Quaoar 27/05/2012
*See updates at the bottom of the page*
Dark
gray is night and light gray is astronomical twilight (Sun at less
than 18° below the horizon).
Shadow moves from right to left, each red dot is separated by one minute, the nominal occultation time on the map, is for the big red dot, the closest approach.
See finding charts bellow.
Shadow moves from right to left, each red dot is separated by one minute, the nominal occultation time on the map, is for the big red dot, the closest approach.
See finding charts bellow.
| Star J2000 coordinates: |
|
RA 17 32 37.8367 DEC -15 25 08.701 |
| Day coordinates: |
| RA
17 33 22.8332 DEC -15 25 35.943 |
| Star R mag | 17.3 |
| Star K mag | 14.7 |
| Magnitude drop in R | 1.8 |
| Max. duration if 1070 km diameter | 46 sec |
Observation tips:
Absolute time accuracy is essential to connect together all the observations after the fact. Check the time of your computer with many sources (phone talked hour, different internet sites, ideally with a GPS). As images should be acquired for a long time (10min at least), 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
(North is up, East is left):
(North is up, East is left):
from WFI R filter 30
X 30 arc sec
from DSS R filter FOV
5 x 5 arc
min.
from Starry Night 5x5 arc min FOV
from Starry Night 10x10 arc min FOV
from Starry Night 20x20 arc min FOV
from DSS R filter 20 X 20 arc min.
Get the 'fits' version of this image here: [ .fits ]
from Starry Night 30 arc min FOV
from Starry Night 1 degree FOV
Astrometric Updates
On April 9, François Colas observed Quaoar from Pic du Midi. Julio Camargo obtained the offset used on the following map.
[update of April 9]
Quaoar and the star were observed from Observatorio do Pico dos Dias (each with a different telescope) on May 20th.
[updated on May 20]
José Ortiz have mesaured six night of observations of the target star and Quaoar made with 45cm ASH2 telescope.
[updated on May 22]