Hylonome 14/07/2018

*Prediction based on Gaia DR2

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 15:51 to 15:56 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  18 36 55.468
DEC  -18 55 10.421
Day coordinates of the object:
RA  18 38 01.291
DEC  -18 54 03.383

Hylonome V mag 22.4
Star G mag 10.0
Star Rp mag 9.7
Star Bp mag 10.2
Star K mag 9.2
Magnitude drop in G 12.4
Maximum duration
3.5 sec
Moon | 3.5% illum.
@ 145 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)

Please, see the observation tips at the top!