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This data set consists of reflectance spectra of small lunar areas (3-10 km in diameter) measured in 120 spectral channels from 0.62 to 2.6 micrometers using the McCord two-component circular-variable-filter (CVF) near-infrared photometer. Approximately 400 spectra are included that were acquired in the late 1970s and 1980s. Observational approach is described in McCord et al., 1981 (MCCORDETAL1981), Pieters, 1986 (PIETERS1986), and Pieters and Pratt, 2000 (PIETERSANDPRATT2000). (See CATALOG/REF.CAT for complete references.) A small aperture allows light from the selected lunar area to pass through the CVF and onto a single InSb detector. Each spectral channel is obtained sequentially as the CVF is rotated. Data were acquired using the 2.2 m telescope on Mauna Kea, Hawaii. Since absolute albedo information is not obtained, all spectra have been scaled to unity near 1.02 micrometers, a wavelength relatively free of atmospheric absorptions. The precise wavelengths of spectral channels varies somewhat from run to run because wavelength calibration shifts the effective band center from night to night. The first half of the CVF produces data at a spectral resolution of ~100 Angstroms while resolution of the second half is ~200 Angstroms. Data points where the two sections of the CVF were joined are unreliable. The overlap area typically involves about 5 data points near 1.34 micrometers. All data were acquired as relative reflectance spectra and were calibrated to scaled reflectance data using a directional-hemispheric (diffuse) spectrum of Apollo 16 soil acquired by J. B. Adams. At the time these telescopic spectra were acquired, bi-directional reflectance data for lunar soils were not available for calibration.
Acquisition of the 120 data points takes a few minutes; thus, a 120-point spectrum can be affected by the accuracy of guiding on the Moon as well as changing sky conditions and instrument stability. In most cases, several independent runs of data taken in sequence were averaged. Error bars are the standard deviation of this average and only refer to the repeatability of the measurement under these conditions. Data values of zero or error bar values of 99.99 or negative numbers are used to designate data for a channel that is likely to be in error (typically at the beginning, end, or join of the CVF).
Spectral calibration and correction factors for bi-directional data are discussed in more detail under Spectral Calibration, in the file DOCUMENT/CALIB.TXT (hypertext version CALIB.HTM). See Pieters, 1993 (PIETERS1993), for a review of data interpretations.
In addition to file identification, the following information is provided for each spectrum: name of the area designated by the astronomer, date of data acquisition, lunar coordinates of the area observed derived from images and finding charts, general classification (see below), and an overall data quality assessment made by astronomers after data reduction. Lunar coordinates are in decimal degrees with positive being north and east from 0 latitude, 0 longitude on the central nearside. Negative values are south and west from 0, 0. Coordinates for areas observed use the reference images of Whitaker (WHITAKERETAL1963). For areas named after Apollo and Luna landing sites the coordinates given are for the region actually observed, which are not necessarily directly over the landing site.
General classification of the areas observed includes the following:
The spatial resolution of these telescopic data depends on the aperture used and the telescope configuration. Most data are for areas 5-10 km in diameter. For small lunar features the measured spectrum also contains radiation from surrounding soil. An example of this relation is shown by the figure in the file document/clemspec.gif where the telescopic spectrum for a small crater in Mare Serenitatis (MSA: located at 19.5 degrees north, 24.5 degrees east) is compared with multispectral data from Clementine. All the Clementine spectra are centered on the crater, but are sampled at 1, 3, 5, 7, 9, 11,13, 15, 17, and 19 kilometers (square). The aperture used for this telescopic data was estimated to cover about a 5 km region, a value consistent with the Clementine data.
The documentation files in the CATALOG directory contain more information about the data set (DATASET.CAT), the photometer (INST.CAT), and the telescope (INSTHOST.CAT), along with a list of personnel associated with the data set (PERSON.CAT) and references to other documentation (REF.CAT).
This archive contains data files in the DATA directory, documentation in the CATALOG and DOCUMENT directories, and an index to the data files in the INDEX directory, including a tabular summary of data available. The table below shows the organization and content of each of these directories.
AAREADME.HTM - The file you are reading
AAREADME.TXT - Plain text version of AAREADME.HTM
AAREADME.LBL - PDS label that describes AAREADME.HTM and AAREADME.TXT
VOLDESC.CAT - Description of this volume for the PDS Catalog
CALINFO.TXT - Description of files in the CALIB directory
JBADHR.TAB - Table containing original Adams directional hemispheric Apollo 16 62231 data used to calibrate the telescopic data
JBADHR.LBL - PDS label for JBADHR.TAB
JBADHRWC.TAB - Table containing Adams directional hemispheric Apollo 16 62231 wavelength corrected data
JBADHRWC.LBL - PDS label for JBADHRWC.TAB
RELABBDR.TAB - Table containing bi-directional reflectance data for Apollo 16 62231, used for Clementine calibrations
RELABBDR.LBL - PDS label for RELABBDR.TAB
CORRBDR.TAB - Table containing correction factors used to correct the 120 channel lunar data to bi-directional reflectance
CORRBDR.LBL - PDS label for CORRBDR.TAB
CATINFO.TXT - Description of files in the CATALOG directory
DATASET.CAT - Data set description
INST.CAT - Instrument description
INSTHOST.CAT - Instrument host (observatory) description
PERSON.CAT - Personnel associated with this archive volume
REF.CAT - References mentioned in the above catalog files
Data subdirectories HnXXXX, where n = one of {8, 9, A, B, C, D, E}. For example, subdirectory H8XXXX contains files with names between H80001 and H89999. The "n" represents the original tape, and the following four-digit integer represents the number of the file on the tape.
DOCINFO.TXT - Description of files in this directory
CALIB.TXT - Description of calibration applied to this data set
CALIB.HTM - HTML version of CALIB.TXT
CALIB.LBL - PDS label that describes CALIB.TXT and CALIB.HTM
CALFIG1.GIF - Figure 1 to accompany CALIB.TXT and CALIB.HTM
CALFIG2.GIF - Figure 2 to accompany CALIB.TXT and CALIB.HTM
CLEMSPEC.GIF - Figure comparing telescopic spectra with Clementine spectra of the same area
CLEMSPEC.LBL - PDS label that describes CLEMSPEC.GIF
PIETER00.PDF - Description of this data set (LPSC XXXI Abstract #2059)
PIETER00.LBL - PDS label that describes PIETER00.PDF
PIETER99.PDF - Discussion of spectral calibration of lunar data
PIETER99.LBL - PDS label that describes PIETER99.PDF
INDXINFO.TXT - Description of files in this directory
INDEX.TAB - Index table of data products in this archive
INDEX.HTM - HTML version of INDEX.TAB. Open this file in a Web browser to begin browsing the data.
INDEX.LBL - PDS label for INDEX.TAB and INDEX.HTM
The spectral data in this archive are stored as tables in ASCII files with fixed-length records. Each record is terminated with a carriage return and a line feed character, so that the files are readable on various computer platforms. Each table file has an associated PDS label in a separate file with the same name and the extension ".LBL". The PDS label describes the content and format of the table file.
All text files in this archive are stream format files, with a carriage return and line feed at the end of each record.
For questions concerning this data set, contact:
Dr. Carle M. Pieters
Dept. of Geological Sciences
Box 1846
Brown University
Providence, RI 02912
Electronic mail: Carle_Pieters@brown.edu
The spectra data files and data set documentation were provided by Carle Pieters and Stephen Pratt of the Keck/NASA Reflectance Experiment Laboratory (RELAB), Brown University. Raymond Arvidson and Susan Slavney of the PDS Geosciences Node, Washington University, provided ancillary documentation and prepared the archive in PDS-compatible format.
