## Orbit of Asteroid (99942) Apophis from Observations 2004—2013

Transactions of IAA RAS, Issue 31, 49–58 (2014)

**Keywords**:
asteroid Apophis, orbit, weighting observations, optical observations, radar observations

### Abstract

This article describes a method of improving Apophis orbit from combination of radar and optical observations. Weights to radar observations are assigned in an ordinary way. It is considered that the weights of an observatory's optical observations are inversely proportional to the mean residuals of observations based on some reference orbit. Several variants of orbits were considered as alternatives: a reference orbit found from optical observations considered as equally precise; an orbit based on radar observations only; and an orbit found as a result of combining radar observations and optical observations made by five independent observatories. The weights for these measurements were assigned due to the mean residuals of observations taken from the Minor Planet Center data within the ten years period. Several solutions found under various assumptions were compared with those reported on the websites of JPL and NEODyS. Also, solutions with reduced weights of observations made the same night were obtained. These solutions demonstrate good representation both for optical and radar observations and in some respects exceed those published on the sites of JPL and NEODyS.

### Citation

`O. M. Kochetova, Yu. A. Chernetenko, V. A. Shor. Orbit of Asteroid (99942) Apophis from Observations 2004—2013 // Transactions of IAA RAS. — 2014. — Issue 31. — P. 49–58.`

```
@article{kochetova2014,
abstract = {This article describes a method of improving Apophis orbit from combination of radar and optical observations. Weights to radar observations are assigned in an ordinary way. It is considered that the weights of an observatory's optical observations are inversely proportional to the mean residuals of observations based on some reference orbit. Several variants of orbits were considered as alternatives: a reference orbit found from optical observations considered as equally precise; an orbit based on radar observations only; and an orbit found as a result of combining radar observations and optical observations made by five independent observatories. The weights for these measurements were assigned due to the mean residuals of observations taken from the Minor Planet Center data within the ten years period. Several solutions found under various assumptions were compared with those reported on the websites of JPL and NEODyS. Also, solutions with reduced weights of observations made the same night were obtained. These solutions demonstrate good representation both for optical and radar observations and in some respects exceed those published on the sites of JPL and NEODyS.},
author = {O.~M. Kochetova and Yu.~A. Chernetenko and V.~A. Shor},
issue = {31},
journal = {Transactions of IAA RAS},
keyword = {asteroid Apophis, orbit, weighting observations, optical observations, radar observations},
pages = {49--58},
title = {Orbit of Asteroid (99942) Apophis from Observations 2004—2013},
url = {http://iaaras.ru/en/library/paper/1031/},
year = {2014}
}
```

```
TY - JOUR
TI - Orbit of Asteroid (99942) Apophis from Observations 2004—2013
AU - Kochetova, O. M.
AU - Chernetenko, Yu. A.
AU - Shor, V. A.
PY - 2014
T2 - Transactions of IAA RAS
IS - 31
SP - 49
AB - This article describes a method of improving Apophis orbit from
combination of radar and optical observations. Weights to radar
observations are assigned in an ordinary way. It is considered that
the weights of an observatory's optical observations are inversely
proportional to the mean residuals of observations based on some
reference orbit. Several variants of orbits were considered as
alternatives: a reference orbit found from optical observations
considered as equally precise; an orbit based on radar observations
only; and an orbit found as a result of combining radar observations
and optical observations made by five independent observatories. The
weights for these measurements were assigned due to the mean
residuals of observations taken from the Minor Planet Center data
within the ten years period. Several solutions found under various
assumptions were compared with those reported on the websites of JPL
and NEODyS. Also, solutions with reduced weights of observations made
the same night were obtained. These solutions demonstrate good
representation both for optical and radar observations and in some
respects exceed those published on the sites of JPL and NEODyS.
UR - http://iaaras.ru/en/library/paper/1031/
ER -
```