I report the synodic period of asteroid (623) Chimaera
to be 14.635 +/- 0.001 hr with an amplitude of 180 +/- 12.8 mmag.

Volunteer Observatory's 0.35m SCT operating at f/6.4  was used for observations of MPL 623 during three nights in December 2006. 90 sec exposures were used with  an R band filter and an  SBIG ST10XME CCD, binned 2x2 operating at -30C. This asteroid was selected from the CALL website's "List of Potential Lightcurve Targets" for 4Q 2006. ( B. Warner, Dr. Allan Harris,  2006). Observations were started while the asteroid was < 30 degrees elevation. The R band filter limited the first order effects of atmospheric extinction and magnitude errors were between 0.005 and 0.012mag for the data set.

ACP ver 4.2 is used for observatory automation with Maxim DL 4.53 for CCD control and acquistion. The temperature tracking feature was also enabled in Maxim permitting the temp compensation feature of the Optec TCF-s focuser. CCD image calibration was performed utilizing master bias, darks and flat frames. Images were calibrated as well as plate solved immediately after acquisition using ACP /Maxim. AIP4Win version 2.1.10 was used to perform differential photometry of the calibrated data and an initial period determination of ~14.6 hrs was made as well as a computation of the maximum amplitude . MPO Canopus 9.1.0.2 was utilized for differential photometry  to refine the period determination. The results of the analysis are graphically displayed below in  Fig. 1. The Star B Gone feature in Canopus was used extensively to recover data that would have been lost as the asteroid traveled through dense star fields.
 

Fig. 1

Spreadsheet Analysis

Fig. 2

 
 

Notes

Initial lightcurve generated with AIP4Win Version 2.1.10 and plotted in MS Excel 2003.
MPL 623 was moving through dense star fields during JD 4086 and JD 4088.
Assuming a bimodal curve the preliminary spreadsheet analysis gives a period of approximately 14.6 hrs.
Light curve amplitude was determined to be  180 +/- 12.8 mmag.
 Error = SQRT((Error1^2 ) + (Error2 ^2))
 
 
 
 

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Last Updated 2006.12.19