Occultation by Quaoar (2018-07-26)
This occultation has a more recent update available here
Occultation map
Information about the map:
- The straight and continue lines are the shadow limits considering the estimated radius; when the shadow crosses the Earth's surface, the path is projected on the Earth;
- Each blue dot is spaced by one minute and the big blue dot corresponds to the nominal occultation time (which is the geocentric closest approach);
- The arrow shows the direction of the shadow motion;
- The 1-σ precision along the path is represented by the red dotted line;
- The star G* and RP* are the G (from Gaia) and RP (red photometer from GaiaDR2) magnitudes, normalized to a body moving at 20km/s in order to enhance very slow events;
- The body offset is at the upper right corner, if JPL ephemeris is used;
- Areas in dark grey correspond to full night (Sun elevation below -18 degrees) and areas in light grey correspond to twilight (Sun elevation between -18 and 0 degrees) while daytime is in white;
- Be careful, the dates are from the moment of the event in Universal Time, the night of the event may begin at the date before.
Occultation circumstances
| Date | Thu. 26 Jul. 2018 15:07:45 |
| Star position (ICRF) | 18 00 39.4071 -15 21 58.418 |
| C/A | 0.135 arcsec |
| P/A | 173.57 ° |
| velocity | -19.98 km/s |
| Geocentric distance Δ | 42.0382 au |
| G mag* | 16.1 |
| RP mag* | 15.0 |
| Magnitude drop | 2.9 |
| Uncertainty in time | 25.4 sec |
| Uncertainty in C/A | 18.8 mas |
| Uncertainty in projected distance | 572.0 km |
| Probability of occultation on centrality | 69.4% |
| Maximum duration | 58.6 sec |
| Moon distance to the object | 21.0° |
| Fraction of illuminated Moon | 98.7 % |
| Solar elongation | 145.7° |
Occulted star
| Star source ID | 4145438426258652032 |
| Stellar catalogue | GAIADR2 |
| Star astrometric position in catalogue (ICRF) | 18 00 39.4068 -15 21 58.416 |
| Star astrometric position with proper motion (ICRF) | 18 00 39.4071 -15 21 58.418 |
| Star apparent position (date) | 18 01 43.5933 -15 21 49.238 |
| Proper motion | μRA* = (1.5 ± 0.1)mas; μDEC = (-0.8 ± 0.1) mas |
| Source of proper motion | GAIADR2 |
| Uncertainty in the star position | RA* = 0.3 mas; DEC= 0.3 mas |
| G magnitude | 16.1 |
| RP magnitude (GaiaDR2) | 15.0 |
Objet
| Object | (50000) Quaoar |
| Diameter | 1170.0 km |
| Apparent diameter | 38.4 mas |
| Object astrometric position (ICRF) | 18 00 39.4082 -15 21 58.552 |
| Object apparent position (date) | 18 01 43.5944 -15 21 49.372 |
| Uncertainty in position | RA* = 16.8mas DEC = 18.7mas |
| Apparent magnitude | 18.9 |
| Ephemeris | NIMAv11 |
| Dynamic class(1) | cubewano |
| Semi major axis(1) | 43.6 au |
| Eccentricity(1) | 0.037 |
| Inclination(1) | 8.0° |
| Perihelion(1) | 42.0 au |
| Aphelion(1) | 45.2 au |
(1) Data from the johnston archive list.