Roy Axelsen and Tim Napier-Munn have published a paper on the δ Scuti star AD Canis Minoris in the JAAVSO.
The high amplitude δ Scuti star AD Canis Minoris was studied by photoelectric photometry (PEP) during one night in February 2011 and by digital single lens reflex (DSLR) photometry during seven nights in January and February 2016. Nine light curve peaks were captured, eight of them by DSLR photometry. A review of the literature enabled us to tabulate 109 times of maximum since 1959, to which we added 9 times of maximum from our data, thus creating the largest dataset to date for this star. Assuming a linear ephemeris, the period of AD CMi was calculated to be 0.122974511 (±0.000000004)d, almost identical to that quoted in earlier literature. We constructed an observed minus computed (O–C) diagram which exhibited a quasi-sinusoidal shape, and fitted a weighted model characterized by combined quadratic and trigonometric functions. The fit indicates that the shape of the O–C diagram is attributable to the effects of a slow increase in the pulsation period of AD CMi at a constant rate, modulated by the light time effect of a binary system. These results confirm those of previous authors, and update most of the coefficients of the equation for the fitted model. The values of all of the coefficients in the function are statistically significant. The rate of increase in the pulsation period of AD CMi was calculated from the entire dataset to be dP/ dt = 6.17 (± 0.75) × 10–9 d yr–1 or dP/Pdt = 5.01 (± 0.61) × 10–8 yr–1.
Axelsen, R., & Napier-Munn, T. (2016). The High Amplitude δ Scuti Star AD Canis Minoris. JAAVSO, 44. Retrieved from https://www.aavso.org/media/jaavso/3225_M0gcYiE.pdf