////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  23800
SUBJECT: Swift Trigger 886157: Swift detection of a new transient Swift J1728.9-3613
DATE:    19/01/28 01:47:01 GMT
FROM:    Jamie A. Kennea at PSU/Swift-XRT  <kennea@swift.psu.edu>

S. D. Barthelmy (GSFC), A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC),
J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester),
D. M. Palmer (LANL) and A. Tohuvavohu (PSU) report on behalf of the
Neil Gehrels Swift Observatory Team:

At 01:22:25 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a new transient which we name Swift J1728.9-3613 (trigger=886157).  
The BAT on-board calculated location is 
RA, Dec 262.232, -36.237 which is 
   RA(J2000) = 17h 28m 56s
   Dec(J2000) = -36d 14' 13"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty). As is normal for an image trigger, the onboard
light-curve showed no significant structure. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 09:11 UT on 2019 January 29. There will thus be no XRT
or UVOT data for this trigger before this time. 

The rise of this transient was seen by the BAT transient monitor
(Krimm et al., 2013), with the first detection on 2019 January 25. The BAT 
light-curve can found at the following link:   

https://swift.gsfc.nasa.gov/results/transients/weak/SWIFTJ1728.9-3613/SWIFTJ1728.9-3613.html

////////////////////////////////////////////////////////////////////////
TITLE:           GCN/MAXI NOTICE
NOTICE_DATE:     Mon 28 Jan 19 01:48:18 UT
NOTICE_TYPE:     MAXI Unknown Source Position
EVENT_ID_NUM:    509624954
EVENT_RA:        261.59d {+17h 26m 22s} (J2000),
                 261.91d {+17h 27m 40s} (current),
                 260.75d {+17h 23m 00s} (1950)
EVENT_DEC:       -36.37d {-36d 21' 53"} (J2000),
                 -36.38d {-36d 22' 48"} (current),
                 -36.32d {-36d 19' 19"} (1950)
EVENT_ERROR:     1.0 [deg radius, stat+sys, 90% containment]
EVENT_FLUX:      45.0 +- 0.0 [mCrab]
EVENT_DATE:      18509 TJD;    26 DOY;   19/01/26
EVENT_TIME:      67811.00 SOD {18:50:11.00} UT
EVENT_TSCALE:    1day
EVENT_EBAND:     Low, 2-4 keV
SUN_POSTN:       310.25d {+20h 41m 00s}  -18.31d {-18d 18' 27"}
SUN_DIST:         46.02 [deg]
MOON_POSTN:      219.37d {+14h 37m 28s}   -9.91d {-09d 54' 42"}
MOON_DIST:        46.66 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      351.56, -0.60 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      263.06,-13.13 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        MAXI Unknown Source Position. GRB or unknown X-ray Transient.

////////////////////////////////////////////////////////////////////////
ATel #12436
 S. D. Barthelmy (GSFC), A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester), D. M. Palmer (LANL) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
on 28 Jan 2019; 01:54 UT
Subjects: X-ray, Transient

At 01:22:25 UT, the Swift Burst Alert Telescope (BAT) triggered and located a new transient which we name Swift J1728.9-3613 (trigger=886157, GCN #23800). The BAT on-board calculated location is RA, Dec 262.232, -36.237 which is 

RA(J2000) = 17h 28m 56s, 
Dec(J2000) = -36d 14' 13", 

with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is normal for an image trigger, the onboard light-curve showed no significant structure.

Due to a Sun observing constraint, Swift cannot slew to the BAT position until 09:11 UT on 2019 January 29. There will thus be no XRT or UVOT data for this trigger before this time.

The rise of this transient was seen by the BAT transient monitor (Krimm et al., 2013), with the first detection on 2019 January 25. The BAT light-curve can found at the link below.

We note that this transient has also been reported as being detected by MAXI.