2010 EK139 15/07/2018

*Prediction based on Gaia DR2

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 00:00 to 00:10 Universal Time.   

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

Useful information:
Star J2000 coordinates:
  RA  13 51 37.298
DEC  -38 33 00.216
Day coordinates of the object:
RA  13 52 43.180
DEC  -38 38 30.881

2010 EK139 V mag 19.68
Star G mag 17.0
Star Rp mag 16.5
Star Bp mag 17.4
Star K mag 15.2
Magnitude drop in G 2.7
Maximum duration
40 sec
Moon | 5% illum.
@ 83 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 from Lucky Star web page (i).

(i) http://lesia.obspm.fr/lucky-star/predictions/single.php?p=5579

  Observations made on June, from Bosque Alegre, give the followig prediction provided by J.L. Ortiz.

Observations made on early July, from Obs. do Pico dos Dias by B. Morgado and measured by J. Camargo, give a small offset of the TNO wrt NIMA ephem.

Please, see the observation tips at the top!