Data Set Information
DATA_SET_NAME IHW COMET HALLEY PHOTOMETRIC FLUXES, V2.0
DATA_SET_ID IHW-C-PPFLX-3-RDR-HALLEY-V2.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview : This data set presents the fluxes derived from narrow band photometry of Comet 1P/Halley as part of the International Halley Watch (IHW) Photometry and Polarimetry Netword (PPN). Standard filters, reference stars and reduction procedures were used as far as possible to reduce all narrowband data submitted to the PPN. The original data have been reformatted data supplied as addenda to the original submission have been added and the accompanying documentation updated in this revised version. The data are in tabular form, and are presented as a single summary table sorted chronologically. Information identifying the original source file from version 1 of this data set has been included for historical reference. Filters : A standard narrow-band filter set, already in development prior to the IHW, was formalized and extended during the Halley Watch project. The general filter parameters were summarized in tables in Sekanina (1991) ('JPL D-400-450' in the reference list), and have been included in the documentation files of this data set. An initial set of five filters was manufactured and distributed at the beginning of the IHW period: 3650 A Continuum 3871 A CN 4060 A C3 4845 A Continuum 5140 A C2 A second set of filters was added as they were produced after the start of the Halley Watch: 3085 A OH 4260 A CO+ 6840 A Continuum 7000 A H2O+ In addition, three observatories (Lowell, Cerro Tololo and Perth) also made use of an existing NH filter centered at 3365 A. Standard Stars : A set of standard stars specifically selected for narrowband photometry of comets was defined and distributed to PPN observers. An organized campaign to observe suitable standards using the IHW filter set took place in two parts: first, Zellner and Wisniewski (1985) observed standards using the initial set of five filters; second, the PPN disipline specialists themselves as well as a number of colleagues undertook a campaign to establish standard star magnitudes for the filters not included in the work of Wisniewski and Zellner (1985). A summary of this second observing program is in Osborne et al. (1990). Data Reduction : In order to minimize variations due to differences in local reduction procedures (in calculating airmass, for example), the PPN requested observers submit instrumental magnitudes outside the atmosphere, and completed the reduction to magnitude and flux using a single standard technique, described in detail in Sekanina (1991) ('JPL D-400-450' in the reference list). Where possible, data that were received in a more advances state of reduction were back-processed to the instrumental magnitude stage and rereduced using the standard procedures. Thus, values for fluxes, errors and airmasses may vary substantially in this data set from those present in the original file submissions of version 1. Modification History : The first version of this data set contained 2500 sets of individual observation files. Each individual observation was a table of results from a specific observer using a particular system (observatory + telescope + detector) on a single night. For each such file, there was a PDS label file, a FITS table header file detached from the data, and the FITS table data segment. After the first version was archived, personnel at the PDS Small Bodies Node (SBN) re-reduced a large part of the data using the standard technique described in 'Photometry and Polarimetry' chapter of 'The Comet Halley Archive Summary Volume' (cited in the reference list as 'JPL 400-450'). An abbreviated list of notes about specific reprocessing was created as an HTML errata file displayed on the SBN archive pages. A summary table of all results was also created and offered as an 'index table'. To create version 2, SBN personnel did the following: o Observer, telescope and observatory information was recovered from the FITS headers and inserted into the 'index table'. o Observing times in the 'index table', originally stated as day number and fraction, were converted to the ISO standard time format (yyyy-mm-ddThh:mm:ss). Day fractions were always supplied with at least four significant digits (five in some unusual cases). Note that, therefore, times are never more accurate than the nearest second, and typically are only accurate to +/- 5 seconds. o A check of 'index table' lines vs total observations in the original FITS tables revealed a discrepancy of 25 lines submitted but not included in the 'index table'. These were accounted for thus: - Three files, each with eight record - pflx2285, pflx2370 and pflx2388, contained no aperture size information in the original submission. A subsequent errata list stated that these files were 'accidentally included' in the original archive. - One file, pflx1326, had an incorrect value of NAXIS2 in the FITS header, resulting in the last record (of 11) being omitted from the reprocessing of the file. All of these records are also omitted from the final summary table. o The original PDS and FITS files were discarded. o Addenda, submitted after the original archive was complete, were incorporated into the summary table. 30 October 2006, A.C.Raugh
DATA_SET_RELEASE_DATE 1992-09-30T00:00:00.000Z
START_TIME 1985-08-24T10:38:38.000Z
STOP_TIME 1987-03-04T08:55:58.000Z
MISSION_NAME INTERNATIONAL HALLEY WATCH
MISSION_START_DATE 1980-09-01T12:00:00.000Z
MISSION_STOP_DATE 1992-09-30T12:00:00.000Z
TARGET_NAME 1P/HALLEY 1 (1682 Q1)
TARGET_TYPE COMET
INSTRUMENT_HOST_ID PPN
INSTRUMENT_NAME PHOTOMETRIC FLUX DATA
INSTRUMENT_ID PPFLX
INSTRUMENT_TYPE PHOTOMETER
NODE_NAME Small Bodies
ARCHIVE_STATUS IN_LIEN_RESOLUTION
CONFIDENCE_LEVEL_NOTE Confidence Level Overview : Because these observations were rereduced by the IHW Photometry and Polarimetry Network (PPN) personnel, errors have been calculated for each flux in a uniform way wherever sufficient information was available. See Sekanina et al. (1991) ('JPL D-400-450' in the reference list') for details of the reduction process and error propagation. Note that, because times were reported as day fractions with only four (or sometimes five) significant digits, all time values listed anywhere in this data set - data files, labels, or elsewhere - are never accurate to more than one second, and are typically accurate to only +/- about five seconds. Also, the following comment was included among the errata for these data: For a number of NARROW BAND measurements, the integration times are not given; in these instances the original submissions only reported 'average' values.
CITATION_DESCRIPTION A'Hearn, M.F. and V. Vanysek, IHW COMET HALLEY PHOTOMETRIC FLUXES, V2.0, IHW-C-PPFLX-3-RDR-HALLEY-V2.0, NASA Planetary Data System, 2006.
ABSTRACT_TEXT This data set presents the fluxes derived from narrow band photometry of Comet 1P/Halley as part of the International Halley Watch (IHW) Photometry and Polarimetry Netword (PPN). Standard filters, reference stars and reduction procedures were used as far as possible to reduce all narrowband data submitted to the PPN. The original data have been reformatted data supplied as addenda to the original submission have been added and the accompanying documentation updated in this revised version.
PRODUCER_FULL_NAME GRAYZECK, E.J., KLINGLESMITH, D.A., III, NIEDNER, M.B., JR
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