ROTATIONAL PERIOD DETERMINATION OF TWO MARS CROSSING, A MAIN BELT ASTEROID AND A PHA: (14309) DEFOY, (56116) 1999 CZ7, (5813) EIZABURO AND (3122) FLORENCE

Angelo Tomassini, Maurizio Scardella,
Francesco Franceschini, Fernando Pierri
ATA (Associazione Tuscolana di Astronomia)
“F. Fuligni” Observatory (MPC D06)
Via Lazio, 14 – Rocca di Papa (RM) – 00040 – ITALY

The main-belt asteroids (5813) Eizaburo and two Mars crossing minor bodies, (14309) Defoy and (56116) 1999 CZ7, have been observed over several nights throughout 2017 March-September in order to determine their synodic rotational period. We also took the opportunity of the (3122) Florence close passage with the Earth in September-October to find its lightcurve.

The observations of the analysed asteroids were carried out from F. Fuligni Observatory using a 0.35-m f/10 ACF telescope and SBIG ST8-XE CCD camera with Clear filter and from Franceschini’s equipment using a 9.25″ f/6.3 reflector telescope equipped with Atik 314L- CCD camera with Clear filter.  All images were dark and flat-field calibrated with Maxim DL. Differential photometry and period analysis was done using MPO Canopus (Warner, 2012).

3122 Florence. This asteroid, discovered from the Siding Spring observatory at the beginning of the ‘80s, belongs to the Amor family and being potentially dangerous for the Earth is also classified as PHA. A diameter of 4.9 Km makes it one of the biggest PHA known. Its orbit, resonant with the Earth, brings this big object close to our planet every 40 years and the 2017 passage has been the closest for at least the next 160 years. During this close flyby a radar observation has shown the presence of 2 natural moons with diameter of around 180-240m and 300-360m. Our measurements have been taken since the first days of September (8 sessions in total) but only the last observations have been used for the lightcurve, fitting these data more coherently with the known asteroid properties. The synodic period found has been of P = 2.36 ± 0.01 h and an amplitude of A = 0.14 mag (Figure 1)

5813 Eizaburo. This Main Belt Asteroid (also called 1988 VL) has been discovered in 1988 by Takuo Kojima. Its semi-major axis is 2.60 AU and the inclination is 11.24º. The observations lasted more than one month, from the Franceschini’s equipment and from the “F. Fuligni” Observatory have confirmed for this MBA a synodic period of P = 2.93 ± 0.01 h and an amplitude of A = 0.26 mag (Figure 2).

14309 Defoy.  Discovered by J. Palisa in 1908 in Vienna, this asteroid is a Mars Crossing Asteroid with a semi-major axis of 2.60 AU and 0.447 as eccentricity. The observations carried out from “F. Fuligni” Observatory and from Francesco Franceschini during four nights in June 2017 allowed us to derive the synodic period of P = 3.4 ± 0.1 h with an amplitude of A = 0.16 mag (Figure 3).

  (56116) 1999 CZ7.  Discovered in 1999 at Socorro (New Mexico), this minor body is classified as Mars Crossing Asteroid, having a perihelion (1.6653 AU) barely lower than the Mars aphelion (1.666 AU). Its aphelion is about 2.97 AU while the orbital period is 3.53 years. The observations of this asteroid have been carried out by our team during March-April 2017 over four nights. The resulting lightcurve has a synodic period of P = 3.12 ± 0.01 h and amplitude 0.27 mag (Figure 4).

 Acknowledgement
We would like to thank Simone Nodari and Samuele Piscitello for their help in taking the images and for the maintenance tasks of the ATA observatory instruments.

References
Warner, B.D. (2012). The MPO Software, Canopus version 10.4.1.9. Bdw Publishing, http://minorplanetobserver.com/
Warner, B.D. (2012). The MPO User Guide: A Companion Guide To The MPO Canopus/PhotoRed Reference Manual. BDW Publishing, Colorado Spring, CO.
Warner, B.D. (2017) “Lightcurve Photometry Opportunities: Jan-Mar 2017”. MPC 44-1.
Warner, B.D. (2017) “Lightcurve Photometry Opportunities: April-June 2017”. MPC 44-2.
http://www.MinorPlanet.info/PHP/call_OppLCDBQuery.php

 

 

 

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