Two important occultations: 17-18/Oct GZ32 and 31/oct-01/Nov Lempo

[Felipe Braga Ribas]

Dear all, I hope you are all in good health.

I want to alert you about two important stellar occultations in South America that are approaching. We will observe both using SOAR, OPD, and ASH telescopes, so please join us to have better coverage.

17-18/October 00:30 - 00:40 Gmag = 15.9

2002 GZ32 is a Centaur with the potential to have rings. Former observations had shown an elongated body but could not rule out the presence of rings. You can see an updated map attached and further information in this link:

https://lesia.obspm.fr/lucky-star/occ.php?p=75921

31/Oct - 01/Nov 07:50-08:10 Gmag = 14.8

The TNO (47171) Lempo, is a triple system composed of two ~250 km objects orbiting each other with a semi-major axis of around 900 km, and a third ~132 km component at about 7400 km from the double system. Having a reliable size determination is very important to calculate their densities, and better understand the system's origin.

Note that the shadow of the bigger components can be anywhere in between the red dashed lines (and the event lasts for about 10 sec) and that the third can be anywhere on Earth (and lasts for about 5 sec). So we should all observe for about 20 minutes around the predicted time.

Further information can be found here:

https://lesia.obspm.fr/lucky-star/occ.php?p=75898

The prediction was made for the system barycenter and the shadow path considers a crude size estimation from the system's flux. 

Clear skies,

Felipe.