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Alert Notice 578: Nova in Centaurus - ASASSN-17gk

May 23, 2017

Event: Nova in Centaurus - ASASSN-17gk

Discovered by: All Sky Automated Survey for SuperNovae (ASAS-SN, (K. Z. Stanek (OSU) et al., ATel #10387)

Discovery magnitude: 10.9 V

Discovery date: 2017 May 17.28 UT
 
Coordinates (2000.0): R.A. 13 20 55.32  Dec. -63 42 18.5 (from discovery and VSX)
 
Spectra: Spectroscopy indicating that ASASSN-17gk is a galactic nova was obtained by P. Luckas (International Centre for Radio Astronomy Research, Univ. Western Australia) on 2017 May 18.0598  UT (ATel #10399). His spectrum (non-instrument corrected) may be viewed at asassn-17gk_20170518_428_Paul Luckas.png.

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:
2017 Apr. 23.16 UT, <17.4 V (ASAS-SN,K. Stanek et al., ATel #10387);
25.08, 13.3V (ASAS-SN);
28.11, 11.6V (ASAS-SN);
May 04.19, 12.05V (ASAS-SN);
17.28, 10.9V (ASAS-SN, discovery);
18.43056, 10.9 (PEX, A. Pearce, Nedlands, W. Australia);
18.51388, 10.705 V +/-0.0069 (LPAE, P. Luckas, Crawley, W. Australia);
18.51582, 11.781 B +/-0.0027 (Luckas);
18.59167, 10.9 (Pearce);
19.45139, 10.5 (Pearce);
20.05769, 11.803 B +/-0.018 (HMB, F.-J. Hambsch, Mol, Belgium);
20.05790, 11.803 B +/-0.018 (Hambsch);
20.05811, 11.806 B +/-0.016 (Hambsch);
20.05835, 10.706 V +/-0.008 (Hambsch);
20.05856, 10.706 V +/-0.008 (Hambsch);
20.05878, 10.720 V +/-0.008 (Hambsch);
20.05902, 8.865 I +/-0.009 (Hambsch);
20.05923, 8.851 I +/-0.009 (Hambsch);
20.05945, 8.839 I +/-0.009 (Hambsch);
20.45486, 10.6 (Pearce);
21.48395, 10.990 V +/-0.039 (BHQ, T. Bohlsen, Armidale, NSW, Australia);
21.48505, 9.827 R +/-0.066 (Bohlsen);
21.48611, 10.8 (Pearce);
21.48623, 11.926 B +/-0.076 (Bohlsen);
21.48712, 9.036 I +/-0.063 (Bohlsen);
22.44375, 11.2 (Pearce);
22.47641, 12.217 B +/-0.021 (Bohlsen);
22.47841, 9.997 R +/-0.043 (Bohlsen);
22.47933, 9.185 I +/-0.054 (Bohlsen);
22.48090, 11.175 V+/- 0.011 (Bohlsen);
22.77400, 11.041 V +/-0.019 (BLD, D. Blane, Henley-on-Klip, S. Africa);
22.89792, 11.1 (AAX, A. Amorim, Florianopolis, Brazil);
23.61458, 11.5 (Pearce);

Charts: Charts with a comparison star sequence for ASASSN-17gk may be created using the AAVSO Variable Star Plotter (VSP). Be sure to include the hyphen in the name as shown.

Submit observations: Please submit observations to the AAVSO International Database using the name ASASSN-17gk. Once a GCVS name is announced in an IAU Circular or CBET, please use that name.

Notes:
a. Some of the information in this Alert Notice is taken from ATel #10387 , ATel #10399, and ATel #10404.

b. P. Schmeer (Saarbruecken-Bischmisheim, Germany) reports that a Gaia DR1 source (G=18.767 mag) is located at RA 13 20 55.334, Dec -63 42 19.16 (J2000.0), 0.7" from the reported position of the nova. R. K. Saito (Universidade Federal de Santa Catarina) and D. Minniti (Univ. Andres Bello,  Millennium Inst. Astrophysics, Vatican Obs.) report that multiband near-IR VVV observations taken in 2010 show the presence of a faint source (RA 13 20 55.371, Dec -63 42 19.25 (J2000.0)) 0.822 arcsec from the reported target position, and that during 2010-2013 it showed no significant variation in brightness (ATel #10404).

Congratulations to the ASAS-SN team on this discovery!

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

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