.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 34289
SUBJECT: GRB 230728A: LCOGT Optical Upper Limit
DATE: 23/07/28 14:44:26 GMT
FROM: Robert Strausbaugh at University of Minnesota <rstrausb(a)umn.edu>
R. Strausbaugh (University of Minnesota), A. Cucchiara (NASA) report on
behalf of a larger collaboration:
We observed the GRB 230728A (Salvaggio et al., GCN 34282) field with the
LCOGT 1-meter Sinistro instrument at the Teide Observatory, Tenerife site,
on July 28, from 03:15 to 03:48 UT (corresponding to 0.42 to 0.97 hours
from the GRB trigger time) with the SDSS r and i filters.
We performed a series of 3x300s exposures in each band. We do not detect
any source within the enhanced Swift-XRT error region (Evans et al., GCN
34286) in either band, consistent with later optical upper limits (Xu et
al., GCN 34285).
The following upper limits are calculated using the PanSTARRS catalog as
reference:
r > 23.3
i > 22.8
These magnitudes are not corrected for galactic extinction.
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 34288
SUBJECT: GRB 230728A: Swift/UVOT Upper Limits
DATE: 23/07/28 14:37:00 GMT
FROM: Samantha Oates at University of Birmingham <samantha.oates(a)alumni.ucl.ac.uk>
S. R. Oates (U. Birmingham) and C. Salvaggio (INAF-OAB)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 230728A
100 s after the BAT trigger (Salvaggio et al., GCN Circ. 34282).
No optical afterglow consistent with the XRT position (Evans et al.,
GCN Circ. 34286) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 100 250 147 >20.9
u_FC 312 562 246 >20.1
white 100 1361 372 >21.1
v 641 5845 274 >19.4
b 567 1338 78 >19.5
u 312 1313 304 >20.0
w1 691 1289 58 >18.5
m2 5851 6048 194 >19.5
w2 1023 1380 52 >18.5
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.080 in the direction of the burst
(Schlegel et al. 1998).
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 34287
SUBJECT: GRB 230728A: Swift-XRT refined Analysis
DATE: 23/07/28 12:26:15 GMT
FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk>
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), B. Sbarufatti
(INAF-OAB), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAR), J. D. Gropp
(PSU), S. Dichiara (PSU), J.A. Kennea (PSU), A.P. Beardmore (U.
Leicester) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 6.7 ks of XRT data for GRB 230728A, from 86 s to 28.9
ks after the BAT trigger. The data comprise 94 s in Windowed Timing
(WT) mode (the first 3 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode.
The late-time light curve (from T0+5.6 ks) can be modelled with a
power-law decay with a decay index of alpha=1.19 (+0.20, -0.22).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.97 (+0.24, -0.23). The
best-fitting absorption column is 4.4 (+1.4, -1.2) x 10^21 cm^-2, in
excess of the Galactic value of 6.3 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.04 (+0.19, -0.18)
and a best-fitting absorption column of 7.0 (+1.5, -1.3) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 4.3 x 10^-11 (7.6 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 7.0 (+1.5, -1.3) x 10^21 cm^-2
Galactic foreground: 6.3 x 10^20 cm^-2
Excess significance: 8.1 sigma
Photon index: 2.04 (+0.19, -0.18)
If the light curve continues to decay with a power-law decay index of
1.19, the count rate at T+24 hours will be 6.2 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.6 x
10^-13 (4.7 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01181187.
This circular is an official product of the Swift-XRT team.
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 34286
SUBJECT: GRB 230728A: Enhanced Swift-XRT position
DATE: 23/07/28 11:08:36 GMT
FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk>
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1173 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 230728A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 343.51572, +28.17433 which is equivalent
to:
RA (J2000): 22h 54m 3.77s
Dec (J2000): +28d 10' 27.6"
with an uncertainty of 2.1 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the
Swift-XRT team.
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…