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PNV J18040967-1803581: possible nova (11.2 mag) in Sagittarius

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SPK
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PNV J18040967-1803581: possible nova (11.2 mag) in Sagittarius

PNV J18040967-1803581 (N:)

RA 18h04m09.67s, DEC -18°03'58.1" (J2000.0)
2018 April 8.7229 UT, 11.2 mag (CCD, unfiltered)

Independent discoverers: Tadashi Kojima (Gunma-ken, Japan) and Hideo Nishimura (Shizuoka-ken, Japan)

2018 04 08.723 UT
Discovered by T. Kojima, Gunma-ken and H. Nishimura, Shizuoka-ken, independently. Kojima found this star on six frames with five second exposure using Canon EOS 6D digital camera + 200-mm f/3.2 lens under the limiting mag = 12.5, who writes nothing is visible at this location on a frames (limit mag = 13.2) taken 2018 March 27.767 UT. Nishimura also found this star (mag.= 11.2) on five frames taken on 2018 April 8.728 UT with ten second exposure using Canon EOS 6D digital camera + 200-mm f/3.2 under the limiting mag.= 14.3, who writes nothing is visible on a frame taken on Apr. 7.723 UT (limit mag.= 14) and gives the position at end
figures 09s.46, 57".3.

2018 04 08.728 UT
Both images at
http://www.oaa.gr.jp/~oaacs/image/PNVSgr2018K.JPG
http://www.oaa.gr.jp/~oaacs/image/PNVSgr2018N.JPG

2018 04 08.82 UT
The nearest USNO-B1.0 star is 4" away: USNO-B1.0 0719-0746451 at RA 18h04m09.67s, DEC -18°03'54.4" (J2000.0, R= 18.16 mag, B= 21.42 mag; G= 18.31 mag in Gaia DR1; r= 19.11, g= 20.95 mag in Pan-STARRS DR1). No previous outbursts or eruptions were recorded at the transient's position by the ASAS-SN Sky Patrol
(Shappee et al. 2014ApJ...788...48S and Kochanek et al. 2017PASP..129j4502K) since 2015 February; the latest available observation is 2018 March 29.605 UT, fainter than mag 16.1 V:
https://asas-sn.osu.edu/light_curves/bec38ad2-4de7-4d4c-8439-4d1230931d53
--- Patrick Schmeer (Saarbrücken-Bischmisheim, Germany)

Follow-up reports:
http://www.cbat.eps.harvard.edu/unconf/followups/J18040967-1803581.html

Spectroscopy, multiband photometry, and precise astrometry are urgently required.

Clear skies,
Patrick

SPK
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Expected extinction (V band): about 8 magnitudes
FRF
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11.74V

2018 04 08.9274UT
Photometry results by Vikrant Kumar Agnihotri, Cepheids AStronomy Group, Rawatbhata, India:  11.74V (0.04), 13.63B (0.04).
--- Fidrich Robert (Budapest, Hungary)

SPK
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Independent discovery by Yuji Nakamura

2018 04 08.7876 UT
Yuji Nakamura, Kameyama, Mie, Japan, reported his independent discovery of this PNV (mag 11.3) on a CCD frame taken on 2018 Apr 08.7876 UT (limiting mag 13) using a f135mm F4.0 telephoto lens. The position end figures he reported were 09.5s, 04' 01" (J2000). He also reported that this PNV was not on his past frame (limiting magnitude 13) taken on 2018 Mar 30.7861. He reported these facts to NAOJ on Apr 08.8667 UT.
http://www.cbat.eps.harvard.edu/unconf/followups/J18040967-1803581.html

SPK
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Astrometry by V. K. Agnihotri. Possible progenitor (r=21.89 mag)

2018 04 08.9274 UT
Vikrant Kumar Agnihotri also reports position end figures 09.46s, 55.7" (J2000.0). A Pan-STARRS DR1 source (position end figures 09.45s, 55.8"; r= 21.89, i= 21.03 mag) is only 0.2" away from this position. --- Patrick Schmeer (Saarbrücken-Bischmisheim, Germany)
http://www.cbat.eps.harvard.edu/unconf/followups/J18040967-1803581.html

SPK
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Nova in Sagittarius = PNV J18040967-1803581 (CBET 4504)

Electronic Telegram No. 4504 (behind paywall): http://www.cbat.eps.harvard.edu/iau/cbet/004500/CBET004504.txt

weo
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AAVSO Alert Notice 629 on N Sgr 2018

AAVSO Alert Notice 629 announces and reports on N Sgr 2018 = PNV J18040967-1803581. Please see the notice for details and observing recommendations.

Many thanks, and Good observing,

Elizabeth Waagen, AAVSO HQ

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