- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Tue 23 Jun 20 03:18:25 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 45
TRIGGER_NUM: 614575085
GRB_RA: 234.950d {+15h 39m 48s} (J2000),
235.025d {+15h 40m 06s} (current),
234.769d {+15h 39m 05s} (1950)
GRB_DEC: +63.583d {+63d 34' 60"} (J2000),
+63.518d {+63d 31' 04"} (current),
+63.744d {+63d 44' 37"} (1950)
GRB_ERROR: 24.28 [deg radius, statistical plus systematic]
GRB_INTEN: 473 [cnts/sec]
DATA_SIGNIF: 5.60 [sigma]
INTEG_TIME: 0.064 [sec]
GRB_DATE: 19023 TJD; 175 DOY; 20/06/23
GRB_TIME: 11880.64 SOD {03:18:00.64} UT
GRB_PHI: 180.00 [deg]
GRB_THETA: 25.00 [deg]
DATA_TIME_SCALE: 0.0640 [sec]
HARD_RATIO: 0.21
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 91% GRB
2nd_MOST_LIKELY: 5% Cyg X-1
SUN_POSTN: 92.33d {+06h 09m 18s} +23.42d {+23d 25' 08"}
SUN_DIST: 88.27 [deg] Sun_angle= -9.5 [hr] (East of Sun)
MOON_POSTN: 117.32d {+07h 49m 17s} +23.34d {+23d 20' 19"}
MOON_DIST: 80.55 [deg]
MOON_ILLUM: 4 [%]
GAL_COORDS: 98.17, 44.60 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 175.06, 75.14 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200623138/quicklook/glg_lc_medres34_bn200623138.gif
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Tue 23 Jun 20 03:18:44 UT
NOTICE_TYPE: Fermi-GBM Ground Position
RECORD_NUM: 58
TRIGGER_NUM: 614575085
GRB_RA: 233.670d {+15h 34m 41s} (J2000),
233.741d {+15h 34m 58s} (current),
233.499d {+15h 34m 00s} (1950)
GRB_DEC: +64.410d {+64d 24' 36"} (J2000),
+64.343d {+64d 20' 33"} (current),
+64.575d {+64d 34' 31"} (1950)
GRB_ERROR: 14.82 [deg radius, statistical only]
DATA_SIGNIF: 6.30 [sigma]
DATA_INTERVAL: 0.064 [sec]
GRB_DATE: 19023 TJD; 175 DOY; 20/06/23
GRB_TIME: 11880.64 SOD {03:18:00.64} UT
GRB_PHI: 180.00 [deg]
GRB_THETA: 24.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 4173 (Gnd S/W Version number)
SUN_POSTN: 92.33d {+06h 09m 18s} +23.42d {+23d 25' 08"}
SUN_DIST: 87.27 [deg] Sun_angle= -9.4 [hr] (East of Sun)
MOON_POSTN: 117.32d {+07h 49m 18s} +23.34d {+23d 20' 18"}
MOON_DIST: 79.62 [deg]
MOON_ILLUM: 4 [%]
GAL_COORDS: 99.57, 44.60 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 171.22, 74.99 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200623138/quicklook/glg_lc_medres34_bn200623138.gif
POS_MAP_URL: http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_614575085.fits
COMMENTS: Fermi-GBM Ground-calculated Coordinates.
COMMENTS: In the LAT Field-of-view.
COMMENTS: This Notice was ground-generated -- not flight-generated.
COMMENTS: The LC_URL file will not be created/available until ~15 min after the trigger.
COMMENTS: The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Tue 23 Jun 20 03:27:09 UT
NOTICE_TYPE: Fermi-GBM Final Position
RECORD_NUM: 0
TRIGGER_NUM: 614575085
GRB_RA: 224.310d {+14h 57m 14s} (J2000),
224.432d {+14h 57m 44s} (current),
224.013d {+14h 56m 03s} (1950)
GRB_DEC: +60.430d {+60d 25' 48"} (J2000),
+60.349d {+60d 20' 55"} (current),
+60.630d {+60d 37' 47"} (1950)
GRB_ERROR: 11.17 [deg radius, statistical only]
GRB_DATE: 19023 TJD; 175 DOY; 20/06/23
GRB_TIME: 11880.64 SOD {03:18:00.64} UT
GRB_PHI: 166.00 [deg]
GRB_THETA: 25.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 41731 (Gnd S/W Version number)
SUN_POSTN: 92.33d {+06h 09m 20s} +23.42d {+23d 25' 07"}
SUN_DIST: 87.65 [deg] Sun_angle= -8.8 [hr] (East of Sun)
MOON_POSTN: 117.41d {+07h 49m 38s} +23.33d {+23d 19' 50"}
MOON_DIST: 77.81 [deg]
MOON_ILLUM: 4 [%]
GAL_COORDS: 99.07, 50.47 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 175.19, 69.25 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200623138/quicklook/glg_lc_medres34_bn200623138.gif
LOC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200623138/quicklook/glg_locplot_all_bn200623138.png
COMMENTS: Fermi-GBM Final Position.
COMMENTS: This Notice was ground-generated -- not flight-generated.
COMMENTS: The LC_URL file should be available by the time this FINAL notice is produced.
COMMENTS: This notice was generated completely by automated pipeline processing.
COMMENTS: In the LAT Field-of-view.
COMMENTS: This is likely a Short GRB.
- GCN Circular #28011
The Fermi GBM team reports the detection of a likely SHORT GRB
At 03:18:00 UT on 23 Jun 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 200623A (trigger 614575085.637496 / 200623138).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 224.3, Dec = 60.4 (J2000 degrees, equivalent to J2000 14h 57m, 60d 23'), with a statistical uncertainty of 11.2 degrees.
The angle from the Fermi LAT boresight is 25.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200623138/quicklook/glg_skymap_all_bn200623138.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200623138/quicklook/glg_healpix_all_bn200623138.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200623138/quicklook/glg_lc_medres34_bn200623138.gif
- GCN Circular #28012
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin,
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov, D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile
(Observatorio Astronomico Felix Aguilar OAFA),
H.Levato
(Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE),
R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),
D. Buckley
(South African Astronomical Observatory),
O.A. Gres, N.M. Budnev, O.Ershova
(Irkutsk State University, API),
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko
(Blagoveschensk Educational State University)
MASTER-IAC robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Spain (IAC Teide Observatory) started inspect of the Fermi GRB 200623A ( Fermi GBM team, GCN 28011) errorbox 924 sec after notice time and 957 sec after trigger time at 2020-06-23 03:33:58 UT, with upper limit up to 18.8 mag. The observations began at zenith distance = 63 deg. The sun altitude is -27.3 deg.
The galactic latitude b = 45 deg., longitude l = 98 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1387999
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
988 | 2020-06-23 03:33:58 | MASTER-IAC | (15h 03m 20.96s , +60d 01m 51.3s) | C | 60 | 18.8 |
988 | 2020-06-23 03:33:58 | MASTER-IAC | (14h 46m 59.24s , +60d 06m 59.1s) | C | 60 | 18.3 |
1108 | 2020-06-23 03:35:59 | MASTER-IAC | (14h 53m 55.06s , +62d 00m 52.3s) | C | 60 | 18.5 |
1108 | 2020-06-23 03:35:59 | MASTER-IAC | (14h 36m 29.92s , +62d 06m 01.8s) | C | 60 | 18.2 |
1226 | 2020-06-23 03:37:56 | MASTER-IAC | (15h 12m 34.01s , +58d 01m 45.3s) | C | 60 | 18.6 |
1226 | 2020-06-23 03:37:56 | MASTER-IAC | (14h 57m 07.88s , +58d 06m 52.4s) | C | 60 | 18.3 |
1346 | 2020-06-23 03:39:56 | MASTER-IAC | (15h 03m 20.54s , +60d 00m 47.4s) | C | 60 | 18.7 |
1346 | 2020-06-23 03:39:56 | MASTER-IAC | (14h 46m 59.37s , +60d 05m 55.7s) | C | 60 | 18.5 |
1466 | 2020-06-23 03:41:56 | MASTER-IAC | (14h 53m 54.70s , +61d 59m 46.6s) | C | 60 | 18.5 |
1466 | 2020-06-23 03:41:56 | MASTER-IAC | (14h 36m 30.27s , +62d 04m 56.3s) | C | 60 | 18.2 |
1587 | 2020-06-23 03:43:57 | MASTER-IAC | (15h 12m 38.65s , +57d 59m 56.1s) | C | 60 | 18.6 |
1587 | 2020-06-23 03:43:58 | MASTER-IAC | (14h 57m 13.35s , +58d 05m 03.5s) | C | 60 | 18.4 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Tue 23 Jun 20 12:53:30 UT
NOTICE_TYPE: Fermi-GBM Final Position
RECORD_NUM: 0
TRIGGER_NUM: 614575085
GRB_RA: 222.490d {+14h 49m 58s} (J2000),
222.631d {+14h 50m 31s} (current),
222.146d {+14h 48m 35s} (1950)
GRB_DEC: +57.610d {+57d 36' 36"} (J2000),
+57.526d {+57d 31' 34"} (current),
+57.816d {+57d 48' 57"} (1950)
GRB_ERROR: 10.32 [deg radius, statistical only]
GRB_DATE: 19023 TJD; 175 DOY; 20/06/23
GRB_TIME: 11880.64 SOD {03:18:00.64} UT
GRB_PHI: 161.00 [deg]
GRB_THETA: 27.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 41731 (Gnd S/W Version number)
SUN_POSTN: 92.74d {+06h 10m 58s} +23.41d {+23d 24' 43"}
SUN_DIST: 88.90 [deg] Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN: 123.12d {+08h 12m 29s} +22.70d {+22d 42' 04"}
MOON_DIST: 75.89 [deg]
MOON_ILLUM: 6 [%]
GAL_COORDS: 96.77, 53.08 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 179.43, 66.73 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200623138/quicklook/glg_lc_medres34_bn200623138.gif
LOC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200623138/quicklook/glg_locplot_all_bn200623138.png
COMMENTS: Fermi-GBM Final Position.
COMMENTS: This Notice was ground-generated -- not flight-generated.
COMMENTS: The LC_URL file should be available by the time this FINAL notice is produced.
COMMENTS: This notice was generated completely by automated pipeline processing.
COMMENTS: In the LAT Field-of-view.
COMMENTS: This is likely a Short GRB.
- GCN Circular #28013
James DeLaunay (PSU), Aaron Tohuvavohu (U Toronto), Jamie Kennea
(PSU), and Peter Veres (UAH) report:
Swift/BAT did not trigger on GRB 2006023A (T0: 2020-06-23 03:18:00
UTC, Fermi/GBM Team GCN 28011).
The Fermi/GBM notice, distributed at T0+24 seconds triggered the Swift
Mission Operations Center operated Gamma-ray Urgent Archiver for Novel
Opportunities (GUANO; Tohuvavohu et al. 2020, arXiv: 2005.01751). Upon
trigger by these notices, 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.
In a ground analysis of the data, we detect the burst in the full
detector-summed rates (no localization information) with an SNR of
~12.
The detected duration is ~0.2 seconds.
With a maximum likelihood analysis (DeLaunay et al. 2020, in prep.) on
the event-mode data we detect a location for the burst with a square
root of the test statistic, sqrt(TS), of 9.8. The sqrt(TS) behaves
similarly to SNR.
Using the normal BAT imaging technique, we find an SNR of 6.4 at the
same location.
The BAT ground-calculated position is
RA, Dec = 242.0952, +53.4678 deg which is
RA(J2000) = 16h 8m 22.8s
Dec(J2000) = +51d 28’ 4”
with an uncertainty of 4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 67.19%.
This position is consistent with the Fermi GBM localization (GCN
28011), falling on the 58% containment contour.
XRT and UVOT follow-up has been triggered. Results of follow-up
observations will be reported in future circulars.
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/
- GCN Circular #28015
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the Swift/BAT GRB 200623A.
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021005
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Swift/BAT event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a
GCN Circular after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
- GCN Circular #28016
A. Tohuvavohu reports:
The sexagesimal coordinates reported for the Swift/BAT-GUANO
localization of GRB 200623A have a typo.
The decimal coordinates in the original circular are correct.
The correct coordinates are RA, Dec: 242.0952, +53.4678:
RA(J2000) = 16h 8m 22.8s
Dec(J2000) = +53d 28' 04"
I apologize for any inconvenience caused.
- GCN Circular #28019
P. Veres and C. Meegan (both UAH)
report on behalf of the Fermi GBM Team:
"At 03:18:00.64 UT on 23 June 2020, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 200623A (trigger 614575085 / 200623138)
which was also detected by the Swift/BAT-GUANO (DeLaunay et al., GCN 28013).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 36
degrees.
The GBM light curve consists of a single pulse
with a duration (T90) of about 0.6 s (50-300 keV).
The time-averaged spectrum from T0-64 ms to T0 is
best fit by a simple power law function with index -1.09 +/- 0.09.
The event fluence (10-1000 keV) in this time interval is
(5.2 +/- 0.6)E-7 erg/cm^2. The 64-ms peak photon flux measured
starting from T0-64 ms in the 10-1000 keV band
is 4.7 +/- 1.0 ph/s/cm^2.
A power law function with an exponential
high-energy cutoff fits the spectrum equally well
with Epeak= 353 +/- 131 keV, alpha = -0.07 +/- 0.53.
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/"
- GCN Circular #28020
S. Belkin (IKI), A. Pozanenko (IKI), R. Ya. Inasaridze (AbAO), V.R.
Ayvazian (AbAO), G. V. Kapanadze (AbAO), E. Mazaeva (IKI), A.
Volnova (IKI), I. Molotov (KIAM) report on behalf of GRB IKI FuN:
We observed the field of Swift/BAT-GUANO position (DeLaunay et al., GCNs
28013, 28016) of GRB 200623A (Fermi GBM team, GCN 28011; Veres et al.,
GCN 28019) with AS-32 (0.7m) telescope of Abastumani Observatory
starting on 2020-06-23 (UT) 18:46:58. We detected only one object
within the XRT #2 source localization
(https://www.swift.ac.uk/ToO_GRBs/00021005/). The source is not
presented in SDSS DR12. We suggest the object could be afterglow of GRB
200623A. However at this time we cannot confirm variability of the
object. Preliminary photometry of the object is following.
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2020-06-23 18:46:58 0.66456 R 56*60 21.88 0.17 22.6
No new objects were found in the localization of the XRT # 3 source.
The photometry is based on nearby USNO-B1.0 stars
UUSNO-B1.0_id R2
1434-0283797 15.99
1434-0253851 17.48
- GCN Circular #28021
P. D'Avanzo (INAF-OAB), V. D'Elia (ASI-SSDC), G. Andreuzzi, D. Carosati (INAF-TNG) on behalf of the CIBO collaboration report:
We observed the field of GRB 200623A (Fermi/GBM Team, GCN Circ. 28011; DeLaunay et al., GCN Circ. 28013; Veres and Meegan,
GCN Circular. 28019) with the Italian 3.6m TNG telescope equipped with DOLORES in imaging mode. A series of images were
obtained with the r-sdss filter on 2020-06-23 from 21:23:29 UT to 21:44:01 UT (i.e. about 18.3 hours after the burst) covering the entire
Swift/BAT-GUANO error circle reported by DeLaunay et al. (GCN Circ. 28013,). Further observations are in progress.
No obvious afterglow candidate is detected inside the BAT-GUANO error circle.
Inside the 5" radius error circle of the Swift/XRT source #3 (see Evans, GCN Circ. 28015 and https://www.swift.ac.uk/ToO_GRBs/00021005)
we detect a faint source at the following coordinates:
RA(J2000), Dec (J2000) = 16:07:59.11, +53:28:39.0 (+/- 0.5").
From preliminary photometry, we estimate for this object a magnitude r ~ 24.2 (AB, calibrated against the SDSS catalogue). This source is
apparently not visible in the SDSS and Pan-STARRS archival images of this field. Given the faintness of the source, no conclusion can be
derived about its variability and about its association to GRB 200623A.
We note that the 5" radius error circle of the Swift/XRT source #3 is consistent with the catalogued galaxy SDSS J160758.62+532842.2 whose
photometric redshift is 0.33 +/- 0.05.
The position of the the Swift/XRT source #2 is outside the field of view of our images, therefore we cannot provide information on the optical
afterglow candidate reported by Belkin et al. (GCN Circ. 28020).
- GCN Circular #28022
D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC,
DARK/NBI), M. Blazek, C. C. Thoene, J. F. Agui Fernandez (all
HETH/IAA-CSIC), V. Tilve, A. Moreno Signes, and H. Vasquez Ramio (all
CEFCA) report:
We observed the error circle of the short GRB 200623A (Fermi GBM
detection and analysis: Fermi GBM Team, GCN #28011, Veres & Meegan, GCN
#28019; Swift BAT/GUANO localization: DeLaunay et al., GCN #28013) with
the T80 0.8m telescope at the Observatorio de Javalambre (Teruel,
Spain). Observations consisted of 3 x 500 s in g', 3 x 500 s in r', 8 x
180 s in i', and 8 x 180 s in z', at midtimes 0.816779, 0.798439,
0.779694, and 0.755722 days after the GRB, respectively.
At the position of XRT source #1, the known quasar from the Veron-Cetty
& Veron 2006 catalog is clearly detected.
At the position of XRT source #2, we clearly detect the source proposed
by Belkin et al. (GCN #28020) as a candidate afterglow. Measured against
three nearby SDSS comparison stars, we find (AB mags):
g' = 23.70 +/- 0.30 mag;
r' = 22.55 +/- 0.15 mag;
i' = 21.54 +/- 0.15 mag;
z' = 20.74 +/- 0.10 mag,
indicating this is a very red source. We assume that the observations of
Belkin et al. were performed without a filter, this would explain the
brighter magnitude they find (their use of comparison stars from the
USNO catalog may also play a role).
These very red colors are untypical for a GRB afterglow. Furthermore,
comparison with images form PanSTARRS clearly reveals a pre-detection of
the source at a similar magnitude and color, see:
https://www.iaa.csic.es/~deugarte/GRBs/200623A/200623A_color2.jpg
for a comparison. We therefore believe it is unlikely that this source
is associated with GRB 200623A (additionally, the XRT detection is of
low significance for now).
At the position of XRT source #3, we detected multiple sources in the
vicinity also seen in PanSTARRS imaging. The faint source detected by
the TNG (D'Avanzo et al., GCN #28021), may be vaguely detected in our r'
and z' images, but it is unclear how much this could be due to the PSF
of a nearby bright star. We present a second comparison image here:
https://www.iaa.csic.es/~deugarte/GRBs/200623A/200623A_color.jpg
No other obviously bright afterglow candidate is detected in the BAT
error circle, however, a second epoch of comparable depth would be
needed for a more detailed analysis.
- GCN Circular #28023
A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), T.
Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini
(INAF-OAB), D.N. Burrows (PSU) and P.A. Evans (U. Leicester) report on
behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the
Swift/BAT-detected burst GRB 200623A (James DeLaunay et al. GCN Circ.
28013), collecting 5.0 ks of Photon Counting (PC) mode data between
T0+37.8 ks and T0+50.1 ks.
Three uncatalogued X-ray sources have been detected, however none of
them is above the RASS limit or shows definitive signs of fading.
Therefore, at the present time we cannot identify which, if any, is the
afterglow. Details of these sources are given below:
Source 1:
RA (J2000.0): 242.2874 = 16:09:8.97
Dec (J2000.0): +53.5321 = +53:31:55.6
Error: 4.4 arcsec (radius, 90% conf. [Enhanced position])
Count-rate: (3.5 [+1.2, -1.0])e-3 ct s^-1
Distance: 406 arcsec from Swift/BAT position.
Flux: (1.09 [+0.39, -0.32])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Source 2:
RA (J2000.0): 242.1106 = 16:08:26.55
Dec (J2000.0): +53.3466 = +53:20:47.9
Error: 5.1 arcsec (radius, 90% conf.)
Count-rate: (1.19 [+0.79, -0.56])e-3 ct s^-1
Distance: 462 arcsec from Swift/BAT position.
Source 3:
RA (J2000.0): 241.9966 = 16:07:59.18
Dec (J2000.0): +53.4786 = +53:28:42.8
Error: 5.0 arcsec (radius, 90% conf.)
Count-rate: (3.10 [+1.11, -0.91])e-3 ct s^-1
Distance: 272 arcsec from Swift/BAT position.
Flux: (1.96 [+0.70, -0.58])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Source 1 is consistent with a known quasar, [VV2006] J160908.9+533153.
Source 2 is poorly detected and is likely to be a background
fluctuation.
Source 3 is not a known X-ray source, its position is consistent with a
background galaxy, SDSS J160758.62+532842.2 (D'Avanzo et al., GCN
#28021).
Follow up observation of source 3 are planned to be carried out at the
end of this week.
The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/00021005.
This circular is an official product of the Swift-XRT team.
- GCN Circular #28025
A. A. Breeveld (UCL-MSSL) and B. Sbarufatti (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began target-of-opportunity observations of the field of GRB 200623A 37910 s after
the Guano and GBM trigger (Fermi GBM team, GCN Circ. 28011; Debaunay et al., GCN Circ. 28013).
No significant new sources were found at the positions of the XRT candidate sources 1 and 3
(Tohuvavohu et al., GCN Circ. 28023). XRT source 2 was outside the field of view for all exposures.
Preliminary 3-sigma upper limit using the UVOT photometric system (Breeveld et al. 2011, AIP Conf.
Proc. 1358, 373) for the initial exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 37910 45836 4299 >22.4
The magnitude in the table is not corrected for the Galactic extinction due to the reddening of
E(B-V) = 0.012 in the direction of the burst (Schlegel et al. 1998).
- GCN Circular #28033
Kuiyun Huang (CYCU), Yuji Urata (NCU), Glen Petitpas (CfA)
report
We used SMA to observe the location of the Swift/XRT source #3
(Evans, GCN Circ. 28015) as one of the afterglow candidates of
GRB200623A (Fermi/GBM Team, GCN Circ. 28011; DeLaunay et al., GCN
Circ. 28013, 28016). The 230 GHz observation was started at ~1 days
after the burst. No clear submm source at the Swift/XRT sources #3
position was found brighter than ~1 mJy.
We thank the staff of SMA.
- GCN Circular #28034
A. Rossi (INAF-OAS) and P. D'Avanzo (INAF-OA Brera) report on behalf of
the CIBO collaboration:
We observed the field of GRB200623A (DeLaunay et al., GCN 28013)
simultaneously in the r' and z' bands with the LBC imager mounted on LBT
(Mt Graham, AZ, USA). Observations started at 05:58 UT on 2020-06-25,
50.7 hr after the GRB trigger and finished at 06:24 UT and allowed us to
obtain 20min of exposure in each band. Observations were performed under
good seeing conditions (seeing ~0.9") and reached a depth of r~26 mag.
The images covered all the three sources found by XRT (Sbarufatti et
al., GCN 28023). No new point source is detected within their error circles.
Image subtraction against TNG r-band images obtained on 2020-06-23
(D'Avanzo et al., GCN 28021) using HOTPANTS (v5.1.11) does not reveal
any flux variation in the candidate found within the error circle of the
XRT source #3. The near-by galaxy at z~0.33 noticed by D'Avanzo et al.
(GCN 28021) is too close to saturation in LBC images, preventing us to
make any statement about possible flux variations within the galaxy.
We also note that a faint, extended source is present within the XRT
error circle of source #3, visible in both the r' and z' images, and not
mentioned in previous reports about this event. This is also a candidate
host galaxy of XRT source #3 though with a higher chance association
probability compared to the brighter galaxy. Further Swift/XRT
observations will help establishing variability and possibly reducing
the X-ray position uncertainty.
We acknowledge the excellent support from the LBTO and LBT-INAF staff,
particularly B. Rothberg, F. Cusano, S. Paiano and D. Paris, in
obtaining these observations.
- GCN Circular #28036
W. Fong (Northwestern) reports:
"We re-visited the location of XRT source #3 of the short GRB 200623A (Fermi-GBM Collab. et al., GCN 28011; DeLaunay et al., GCN 28013; Tohuvavohu et al., GCN 28023) with the MMT/MMTCam at a mid-time of 2020 June 26.176 UT (3.04 days post-burst and 2.0 days after our initial observations: Rastinejad et al., GCN 28026). We acquired 21x120-sec of r-band imaging in 0.88" seeing, and the 3-sigma depth of our image is 24.4 AB mag.
Upon inspection of the XRT source #3 position (90% confidence), we detect the faint optical source first reported in TNG observations (D'Avanzo et al.; GCN 28021) with r = 24.3 +/- 0.3 mag, at the same flux level as previous detections. In addition to a few catalogued sources, we report on an additional source toward the Eastern edge of the XRT position and in the wings of the bright star, with RA = 16:07:59.64, Dec = +53:28:43.6 (J2000) and r~22.2 AB mag. This source was marginally detected in our previous set of imaging although partially blended with the bright star, and it is not possible to discern at present whether this source is point-like or extended in nature. Finally, we do not detect the extended LBT source at the center of the XRT position (Rossi and D'Avanzo et al., GCN 28034), likely due to lack of sensitivity.
We perform image subtraction relative to our previous epoch, and do not detect any significant residuals. Thus, we find no evidence for significant variability in or around the XRT source #3 position, enabling a limit of r > 23.0 AB mag at 25.03 hrs post-burst on optical afterglow emission associated with this XRT candidate (c.f., Rastinejad et al., GCN 28026).
We thank Nelson Caldwell and Michael Calkins at the MMT for the rapid scheduling and execution of these observations."
- GCN Circular #28047
B. Sbarufatti (PSU), P.A. Evans (U. Leicester) and K. K. Simpson (PSU) report on behalf of the Swift XRT team.
Swift performed a second observation of the field of GRB 200623A, with a 4.5 ks exposure.
The only uncatalogued source in the field, Source 3 (Tohuvavohu et al., GCN 28023), is still detected and shows no evidence of fading, so we conclude that it is not the GRB afterglow.
This circular is an official product of the Swift XRT team.
Previous IAU Circulars 