PNV J17244011-2421463: new transient (12.5 mag) in Ophiuchus

PNV J17244011-2421463
https://www.aavso.org/vsx/index.php?view=detail.top&oid=608210

RA 17h24m40.11s, DEC -24°21'46.3" (J2000.0)
2018 Feb. 12.8339 UT, 12.5 mag (CCD, unfiltered)
Discoverer: Tadashi Kojima (Gunma-ken, Japan)

"2018 02 12.834 UT
Discovered by T. Kojima, Gunma-ken, Japan, on three frames with five second exposure using Canon EOS 6D digital camera + 200-mm f/3.2 lens under the limiting mag = 13.5, who writes nothing is visible at this location on the previous frame (limit mag = 12.0) taken 2018 Feb. 8.844 UT and also a frame on 2017 Apr. 27 UT. There is a star (mag= 15.6) at the position of 39s.95 and 47".0.

Follow-up reports:
http://www.cbat.eps.harvard.edu/unconf/followups/J17244011-2421463.html
(see also my comments there)

Spectroscopy and precise astrometry are urgently required.

Clear skies,
Patrick