Quaoar 08/07/2018
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 05:25 to 05:35 Universal Time.
- Quaoar satellite (Weywot) position is not well known, so, to have a chance to detect it, we recommend to observations from 5:15 to 5:45.
After the observation, please fill the form available on this link (form), and send it to ribas(at)on.br.
| Star J2000 coordinates: |
|
RA 18 01 58.790 DEC -15 20 32.39 |
| Day coordinates of the object: |
| RA 19 00 38.781 DEC -15 22 16.067 |
| Star V mag | 13.880 |
| Star R mag | 14.360 |
| Star G mag | 14.562 |
| Star K mag | 12.290 |
| Magnitude drop in R | 6.6 |
| Maximum
duration |
47
sec |
| Moon
| 30% illum. |
@
115 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:
aprox.
02 x 03
arcmin FOV (North
is up, East is
left)
**-Those telescopes that were not able to resolve the stars, should consider that the SW (G=14.9) star was occulted, and that the expected magnitude drop is of about 1 mag.--*
**-Those telescopes that were not able to resolve the stars, should consider that the SW (G=14.9) star was occulted, and that the expected magnitude drop is of about 1 mag.--*
20 x 20 arcmin FOV (North is up, East is left)
Prediction
Prediction from Lucky Star web page (i).
Please, see the observation tips at the top!