| DATA_SET_DESCRIPTION |
Data Set Overview
=================
Goldstone radar observations of 1620 Geographos from August 28
through Sept. 2, 1994 yield delay-Doppler images whose linear
spatial resolutions range from ~75 to ~151 meters, and 138 pairs
of continuous-wave, dual-polarization (OC/SC) (opposite circular/
same circular) spectra with one-dimensional resolution of 103 m.
These data are presented in Ostro, et al. (1996), Icarus 121, 46
[OSTROETAL1996], and are included in this data set. A full
description of the observations and the reduction process is
provided in the paper.
Data
====
Individual images from each successful radar run are in FITS files
'ge[Nxx].fit' where N is the last digit of DOY (day of year) and
xx is the run number within that day. The low-resolution images
are collected in a collage image 'gelrcoll.fit', and the high-
resolution images in a collage image 'gehrcoll.fit'. Multi-run
sums of co- registered images from 30 degree blocks of rotational
phase, for the low- and high-resolution images respectively, are
in files 'gelrsum.fit' and 'gehrsum[N].fit' (N=1,3 for the three
high- resolution summed images). The collages and summed images
are the same as the data presented in Figures 8-11 of the paper.
The scaling of the images is explained in the following excerpt
from the paper: 'Data values for each image in this paper are
mapped onto a 256-level gray scale. Since the noise background is
not interesting, all data values below a clipping level near the
noise mean are mapped to black to make the most of the gray
scale's available dynamic range. Similarly, all data values above
some saturation level are mapped to white, since the contrast at
the very highest echo levels contains less interesting information
than contrast among the more abundant dimmer pixels.' The levels
chosen for clipping and saturation level for each image are
recorded in the label description for that image.
138 individual continuous wave (cw) power spectra are collected in
the file 'gecwall.tab', and spectra from the bandwidth extrema are
in 'gecwext.tab'. These spectra are the same as those presented in
Figures 2 and 7 of the paper.
Ancillary Data
==============
An index of the data with observational circumstances for each run
is given in the file geindex.tab.
Modification History
====================
These data were reviewed internally as part of a general review of
all Small Bodies Node holdings in April 2002. Minor modifications
were made to the data labels and documentation files to bring this
data set up to current SBN standards. The following changes were
made:
o Specific times for each image and spectrum file were
retrieved from Ostro, et al. (1996) and inserted into labels
and catalog files as appropriate.
o The AXIS_ORDER_TYPE keyword was added to all image labels to
reflect the column-major ordering of the FITS images.
o The TARGET_NAME value was changed from 'GEOGRAPHOS' to the
standard format '1620 GEOGRAPHOS' everywhere it occured.
o DESCRIPTION fields were added to individual image files to
indicate whether each image is high or low resolution.
o Additional description was added to some labels to clarify
the relationship between the data presented here and the
corresponding plots and images in Ostro, et al. (1996)
[OSTROETAL1996].
o Some file names in the 'Data' section above were discovered
to be in error and were corrected.
o The object type in the 'gecwall' and 'gecwext' label files
was changed from SPECTRUM to TABLE, because the files do not
meet the strict PDS requirements on the SPECTRUM object.
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