Description

ESO Document:

https://www.eso.org/sci/publications/messenger/archive/no.67-mar92/me…

In the early morning of January 26, after a night of observations at the ESO 50-cm telescope, we left the dome and stopped to have a look at the beautiful dawn in the eastern sky over the Andean mountains. We were trying to find all the planets visible in that part of the sky. It was indeed a very nice constellation: the Moon, Venus, Mars, Ceres, Uranus and Neptune were all within a few degrees of each other; the technical term for this is a syzygy. Mercury and Saturn were also in that region, but they were too close to the Sun to be visible.

It was Alain who first noticed a bright, diffuse object in the south-east direction. It was moving towards north, about 15" over the horizon. We could follow it during about three minutes, then it was no longer visible as the morning sky became brighter and brighter. During that short time, it had moved over an arc of -20" in the sky! We checked the appearance of the object through 7x50 binoculars; it had a bright condensation of magnitude -1, surrounded by a 2" wide, circular nebulosity. Indeed, it looked completely different from a satellite or an airplane: it was much more like a comet. We took some photos of the object and one of them is reproduced here; due to its quite fast motion, it appears like a long trail.

From the observed form and brightness, we feel rather sure that this was not a usual artificial object, like a highflying aircraft plane or a satellite (it was too bright and diffuse), nor a meteor (for this it was much too slow). From time to time there are some Barium and Lithium release experiments in the magnetosphere which may have this comet-like aspect (IAUC 51 54, 51 79), but they are normally even brighter. We checked with the coordination office for these experiments and learned that no release was planned for that period.

https://preview.redd.it/c01luy4jjgca1.png?width=454&format=png&auto=w…