GRB 190630C

M.G. Bernardini (INAF-OAB), E. Ambrosi	(INAF-IASFPA) , V. D'Elia
(ASDC), B. Sbarufatti (PSU), D.N. Burrows (PSU), J. D. Gropp (PSU),
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore
(U. Leicester) and T.N. Ukwatta report on behalf of the Swift-XRT team:

We have analysed 5.7 ks of XRT data for GRB 190630C (Ukwatta et al. GCN
Circ. 24927
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 ), from 155 s to 57.3 ks after the  BAT trigger. The data
comprise 56 s in Windowed Timing (WT) mode with the remainder in Photon
Counting (PC) mode. The enhanced XRT position for this burst was given
by Goad et al. (GCN Circ. 24930
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 ).

The light curve can be modelled with an initial power-law decay with an
index of alpha=4.3 (+0.7, -0.5), followed by a break at T+310 s to an
alpha of 1.06 (+0.12, -0.23).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 3.09 (+0.33, -0.29). The
best-fitting absorption column is  2.7 (+/-0.7) x 10^21 cm^-2, in
excess of the Galactic value of 1.1 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.2 (+/-0.3) and a
best-fitting absorption column of 2.0 (+1.0, -0.9) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.2 x 10^-11 (4.8 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     2.0 (+1.0, -0.9) x 10^21 cm^-2
Galactic foreground: 1.1 x 10^21 cm^-2
Excess significance: 1.7 sigma
Photon index:	     2.2 (+/-0.3)

If the light curve continues to decay with a power-law decay index of
1.06, the count rate at T+24 hours will be 3.0 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.7 x
10^-14 (1.4 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00912239.

This circular is an official product of the Swift-XRT team.

S. Belkin (IKI), S. Schmalz (KIAM), A. Pozanenko (IKI), A. Volnova 
(IKI),  E. Mazaeva  (IKI),  I. Molotov (KIAM) report on behalf of larger 
GRB IKI FuN collaboration:

We observed the field of GRB 190630C (Ukwatta et al., GCN 24927
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 ) with 
ORI-22 (22 cm) telescope of ISON-Castelgrande observatory in Clear 
filter starting on July 01  (UT) 00:03:42.  We do not detect any object 
within enhanced Swift-XRT position (Goad et al., GCN 24930
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 ). Preliminary 
photometry of the field is following

Date       UT start t-T0    Filter Exp.   OT    Err. UL
                     (mid, days) (s)

2019-07-01 00:03:42 0.02584  CR    53*60  n/d   n/d 18.8

The photometry is  based on nearby USNO-B1.0 (R2) stars.

GRB 190630C: Swift/UVOT Upper Limits

K. K. Simpson (PSU) and T. N. Ukwatta (LANL)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 190630C
136 s after the BAT trigger (Ukwatta et al., GCN Circ. 24927
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 ).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 24930
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 )
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           157          307          147         >20.5
white              157          307          147         >20.5
v                  136          412           32         >18.1
w2                 367          387           19         >20.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.11 in the direction of the burst
(Schlegel et al. 1998).

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 Swift GRB 190630C (Ukwatta et al.,
GCN 24927
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 ) starting at ~0.379 days after the burst. Observations
were performed in the clear (roughly R) filters, a total of 31
images were obtained and the exposure time was 60 s per image.
We do not detect any optical afterglow candidate within the Enhanced
XRT position error circle (Goad et al., GCN 24930
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 ), neither in single
image, nor in the co-add images. We estimate our limiting magnitude
of our co-added image is ~19.0 mag calibrated to the APASS catalog.

H. A. Krimm (NSF), S. D. Barthelmy (GSFC),  J. R. Cummings (CPI),
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 190630C (trigger #912239)
(Ukwatta, et al., GCN Circ. 24927
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 ).  The BAT ground-calculated position is
RA, Dec = 293.890, -32.759 deg which is 
  RA(J2000)  =  19h 35m 33.6s 
  Dec(J2000) = -32d 45' 32.5" 
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 57%.

The mask-weighted light curve shows a single FRED-shaped burst, beginning 
at ~T-5 sec, peaking at T+0 sec, and declining to background by ~T+40 sec.
A spacecraft slew took the burst position out of the BAT field of view just before
T+500 sec. T90 (15-350 keV) is 38.4 +- 9.3 sec (estimated error including systematics).

The time-averaged spectrum from T-1.92 to T+50.23 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.96 +- 0.11.  The fluence in the 15-150 keV band is 2.3 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.12 sec in the 15-150 keV band
is 2.0 +- 0.3 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/912239/BA/

V. Sharma, R. Gaikwad, D. Bhattacharya and A. Vibhute (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data showed the detection of a long GRB 190630C, which was also detected by Swift (Ukwatta T. N. et al., GCN # 24927) and Swift-XRT (Goad M. R. et al., GCN # 24930).

The source was clearly detected in the 40-200 keV energy range. The light curve shows single pulse of emission with strongest peak at 23:53:01 UT. The measured peak count rate associated with the burst is 153 cts/s above the background in the combined data of four quadrants, with a total of 1301 cts. The local mean background count rate was 571 cts/s. Using cumulative rates, we measure a T90 of 21.3 s.

It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.

M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 195 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 190630C, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 293.88034, -32.74405 which is equivalent
to:

RA (J2000): 19h 35m 31.28s
Dec (J2000): -32d 44' 38.6"

with an uncertainty of 1.9 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.

T. N. Ukwatta (LANL), J.D. Gropp (PSU), H. A. Krimm (NSF),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
D. M. Palmer (LANL) and A. Tohuvavohu (PSU) report on behalf of the
Neil Gehrels Swift Observatory Team:

At 23:52:59 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 190630C (trigger=912239).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 293.908, -32.751 which is 
   RA(J2000) = 19h 35m 38s
   Dec(J2000) = -32d 45' 03"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 120 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 23:55:28.8 UT, 149.3 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 293.87874,
-32.74273 which is equivalent to:
   RA(J2000)  = 19h 35m 30.90s
   Dec(J2000) = -32d 44' 33.8"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 93 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. No
spectrum from the promptly downlinked event data is yet available to
determine the column density. 

The initial flux in the 2.5 s image was 1.02e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 157 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT 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
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.11. 

This source lies within the current (Sector 13) field-of-view of TESS camera 1. 

Burst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta AT gmail.com). 
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/)