Triton Occultation - 2017 October 5

Artwork by Liem Bahneman
Prediction   Occultation Star Information   Station Lists   Finder Charts   Observing Tips


Current update - (CAZ 20171005 UT1400)

This update is based on Triton observations from the Lowell Observatory's 4.3-m Discovery Channel Telescope and the U.S. Naval Observatory's 1.55-m Kaj Strand Astrometric Reflector. The analysis was made possible by the pre-release of preliminary astrometry and proper motions from the Gaia DR2 catalog, used for the astrometric reference network stars.

Across the globe pictured above, the three solid lines correspond to the northern limit, centerline, and southern limit of Triton's shadow. The northern and southern limits correspond to a radius of 1353 km. The dashed error bars on this plot are 1-sigma, approximately 6 mas. They are based on the std error of the sample mean for the observations from UT20171005.

Table 1: Prediction Details
Triton Geocentric Mid-time (yyyy month dd hh:mm:ss)

2017 October 5 23:51:06± 00:00:12 UT

Triton Minimum Geocentric Separation 0.189± 0.0552 arcsec
Position Angle (Triton relative to the star; measured north through east) –12.48 degrees
Geocentric Velocity 16.84 km/sec
Occultation Star UCAC2 magnitude 12.42
Prediction 20171005 UT1400
Moon Phase and separation Full Moon (100%) approximate 33 degrees away

This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.