Astyanax  08/05/2018

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

Observation tips:

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

- 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 23:50 to 23:55 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  08 39 30.156
DEC  +17 15 42.564
Day coordinates of the object:
RA  08 40 31.133
DEC +17 11 45.843

Star V mag 9.90
Star R mag 9.39
Star G mag 9.55
Star K mag 7.77
Magnitude drop in R 9.8
Maximum duration
2 sec
Moon | 41% illum.
@ 159 deg

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:
  05 x 05 arcmin FOV (North is up, East is left)

x 20 arcmin FOV (North is up, East is left)

Prediction maps




Please, see the observation tips at the top!