Gaia mission helps TRITON Occultation observations

On Thursday 5 October an important and rare astronomical event will take place: Triton will be occulting a star (called UCAC4 410-143659 or GaiaDR2 2610107907030969600). This stellar occultation will be visible from Europe across the Atlantic to the USA. A predicted occultation path has been computed using the preliminary Gaia DR2 position and proper motion for this star (see the table below).

The Triton position can, however, still be improved. In order to maximise the scientific output of the occultation event, we have decided to release astrometry for 119 stars in the field surrounding Triton at this moment. The most suitable stars between magnitudes 12 and 17 have been chosen for astrometric calibration purposes. Please note that full validation of the data is not yet done and therefore some caution is required when interpreting the results. Nevertheless, we believe the data will allow improvement of the occultation prediction.

Scientists using these data to improve Triton astrometry are encouraged to make their deduced positions public so that science return can be maximised for all groups observing the event. Please keep us informed of your efforts and results in this topic.

The 119 stars are available for download through the links below:

VOT format

CSV format

In order to facilitate earlier conducted Triton campaigns from September, we also provide preliminary astrometry for a second field containing 334 stars available for download through the links below:

VOT format

CSV format

When using these data, please follow the acknowledgment and citation guidelines as given here.

Good luck with the observations!

Object to be observed Description Triton
Date of occulation event   5 October 2017
Gaia DR2 source ID   2610107911326516992
Epoch / Reference frame   2015.5 / ICRF
Right Ascension (RA) [degrees] \alpha 343.57680102738027
RA uncertainty [mas] \sigma_{\alpha *} 0.02594210959801702
Declination (DEC) [degrees] \delta -8.002309353392844
DEC uncertainty [mas] \sigma_{\delta} 0.02562803600505263
Proper Motion in Right Ascension
(PM in RA) [mas/yr]
\mu_{\alpha *} 27.40550589357325
Uncertainty of
PM in RA [mas/yr]
\sigma_{\mu\alpha *} 0.06058720414916614
Proper Motion in Declination
(PM in DEC) [mas/yr]
\mu_{\delta} -1.7372397594374407
Uncertainty of
PM in DEC [mas/yr]
\sigma_{\mu\delta} 0.05330185051213821
Parallax [mas] \varpi 1.873887315487941
Parallax uncertainty [mas] \sigma_{\varpi} 0.029208257838762786
Table: Excerpt from the preliminary data from Gaia DR2 on the star that will be occulted by Triton as taken from the released 119 stars. (Credit: ESA/Gaia/DPAC, please follow the acknowledgment guidelines as given here and please also cite the Gaia mission paper)

[published: 30/09/2017, updated: 02/10/2017, updated: 04/10/2017]