V1666 Cyg disappears

Hello,

V1666 Cyg is a SRA carbon star with a period of 376d and an amplitude of 10.9-12.9V. According to Alksne, Alksnis, Dzervitis: Properties of Galactic Carbon Stars, 1991 a secondary variability component exists. So far so good. My first observations around JD 2450490 till 2452200 matching good to this data.

Unfortunately I can not observe variable stars during the next years. Later I am starting again and try V1666 Cyg two times. But it seems that the star only shows slight variations. Therefore I was not sure whether I should start with V1666 agian or not.  

The third time I look at V1666 the variable was fainther as I ever has seen it. Therefore I put V1666 on my list again and was very surprised about what happens now. Please be aware by looking at my observations that I have used different sequences and look at my comments about the first minimum (was around 14mag).

So far so nice! But now V1666 Cyg was to faint for my instrument. I ask for help from someone who can carry one my observations to see how faint V1666 Cyg will get. A cart is available but only with comp. stars up to 14.4 mag.

Because V1666 Cyg is a carbon stars this behavior may is connected with some kind of dust shell like CW Leo or RW LMi. Maybe therefore V1666 Cyg is also interesting for spectral analysis.

Peter Maurer