GRB 210509A
GCN Circular 29979
Subject
GRB 210509A: RATIR Optical and NIR Upper Limits
Date
2021-05-10T14:11:26Z (4 years ago)
From
Alan M Watson at UNAM <alan@astro.unam.mx>
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), Jes��s Gonz��lez (UNAM), Carlos
Rom��n-Z����iga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou
(U. Wash.), and Vicki Toy (UMD) report:
We observed the field of GRB 210509A (Page et al., GCN Circ. 29970) with the
Reionization and Transients Infrared Camera (RATIR) on the 1.5m Harold Johnson
Telescope at the Observatorio Astron��mico Nacional on Sierra San Pedro M��rtir
from 2021/05 10.47 to 2021/05 10.48 UTC (19.34 to 19.70 hours after the BAT
trigger), obtaining a total of 0.21 hours exposure in the r and i bands and 0.08
hours exposure in the Z, Y, J, and H bands.
For a source within the Swift-XRT error circle, in comparison with the SDSS DR9
and 2MASS catalogs, we obtain the following upper limits (3-sigma):
r > 21.28
i > 21.09
Z > 18.17
Y > 19.19
J > 19.57
H > 17.30
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
GCN Circular 29978
Subject
GRB 210509A: Swift/UVOT Upper Limits
Date
2021-05-10T10:10:56Z (4 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210509A
3202 s after the BAT trigger (Page et al., GCN Circ. 29970).
No optical afterglow consistent with the XRT position (Evans et al.
GCN Circ. 29971) 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 3202 3352 147 >20.8
white 3202 4585 344 >21.0
v 3358 4934 332 >19.0
b 4180 4380 197 >19.5
u 3974 4174 197 >19.6
w1 3769 3969 197 >19.5
m2 3563 3763 197 >20.3
w2 4592 4792 197 >19.6
The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.074 in the direction of
the burst (Schlegel et al. 1998).
GCN Circular 29977
Subject
GRB 210509A: Swift-XRT refined Analysis
Date
2021-05-10T08:38:51Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U.
Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo (INAF-OAB), M.G.
Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , A. Tohuvavohu (U.
Toronto), B. Sbarufatti (PSU) and K.L. Page report on behalf of the
Swift-XRT team:
We have analysed 7.2 ks of XRT data for GRB 210509A (Page et al. GCN
Circ. 29970), from 3.2 ks to 56.6 ks after the BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Goad et al. (GCN Circ. 29973).
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.11 (+0.20, -0.17).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.63 (+0.36, -0.16). The
best-fitting absorption column is consistent with the Galactic value
of 7.1 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum is 4.0 x 10^-11 (4.4 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 7.1 (+/-8.9) x 10^20 cm^-2
Galactic foreground: 7.1 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.63 (+0.36, -0.16)
If the light curve continues to decay with a power-law decay index of
1.11, the count rate at T+24 hours will be 2.2 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.7 x
10^-14 (9.6 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01047531.
This circular is an official product of the Swift-XRT team.
GCN Circular 29975
Subject
GRB 210509A: Swift-BAT refined analysis
Date
2021-05-10T04:33:00Z (4 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), C. B. Markwardt (GSFC),
K. L. Page (U Leicester), 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-60 to T+243 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 210509A (trigger #1047531)
(Page et al., GCN Circ. 29970