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Alert Notice 561: Nova in Sagittarius = ASASSN-16ma = PNV J18205200-2822100 [V5856 Sgr]

October 28, 2016

Event: Nova in Sagittarius  [V5856 Sgr]

Discovered by:
 - ASAS-SN (K. Z. Stanek (Ohio State University) et al.; ATel #9669)
 - Yukio Sakurai (Mito, Japan; via TOCP page)

Discovery magnitude:
 - ASAS-SN: V~13.7, using quadruple 14-cm "Cassius" telescope at CTIO
 - Sakurai: 10.4 unfiltered CCD, using Nikon D7100 digital camera + 180-mm f/2.8 lens

Discovery date:
 - ASAS-SN: 2016 October 25.02 UT
 - Sakurai: 2016 October 26.380 UT
 
Coordinates (2000.0): R.A. 18 20 52.25  Dec. -28 22 12.1  (from VSX)
 
Spectra: Spectroscopy indicating that ASASSN-16ma is a classical nova in the optically thick (Fe-curtain) stage was obtained 2016 Oct. 27.5 UT by P. Luckas (International Centre for Radio Astronomy Research, Univ. of Western Australia; ARAS Group; ATel #9678).

Observing recommendations: Observations of all types (visual, CCD, DSLR, spectroscopy) and all bands as instrumentation permits are strongly encouraged as the nova evolves.

Observations reported to the AAVSO:
2016 Oct. 20.04 UT,  <17.3 V (ASAS-SN; Stanek et al., ATel #9669);
23.398, <11.0 unfiltered CCD (Y. Sakurai, Mito, Japan; via TOCP page);
25.02, 13.7: V +/-0.02 (ASAS-SN; Stanek et al., ATel #9669);
26.02, 11.6: V +/-0.01 (ASAS-SN; Stanek et al., ATel #9669);
26.05670, 11.76 B +/-0.07 (S. O'Connor, St. George, Bermuda);
26.05750, 11.44 V +/-0.03 (O'Connor);
26.05900, 11.44 CV +/-0.12 (O'Connor);
26.48750, 11.0 (A. Pearce, Nedlands, W. Australia);
27.0474, 11.04 B (S. Kiyota, Kamagaya, Japan; red color noted; with 0.50-m f/4.5 CDK astrograph + FLI-PL11002M at Mayhill, NM, USA remotely; via TOCP page);
27.0474, 10.65 V (Kiyota, as above; red color noted);
27.0474, 10.18 Ic (Kiyota, as above; red color noted);
27.48890, 10.6 (Pearce);
27.50153, 10.4 (D. Benn, Klemzig, S. Australia);
27.95490, 10.3 (A. Amorim, Florianopolis, Brazil);
28.49387, 10.3 (Benn);
28.71389, 10.3 (D. Blane, Henley-on-Klip, South Africa);

Charts: Charts with a comparison star sequence for ASASSN-16ma may be created using the AAVSO Variable Star Plotter (VSP). Be sure to include the hyphen and no spaces in the name, as shown.

Submit observations: Please submit observations to the AAVSO International Database using the name ASASSN-16ma. Once a GCVS name is announced in an IAU Circular or CBET, please use that name.

Notes:
a. Designated PNV J18205200-2822100 when posted to the IAU Central Bureau for Astronomical Telegrams Transient Object Confirmation Page (TOCP). Most of the information in this Alert Notice is taken from the TOCP page or ATel #9669, #9678, #9680, and #9683.

b. Stanek et al. report no previous outbursts have been detected at the nova's location since ASAS-SN started observing the Galactic center in March 2016 (ATel #9669).

c. Position end figures
 - ASAS-SN (discovery, 2016 Oct. 25.02 UT): 52.12s, 13.52"
 - Sakurai (discovery, 2016 Oct. 26.380 UT): 52.00s, 10.0"
 - P. Mroz et al. for OGLE (2016 Oct. 27 UT; ATel #9683): 52.25s, 12.1"

d. Progenitor: R. K. Saito (Universidade Federal de Santa Catarina) et al. (ATel #9680) report a likely progenitor candidate is VVV J182052.14-282212.8, located at position end figures 52.141s, 12.79" (0.78 arcsec from the reported nova position). They also report that photometric flags in the VVV photometry as well as visual inspection of the images show the object may be a blend of two even fainter sources.

However, P. Mroz (Warsaw University Observatory) et al., on behalf of the OGLE team, conclude that the VVV star cannot be the progenitor, as measurement of OGLE images taken 2016 October 27 UT show it is 1.16 arcsec from the nova (ATel #9683). They also report the nova is not seen down to magnitude I=22 on the OGLE deep template image.

Congratulations to the ASAS-SN team and to Yukio Sakurai on this discovery!

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.

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