PNV J05580574-0011155 (UG:)
https://www.aavso.org/vsx/index.php?view=detail.top&oid=554613
RA 05h58m05.74s, DEC -00°11'15.5" (J2000.0)
2017 11 21.6305 UT, 11.7 mag (CCD, unfiltered)
Discoverer: Tadashi Kojima, Gunma-ken, Japan
"2017 11 21.630 UT
Discovered by T. Kojima, Gunma-ken, Japan, who found this on three frames taken by Canon EOS 6D + 135-mm f/3.2 lens under the limiting mag.= 13s and confirmed this (mag.= 12.2) taken on 2017 Nov. 21.651 UT using 200-mm f/3.2 lens. Nothing is visible at this location on a frame taken on 2017 Nov. 19.609 UT. There is a star (mag.=17.3, 05 58 05.94, -00 11 16.4) on USNO-A2."
Follow-up reports:
http://tamkin1.eps.harvard.edu/unconf/followups/J05580574-0011155.html
ASAS-SN Sky Patrol observations (Shappee et al., 2014ApJ...788...48S and Kochanek et al., 2017PASP..129j4502K):
PNVJ05580574-0011155 20171115.189 <16.36V ASN
PNVJ05580574-0011155 20171117.268 <16.34V ASN
PNVJ05580574-0011155 20171120.493 13.13V ASN
PNVJ05580574-0011155 20171121.526 12.57V ASN
A blue Gaia DR1 source (G= 17.82 mag) is 2" from the reported position of this transient.
PNV J05580574-0011155 is possibly a dwarf nova outburst with an amplitude of at least 6 magnitudes.
Time-resolved photometry, spectroscopy, and precise astrometry are urgently required.
Clear skies,
Patrick
ASASSN-17pm
"very bright CV candidate, on the rise, matches to blue g=17.7 SDSS source, V>17.5 on 2017-11-17.26, V=13.2 on 2017-11-20.49, V=12.6 on 2017-11-21.52"
http://www.astronomy.ohio-state.edu/~assassin/transients.html
Thank you Patrick
I just did 2 visual estimations with different Tycho-2 stars: 22/11/2017 UTC 0h27 +12.30 UTC 0h32 +12.38
Michel