Updated Ephemeris and Evidence for a Period Change in the Eclipsing Novalike Variable 1RXS J064434.5+334451

Abstract

We report seven new eclipse timings for the novalike variable 1RXS J064434.5+334451. An analysis of our data, along with all previously available timings (36 published and 16 unpublished), yields a best-fitting linear ephemeris of BJD${}_{\mathrm{ecl}}=2,453,403.7611(2)+0.26937443(2)\mathrm{E}$. We find a somewhat improved fit with a quadratic ephemeris given by: BJD${}_{\mathrm{ecl}}=2,453,403.7598+0.26937487\mathrm{E}-2.0\times 10^{-11}{\mathrm{E}}^2$, which suggests that the orbital period may be decreasing at a rate given by $\dot{P}\simeq -1.5\times 10^{-10}$.

5 pages, 1 figure, 1 table, accepted for publication in the Research Notes of the AAS