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127
ASTEROID LIGHTCURVE ANALYSIS AT THE VIA
CAPOTE OBSERVATORY: 2009 1ST QUARTER
James W. Brinsfield
Via Capote Observatory
5180 Via Capote, Thousand Oaks CA 91320
jbrinsfi@gmail.com
References
Harris, A.W., Young, J.W., Bowell, E., Martin, L.J., Millis, R.L.,
Poutanen, M., Scaltriti, F., Zappala, V., Schober, H.J., Debehogne,
H., and Zeigler, K.W., (1989). “Photoelectric Observations of
Asteroids 3, 24, 60, 261, and 863.” Icarus 77, 171-186.
(Received: 2009 Apr 10)
Lightcurves for 4 asteroids were measured at the Via
Capote Observatory from 2009 January through March:
1254 Erfordia (P = 12.287 h), 2678 Aavasaksa (P >24
h), 2679 Kittisvaara (P = 10.123), 4606 Saheki (P =
5.032).
Observations of 4 asteroids were made using a Meade LX200
0.35-m Schmidt-Cassegrain working at f/10. The CCD imager was
an Alta U6 featuring a 1024x1024 array of 24-micron pixels. All
observations were made unfiltered at 1x binning yielding an image
scale of 1.44” per pixel. All images were dark and flat field
corrected. Images were measured using MPO Canopus (Bdw
Publishing) and differential photometry. The data were light-time
corrected. Period analysis was also done with Canopus,
incorporating the Fourier analysis algorithm developed by Harris
(1989). Target selections were made using the Collaborative
Asteroid Lightcurve Link (CALL) web-site and “Lightcurve
Opportunities” articles from the Minor Planet Bulletin. Priority
was given to asteroids that did not have a published rotational
period. The results are summarized in the table below and include
average phase angle information across the observational period.
Where 3 numbers are indicated for phase angle, measurements of
the target occurred over opposition. The middle value is the
minimum phase angle observed and the two end values are the
phase angles at the beginning and end of the observing campaign.
Individual lightcurve plots along with additional comments, as
required, are also presented.
None of the four targets studied during the reporting period have
published lightcurves. 1254 Erfordia exhibits and interesting
departure on its ascending node around phase 0.65, perhaps the
effects of an impact crater on one end of the object. Observations
of 2678 Aavasaksa were interrupted during the second session of
the campaign due to equipment malfunction. With only limited
partial coverage of the target, the continuous rising amplitude of
the first session over approximately 6 hours would suggest a
rotation period of greater than 24 hours and amplitude greater than
0.35 mag. The longer of the two observing sessions are plotted in
this report.
Acknowledgments
The author whishes to thank Brian Warner for his assistance with
interpreting the lightcurve shape of 1254 Erfordia.
# Name
Dates Data
(mm/dd/2009) Points Phase L PAB B PAB Per(h) PE Amp(m) AE
1254 Erfordia 03/16-03/29 369 9.6 157 -7 12.287 0.001 0.47 0.02
2678 Aavasaksa 01/05-01/06 95 3.0 108 +4 >24 hr >0.35
2679 Kittisvaara 03/19-03/27 219 9.0 167 -8 10.123 0.003 0.22 0.03
4606 Saheki 03/07–03/25 135 15 151 -4 5.032 0.001 0.68 0.01
Table 1. Observing circumstances.
Minor Planet Bulletin 36 (2009)