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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-24 11:25 |
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Conference: Bucharest University Faculty of Physics 2021 Meeting
Section: Atmosphere and Earth Science; Environment Protection
Title:
Photometry of the minor planet (99942) Apophis
Authors:
Elisabeta PETRESCU (1,2), Marco MICHELI (3), Detlef KOSCHNY (3,4)
Affiliation:
(1) ESA ESOC, Robert-Bosch-Strasse 5, 64293 Darmstadt, Germany;
(2) Astronomical Observatory "Amiral Vasile Urseanu", Bucharest, Romania;
(3) ESA NEO Coordination Center, Via Galileo Galilei, 00044 Frascati, Italy;
(4) ESA ESTEC, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands.
E-mail
elisabetaa.petrescu@gmail.com
Keywords:
Apophis, asteroid, photometry, light curve, minor planet, NEA, PHA.
Abstract:
Asteroids have the answer about how our solar system was formed, them being remains from that time. Most of the asteroids are found in the first asteroid belt between Mars and Jupiter, but even those are too far away and too many to send at each one of them a space probe to learn about them. What are we trying to do is to obtain as many information possible we can from the ground with telescopes.
Obtaining a light curve is a method used to determine the rotational period of an asteroid. The most common one is the differential photmetry, where the brightness of an asteroid is compared with the magnitude of a star or more, stars that are not variable and similar to the light that the asteroid is reflecting, so Sun type stars. To do this, we need to observe and measure the brightness of an asteroid for a long period of time. The result of the photometric measurements is called a light curve, and it's a brightness variation graphic in time of the asteroid.
Depending on the shape of the asteroid and the orientation of the axis of rotation, the minims and the maxims of a light curve may be uneven or even non-existent in case of a round asteroid. Using Fourier analysis we can identify a specific period of an asteroid. The rotation period of an asteroid, named synodic is equal with the time between two minimum or two maximum. The light curve depends on geometric considerations, phase angle, the angle that the axis of rotation makes with the direction of observation and the obliquity orbit.
In this conference, we present the photometry of the minor planet (99942) Apophis between January - March 2021. The images were taken with an 0.8 meter telescope - Calar Alto Schmidt (Z84) from Spain. The observations and measurements were part of the IAWN Apophis Campaign 2021.
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