Quaoar 28/05/2019


Observation tips:

- Observations are requested from 23:37 to 23:45 Universal Time.

- Shadow moves from **East to West**;
- The nominal occultation time on the map, corresponds to the big dor, the closest approach.
- Each 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);

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

Event information: 

Star J2000 coordinates:
RA 18 10 38.933
DEC -15 18 37.73
Day coordinates of the object:
RA 18 11 45.77
DEC   -15 18 16.4

Star G mag 16.9
Star R mag 15.8
Star K mag 13.2
Magnitude drop in R 2.1
Maximum duration 51 sec
Moon | 29% illum. @ 90 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)


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



From the detection of the April 26 event from Chile (using SOAR and Trappist), we updated the prediction map:


Zoom (red dashed line is the shadow's border error bar):


Link to Lucky Star Prediction

Click for a Open Street Interactive Map