| Summary table |
|---|
| Variable |
Value |
Source |
| T0 |
19:07:55 UTC |
Swift |
| ra |
122.5827° |
Swift |
| decl |
-21.9253° |
Swift |
| pos_error |
3.11e-04° |
Swift |
| T90 |
23.6 s |
Swift |
| T90_start |
19:07:55 UTC |
Swift |
| fluence |
4.60e-07 erg/cm² |
Swift |
| T100 |
23.6 s |
|
| GBM_located |
False |
|
| mjd |
60057.797164351854 |
Swift |
| IPN table |
|---|
| GRB_name |
GRB230423A |
| ra |
122.6042° |
| decl |
-21.9167° |
| pos_error |
5.00e-02° |
| Swift table |
|---|
| GRB_name |
GRB230423A |
| t_trigger |
19:07:55 UTC |
| ra |
122.5827° |
| decl |
-21.9253° |
| pos_error |
3.11e-04° |
| T90 |
23.6 s |
| fluence |
4.60e-07 erg/cm² |
| GCN 33677 table |
|---|
| GRB_name |
GRB230423A |
| GCN_number |
33677 |
| Detection_method |
Swift Other |
| ra |
122.6050° |
| decl |
-21.9200° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 33677
SUBJECT: Swift Trigger 1165354 is probably not a GRB
DATE: 23/04/23 19:40:27 GMT
FROM: David Palmer at LANL
R. Brivio (INAF-OAB), J.D. Gropp (PSU), J. A. Kennea (PSU),
N. J. Klingler (GSFC/UMBC/CRESSTII), N. P. M. Kuin (UCL-MSSL),
S. Laha (GSFC/UMBC), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL),
C. Salvaggio (INAF-OAB) and T. Sbarrato (INAF-OAB) report on behalf of
the Neil Gehrels Swift Observatory Team:
At 19:07:55 UT, the Swift Burst Alert Telescope (BAT) triggered and located
a marginal image peak, which is possibly GRB 230423A (trigger=1165354).
Swift slewed immediately to the image location.
The BAT on-board calculated location is
RA, Dec 122.605, -21.920 which is
RA(J2000) = 08h 10m 25s
Dec(J2000) = -21d 55' 12"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a complex
structure with a duration of about 30 sec. The peak count rate
was ~600 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 19:09:36.5 UT, 101.1 seconds after
the BAT trigger. No source was detected in 777 s of promptly downlinked
data. We are waiting for the full dataset to detect and localise the
XRT counterpart.
UVOT took a finding chart exposure of 150 seconds with the White
filter starting 885 seconds after the BAT trigger. No credible
afterglow candidate has been found in the initial data products. The
2.7'x2.7' covers 25% of the BAT 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 BAT error circle. No
correction has been made for the expected extinction corresponding
to E(B-V) of 0.136.
Due to the marginal significance (7.3 sigma) of this detection in BAT
and the lack of an observed XRT counterpart, we cannot confirm
that this is a real GRB. However, the XRT observation was
interrupted by entry into the South Atlantic Anomaly (SAA)
so the bulk of the XRT exposure time may have been after
any source could have faded significantly. For this reason,
we will not be able to verify or refute the reality of this
detection until the full dataset is downloaded.
|
| GCN 33679 table |
|---|
| GRB_name |
GRB230423A |
| GCN_number |
33679 |
| Detection_method |
Swift-XRT Other |
| ra |
122.5831° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 33679
SUBJECT: GRB 230423A: Swift-XRT afterglow detection
DATE: 23/04/24 14:11:56 GMT
FROM: Chiara Salvaggio at INAF OABrera
C. Salvaggio (INAF-OAB), P. D’avanzo (INAF-OAB), T. Sbarrato (INAF-OAB), R.
Brivio (INAF-OAB), M. Ferro (INAF-OAB), M.G. Bernardini (INAF-OAB), A. Y.
Lien (U Tampa), K.L. Page (U. Leicester), P.A. Evans (U. Leicester) report
on behalf of the Swift-XRT team:
We have analysed 852s of Swift/XRT data for GRB 230423A (R.Brivio et al.,
GCN CIrc. 33677), from t-t0=704.5 s to t+t0=4893.3 s after the BAT trigger
1165354. The trigger was previously indicated as non-burst due to a low BAT
significance detection and the absence of an XRT counterpart (GCN circ.
33677).
We found an uncatalogued fading source with coordinates:
RA (J2000): 08h 10m 19.94s
DEC (J2000): -21d 55’ 33.5â€
with an uncertainty of 3.8†(radius, 90% confidence).
We propose this source as the X-ray afterglow of GRB 230423A.
The results of the XRT-team automatic analysis are available at
https://www.swift.ac.uk/xrt_products/01165354
This circular is an official product of the Swift-XRT team
|
| GCN 33681 table |
|---|
| GRB_name |
GRB230423A |
| GCN_number |
33681 |
| Detection_method |
Swift-XRT Other |
| ra |
122.5830° |
| decl |
-21.9259° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 33681
SUBJECT: GRB 230423A: Swift-XRT refined Analysis
DATE: 23/04/25 04:27:05 GMT
FROM: Phil Evans at U of Leicester
J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU), P.A.
Evans (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR), V.
D'Elia (SSDC & INAF-OAR) and report on behalf of the Swift-XRT team:
We have analysed 2.5 ks of XRT data for GRB 230423A, from 680 s to 57.3
ks after the BAT trigger. The data comprise 22 s in Windowed Timing
(WT) mode with the remainder in Photon Counting (PC) mode. The refined
XRT position is RA, Dec = 122.5830, -21.9259 which is equivalent to:
RA (J2000): 08 10 19.91
Dec(J2000): -21 55 33.1
with an uncertainty of 3.7 arcsec (radius, 90% confidence).
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.19 (+0.39, -0.28).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.6 (+/-0.8). The
best-fitting absorption column is 3.3 (+1.5, -1.3) x 10^22 cm^-2, in
excess of the Galactic value of 2.0 x 10^21 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 5.9 x 10^-11 (2.8 x 10^-10) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 3.3 (+1.5, -1.3) x 10^22 cm^-2
Galactic foreground: 2.0 x 10^21 cm^-2
Excess significance: 4.1 sigma
Photon index: 2.6 (+/-0.8)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01165354.
This circular is an official product of the Swift-XRT team.
|
| GCN 33683 table |
|---|
| GRB_name |
GRB230423A |
| GCN_number |
33683 |
| Detection_method |
Swift-UVOT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 33683
SUBJECT: GRB 230423A: Swift/UVOT Upper Limits
DATE: 23/04/25 20:34:48 GMT
FROM: Paul Kuin at MSSL
N. Paul Kuin (UCL-MSSL) and Riccardo Brivio (INAF-OAB)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 230423A
731 s after the BAT trigger (Brivio et al., GCN Circ. 33677). No optical
afterglow consistent with the XRT position Salvaggio et al., GCN
Circulars 33679, 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 731 881 147 >20.9
white 731 5415 491 >21.4
b 5010 5210 197 >20.0
u 4805 5004 197 >19.2
w2 5420 5544 122 >19.5
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.137 in the direction of the burst
(Schlegel et al. 1998).
|
| GCN 33694 table |
|---|
| GRB_name |
GRB230423A |
| GCN_number |
33694 |
| Detection_method |
Swift-BAT Det |
| ra |
122.6180° |
| decl |
-21.9010° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 33694
SUBJECT: GRB 230423A(trigger #1165354): Swift-BAT refined analysis
DATE: 23/04/27 21:21:35 GMT
FROM: Sibasish Laha at GSFC
T. Sakamoto (AGU), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC),
M. Stamatikos (OSU)(i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we have found that BAT trigger #1165354 is a GRB 230423A even though
the original GCN Circular (Brivio et al., GCN Circ. 33677) based on the immediately
available data suggested that it was probably a statistical fluctuation.
The BAT ground-calculated position is
RA, Dec = 122.618, -21.901 deg which is
RA(J2000) = 08h 10m 28.2s
Dec(J2000) = -21d 54' 03.6"
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
The BAT light curve showed a complex structure with a duration of about 30 sec.
T90 (15-350 keV) is 23.60 +- 4.27 sec (estimated error including systematics).
The time-averaged spectrum from T-2.25 to T+24.49 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.69 +- 0.27. The fluence in the 15-150 keV band is 4.6 +- 0.8 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+10.62 sec in the 15-150 keV band
is 0.6 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1165354/BA/
|