Alert Notice 519: Nova Sgr 2015 No. 2 fading as dust production rises [V5668 Sgr]

June 15, 2015: Nova Sgr 2015 No. 2 (V5668 Sgr, PNV J18365700-2855420; see AAVSO Alert Notice 512) is undergoing a significant fading visually as its infrared excess increases, indicating that substantial dust production is underway.

Nova Sgr 2015 No. 2 was discovered by John Seach (Chatsworth Island, NSW, Australia) at DSLR magnitude 6.0 on 2015 March 15.634 UT. It brightened to V=4.3 by March 21, and has undergone five subsequent re-brightenings, the last to V=5.7 on June 1. Since then it has faded steadily to V=8.2 on June 15, 1.6 magnitudes fainter than its faintest previous minimum since outburst. For a light curve of observations in the AAVSO International Database, see below.

The Spitzer Space Telescope may observe this classical nova if it can be diverted from its current mode and target. Several professional astronomers are planning observations with other instrumentation.

Photometry and visual observations, spectroscopy, and polarimetry are strongly encouraged. Near-infrared observations (J and H bands) would be particularly helpful.

Coordinates:  R.A. 18 36 56.84   Dec. -28 55 39.8  (2000.0)

Charts for Nova Sgr 2015 No. 2 may be created using the AAVSO Variable Star Plotter (VSP). A binocular sequence for this nova exists. Brighter comparison stars may also be found using VSP and requesting an 'a' or 'b' scale chart. Charts showing fainter comparison stars may also be created.

Please submit observations to the AAVSO International Database using the name "NOVA SGR 2015 NO. 2". Once a GCVS name has been assigned, please use that name.

Nova Sgr 2015 No. 2, March - June 2015 (JD 2457094-2457188). 109 observers worldwide contributed the 2,081 visual and multicolor observations in this light curve from the AAVSO International Database. For an up-to-the-minute light curve of this star, go to, enter "Nova Sgr 2015 No. 2" (without quotes) under Pick a Star, and choose the Plot a light curve option.

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


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