THE MINOR PLANET BULLETIN OF THE MINOR PLANETS SECTION OF THE BULLETIN ASSOCIATION OF LUNAR AND PLANETARY OBSERVERS VOLUME 43, NUMBER 4, A.D. 2016 OCTOBER-DECEMBER 283. LIGHTCURVES FOR TWO NEAR-EARTH-ASTEROIDS BY Observatory Telescope (meters) CCD ASTEROIDS OBSERVERS (OBAS) – MPPD: C.A.A.T. 0.45 DK SBIG STL-11002 2016 APRIL - MAY Zonalunar 0.20 NW QHY6 Vicente Mas Martinez, Gonzalo Fornas Silva, Angel Flores Vallbona 0.25 SCT SBIG ST7-XME Martinez, CAAT - Centro Astronómico del Alto Turia, SPAIN TRZ 0.20 R-C QHY8 [email protected] Elche 0.25 DK SBIG ST8-XME Alfonso Carreño Garcerán Oropesa 0.20 SCT Atik 16I Zonalunar Observatory,Valencia, SPAIN Bétera 0.23 SCT Atik 314L+ Serra Observatory 0.25 NW Atik 414L+ Enrique Arce Mansego Table I. List of instruments used for the observations. SCT is Vallbona Observatory, Valencia, SPAIN Schmidt-Cassegrain. R-C is Ritchey-Chrétien. DK is Dall-Kirkham. NW is Newton. Pedro Brines Rodriguez TRZ Observatory, Valencia, SPAIN Table I shows the equipment at the observatories that participated in this work. We concentrated on asteroids with no reported period Juan Lozano de Haro and those where the reported period was poorly established and Elche Observatory, Alicante, SPAIN needed confirmation. All the targets were selected from the Collaborative Asteroid Lightcurve (CALL) website at Alvaro Fornas Silva (http://www.minorplanet.info/call.html) and Minor Planet Center Oropesa Observatory, Castellón, SPAIN (http://www.minorplanet.net) Onofre Rodrigo Chiner Images were measured using MPO Canopus (Bdw Publishing) Bétera Observatory, Valencia, SPAIN with a differential photometry technique. David Herrero Porta (35396) 1997 XF11 was discovered in 1997 December (Sugie et Serra Observatory, Valencia, SPAIN al., 1997) and remained fainter than V ~ 18 until its predicted (Received: 2016 Jun 14) brightening to V = 13.4 in mid-2002. It won’t reach this brightness again until 2028. We report on the results of photometric analysis of two In 1998 March, then-unnumbered 1997 XF11 made headlines in near-Earth asteroids (NEA) by Asteroids Observers the popular media after some interpretations of preliminary (OBAS). This work is part of the Minor Planet calculations of its orbit suggested that it could collide with Earth in Photometric Database (MPPD) project initiated by a 2028. Disagreement among researchers about how close it was group of Spanish amateur astronomers. We have likely to pass to Earth and how to characterize the uncertainties managed to obtain a number of accurate and complete involved Marsden (1999), Chodas and Yeomans (1999), Milani lightcurves as well as some additional incomplete and Valsecchi (1999) Yeomans et al. (1998), Helin et al. (1998), lightcurves to help analysis at future oppositions. and Scotti and Shelus (1998) and how best to communicate such information to the media. This led to confusion and sensationalism. The incident raised important issues about impact risk assessment In this paper we publish the results of lightcurve analysis for two and how best to balance the interests of scientific research with near-Earth asteroids observed under the Minor Planet Photometric those of the public’s right to know. Database project (http://www.minorplanet.es). The data and results were made possible thanks to the collaboration of the The OBAS group obtained images of (35396) 1997 XF11 on three Astronomical Center Alto Turia (CAAT) Observatory located in nights 2016 April, when the sky motion was 3 arcsec/min and so Aras de los Olmos and operated by members of the Valencia exposures were no more than 60 seconds. Three OBAS group Astronomy Association (AVA) (http://www.astroava.org). observatories worked together to obtain these results, especially the team of the Astronomical Center Alto Turia (CAAT). From our Minor Planet Bulletin 43 (2016) Available on line http://www.minorplanet.info/mpbdownloads.html 284 data, we derived a rotation period of 3.252 ± 0.002 h and Marsden. B.G. (1999). “Asteroid 1997 XF11 Could Collide with amplitude of 0.60 mag. Earth.” AAS/Division of Dynamical Astronomy Meeting. Scotti. I.V. Shelus, P.J. (1998). “1997 XF11”. IAUC 6837. Sugie, A., Scotti, J.V., Kojima, T., Williams, G.V. (1997). “1997 XF11.” Minor Planet Electronic Circular (MPEC) 1997-Y11. Yeomans, D., Chodas, P., Muinonen, K., Bowell, E., Shoemaker, E.M., Williams, G.V., Marsden, B.G. (1998). “1997 XF11”. IAUC 6879. THE ROTATION PERIOD OF ASTEROIDS 4931 TOMSK AND 5232 JORDAENS Russell I. Durkee, Shed of Science Observatory Minneapolis, MN 55410, USA [email protected] Jessie L. Houghton, Carmen L. Eggleston (154555) 2003 HA was discovered in 2003 April by LINEAR. The Minnetonka High School Minnetonka, MN 55345, USA OBAS group obtained images on three nights in 2016 May. At the time, the asteroid’s sky motion was 4 arcsec/min, which limited (Received: 2016 Jun 25) exposures to 60 seconds or less. From our data we derive a rotation period of 5.171 ± 0.004 hours and amplitude of 0.36 magnitudes. Three OBAS group observatories worked together to obtain these CCD observations of two main-belt asteroids were made results, especially the team of the Astronomical Center Alto Turia in 2016 March and May. Analysis of the data for 4931 (CAAT). Tomsk indicates a synodic period of P = 7.02 ± 0.01 h, A = 0.46 ± 0.10 mag. For 5232 Jordaens, the analysis indicates a synodic period of P = 10.58 ± 0.01 h, A = 0.73 ± 0.15 mag. CCD photometry observations of the main-belt asteroids 4931 Tomsk and 5232 Jordaens were made in 2016. At the Shed of Science Observatory, a 0.35-m Schmidt Cassegrain (SCT) working at f/8.5 and SBIG ST-10XE CCD camera were used. The resulting plate scale was 0.94 acrsec/pixel. Exposures were made through a Celestron UHC LPR filter. The R-COP telescope at Perth Observatory used a 0.35-m Schmidt Cassegrain (SCT) working at f/6.0 and SBIG ST-10XME camera. The plate scale was 0.67 arcsec/pixel. The exposures were unfiltered. All images were dark and flat-field corrected. Images were measured using MPO Canopus (Bdw Publishing) with a differential photometry technique. The MPO Canopus Comp Star Selector was used to link sessions. The data were light-time corrected. Period analysis was also done with MPO Canopus, Acknowledgements incorporating the Fourier analysis algorithm developed by Harris We would like to express our gratitude to Brian Warner for (Harris et al., 1989). supporting the CALL web site and his suggestions made to the 4931 Tomsk was observed over two nights in 2016 March from OBAS group. the Shed of Science Observatory. The third night used the R-COP References telescope at the Bickley Observatory in Perth, Australia, through the Skynet observatory network. Conditions did not allow more Chodas, P.W., Yeomans, D.K. (1999). “Could Asteroid 1997 XF11 than three nights of observations. As a result, there are possible Collide with Earth After 2028?” AAS/Division of Dynamical solutions other than the period given here. Additional observations Astronomy Meeting. of this object are required to refine the period. Helin, E.F., Lawrence, K.I., Roman, B., Williams, G.V., Yeomans, D, K., Chodas, P., Muinonen, K., Bowell, E. (1998). “l997 XF11”. IAUC 6839. Minor Planet Bulletin 43 (2016) 285 LIGHTCURVE ANALYSIS OF NEA (331471) 1984 QY1: A TUMBLING ASTEROID Brian D. Warner Center for Solar System Studies – Palmer Divide Station 446 Sycamore Ave. Eaton, CO 80615 USA [email protected] Vladimir Benishek Belgrade Astronomical Observatory Volgina 7, 11060 Belgrade 38, SERBIA (Received: 9 July 2016) Analysis of CCD photometric observations of the near- Earth asteroid (331471) 1984 QY1 show that it is likely in non-principal axis rotation (NPAR), or tumbling. A single period analysis found a dominant period of 45.5 ± 5232 Jordaens was observed over three nights in 2016 May from 0.5 h, but the true periods of rotation and precession the Shed of Science Observatory. Conditions were not suitable for could not be determined. more than three nights of observations before the object became too dim. Additional observations of this object are needed to refine the period. CCD photometric observations were made of the near-Earth asteroid (331471) 1984 QY1 from 2016 June 6-20. Table I lists the equipment and dates of observation for each observer. Obs Telescope 2016 June Warner 0.35-m 6-10,12,14,15-17,20 Benishek 0.35-m 8,9,14,17 Table I. List of telescopes used and dates of observations for each observer. In all, more than 2000 observations were made using a clear or no filter to obtain maximum SNR. Exposures ranged from 60 to 90 seconds, while the asteroid faded from V ~ 15.5 to 16.3. Longer exposures were not possible because of the asteroid’s sky motion, which started at about 9 arcsec/min and decreased to 4 arcsec/min. Each observer used MPO Canopus to process the raw images with dark and flat field frames and then to perform differential photometry. Because of slight trailing, elliptical apertures were used for the asteroid, the major axis being kept parallel to the asteroid’s motion. Acknowledgements Up to five solar colored comparison stars were used each night to help minimize errors due to color differences between the asteroid Partial funding for work at the Shed of Science Observatory is and comparison stars. V magnitudes from the MPOSC3 catalog provided by 2009 and 2010 Shoemaker NEO Grants from the supplied with MPO Canopus were used for the comparison Planetary Society. Access to the R-COP telescope at the Perth stars. This catalog is based on the 2MASS catalog Observatory was made possible thanks to R.