GRB 230824A
GCN Circular 35823
Subject
Swift J1727.8-1613 (GRB 230824A): Madrona Peak Observatory - optical follow-up
Date
2024-02-27T19:08:13Z (2 years ago)
From
Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy - MPC Code C82 <osservatorionastroverde@gmail.com>
Via
Web form
TITOLO: Swift J1727.8-1613 (GRB 230824A): Madrona Peak Observatory - optical follow-up
Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
AstroCampania Associazione.
report:
Following the Swift trigger no. 1186959 (GCN 34537), using the 24 Inch RC Optical Ritchey-Chretien Reflector telescope and the Apogee Aspen CG16M camera of the Madrona Peak Observatory connected to the AAVSONet network,
we obtained a series of B,V,R images of the transient approximately 6 months after the first detection.
The images were measured with the VPhot AAVSO software, using the APASS catalogue. The photometry obtained on 19/23/25 February 2024 are as follows:
with the following photometry:
JD Mag Filter
2460363.97895 15.830 V
2460363.97781 15.987 V
2460359.99249 15.864 V
2460359.99139 15.837 V
JD Mag Filter
2460365.97083 15.713 R
2460363.98126 15.552 R
2460363.98014 15.535 R
2460359.99473 15.530 R
2460359.99362 15.512 R
JD Mag Filter
2460363.97611 15.230 B
2460363.97427 16.275 B
2460359.98979 16.096 B
2460359.98799 16.131 B
The magnitudes are calibrated with stars of the APASS catalog are not corrected for the expected Galactic extinction.
The message may be cited.
GCN Circular 34577
Subject
Swift J1727.8-1613 (GRB 230824A): Osservatorio Astronomico "Nastro Verde" optical observations
Date
2023-08-27T19:24:18Z (2 years ago)
From
Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy - MPC Code C82 <osservatorionastroverde@gmail.com>
Via
Web form
Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report:
Following the Swift trigger no. 1186959 (GCN 34537), we pointed at the coordinates RA(J2000)=17h 27m 46s: Dec(J2000)=-16d 12' 53" and started our observations with telescope of Nastro Verde Observatory - Sorrento (Naples), Italy.
Member of:
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
AstroCampania Associazione.
The observations started at 19:23 UT of 2023/08/24, after about 5,25 hours after the GRB trigger, at the end of twilight with clear skies, with principal telescope SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME
I took 9 image of 120 sec each in fotometric V and 13 in Rc . All images, calibrated with masterdark and masterflat have been measured with Maxim DL software
We have detected a clear visible source at the enhanced position reported by Swift Burst Alert Telescope (BAT) (Page et al., GCN 34537 ) and by other telescopes ( Jamie A. Kennea (PSU) et al GCN 34540., S. Dichiara (PSU) et al GCN 34542, 34547, 34554,34555., Mohammad Odeh et al GCN 34543, 34561., H. Negoro (Nihon U). et al GCN 34544., Brendan O'Connor et al GCN 34549.,Dylan Dutton et al GCN 34556., T. M. Parsotan et al GCN 34557., U.Quadri et al GCN 34562., Claudio Lopresti et al GCN 34566., S. Leonini et al GCN 34573)
at following position
RA (J2000.0) 17:27:43.32
Dec (J2000.0) -16:12:19
with the following photometry:
JD Mag Filter
2460181.317 13.69 V
2460181.32 13.74 V
2460181.323 13.66 V
2460181.326 13.59 V
2460181.329 13.63 V
2460181.332 13.55 V
2460181.335 13.54 V
2460181.338 13.62 V
2460181.341 13.55 V
JD Mag Filter
2460181.309 13.49 Rc
2460181.31 13.51 Rc
2460181.312 13.54 Rc
2460181.313 13.45 Rc
2460181.315 13.47 Rc
2460181.318 13.48 Rc
2460181.321 13.50 Rc
2460181.324 13.52 Rc
2460181.33 13.45 Rc
2460181.333 13.46 Rc
2460181.336 13.50 Rc
2460181.339 13.50 Rc
2460181.342 13.50 Rc
The magnitudes are calibrated with stars of the PanSTARRS catalog, espressed in AB system and are not corrected for the expected Galactic extinction.
The peculiar transient ( detected by other observatories ) is confirmed in our observations. Further observations are encouraged.
GCN Circular 34573
Subject
Swift J1727.8-1613 (GRB 230824A): Montarrenti Observatory photometric observations
Date
2023-08-27T14:57:12Z (2 years ago)
From
Simone Leonini at Montarrenti Observatory (Siena, Italy) <s.leonini@iol.it>
Via
Web form
S. Leonini, M. Conti, P. Rosi, L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy) report:
We observed the field of Swift J1727.8-1613 (GRB 230824A)
(Page et al., GCN 34537; Odeh et al., GCN 34543; Dutton et al., GCN 34556; Odeh et al., GCN 34561; Quadri et al., GCN 34562; Lopresti, GCN 34566; Pavoni & Moretti, GCN 34570) with the remote controlled 0.53m Ritchey-Chretien telescope + U47 detector at Montarrenti Observatory (Siena, Italy, IAU code C88) in 2 epochs, starting on Aug 24.78994 (5 hours after trigger) and Aug. 26.79422 2023 (53 hours after trigger) with multiple exposures in V, Rc and Ic band.
The OT was detected at the following position:
RA (J2000.0) 17h 27m 43.32s +/-0.2
Dec. (J2000.0) -16° 12' 18.60" +/-0.2
Photometry was obtained using nearby PanSTARRS stars as follows:
==============================
Obs. midtime UT Filter Mag. Err.
==============================
2460181.2962325 V 13.45 0.002
2460181.3049015 V 13.48 0.002
2460181.3127082 V 13.50 0.002
2460181.3205208 V 13.50 0.002
2460181.3305952 V 13.47 0.002
2460183.3018576 V 12.54 0.003
2460183.3062470 V 12.52 0.003
2460183.3143382 V 12.48 0.004
2460183.3208796 V 12.50 0.004
-----------------------------------------------
2460181.2973320 R 13.39 0.001
2460181.3053240 R 13.42 0.001
2460181.3131307 R 13.42 0.001
2460181.3213754 R 13.44 0.001
2460181.3315657 R 13.39 0.001
2460183.2976407 R 12.43 0.002
2460183.3047650 R 12.43 0.002
2460183.3089728 R 12.41 0.002
2460183.3200694 R 12.44 0.002
-----------------------------------------------
2460181.2940451 I 13.29 0.002
2460181.3031443 I 13.28 0.002
2460181.3109548 I 13.26 0.002
2460181.3187615 I 13.22 0.002
2460181.3265489 I 13.26 0.001
2460181.3336487 I 13.26 0.001
2460183.2980439 I 12.28 0.003
2460183.3052912 I 12.26 0.003
2460183.3164382 I 12.27 0.003
2460183.3204745 I 12.26 0.003
-----------------------------------------------
Magnitudes were converted using Lupton 2005 equations and are not corrected for galactic dust extinction.
Further observations are planned.
GCN Circular 34570
Subject
Swift J1727.8-1613 (GRB 230824A): Leavitt Observatory optical observations
Date
2023-08-27T10:40:23Z (2 years ago)
From
leavittob@gmail.com
Via
Web form
E. Pavoni and L. Moretti (Leavitt Observatory, Italy), in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Università degli Studi Di Salerno)
report:
We observed the field of Swift J1727.8-1613 (GRB 230824A: Page et al., GCN 34537; Navaneeth et al., GCN 34538, Odeh et al., GCN 34543; U.Quadri et al., GCN 34562; C. Lopresti, GCN 34566) with the telescope of Leavitt Observatory, Italy. Member of:
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili, GRB section.
ATA - Associazione Tuscolana di Astronomia.
The observations began at 20:02 UT on 2023/08/24 (~6 hours after the Swift trigger), with our RC telescope D=250 mm F/D=8.
Weather conditions were good.
We took 25 images of 120 sec each. All images are Rc filtered, calibrated with master dark and master flat, stacked with ASTAP software and analyzed with AstroImageJ software.
We clearly detected a bright object, in the same location as M.Odeh et al., GCN 34543, within the uncertainty radius of the Swift localization, at:
R.A. (J2000): 17:27:43.32
Dec. (J2000): -16:12:18.8
The results of our photometry in Rc band are:
JD_UTC Source_Mag Source_Mag_Err
2460181.3385997 13,766 0,006
2460181.3457458 13,725 0,006
2460181.3528939 13,731 0,006
2460181.3603810 13,694 0,006
2460181.3689481 13,671 0,005
Magnitudes were estimated with PanSTARRS cat. and are not corrected for galactic dust extinction.
The message may be cited.
GCN Circular 34566
Subject
Swift J1727.8-1613 (GRB 230824A): GAD Observatory La Spezia - optical observations
Date
2023-08-26T20:45:21Z (2 years ago)
From
Claudio Lopresti <cl3lop@gmail.com>
Via
legacy email
Claudio Lopresti (Gruppo Astronomia Digitale - GAD Observatory, La Spezia, Italy - UAI SSV- GRB Section)
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
Unione Astrofili Italiani (UAI SSV- GRB Section)
report:
I imaged the field of of Swift J1727.8-1613 (GRB 230824A) (Page et al., GCN 34537; Navaneeth et al., GCN 34538, Odeh et al., GCN 34543) with the following telescope: 0.18-m f/4 Mak-Newton reflector at GAD Observatory, Italy, with filters Infrared, Red, and V. I clearly detected a bright object, in the same location as M.Odeh et al., GCN 34543, within the uncertainty radius of the Swift localization, at: R.A. (J2000): 17:27:43.32 Dec. (J2000): -16:12:18.8.
The results of photometry are:
In Infrared band:
=============================================
Date UT Exp Time I-mag Err
=============================================
2460181.3096064800 90s 13.71 0.10
2460181.3143750000 90s 13.85 0.08
2460181.3191319400 90s 13.83 0.04
2460181.3239004600 90s 13.78 0.03
2460181.3286689800 90s 13.80 0.02
2460181.3334259200 90s 13.82 0.06
2460181.3519444400 90s 13.90 0.09
2460181.3559490700 180s 13.72 0.09
2460181.3599537000 180s 13.79 0.05
2460181.3639583300 180s 13.69 0.03
2460181.3679745300 180s 13.73 0.03
2460181.3719907400 180s 13.83 0.07
2460181.3760069400 180s 13.71 0.09
In Red band:
=============================================
Date UT Exp Time R-mag Err
=============================================
2460181.3119675900 90s 14.09 0.00
2460181.3167361100 90s 14.09 0.02
2460181.3215046200 90s 14.05 0.04
2460181.3262615700 90s 14.14 0.05
2460181.3310300900 90s 14.15 0.08
2460181.3532407400 90s 14.01 0.07
2460181.3572569400 180s 14.06 0.05
2460181.3612615700 180s 13.96 0.06
2460181.3652662000 180s 13.96 0.00
2460181.3692824000 180s 13.96 0.01
2460181.3732986100 180s 13.98 0.01
In V band:
=============================================
Date UT Exp Time V-mag Err
=============================================
2460181.3586111100 90s 13.51 0.09
2460181.3626157400 90s 13.37 0.07
2460181.3666203700 90s 13.44 0.04
2460181.3706365700 90s 13.46 0.01
2460181.3746527700 90s 13.45 0.01
Magnitudes were estimated with the PanSTARRS cat., not corrected for galactic dust extinction. Weather conditions were good.
Reference:
https://www.parcodellestelle.com/
The message may be cited.
GCN Circular 34562
Subject
Swift J1727.8-1613 (GRB 230824A): Bassano Bresciano Observatory optical observations
Date
2023-08-26T08:05:10Z (2 years ago)
From
Ulisse Quadri at Bassano Bresciano Obs <oabb@ulisse.bs.it>
Via
legacy email
U.Quadri, P.Madurini and L.Strabla (Bassano Bresciano Astronomical Observatory),
Member of:
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
GAC - Gruppo Astrofili Cremonesi.
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report:
We imaged the field of Swift J1727.8-1613(GRB 230824A)
(Page et al., GCN 34537; Navaneeth et al., GCN 34538, Odeh et al., GCN 34543)
with the following telescopes:
0.25-m f/4.8 Newton reflector at Bassano Bresciano Observatory, Italy - MPC Code 565.
0.32-m f/8.0 (iTelescope) reflector at AstroCamp at Nerpio, Spain - MPC Code I89.
0.51-m f/6.8 (iTelescope) Dall-Kirkham at Rio Hurtado Valley, Chile - MPC Code X07.
We clearly detected a bright object, in the same location as M.Odeh et al., GCN 34543, within
the uncertainty radius of the Swift localization, at:
R.A. (J2000): 17:27:43.32
Dec. (J2000): -16:12:18.8
The results of our photometry are:
------------------------------------------------------
Date UT Exp Time R-mag Err IAU STATION
------------------------------------------------------
2023-08-24.7967 18x20s 13.25 0.057 565
2023-08-24.8018 18x20s 13.25 0.049 565
2023-08-24.8071 12x30s 13.24 0.048 565
2023-08-24.8124 12x30s 13.24 0.043 565
2023-08-24.8185 12x30s 13.24 0.042 565
2023-08-24.9030 10x60s 13.05 - I89
2023-08-25.1470 10x60s 12.80 - X07
------------------------------------------------------
Magnitudes were estimated with the pan-STARRS cat.
and are converted using Lupton (2005) equations.
Not corrected for galactic dust extinction.
Further observations are planned.
Reference:
http://www.osservatoriobassano.org/GRB.asp
The message may be cited.
GCN Circular 34561
Subject
GRB 230824A: AKO Photometric Follow-up Observations
Date
2023-08-26T07:30:58Z (2 years ago)
From
Mohammad Odeh at Al Khatim Observatory M44 <mshodeh@gmail.com>
Via
legacy email
Mohammad Odeh, Osama Ghannam, Anas Mohammad, Khalfan Al-Noaimy, and Sameh
Al-Ashi, report on behalf of Al-Khatim Observatory (AKO) operated by the
International Astronomical Center in Abu Dhabi, UAE:
As a follow-up for the GRB 230824A (Page et al., GCN 34537), also known as
Swift J1727.8-1613 (Dichiara et al., GCN 34542), also known as AT 2023qql
(Zhang and Gao, https://www.wis-tns.org/object/2023qql), we observed the
target with our 0.36m f/7.7 robotic telescope for the second night on 25
August 2023, and we obtained multiple 180-sec exposures in R filter. The
below table summarizes the results of the two nights:
R.A. (J2000)= 17:27:43.32
Dec. (J2000)= -16:12:19.2
-----------------------------------------------------------------------------
ObsTime (mid), t(mid) – t(0) (hours), Exposure (sec), Filter, Mag
-----------------------------------------------------------------------------
2023-08-24T18:29:24Z, 04.5, 180s, R, 13.5 +/- 0.04
2023-08-25T16:29:44Z, 26.5, 180s, R, 13.0 +/- 0.01
-----------------------------------------------------------------------------
The observations were calculated using the Atlas catalogue as a reference
and are not corrected for galactic extinction.
The object is added to The International Variable Star Index catalogue and
photometric observations can be submitted through AAVSO website.
Object Page:
https://www.aavso.org/vsx/index.php?view=detail.top&oid=2387757
Submission Form:
https://www.aavso.org/webobs
Current Photometric Results:
https://www.aavso.org/LCGv2/
GCN Circular 34557
Subject
Trigger 1187225: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
Date
2023-08-25T23:43:16Z (2 years ago)
From
Tyler Parsotan at UMBC/GSFC/CRESST II <parsotat@umbc.edu>
Via
email
T. M. Parsotan (GSFC/UMBC/CRESSTII) and T. Sakamoto (AGU) report on
behalf of the Neil Gehrels Swift Observatory Team:
At 23:31:52 UT, the Swift Burst Alert Telescope (BAT) triggered again
on the Galactic transient Swift J1727.8-1613 (AKA GRB 230824A) (trigger number
1187203); this is another BAT trigger on this event (see eg GCN Circ.
34537, 34542 and 34547). Swift XRT and UVOT observations are planned
for after the source exits Moon constraint on August 27.
GCN Circular 34556
Subject
Swift J1727.8-1613 (GRB 230824A): Skynet Optical Observations
Date
2023-08-25T21:25:27Z (2 years ago)
From
Dylan Dutton at UNC Chapel Hill <ddutton59@gmail.com>
Via
Web form
Dylan Dutton, Daniel Reichart, Joshua Haislip, Vladimir Kouprianov, Daryl Janzen, Arie Verveer, John Kennewell, Megan Dubay, Ruide Fu, Logan Selph, and Donovan Schlekat report on behalf of the Skynet Robotic Telescope Network at the University of North Carolina at Chapel Hill.
We observed the field of Swift J1727.8-1613 (GRB 230824A) (Page et al., GCN 34537; Navaneeth et al., GCN 34538, Odeh et al., GCN 34543) with our 0.4m robotic telecope located in Meckering, Australia. The observation began at 14:11:20 UTC on Aug 24 2023, approximately 11 minutes after the first trigger.
We obtained multiple expsoures in the B, V, R, and I filters. Exposure lengths were calculated using our automated exposure length scaling model.
We detected a bright object, in the same location as Odeh et al., GCN 34543, within the uncertainty radius of the Swift localization, at:
R.A. (J2000): 17:27:43.34
Dec. (J2000): -16:12:19.161
Below, we report our photometric measurements.
-------------------------------------------
Date TimeTakenUTC ExpTime Filter Mag MagErr
-------------------------------------------
08-24-2023 | 14:11:20 | 25.721s | B | 14.22 | 0.013
08-24-2023 | 14:11:52 | 28.873s | V | 13.88 | 0.011
08-24-2023 | 14:12:29 | 13.756s | R | 13.69 | 0.012
08-24-2023 | 14:12:49 | 10.774s | I | 13.60 | 0.014
08-24-2023 | 14:15:50 | 37.756s | B | 14.25 | 0.010
08-24-2023 | 14:16:34 | 40.014s | V | 13.89 | 0.008
08-24-2023 | 14:17:21 | 19.012s | R | 13.69 | 0.009
08-24-2023 | 14:17:46 | 15.507s | I | 13.67 | 0.012
08-24-2023 | 14:21:35 | 56.372s | V | 13.89 | 0.007
08-24-2023 | 14:25:40 | 63.628s | B | 14.26 | 0.007
08-24-2023 | 14:26:49 | 66.016s | V | 13.88 | 0.006
08-24-2023 | 14:28:02 | 31.063s | R | 13.64 | 0.006
08-24-2023 | 14:28:40 | 24.327s | I | 13.60 | 0.008
08-24-2023 | 14:33:49 | 84.567s | B | 14.25 | 0.006
08-24-2023 | 14:35:19 | 88.210s | V | 13.86 | 0.005
08-24-2023 | 14:36:53 | 40.934s | R | 13.65 | 0.005
08-24-2023 | 14:37:40 | 32.058s | I | 13.63 | 0.007
08-24-2023 | 14:43:26 | 109.523s | B | 14.25 | 0.006
08-24-2023 | 14:45:23 | 113.289s | V | 13.89 | 0.005
08-24-2023 | 14:47:22 | 51.216s | R | 13.67 | 0.005
08-24-2023 | 14:48:20 | 41.685s | I | 13.61 | 0.007
08-24-2023 | 14:54:51 | 140.854s | B | 14.25 | 0.006
08-24-2023 | 14:57:17 | 147.908s | V | 13.88 | 0.005
08-24-2023 | 14:59:52 | 65.83s | R | 13.65 | 0.006
08-24-2023 | 15:01:05 | 53.273s | I | 13.58 | 0.007
08-24-2023 | 15:09:40 | 177.571s | B | 14.15 | 0.005
08-24-2023 | 15:15:54 | 83.812s | R | 13.65 | 0.006
08-24-2023 | 15:17:25 | 67.06s | I | 13.56 | 0.006
08-24-2023 | 15:27:51 | 225.946s | B | 14.23 | 0.006
08-24-2023 | 15:31:42 | 232.571s | V | 13.86 | 0.006
08-24-2023 | 15:35:41 | 105.216s | R | 13.61 | 0.006
08-24-2023 | 15:37:32 | 82.401s | I | 13.60 | 0.007
08-24-2023 | 15:50:16 | 284.651s | B | 14.31 | 0.006
08-24-2023 | 15:55:06 | 293.376s | V | 13.81 | 0.004
08-24-2023 | 16:00:07 | 131.78s | R | 13.57 | 0.005
08-24-2023 | 16:02:25 | 106.593s | I | 13.51 | 0.005
08-24-2023 | 16:30:17 | 164.791s | R | 13.53 | 0.006
08-24-2023 | 16:33:08 | 133.318s | I | 13.50 | 0.009
Our images have been calibrated using stars from the APASS catalog.
GCN Circular 34555
Subject
Trigger 1187207: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
Date
2023-08-25T21:05:28Z (2 years ago)
From
Simone Dichiara at Pennsylvania State University <sbd5667@psu.edu>
Via
email
S. Dichiara (PSU) and T. M. Parsotan (GSFC/UMBC/CRESSTII) report on
behalf of the Neil Gehrels Swift Observatory Team:
At 20:27:20 UT, the Swift Burst Alert Telescope (BAT) triggered again
on the Galactic transient Swift J1727.8-1613 (AKA GRB 230824A) (trigger number
1187203); this is the fourth BAT trigger on this event (GCN Circ.
34537, 34542 and 34547). Swift XRT and UVOT observations are planned
for after the source exits Moon constraint on August 27.
GCN Circular 34554
Subject
Trigger 1187203: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
Date
2023-08-25T20:33:01Z (2 years ago)
From
K.L. Page at U Leicester <klp5@leicester.ac.uk>
Via
email
S. Dichiara (PSU), N. J. Klingler (GSFC/UMBC/CRESSTII),
M. J. Moss (GWU) and K. L. Page (U Leicester) report on behalf of the
Neil Gehrels Swift Observatory Team:
At 20:20:32 UT, the Swift Burst Alert Telescope (BAT) triggered again
on the Galactic transient Swift J1727.8-1613 (trigger number
1187203); this is the fourth BAT trigger on this event (GCN Circ.
34537, 34542 and 34547). Swift XRT and UVOT observations are planned
for after the source exits Moon constraint on August 27.
GCN Circular 34549
Subject
NICER detection of Swift J1727.8-1613 (GRB 230824A)
Date
2023-08-25T17:08:08Z (2 years ago)
From
Brendan O'Connor at UMD <oconnorb@umd.edu>
Via
Web form
Brendan O'Connor (Carnegie Mellon University), Jeremy Hare (NASA/GSFC/CRESST/CUA), George Younes (NASA/GSFC), Keith Gendreau (NASA/GSFC), Zaven Arzoumanian (NASA/GSFC), Elizabeth Ferrara (NASA/GSFC/CRESST/UMCP):
Following reports of repeated bursts from Swift J1727.8-1613 (GCN #34540) — initially designated GRB 230824A (GCN #34536, GCN #34537; see also ATels #16205, #16206) — we have observed the source with a NICER ToO, prior to the telescope entering a Moon constraint. The observation started on 2023-08-25 at 00:25:40 UT and ended at 00:49:53 UT, with a total exposure of 1,055 s.
The observation began during orbit-day, which, due to the high count rate and a recent light “leak” in NICER’s X-ray Timing Instrument, led to telemetry saturation that created fragmented good-time intervals (GTIs). This is a known issue that leads to a 55 Hz “signal” (and potentially other significant features) in a power-spectral analysis. We caution future observers against astrophysical interpretations of this signal. To minimize calibration complications due to visible-light loading, we restricted our spectral analysis to only the nighttime data, with an exposure of 198 s.
Throughout the observation, the source is prominently detected with a count rate varying between ~5,000 and 20,000 cts/s. Rapid (timescales less than one second) variability is observed, similar to the black-hole system V404 Cyg (ATel #16205, ATel #16206) and/or the neutron-star binary Swift J1858.6–0814 (ATel #12158). In the orbit-night-only data, the 55 Hz signal is no longer visible in power spectra, which lack narrow features (no obvious QPO or sharply periodic signal) but are dominated by a strong red-noise component.
We modeled the time-averaged spectrum (0.5-10 keV) with an absorbed power-law model plus a blackbody. We derive a photon index of 1.47+/-0.01, blackbody temperature of kT = 0.269+/-0.006 keV, and hydrogen column density of N_H = (2.26+/-0.05)e21 cm^-2. The PL+BB model fits the data well with a chi-squared of 87 for 155 degrees of freedom. We identify a hint of an iron line at around 6.4 keV. The absorption-corrected X-ray flux in the 0.5-10 keV energy band is (5.34+/-0.02)e-8 erg/cm^2/s. Assuming a distance of 3 - 6 kpc this corresponds to an X-ray luminosity of ~5e37 to 2e38 erg/s, which suggests that this is a newly discovered X-ray binary in outburst (ATel #16205, GCN #34540).
Further analysis is ongoing and additional NICER observations are planned.
NICER is a 0.2-12 keV X-ray telescope operating on the International Space Station. The NICER mission and portions of the NICER science team activities are funded by NASA.
GCN Circular 34547
Subject
Trigger 1187142: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
Date
2023-08-25T09:16:38Z (2 years ago)
From
P.A. Evans at U. Leicester <pae9@leicester.ac.uk>
Via
email
S. Dichiara (PSU), P. A. Evans (U Leicester) and
K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 09:03:36 UT, the Swift Burst Alert Telescope (BAT) triggered and located
Swift J1727.8-1613 (trigger number 1187142); this is the third BAT trigger on
this event (GCN Circ. 34537; GCN Circ. 34542) which remains unobservable with
XRT and UVOT until 09:35 UT on 2023 August 27; however, MAXI have reported a
very bright (>2 Crab) 10-20 keV X-ray counterpart. This object is believed to be
a Galactic transient, Swift J1727.8-1613 (GCN Circ. 34540).
GCN Circular 34544
Subject
MAXI/GSC detection of Swift J1727.8-1613 (GRB 230824A)
Date
2023-08-25T02:25:47Z (2 years ago)
From
Motoko Serino at Aoyama Gakuin U. <serino@phys.aoyama.ac.jp>
Via
Web form
H. Negoro (Nihon U.), M. Serino (AGU), M. Nakajima, K. Kobayashi, M. Tanaka, Y. Soejima, Y. Kudo (Nihon U.),
T. Mihara, T. Kawamuro, S. Yamada, T. Tamagawa, N. Kawai, M. Matsuoka (RIKEN),
T. Sakamoto, S. Sugita, H. Hiramatsu, H. Nishikawa, A. Yoshida (AGU),
Y. Tsuboi, S. Urabe, S. Nawa, N. Nemoto (Chuo U.), M. Shidatsu (Ehime U.),
I. Takahashi, M. Niwano, S. Sato, N. Higuchi, Y. Yatsu (Tokyo Tech),
S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, S. Ogawa, T. Kurihara (JAXA),
Y. Ueda, K. Setoguchi, T. Yoshitake, Y. Nakatani (Kyoto U.),
M. Yamauchi, Y. Hagiwara, Y. Umeki, Y. Otsuki (Miyazaki U.),
K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), M. Sugizaki (NAOC), and W. Iwakiri (Chiba U.)
report on behalf of the MAXI team:
The MAXI/GSC has detected the hard X-ray transient Swift J1727.8-1613 (GRB 230824A:
GCN #34536, #34537) since the scan transit at 10:20 on 2023 August 24.
The source flux is increasing rapidly, reaching more than 2 Crab at 10-20 keV at 21:10 and
22:44, which supports the possibility that the source is a Galactic transient, not a GRB
(GCN #23540).
The hard and rapid variations suggest that the source is a V404 Cyg like object.
Followup observations are highly encouraged.
We cross-post this report to the ATel and the GCN.
GCN Circular 34543
Subject
GRB 230824A: AKO Optical Afterglow Candidate
Date
2023-08-24T19:12:43Z (2 years ago)
From
Mohammad Odeh at Al Khatim Observatory M44 <mshodeh@gmail.com>
Via
legacy email
Mohammad Odeh, Osama Ghannam, Anas Mohammad, Khalfan Al-Noaimy, and Sameh
Al-Ashi, report on behalf of Al-Khatim Observatory (AKO) operated by the
International Astronomical Center in Abu Dhabi, UAE:
We observed the field of GRB 230824A (Page et al., GCN 34537; Navaneeth et
al., GCN 34538) with our 0.36m f/7.7 robotic telescope. The observation
started at 18:04 UT on 24 August 2023, 4.1 hours after the trigger.
We obtained multiple 180-sec exposures in R filter. We detected a bright
star with a magnitude of R=13.5 at:
R.A. (J2000): 17:27:43.32
Dec. (J2000): -16:12:19.2
Which is within the uncertainty radius of the localization determined by
Swift team (Page et al., GCN 34537), however, our detected object is a
transient object (AT 2023qql) which was discovered today at 14:37:22 (UT)
0.6 hours after the GRB trigger, so more observations are required to
confirm this link.
https://www.wis-tns.org/object/2023qql
GCN Circular 34542
Subject
Trigger 1186982: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
Date
2023-08-24T19:09:08Z (2 years ago)
From
K.L. Page at U Leicester <klp5@leicester.ac.uk>
Via
email
S. Dichiara (PSU), J. A. Kennea (PSU), K. L. Page (U Leicester),
T. M. Parsotan (GSFC/UMBC/CRESSTII) and M. A. Williams (PSU) report on
behalf of the Neil Gehrels Swift Observatory Team:
At 18:54:32 UT, the Swift Burst Alert Telescope (BAT) triggered and
located Swift J1727.8-1613. Due to a Moon observing constraint, Swift
cannot observe this location until 09:35 UT on 2023 August 27.
We note this is the 2nd time BAT has triggered on this source,
previously named GRB 230824A (GCN #34537), now likely a Galactic
transient Swift J1727.8-1613 (GCN #34540)
GCN Circular 34540
Subject
GRB 230824A is likely a Galactic Transient: Swift J1727.8-1613
Date
2023-08-24T18:57:10Z (2 years ago)
From
Jamie Kennea at Penn State U <jak51@psu.edu>
Via
Web form
Jamie A. Kennea (PSU) reports on behalf of the Swift Team
GRB 230824A (GCN #34537) reported by Swift/BAT, previously triggered INTEGRAL at 12:20UT (Weak trigger #10373,0) 100 mins before the BAT trigger, and continued to trigger INTEGRAL several times after the BAT trigger. Given this, and its location in the Galactic Bulge (l,b = 8.64, 10.241), we now believe this is a likely Galactic Transient and not a GRB.
We therefore rename this source Swift J1727.8-1613. Observations to confirm the nature of this transient are requested. Swift will not observe this transient until at least August 27, 2023 due to the proximity of the Moon.
GCN Circular 34537
Subject
GRB 230824A: Swift detection of a burst
Date
2023-08-24T14:12:46Z (2 years ago)
From
K.L. Page at U Leicester <klp5@leicester.ac.uk>
Via
email
K. L. Page (U Leicester), S. Dichiara (PSU), J.D. Gropp (PSU),
H. A. Krimm (NSF), T. M. Parsotan (GSFC/UMBC/CRESSTII) and
M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 13:59:44 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230824A (trigger=1186959).
The BAT on-board calculated location is
RA, Dec 261.941, -16.215 which is
RA(J2000) = 17h 27m 46s
Dec(J2000) = -16d 12' 53"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). As is common for image triggers, the BAT
light curve does not show significant structure. The duration
appears to be about 20 sec. The peak count rate was ~1400
counts/sec (15-350 keV), at ~6 sec after the trigger.
Due to a Moon observing constraint, Swift cannot slew to the BAT
position until 09:35 UT on 2023 August 27. There will thus be no XRT or
UVOT data for this trigger before this time.
Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk).
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/)