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 J* are the G (from Gaia) and J (from 2MASS) 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 15:10:55 |
| Star position (ICRF) | 18 00 39.3981 -15 21 58.472 |
| C/A | 0.079 arcsec |
| P/A | 173.58 ° |
| velocity | -19.98 km/s |
| Geocentric distance Δ | 42.0382 au |
| G mag* | 15.9 |
| J mag* | 13.5 |
| Magnitude drop | 3.1 |
| Uncertainty in time | 176.7 sec |
| Uncertainty in C/A | 120.5 mas |
| Uncertainty in projected distance | 3673.2 km |
| Probability of occultation on centrality | 12.7% |
| 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 | 4145438426204429056 |
| Stellar catalogue | GAIADR1 |
| Star astrometric position in catalogue (ICRF) | 18 00 39.4067 -15 21 58.416 |
| Star astrometric position with proper motion (ICRF) | 18 00 39.3981 -15 21 58.472 |
| Star apparent position (date) | 18 01 43.5843 -15 21 49.292 |
| Proper motion | μRA* = (-34.8 ± 32.6)mas; μDEC = (-15.5 ± 32.6) mas |
| Source of proper motion | UCAC5 |
| Uncertainty in the star position | RA* = 116.5 mas; DEC= 116.4 mas |
| G magnitude | 15.9 |
| J magnitude (2MASS) | 13.5 |
Objet
| Object | (50000) Quaoar |
| Diameter | 1170.0 km |
| Apparent diameter | 38.4 mas |
| Object astrometric position (ICRF) | 18 00 39.3987 -15 21 58.550 |
| Object apparent position (date) | 18 01 43.5849 -15 21 49.370 |
| Uncertainty in position | RA* = 40.7mas DEC = 31.3mas |
| Apparent magnitude | 18.9 |
| Ephemeris | NIMAv8 |
| 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.