New Photometric Observations and the 2015 Eclipse of the Symbiotic Nova Candidate ASAS J174600-2321.3

The eclipsing binary system ASAS J174600-2321.3, which has shown a conspicuous brightening of ~4 magnitudes (V) in the past, was recently identified as a symbiotic nova candidate. A long-term photometric monitoring program was initiated in July 2014. In its present active stage, the system shows deep eclipses with an amplitude of ~3.5 magnitudes (V) that occur about every 33 months. In order to monitor the eclipse of 2015, AAVSO Alert Notice 510 was issued. During the ensuing campaign, AAVSO observers obtained 338 measurements in Johnson B, 393 measurements in Johnson V, and 369 measurements in Cousins I, as well as 27 visual observations. The present paper presents and analyzes these data from the AAVSO International Database, along with observations from the aforementioned photometric monitoring program. From these data, we were able to refine the orbital period to Porb = 1012.4 days. Furthermore, the data are suggestive of a slight decrease in mean brightness, which—if proven real—might indicate a decline of the outburst.