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We are planning a campaign on Nova Cyg 1992 during the next few months (July to December), and we are looking for collaborators from other observatories. The nova was about Mv=15.8 in May, and its recent decay rate has been about 0.5 mag/year. Its estimated visual mag. during the next few months is therefore 16.
In the last 3 years this system had permanent superhumps with a period of 2.04 hr (Skillman et al. 1997, PASP, 109, 114 ; Retter, Leibowitz, and Ofek, 1997, MNRAS, 283, 745). The peak-to-peak amplitude of the superhump is about 7%, but with the orbital variation it is sometimes double this value.
We would like to check the following issues:
1. The change in the superhump period. It decreased during 1994, and increased during 1995 and 1996. This trend might be reversed during 1997. 2. A possible decrease in the orbital period. Semeniuk et al. 1996, Acta Astro. 46, 311 and Skillman et al. 1997 detected a very small decrease in the 1.95 hr orbital period, however it might be explained by a phase shift of the variation. 3. Simple calculations lead to the prediction that the permanent superhumps will cease when the nova magnitude reaches an upper limit of about 17.5-18.5 (it could happen before). We would like to check the evolution of the superhumps as the nova magnitude approaches this value, which corresponds to some critical value of the mass transfer rate M-dot.This is the first time that we may have an opportunity to follow observationally such developments in a classical nova, which makes V1974 Cyg a particularly interesting target.
The Wise Observatory and Kyoto Observatory (Katsura Matsumoto and Taichi Kato) give it a high priority. The CBA group (J. Patterson) also has started to observe this star, and will be back from the summer holiday in September with more telescopes.
If you're interested in joining this campaign, please contact Alon Retter (alon@wise1.tau.ac.il). Since the period is short, even a 2-hr run will be helpful.
Alon Retter and Elia Leibowitz
Wise Observatory
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