- GCN/BACODINE POSITION NOTICE
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Wed 16 Oct 19 04:14:57 UT
NOTICE_TYPE: Swift-BAT GRB Position
TRIGGER_NUM: 929744, Seg_Num: 0
GRB_RA: 30.296d {+02h 01m 11s} (J2000),
30.575d {+02h 02m 18s} (current),
29.592d {+01h 58m 22s} (1950)
GRB_DEC: +24.501d {+24d 30' 03"} (J2000),
+24.596d {+24d 35' 45"} (current),
+24.260d {+24d 15' 35"} (1950)
GRB_ERROR: 3.00 [arcmin radius, statistical only]
GRB_INTEN: 49257 [cnts] Image_Peak=1679 [image_cnts]
TRIGGER_DUR: 16.384 [sec]
TRIGGER_INDEX: 370 E_range: 25-100 keV
BKG_INTEN: 165133 [cnts]
BKG_TIME: 14840.24 SOD {04:07:20.24} UT
BKG_DUR: 64 [sec]
GRB_DATE: 18772 TJD; 289 DOY; 19/10/16
GRB_TIME: 14940.91 SOD {04:09:00.91} UT
GRB_PHI: 52.30 [deg]
GRB_THETA: 26.86 [deg]
SOLN_STATUS: 0x3
RATE_SIGNIF: 19.39 [sigma]
IMAGE_SIGNIF: 17.91 [sigma]
MERIT_PARAMS: +1 +0 +0 +4 +2 +5 -5 +0 +94 +0
SUN_POSTN: 200.82d {+13h 23m 18s} -8.76d {-08d 45' 35"}
SUN_DIST: 161.63 [deg] Sun_angle= 11.3 [hr] (West of Sun)
MOON_POSTN: 47.25d {+03h 08m 59s} +13.45d {+13d 27' 05"}
MOON_DIST: 19.27 [deg]
MOON_ILLUM: 95 [%]
GAL_COORDS: 142.55,-35.70 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 36.72, 11.41 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SWIFT-BAT GRB Coordinates.
COMMENTS: This Notice was delayed by more than 60 sec past the end of the trigger integration interval;
COMMENTS: probably due to it occurring during a Malindi downlink session.
COMMENTS: This is a rate trigger.
COMMENTS: A point_source was found.
COMMENTS: This does not match any source in the on-board catalog.
COMMENTS: This does not match any source in the ground catalog.
COMMENTS: This is a GRB.
COMMENTS: This trigger occurred at longitude,latitude = 263.96,15.32 [deg].
- red DSS finding chart
ps-file
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Wed 16 Oct 19 04:15:18 UT
NOTICE_TYPE: Swift-BAT GRB Lightcurve
TRIGGER_NUM: 929744, Seg_Num: 0
GRB_RA: 30.296d {+02h 01m 11s} (J2000),
30.575d {+02h 02m 18s} (current),
29.592d {+01h 58m 22s} (1950)
GRB_DEC: +24.501d {+24d 30' 03"} (J2000),
+24.596d {+24d 35' 45"} (current),
+24.260d {+24d 15' 35"} (1950)
GRB_DATE: 18772 TJD; 289 DOY; 19/10/16
GRB_TIME: 14940.91 SOD {04:09:00.91} UT
TRIGGER_INDEX: 370
GRB_PHI: 52.30 [deg]
GRB_THETA: 26.86 [deg]
DELTA_TIME: 12.00 [sec]
TRIGGER_DUR: 16.384 [sec]
SOLN_STATUS: 0x3
RATE_SIGNIF: 19.39 [sigma]
IMAGE_SIGNIF: 17.91 [sigma]
LC_URL: sw00929744000msb.lc
SUN_POSTN: 200.82d {+13h 23m 18s} -8.76d {-08d 45' 36"}
SUN_DIST: 161.63 [deg] Sun_angle= 11.3 [hr] (West of Sun)
MOON_POSTN: 47.25d {+03h 09m 00s} +13.45d {+13d 27' 08"}
MOON_DIST: 19.27 [deg]
MOON_ILLUM: 95 [%]
GAL_COORDS: 142.55,-35.70 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 36.72, 11.41 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SWIFT-BAT GRB Lightcurve.
COMMENTS:
COMMENTS: The next comments were copied from the BAT_POS Notice:
COMMENTS: This is a rate trigger.
COMMENTS: A point_source was found.
COMMENTS: This does not match any source in the on-board catalog.
COMMENTS: This does not match any source in the ground catalog.
COMMENTS: This is a GRB.
COMMENTS: This trigger occurred at longitude,latitude = 263.96,15.32 [deg].
- GCN Circular #26008
J.D. Gropp (PSU), N. J. Klingler (PSU), A. Y. Lien (GSFC/UMBC),
M. J. Moss (GWU), D. M. Palmer (LANL) and B. Sbarufatti (PSU) report
on behalf of the Neil Gehrels Swift Observatory Team:
At 04:09:00 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 191016A (trigger=929744). Swift did not immediately
slew due to an observing constraint.
The BAT on-board calculated location is
RA, Dec 30.296, +24.501 which is
RA(J2000) = 02h 01m 11s
Dec(J2000) = +24d 30' 03"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a complex structure
structure with a duration of at least 200 sec. The peak count rate
was ~1500 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 15:17 UT on 2019 October 16. There will thus be no XRT
or UVOT data for this trigger before this time.
This source lies within the current (Sector 17) field-of-view of TESS camera 1.
Burst Advocate for this burst is J.D. Gropp (jdg44 AT psu.edu).
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/)
- GCN Circular #26009
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
(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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the Swift GRB191016.17 (trigger No 929744,02h 01m 11.040s , +24d 30m 03.60s, R=0.05) errorbox 381 sec after trigger time at 2019-10-16 04:15:22 UT, with upper limit up to 15.8 mag. The observations began at zenit distance = 57 deg. The sun altitude is -50.3 deg.
The galactic latitude b = -60 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=1167727
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
421 | MASTER-OAFA | C | 80 | 15.6 |
552 | MASTER-OAFA | C | 100 | 15.8 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
- GCN Circular #26010
Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), Diego González
(UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Margarita Pereyra
(UNAM), and Eleonora Troja (GSFC) report:
Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), Diego González
(UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Margarita Pereyra
(UNAM), and Eleonora Troja (GSFC) report:
We observed the field of GRB 191016A (Gropp et al., GCN Circ. Gropp) with the
COATLI 50-cm telescope and interim imager at the Observatorio Astronómico
Nacional on the Sierra de San Pedro Mártir (http://coatli.astroscu.unam.mx) from
2019-10-16 04:40:19 (378.7 seconds after the trigger and 21.8 seconds after the
alert) to 04:49, obtaining a total of 1200 seconds of exposure in the w filter.
We detect a bright uncataloged source at 02:01:04.75 +24:30:36.8 J2000 (+/- 0.5
arcsec), about 91 arcsec from the BAT position. The source rises from w = 16.5
to w = 15.0 before fading. We suggest this is the afterglow.
Our w magnitudes are calibrated against the Pan-STARRS1 catalog, are on an
approximate AB system (Becerra et al., 2019, ApJ, 872, 118), and are not
corrected for Galactic extinction in the direction of the GRB.
Observations are continuing.
We thank the COATLI technical team and the staff of the Observatorio Astronómico
Nacional.
- GCN Circular #26011
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to the Swift GRB 191016A (Gropp et al.,
GCN 26008) starting at ~1.6 hours after the burst. We obtained
33x60s images in the clear (roughly R) filter. We detect and thus
confirm the optical afterglow at the position reported by Watson et al.
(GCN 26010) in our co-added image. Due to a strong moon light gradient
in our images, we are unable to measure a reliable magnitude of the
target. We estimate the afterglow is between 16.5 to 17.5 mag at a
mid-time of ~2.0 hours after the burst.
- GCN Circular #26012
S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
J.D. Gropp (PSU), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 191016A (trigger #929744)
(Gropp et al., GCN Circ. 26008). The BAT ground-calculated position is
RA, Dec = 30.268, 24.508 deg which is
RA(J2000) = 02h 01m 04.4s
Dec(J2000) = +24d 30' 30.4"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 64%.
The mask weighted light curve shows two overlapping pulses.
Overall structure starts at ~ T-40 s and lasts till ~ T+420 s.
The two peaks occur at ~ T-10 s and ~ T+35 s, respectively.
T90 (15-350 keV) is 219.70 +- 183.35 sec (estimated error including systematics).
The time-averaged spectrum from T-42.82 to T+422.61 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.55 +- 0.09. The fluence in the 15-150 keV band is 6.5 +- 0.4 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T-7.75 sec in the 15-150 keV band
is 1.5 +- 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/929744/BA/
- GCN Circular #26013
Martin Jelinek and Jan Strobl (ASU CAS Ondrejov, CZ)
report:
We observed GRB 191016A (Gropp et al. GCNC 26008) with the 50 cm robotic
telescope (D50) of Ondrejov observatory in the Czech Republic, obtaining a
series of 120s images starting at 17:55UT, i.e. 13.6h post trigger.
We do not detect the optical afterglow (Watson, GCNC 26010; Zheng et al.,
GCNC 26011 and others) in a combined 60x120s I-band image with exposure
mean time 14.6h after the GRB. A rough conservative detection limit of the
image is I(Vega) > 19.5; as mentioned before by Zheng et al., the proximity
of Moon makes any photometric measurement difficult.
- GCN Circular #26015
Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H.
Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska
(UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora Troja (GSFC), Owen
Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jesús González (UNAM), Carlos
Román-Zúñiga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou
(U. Wash.), and Vicki Toy (UMD) report:
We observed the field of GRB 191016A (Gropp et al., GCN Circ. 26008) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m
Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San
Pedro Mártir from 2019/10 16.18 to 2019/10 16.26 UTC (0.12 to 2.13 hours after
the BAT trigger), obtaining a total of 0.99 hours exposure in the r and i bands
and 0.54 hours exposure in the Z, Y, J, and H bands.
We detect a source coincident with the COATLI afterglow candidate (Watson et
al., GCN Circ. 26010). In comparison with the SDSS DR9 and 2MASS catalogs, we
obtain the following detections:
r = 16.42 +/- 0.00
i = 16.16 +/- 0.00
Z = 15.91 +/- 0.01
Y = 15.78 +/- 0.01
J = 15.42 +/- 0.01
H = 15.10 +/- 0.01
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
The light curve shows similar behaviour to that reported by Watson et al. We see
the source rise from r = 16.8 to r = 15.3 before falling to r = 17 at the end of
these observations.
In subsequent observations we added images in the g filter and determined that
the g - r color is 0.44 +/- 0.01. This strongly suggests that the GRB is at z <
4 (Littlejohns et al. 2014).
We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir.
- GCN Circular #26017
Y.-D. Hu, E. Fernandez-Garcia, A. J. Castro-Tirado, I. Olivares, F.
Rendon, A. Sota (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. M.
Carrasco, S. Castillo (Univ. de Malaga), D. Hiriart, W. H. Lee (UNAM),
I. H. Park (SKKU) and M. D. Caballero-Garcia (ASU-CAS, CZ) on behalf of
a larger collaboration, report:
Following the detection of GRB 191016A by Swift (Gropp et al., GCNC
26008), the BOOTES Network robotic telescopes automatically responded to
this burst at the different astronomical stations worlwide.
The 60cm BOOTES-5/JGT robotic telescope at Observatorio Astronomico
Nacional in San Pedro Martir (Mexico) gathered images (clear-filter)
starting at 04:15:06U T (6.0 min after the GRB onset).
The 60cm BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC)
in Algarrobo Costa (Spain) obtained images (i-band filter) starting at
04:15:15 UT (6.3 min after the GRB onset).
The 30cm BOOTES-1B robotic telescope at INTA-CEDEA in Mazagon (Huelva),
southern Spain, imaged the field (clear filter) starting at 04:16:32 UT
(7.5 min after the GRB onset).
The optical afterglow (Watson et al. GCNC 26010, Zheng et al. GCNC
26011, Watson et al. GCNC 26015) is detected in all three BOOTES
stations. Detailed data analysis is ongoing.
Follow-up observations were also triggered at the 1.5m OSN telescope in
Observatorio de Sierra Nevada, Granada (Spain) starting at 19:56 UT
(15.8 h after the GRB trigger). The afterglow was still detected in the
R-band, for which we measure R = 19.8 +/- 0.1 (preliminary).
We thank the staff at Observatorio Astronomico Nacional in San Pedro
Martir, IHSM La Mayora, INTA-CEDEA and Observatorio de Sierra Nevada for
the excellent support.
- GCN Circular #26018
V. Kim (AFIF, Pulkovo Observatory) A. Pozanenko (IKI), M. Krugov (AFIF),
I. Reva (AFIF), E. Mazaeva (IKI), A. Volnova (IKI) report on behalf
of larger GRB IKI FuN collaboration:
We observed the field of the GRB 191016A (Gropp al., GCN 26008) with
AZT-20 telescope of Assy-Turgen observatory (MPC observatory code 217)
starting on Oct. 16 (UT) 14:58:49 in r'-filter. We clearly detect
the optical afterglow (Watson al., GCN 26010; Zheng al., GCN 26011;
Watson al., GCN 26015; Hu et al., GCN 26017).
Preliminary photometry of the afterglow is following.
Date UT start t-T0 Filter Exp. OT Err.
(mid, days) (s)
2019-10-16 14:58:49 0.48336 r' 120*30 20.6 0.15
The photometry is based on the nearby USNO-B1 stars and BRI
transformations to r'.
The photometry in agreement with non detection of the optical afterglow
by Jelinek et al. (GRB 26013).
- GCN Circular #26019
S. Toma, M. Niwano, R. Adachi, K. L. Murata, M. Oeda, K.Shiraishi, K. Iida,
F. Ogawa, R. Hosokawa, Y. Yatsu, and N. Kawai (TokyoTech)
report on behalf of the MITSuME collaboration:
We searched for the optical counterpart of GRB 191016A (J.D. Gropp et
al., GCN Circular #26008) with the optical three color (g', Rc, and
Ic) CCD cameras
attached to the MITSuME 50 cm telescope of Okayama
Astrophysical Observatory, Okayama, Japan.
The observation started on 09:37:49.50 UT which corresponds to
5.5 hours after the trigger.
We detected the point source at the position consistent with the
afterglow detected previously (Alan M. Watson et al. GCN #26010).
The measured magnitudes and 3-sigma limit are listed as follows.
T0+[sec] MID-UT T-EXP[sec] g' Rc Ic
———————————————————————————————————————————————————
20794 13:31:46 20040 19.5+/-0.4
> 19.0 18.6+/-0.2
-------------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 and UCAC4 catalog for flux calibration.
The magnitudes are expressed in the Vega system.
- GCN Circular #26024
M. H. Siegel and J. D. Gropp (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 191016A
45 ks after the BAT trigger (Gropp et al., GCN Circ. 26008). A
source is detected consistent with the XRT position and the optical source reported
by Watson et al. (GCN Circ. 26010, 26015), Zheng and Filippenko (GCN Circ. 26011),
Hu et al. (GCN Circ. 26017), Kim et al. (GCN Circ. 26018) and Toma et al.
(GCN Circ. 26019).
The preliminary UVOT position is:
RA (J2000) = 02:01:04.68 = 30.26948 (deg.)
Dec (J2000) = +24:30:35.7 = 24.50990 (deg.)
with an estimated uncertainty of 0.5 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limit using the UVOT photometric
system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures
are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 45023 46878 1822 21.09+/-0.17
white 50812 52638 1794 21.21+/-0.19
white 56420 56938 506 >21.23
The magnitudes in the table are not corrected for the Galactic extinction due
to the reddening of E(B-V) = 0.09 in the direction of the burst (Schlegel et al. 1998).
- GCN Circular #26026
K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M. Perri
(ASDC), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), B. Sbarufatti (PSU),
D.N. Burrows (PSU), J. D. Gropp (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 191016A (WeiKang Zheng et al. GCN Circ.
26012), collecting 4.2 ks of Photon Counting (PC) mode data between
T0+45.0 ks and T0+56.9 ks.
An uncatalogued X-ray source is detected consistent with being within
296 arcsec of the Swift/BAT position and is above the RASS limit, and
is therefore likely the GRB afterglow. Using 3470 s of PC mode data and
3 UVOT images, we find an enhanced XRT position (using the XRT-UVOT
alignment and matching UVOT field sources to the USNO-B1 catalogue):
RA, Dec = 30.26933, +24.50988 which is equivalent to:
RA (J2000): 02h 01m 04.64s
Dec(J2000): +24d 30' 35.6"
with an uncertainty of 1.9 arcsec (radius, 90% confidence). This
position is 93 arcsec from the Swift/BAT position.
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.8 (+1.5, -0.5).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.9 (+0.5, -0.4). The
best-fitting absorption column is 1.4 (+1.7, -0.4) x 10^21 cm^-2,
consistent with the Galactic value of 1.0 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 3.4 x 10^-11 (4.3 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.4 (+1.7, -0.4) x 10^21 cm^-2
Galactic foreground: 1.0 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.9 (+0.5, -0.4)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00929744.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00929744.
This circular is an official product of the Swift-XRT team.
- GCN Circular #26028
A. Melandri, S.Covino, D. Fugazza, P. D’Avanzo (INAF/OAB), on behalf of the REM team, report:
We observed the field of GRB191016A (Gropp et al. GCN 26008) with the REM 60cm robotic telescope located at the ESO premise of La Silla (Chile). The observations were performed starting from about 6 min after the event and were carried in the g, r, i, z bands.
The optical counterpart (Watson et al. GCN 26010; Zheng & Filippenko GCN 26011; Watson et al. GCN 26015; Hu et al. GCN 26017; Kim et al. 26018; Toma et al. GCN 26019; Siegel & Gropp GCN 26024) is detected in the optical bands. A preliminary photometry gives:
r = 16.1 +- 0.2 at 13 min from the GRB time.
Magnitudes are calibrated against the APASS catalogue.
- GCN Circular #26176
P. Schady (Univ. of Bath) and J. Bolmer (MPE Garching) report:
We observed the field of GRB 161019A (Swift trigger 929744; Gropp et al., GCN #26008) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).
Observations started at 04:19 UT on 2019-10-16, 10 min after the GRB trigger. They were performed at an average seeing of 1.7" and at an average airmass of 1.7.
We detect a bright point source in all optical and near-infrared filters consistent with the reported optical afterglow position (Watson et al., GCN #26010; Siegel et al., GCN #26024). Based on the first 3.3 min of total exposures in g'r'i'z'JHK, we estimate preliminary AB magnitudes of
g' = 16.81 +/- 0.03
r' = 16.33 +/- 0.03
i' = 15.84 +/- 0.04
z' = 15.51 +/- 0.04
J = 15.28 +/- 0.05
H = 14.80 +/- 0.05
K = 14.83 +/- 0.08
Given magnitudes are calibrated against SDSS and 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.09 in the direction of the burst (Schlafly & Finkbeiner 2011).
We acknowledge the excellent support provided by the telescope operator at La Silla.
Previous IAU Circulars 