IOTA Title Image

Call for Observations

(216) Kleopatra occults an 11mag star in Europe on 2023 Jan 21st

In the evening of January 21st the main-belt asteroid (216) Kleopatra with its moons Alexhelios and Cleoselene will occult the 11 mag star UCAC4 468-000711 (TYC 13-01531-1) for a maximum duration of about 4 seconds. The event is of special interest, because the occultation by Alexhelios can be observed from central Europe and the occultation by Cleoselene from northern Africa.

The event will take place onn the 21st of January 2023 around 19h53 UTC for western Europe observers. Record the event +/- 1 minute before and after the central time to allow enough time to cover the satellites. This event is of special interest, because of the two satellites. Recently a new theory has been developed for the orbit of these moons. Using Xitau "An advanced N-body model for interacting multiple stellar systems" . (have a look here) Benoit Carry calculated new orbits for the moons.

The star

UCAC4 468-000711 with a brightness of 11m79 in B-Band and 11m30 in V-Band (from Vizier) is considerably bright and will allow fast image acquisition.

The asteroid

(216) Kleopatra is a main-belt elongated asteroid with a size of about 276km × 94km × 78km) ± 15% km at a distance of 2.1 au with an apparent magnitude of 7.3 .

The path in Europe

The predictions

Keep an eye on the new prediction below, the others may be wrong, except for the main body!

Occult Watcher Cloud for Kleopatra

Occult Map

For Kleopatra main body

For Axelhelios PROBABLY WRONG!!

New Prediction different from Occult

Following the recent works on the dynamics of asteroid (216) Kleopatra (Broz et al. 2021 and Broz et al. 2022)[1] [2], Benoit Carry has identified a real opportunity to catch an occultation by Kleopatra's outer moon (Alexhelios): https://

The ground track of (216) Kleopatra and of the two satellites based on the new theory can be seen here

The blue one is the orbit of Alexhelios, the green is the orbit of Cleoselene. In between the two is the track of the main body Kleopatra, consistent with the occult and occultwatcher prediction.

As Benoit Carry informed us Miroslav Broz ( determined the prediction in OCCULT using Miriade cannot benefit (yet) from the updated dynamical model of Kleopatra's system, and hence the positions of the satellites at the time of the occultation are expected to be offset.

The occultation of Kleopatra itself (Spain, Sardinia, Italy, Greece) should be ok and would be very nice to have for the shape of Kleopatra. The occultation by Alexhelios would be challenging. I do not know how many observers from North Africa are also in contact with the European section, but the occultation by the inner moon Cleoselene will be visible from Marocco-Algeria-Tunisia.


Please report your observations to the Stellar Occultation Data Input System (SODIS). Sample reporting forms and a manual about how to report can be found here:
style="color: blue"https://sodis/sodis_docu.html
Questions can be asked in the SODIS-forum after your registration:
style="color: blue"
Good luck with your observation,

Wolfgang Beisker
IOTA/ES - Research and Development