Binary asteroid!
Short max. duration!
Raphaël Lallemand (GAIAMOONS project) wrote on Sep 02 on Planoccult:
We know that Arecibo is a binary system and we are quite confident in the position of its satellite thanks to the Gaia data and previous stellar occultations.
The satellite may be close to the primary and taking into account the uncertainties, the satellite and the primary can be superimposed from the observer’s point of view (see interactive map on the website, see GAIAMOONS link below).
The size of the primary is about 24.4km and correspond to an occultation of 0.8 sec. The size of the satellite is about 13km and may correspond to an occultation of about 0.2s. So please use a exposure of 100ms max.
Observations are requested at minimum 1 minute before and after the midtime. You can use the interactive map of the GaiaMoons page of the event to determine your local midtime.