📚 SUMMARY.TXT
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149 lines***** File SUMMARY.TXT
The volume of ground-based Halley data archived by the nine IHW
Disciplines is sufficiently large that, even when the Large-Scale Phenomena
(L-SP) image arrays have been substantially subsampled, five CD-ROMs (IHW
Volumes 19-23) are required to hold the data. The full-resolution L-SP images
themselves take up 18 CD-ROMs (Volumes 1-18). Not including the separate
header (extension=.HDR) and PDS label (.LBL) files, the number of datafiles on
the so-called "mixed discs" (Volumes 19-23) is 37,844. Due to the archiving
of multiple observations within FITS tables by some of the Disciplines, the
number of individual IHW observations is substantially greater than the file
count just mentioned, however. The table below lists the number of
observations for each of the IHW Disciplines and sub-Disciplines:
TABLE I
NUMBER OF INDIVIDUAL OBSERVATIONS FOR EACH IHW DISCIPLINE
DISCIPLINE Sub-DISCIPLINE NUMBER
Astrometry 6475
Infrared Studies
Image 95
Photometry 2204
Polarimetry 137
Spectroscopy 84
Large-Scale Phenomena 3383
Meteor Studies
Radar 6962
Visual 1624
Near Nucleus Studies 3523
Photometry & Polarimetry
Broad Band 3318
Narrow Band 18495
Polarimetry 752
Stokes Parameter 164
Radio Studies
Continuum 97
Occultation 6
OH (molecule) 1657
Radar 1
Spectral Line 189
Spectroscopy & Spectrophotometry 3368
Amateur Observations
Drawing 1294
Photography 2170
Spectroscopy 45
Visual 11641
The actual number of files is larger than 37,844 because that count does
not include FITS headers and PDS label files. There are 5468 "dataless"
observations (header and label files only), making the total data-related file
count (2*5,468 + 3*32,376) = 108,064. Also, there are 2717 directory files
not included in the counts.
On these mixed discs (Volumes 19-23) the Halley and Halley-related data
are located in chronological directories. The directory names are based on
date, specified by the year, month, UT day and hours; not all directory names
include all these time parameters. The naming of data directories by time
means that the disc "time splits" can be shown by listing the first and last
data directories for each CD-ROM Volume:
Chronological Range of "Mixed" CD-ROMs
disc start date stop date
19 /Y1981/ /Y1985/M12/D08/
20 /Y1985/M12/D09/ /Y1986/M02/D09/
21 /Y1986/M02/D10/ /Y1986/M04/D13/
22 /Y1986/M04/D14/ /Y1987/M04/D03/
23 /Y1987/M04/D04/ /Y1989/M04/D12/
Some Disciplines submitted non-Halley data, which include filter tables,
non-comet images, flat fields, and laboratory spectra. While many of these
have been placed in the standard (chronologically-based) data directories,
they have also been located in separate directories on Volume 23:
specifically, CALIB and IR_FILTR. Finally, Astrometry data sets for the
apparitions of 1835 and 1909 are contained in separate directories on Volumes
19-23, and the entire Meteor Studies Discipline dataset is contained in a
dedicated directory on Volume 23.
The IHW dataset collection includes images, spectra, data tables, textual
descriptions, and indices; as indicated earlier, some "dataless" files only
point to existing observations but do not include data. To provide the
Archive user the ability to conduct sophisticated searches based on time,
IHW Discipline, or any in a wide variety of FITS keywords, several types of
indices have been placed on these discs. The so-called "Quick Look Indices",
whose files are named QUIK_0nn.* (where nn=19-23), contain all the mandatory
IHW keywords for each of the archived datafiles (including dataless); these
indices are located in the /INDEX directory on each disc, and corrected
versions of all five indices have been placed in the /SUMMARY/INDEX directory
of this disc (Volume 23).
Several of the Disciplines wished to index more than just the mandatory
keyword set and constructed "Discipline-specific indices", which contain
entries for nearly all of the FITS keywords present in the respective headers.
These indices, which bear the generic name NET*.*, are contained in the
/INDEX/NETABLES directory of each mixed disc, as are indices containing
parameters which may be published in the so-called "Printed Archive". Of the
latter (Printed Archive) indices, there is with one exception (Radio Studies
Spectral Line index, which includes OH data) one index table per Discipline or
sub-Discipline, and contained in some of these indices are actual data. Thus,
such indices are directly useable (without referring to the original
datafiles), to plot light curves, extract positions, and identify meteor
trails, for example.
Production of these IHW CD-ROMs took place at the NASA/Goddard Space
Flight Center after all the IHW data were transferred from the IHW Lead Center
at JPL to NASA/GSFC in 1990-1991. The actual production benefited from a
number of factors: use of the National Space Science Data Center's (NSSDC)
CD-ROM pre-mastering facility; a number of outside peer reviews of two
prototype test discs; and the generation of CD-ROM Write Once discs at the
Data Distribution Lab of the PDS at JPL. A more complete discussion of how
the final CD-ROMs were made is contained in the files ACKNWLDG.TXT and
VOLINFO.TXT on this disc.
Finally, there are two important printed volumes to mention. The Comet
Halley Archive Summary Volume edited by Sekanina and Fry (1) contains chapters
from each of the Discipline Specialist Teams describing the collection and
processing of the data. Other articles enumerate activites associated with
actual production of the CD-ROMs, from which this discussion has been drawn. A
second production (2) due out is the IHW Atlas of Large-Scale Phenomena
(Brandt, Niedner, and Rahe, 1992) that is being produced at the University of
Colorado/Laboratory for Atmospheric and Space Physics (a comet subnode of PDS
Small Bodies Node). There has been no decision regarding an independent
Printed Archive volume(s); however, now that the data have been transferred to
NASA/Goddard Space Flight Center (cf. ACKNWLDG.TXT and VOLINFO.TXT files on
this disc), there are renewed discussions to make a version of the Printed
Archive to complement the IHW CD-ROMs.
1. Sekanina, Z. and Fry, L. (1991), The Comet Halley Archive Summary Volume,
JPL 400-450, Jet Propulsion Laboratory, Pasadena, California, August, 1991.
2. Brandt, J. C., Niedner, M. B., and Rahe, J. (1992), IHW Atlas of
Large-Scale Phenomena, in press.