Bienor  29/12/2017

*Prediction based on Gaia DR1 position + UCAC5 proper motion*


Observation tips:

- Shadow moves from **East to West**;

- The nominal occultation time on the map, corresponds to the big red dot, the closest approach
- Each red dot is separated by one minute;
- Dark gray is night and light gray is astronomical twilight (Sun at less than 18 deg below the horizon);
  - *Absolute time accuracy is essential** (see important note below);

- Observations are requested from 16:20 to 16:40 Universal Time.    

After the observation, please fill the form available on this link (form), and send it to ribas(at)

Useful information:
Star J2000 coordinates:
   RA  02 49 15.534
DEC  +38 29 52.27
Day coordinates of Chariklo:
RA  02 50 24.20
DEC  +38 34 19.6

Star V mag 13.3
Star R mag 12.8
Star K mag 11.1
Magnitude drop in R  6.7
Maximum duration
13 sec

Important note

*Absolute time accuracy is essential**

to connect all the observations
together after the fact. Check the time of your computer with many sources (phone talked hour, different internet sites, ideally with a GPS). Its advised to check the registered time right after and right before the integrations, so if there is a drift, we can correct it by having the difference.

Beware of the dead time between the images: if you manage an exposure time of 1 sec (for example), but have your camera takes 2 sec to read the image, then there is a 67% chance that you miss the dis(re)-appearance of the star. So it's better to have, for example, a 4 sec integration, so you have 67% chance to get the occultation in one of your exposures.

Finding charts from DSS:
  10 x10 arcmin FOV (North is up, East is left)

x 45 arcmin FOV (North is up, East is left)


Prediction is based on  GAIA DR1 star position and UCAC5 proper motion. Recent observations of Bienor were made with Sierra Nevada Observatory, that were used to update NIMA ephemeris (i).

The same entries from the map above, but applying an offset to the ephemeris as obotained from the average of the latest Sierra Nevada positions used on the orbital fit.
The dashed lines are the error of the order of 300 km (1 sigma) on the shadow path, and 30 sec in time.



Please, see the observation tips at the top!