SIMBAD references

Photometry obtained with a digital single lens reflex (DSLR) camera and a CMOS astronomical camera from 2016 to 2020 expands the O-C diagram of RS Gru to cover a span of nearly 68 years. Analysis of the data reveals that a previous report of a constant rate of increase of the period between October 2003 and July 2013 may not be correct. Instead, evidence is presented that there was a constant rate of increase of the period from October 2003 to October 2010 followed by a constant but slower rate of increase from July 2011 to July 2020, with the latter described by the expression dP/ dt = 2.99 (0.96) x 10-8 d yr-1 or dP/ Pdt = 2.04 (0.65) x 10-7 yr-1. A new quadratic ephemeris derived from the 2011 to 2020 observations is TOM (HJD) = 2459045.1247 (0.0002) + 0.14701221 (0.00000004) E + 6.0X10-12 (1.9 * 10-12) E2 for which zero time occurred on 14 July 2020 UTC.