FH Ser was discovered visually on its rise to maximum by Minoru Honda of Kurashiki, Japan, who observed it at visual magnitude 7.0 on 1970 February 13.860 UT . Honda observed it again two days later, and by this time the nova had brightened to magnitude 5.0. By February 18th it reached its visual maximum of approximately 4.4. A few days later the nova began to fade, at first slowly and then more rapidly with an abrupt drop of 4.4 magnitudes in 45 days (7.4 to 11.8 mag. from April 15 to May 30). In the first week of June, the nova reached a minimum magnitude of 11.8 and then it rose again to reach a second maximum of magnitude 10.7 in mid-August. The final decline was extremely slow - about 0.0033 then 0.0011 magnitude per day (Burkhead and Seeds 1970). The last positive observation of FH Ser in the AAVSO Database shows the star shining at visual magnitude 15.8 in September 1977. Since then, observations indicate that it has faded below magnitude 16.5.
|Visual light curve of FH Ser from the AAVSO International Database; September 15, 1969, to December 2, 1977.|
FH Ser has been referred to as the 'Rosetta stone of nova energetics' (Gallagher 1977) because observations of this nova over a large range of wavelengths indicate that the outburst of a classical nova is much more complex than had previously been thought. FH Ser was one of the first novae to be observed in the optical, the far-ultraviolet, the far infrared, and in the radiowave regions. These multi-wavelength observations led to the discovery of some unexpected phenomena such as the infrared bright maximum 100 days after the outburst (a feature possibly common to other novae with similar light curves [Bode and Evans, 1981]), and the constancy of the bolometric luminosity for the first two months after optical maximum.