Geoscience Reference
In-Depth Information
repetitions of frequency analysis and fitting to Fourier series. We use Lomb's
spectral analysis
7
or the WindowCLEAN analysis
8
for the frequency anal-
ysis of lightcurves, and fit the data with an eighth order Fourier series.
9
We
have to be particularly careful when we combine the lightcurves of several
observing runs because they generally have different zero-level magnitudes.
We combine the lightcurves of multiple observing runs based on these zero-
levels to obtain our final result.
(832) Karin was observed in 1984 by Binzel.
10
Here we report new obser-
vations of (832) Karin at 2003 opposition and additional observations at
2004 opposition (see also Sec. 3). We report lightcurves for the first time
for the rest of the selected objects. Moreover, 1999 CK16 was observed
at two oppositions (2002 and 2004). All these informations together with
additional information obtained from future lightcurve data will be used to
increase our knowledge of these objects, not only of their rotational periods,
but also of other features such as their pole axis.
11
All the lightcurves that we have determined are displayed in Figs. 1
and 2. The resulting rotation periods, peak-to-peak variations of the
lightcurves, and the solar phase angles are listed in Table 1. Looking at
Figs. 1 and 2, it is obvious that some of the asteroids, such as Einer, 1997
GT36, or Svojsik, need more and better observations to obtain more accu-
rate lightcurves. Our preliminary data analysis, though the result is not
apparent from the figures, indicates that a few members might perform the
so-called tumbling motions (i.e., non-principle axis rotation).
3. Multi-Color Observations of (832) Karin
We twice performed multi-color observations of the largest member of the
Karin family, (832) Karin, in September 2003, and in September 2004 after
an interval of one year.
3.1.
Observation procedure
For our multi-color observation of (832) Karin, we used the 2 K
2 K CCD of
the 1.8-m Vatican advanced technology telescope (VATT) on Mt. Graham,
Arizona, USA. Our first observation was performed in September 2003, and
the second one was done in September 2004. Some of the major parameters
used during this observation are listed in Table 2.
The procedures of these two observations are entirely the same. We use
B
,
V
,
R
,and
I
-filters whose wavelengths are centered at 4359.32, 5394.84,
×
