Call for Observations

(994) Otthild occults a naked-eye star in Europe on 2023 Jan 12

In the evening on January 12th the main-belt asteroid (994) Otthild will occult the 3.9 mag multiple star system 38 Lyncis for a maximum duration of 2.1 seconds.

The star

38 Lyncis (HIP 45668, STF 1334) is a multiple star. The A-component has a magnitude of 3.9 mag. The B-component (6.0 mag) is located at a distance of 2.6 arcsec with a position angle of 222 deg. Two fainter components BC (SEP 217 arcsec, PA 77 deg) and BD (SEP 172 arcsec, PA 262 deg) have magnitudes of 12.5, respectively [1].

The asteroid

(994) Otthild is a main-belt asteroid with an diameter of approx. 23 km at a distance of 1.8 au with an apparent magnitude of 14.3. Its apparent motion across the sky at the time of occultation is 10.87 arcsec/h. 3D-models of the asteroid show an irregular, diamond-like shape [2]. The minor planet was only observed once during a stellar occultation. On 2019 Jan 4 a single positive chord was measured in France [3]. A multi-chord observation this time is highly desired!

The event

It‘s one of the brightest stellar occultations by an asteroid with a shadow path across Europe in 2023. Naked-eye observers have the rare opportunity to see a star disappearing at the sky. A very impressive event. Observers with a telescope or binoculars have the chance to catch an short undisturbed view on the fainter B-component of the system. This could be a fine opportunity for a spectroscophic measurement of this component.

The path in Europe

Due to the brightness and the duplicity of the star the uncertainties in the path predictions are larger than usual. The several predictions differ in about a half path width. Potential observing stations inside the sigma error limits are encouraged to observe the occultation. A path shift is highly possible!

On 2023 Jan 12, the shadow will pass Latvia and Lithuania at 20:19 UT. The shadow will miss Poland and will reach Germany at Peenemünde at 20:20 UT. On its way to the west, the shadow of (994) Otthild will pass Osnabrück in Germany and Eindhoven in the Netherlands. In Belgium the path will be located between the larger cities of Antwerpen and Brussels. The city of Lille is predicted to be inside the path in France. At 20:21 UT the shadow will leave European ground between the cities of Nantes and Brest.

About the maps:

Occult Watcher Cloud path maps for Europe. The green line is the centre line, the blue lines show the path limits, and the red lines the 1-sigma-limit. The occultation will occur between the two red lines with a probability of 68 %. Other lines show the chords of an already announced observing stations. (Map data: © 2023 GeoBasis-DE/BKG, (©2009), Google)

The predictions

Occult Watcher Cloud:

https://cloud.occultwatcher.net/event/741-994-132015-650306-G50607

https://cloud.occultwatcher.net/event/741-994-132015-650306-H45688

Prediction by Steve Preston, IOTA:

https://www.asteroidoccultation.com/2023_01/0112_994_83662.htm

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:
https://sodis/sodis_docu.html
Questions can be asked in the SODIS-forum after your registration:
https://forum.iota-es.de
Good luck with your observation,

Oliver Klös
IOTA/ES - Public Relations

[1] https://www.stelledoppie.it/index2.php?iddoppia=43135

[2] https://3d-asteroids.space/asteroids/994-Otthild

[3] Herald, D., Occult databse, Occult V4.2022.12.29