The Value of Photoelectric Occultation Timings in Lunar Motion Studies

Thomas C. Van Flandern
1971 Highlights of Astronomy  
AbstractThe two most important advantages of photoelectric timings of occultations over visual timings are accuracy and freedom from systematic error. The observational error is so small compared with uncertainties in the lunar ephemeris, star positions, limb corrections, and such, that the value of the observations will continue to increase as time goes on and the other error sources are eliminated.A recent result made possible largely by the availability of photoelectric timings over the last
more » ... mings over the last 20 yr is a new value for the secular acceleration of the Moon, with corresponding consequences for the Ephemeris Time scale.An important current application for simultaneous photoelectric and visual observations is the determination of 'personal equation' for the visual observers. Experiments so far indicate the visual observers require a minimum of 0.1 sec to detect that an event has occurred, plus additional time to react to it; hence, typical personal equations are around 0.4 sec.
doi:10.1017/s1539299600000630 fatcat:i2t22yk6jjfdhccfki2vpa7g4i