THE MINOR PLANET BULLETIN OF THE MINOR PLANETS SECTION OF THE BULLETIN ASSOCIATION OF LUNAR AND PLANETARY OBSERVERS VOLUME 33, NUMBER 2, A.D. 2006 APRIL-JUNE 29. PHOTOMETRY OF ASTEROIDS 133 CYRENE, adjusted up or down to line up with the V-band data). The near- 454 MATHESIS, 477 ITALIA, AND 2264 SABRINA perfect overlay of V- and R-band data show no evidence of color change as the asteroid rotates. This result replicates the lightcurve Robert K. Buchheim period reported by Harris et al. (1984), and matches the period and Altimira Observatory lightcurve shape reported by Behrend (2005) at his website. 18 Altimira, Coto de Caza, CA 92679 USA [email protected] (Received: 4 November Revised: 21 November) Photometric studies of asteroids 133 Cyrene, 454 Mathesis, 477 Italia and 2264 Sabrina are reported. The lightcurve period for Cyrene of 12.707±0.015 h (with amplitude 0.22 mag) confirms prior studies. The lightcurve period of 8.37784±0.00003 h (amplitude 0.32 mag) for Mathesis differs from previous studies. For Italia, color indices (B-V)=0.87±0.07, (V-R)=0.48±0.05, and phase curve parameters H=10.4, G=0.15 have been determined. For Sabrina, this study provides the first reported lightcurve period 43.41±0.02 h, with 0.30 mag amplitude. Altimira Observatory, located in southern California, is equipped with a 0.28-m Schmidt-Cassegrain telescope (Celestron NexStar- 454 Mathesis. DiMartino et al. (1994) reported a rotation period of 11 operating at F/6.3), and CCD imager (ST-8XE NABG, with 7.075 h with amplitude 0.28 mag for this asteroid, based on two Johnson-Cousins filters). Details of the equipment and instrument nights of observation at the 1991 opposition. Their lightcurve was characterization are available at the author’s website incomplete (it showed roughly half of the rotation, with good (http://www.geocities.com/oca_bob). Differential photometry, coverage of only a single maximum). Cieza et al. (1998) reported usually in more than one filter (e.g. BB-VV-RR-...) was done a period of 7.745 h. A total of 8 nights from Sep. 24 to Dec. 4, throughout most nights. On nights that were clear and stable, 2004 UT, were devoted to this object. The R-band lightcurve from standard stars were imaged to calibrate the photometry. this study indicates a rotation period of 8.37784±0.00003 h with amplitude 0.32 mag. This data set provides nearly complete All of these objects were selected for study because the current coverage of the shape of the lightcurve. The lightcurve changes apparition presented the opportunity to observe them at very small noticeably at large waning solar phase angle. Note the data near solar phase angle for determination of their phase curve rotational phase 0.8. The data for Dec. 4, 2004, at solar phase characteristics. Unfortunately, these projects provided angle 14.1 degrees (waning), are significantly different from the circumstantial evidence for a suspected correlation between orbital other nights [which range from 1.3 to 12.2 deg (waxing)]. This parameters and meteorology, in which the presence of an asteroid effect appears to be real, since it is replicated on V-band data (not at near-zero solar phase angle seems to cause cloudy weather in shown). Measured color indices for 454 Mathesis were: southern California. As a result, only medium-quality phase (B-V)=0.63±0.05 and (V-R)=0.35±0.05. The (B-V) measurement curves were determined. is consistent with the value (B-V)=0.662±0.055 reported at the Small Bodies Node. 133 Cyrene. V- and R-band lightcurves were developed from four consecutive nights of data, Feb. 2–5, 2005 UT. The lightcurve The target fields were re-measured in late 2005 to determine the presented is wrapped to the best-fit period of 12.707±0.015 h. The brightness and color indices of comparison stars. Two possible peak-to-peak amplitude is 0.22 mag. For all nights, both the solutions to the phase function were examined. Using the V-band and R-band data are shown (with each night’s R-band data “default” value of G=0.15, the best-fit absolute magnitude is Minor Planet Bulletin 33 (2006) Available on line http://www.minorplanetobserver.com/mpb/default.htm 30 H=9.39 (RMS error: 0.061 mag). The best fit with both parameters free is H=9.48, G=0.32. The latter is a slightly better overall fit (RMS error: 0.044 mag). These are both slightly fainter than the value H=9.2 reported by the Small Bodies Node. References Behrend, et al. (2005). Results and lightcurve are reported at website: http://obswww.unige.ch/~behrend/page2cou.html Bowell, E. et al. (1989), “Application of Photometric Models to 477 Italia. Data were gathered on 6 nights, from March 16 to April Asteroids”, in Binzel, R. P. et al. (ed) Asteroids II, University of 6, 2005 UT. My data alone were insufficient to establish the Arizona Press, Tucson, 1989. lightcurve period. However, Behrend (2005) combined my data with that from Roy and Kitazato (also during the 2005 apparition), Cieza, L.A., Ciliberti, L.N., Iserte, J.A. (1998) “Determination of to establish a provisional value of P≈19.4189 h and an amplitude Rotation Periods of Asteroids Using Differential CCD ≈0.2 mag. That value and the resulting lightcurve shape were used photometry”, IAPPP Communication 74, P 12 ff, December, 1998. for phase curve analysis. Examination of my lightcurve data in different colors each night showed that the color index is constant DiMartino, M., Blanco, C., Riccioli, D., and DeSanctis, G. (1994). during a rotation cycle. Measured color indices were “Lightcurves and Rotational Periods of Nine Main Belt (B-V)=0.87±0.07 and (V-R)=0.48±0.05. The (B-V) result agrees Asteroids”. Icarus 107, 269-274. well with the value reported by the Small Bodies Node [(B-V)=0.884±0.031]. Phase curve analysis found a best fit of Harris, A. W., Carlsson M., Young J. W., and Lagerkvist C. I. H=10.4, G=0.15 when using the parameters of the IAU-accepted (1984). “The lightcurve and phase relation of the asteroid 133 model (Bowell 1989). This value of absolute magnitude is Cyrene”. Icarus 58, 377-382 somewhat different from the value reported by the Small Bodies Node (H=10.25 with G=0.15 assumed). I have no explanation for Small Bodies Node at: http://pdssbn.astro.umd.edu/ this discrepancy; it may simply represent the different viewing orientation of the asteroid between apparitions. Acknowledgements (2264) Sabrina. This object was observed on eleven nights from Asteroid distance and solar phase angle were determined using Aug. 27–Sep. 30, 2005. No previous lightcurve has been reported Chris Marriott’s SkyMapPro. Lightcurves and standard-magnitude for this asteroid. My data provide a subjectively good fit when reductions were done with Brian Warner’s MPO Canopus- wrapped to P=43.41±0.02 h, with amplitude 0.30 mag. This period PhotoRed program. seems to be well-anchored by the three nights that all found the sharp minimum centered at rotational phase 0.75. A search of other possible periods from 6 h to 60 h, considering both subjective “goodness” and RMS error of the Fourier fit, did not find any other plausible periods. The lightcurve presented is based on R-band data. On all of these nights, V-band data were also CALL FOR OBSERVATIONS gathered, but they have a lower signal-to-noise ratio. There was no detectable change (±0.05 mag) in color index during the asteroid’s Frederick Pilcher rotation. Calibrated colors and standard magnitudes were gathered Illinois College on four nights with solar phase angle ranging from 2.8 to 7.5 deg. Jacksonville, IL 62650 USA The color indices were measured to be (B-V)=0.75±0.05 and (V-R)=0.34±0.05. The data from this study yield an incomplete Observers who have made visual, photographic, or CCD phase curve, which can be reasonably fit using the “default” slope measurements of positions of minor planets in calendar 2005 are parameter of G= 0.15, and absolute V-magnitude H=10.9. encouraged to report them to this author on or before April 1, 2006. This will be the deadline for receipt of reports which can be included in the “General Report of Position Observations for 2005,” to be published in MPB Vol. 33, No. 3. Minor Planet Bulletin 33 (2006) 31 LIGHTCURVES OF ASTEROIDS 141 LUMEN, comparison star variation by manually shifting individual night’s 259 ALATHEIA, 363 PADUA, 455 BRUCHSALIA, magnitude scales to obtain a best fit. 514 ARMIDA, 524 FIDELIO, AND 1139 ATAMI The results are summarized in the table below. Columns 1 and 2 Robert A. Koff show the asteroid number and name. Column 3 shows the dates of Antelope Hills Observatory the first and last observations, while column 4 shows the number 980 Antelope Drive West of actual observing sessions. Column 5 shows the range of phase Bennett, CO 80102 angles from the first and last observations. When three numbers [email protected] are shown, the middle number is a minimum phase angle through which the object passed during the interval. Columns 6 and 7 (Received: 30 December) show the ranges for the phase angle bisector longitude and latitude respectively. The four rightmost columns give the period, period error, amplitude and amplitude error. Lightcurve period and amplitude results are reported from Antelope Hills Observatory: 141 Lumen The results are presented without further detail on each asteroid, 19.87±0.01h, 0.12±0.02m; 259 Aletheia 8.143±0.002h, except for any comments that are considered relevant to the 0.12±0.02m; 363 Padua 8.401±0.001h, 0.14±0.02m; 455 analysis.