Data Set Information
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| DATA_SET_NAME |
KECK I LWS MID-IR IMAGES AND PHOTOMETRY OF 9P/TEMPEL 1
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| DATA_SET_ID |
DI/EAR-C-KECK1LWS-3-9P-IMAGES-PHOT-V1.0
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| NSSDC_DATA_SET_ID |
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| DATA_SET_TERSE_DESCRIPTION |
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| DATA_SET_DESCRIPTION |
Data Set Overview : This data set contains raw and reduced mid-infrared images and photometry of comet 9P/Tempel 1, the target of the Deep Impact mission. Images were acquired on the night of 21 August 2000, about 7.5 months after perihelion, by Y. Fernandez, C. Lisse, M. A'Hearn and M. Belton using the Long Wavelength Spectrometer instrument at the Keck I telescope. Observations were made with filters centered at 4.8, 8.0, 8.9, 10.7, 11.7, 12.5, 17.9 and 20.0 microns. The calibration procedure and photometric results are described in detail in the paper 'The nuleus of 'Deep Impact target Comet 9P/Tempel 1' by Fernandez et al. 2003 [FERNANDEZETAL2003]. This data set supports analysis of the size and albedo of the nucleus of 9P/Tempel 1 for the Deep Impact mission. Parameters : The plate scale was 0.080 arcsecond/pixel, yielding a 10.24-arcsecond field of view. Other observational parameters for each image, such as filter name, are incorporated into the PDS labels and FITS headers supplied with the data. STOP_TIME in the PDS data labels is not supplied because the values for START_TIME and EXPOSURE_DURATION cannot be added to calculate the stop time for one observation. For LWS data, EXPOSURE_DURATION, equivalent to OBJTIME in the FITS headers, is the total integration time on the source without instrumental overheads such as time spent on the sky and observational inefficiencies caused by nod delays, chop-frame settling, and data-to-disk writes. The data acquisition software for the LWS did not save the total time, including overheads, for one observation in the FITS headers. Therefore, STOP_TIME is not provided. Processing : The LWS was operated in the chop-nod image mode, with nod throws of 10 arcseconds North and East to acquire high and low airmass, blank sky frames along with comet frames for each observation. Thus, each raw, six-dimensional FITS file produced by the LWS contains multiple of comet and blank sky frames. A two-dimensional FITS image was produced from each raw, six- dimensional FITS file by combining the frames in each chop-nod cycle into one, then stacking the chop-nod cycles. For more details about the layout of the six-dimensional FITS files, refer to the instrument catalog file, CATALOG/LWSINST.CAT. For more details about how the observers combined the frames within a six-dimensional FITS file, refer to the document file, LWS_CONVERT_FITS.TXT. The detector was flattened by making a median, low-airmass blank sky frame and a median, high-airmass blank sky frame, then subtracting the two sky frames. For more details about this process, refer to the the document file, LWS_MAKE_FLAT.TXT. All observations were made using filters centered at 4.8 (M), 8.0, 8.9, 10.7, 11.7, 12.5, 17.9 and 20.0 microns. Images of two bright- infrared standard stars, phi 1 Ceti and beta Andromedae, were used to calibrate the raw images of the comet. Images of phi 1 Ceti were used for atmospheric extinction corrections at 10.7 microns. Images of beta Andromedae were used for absolute flux calibrations and for atmospheric extinction corrections at the other wavelengths. Details of the calibration steps are discussed in Fernandez et al. 2003 [FERNANDEZETAL2003]. Data : This data set consists of 49 raw and reduced images, of which 14 are comet frames and 35 are standard star frames. Raw images are supplied as six-dimensional FITS image files with headers produced by the LWS data acquisition software. Flattened, reduced images are supplied as two-dimensional, FITS image files. PDS labels for the raw and reduced data were generated by the Applied Coherent Technology Corporation and the Small Bodies Node. The tranmission profiles for the eight filters used for the observations are provided in this data set as ASCII tables. This data set also includes an ASCII table of the mid-IR fluxes of 9P/Tempel 1 as measured by Fernandez et al. 2003 [FERNANDEZETAL2003]. The authors attempted to calculate the albedo of the nucleus but noted it was difficult to measure because the coma was extensive in the simultaneous optical observations. The geometric circumstances of the comet and sky conditions from Fernandez et al. 2003 [FERNANDEZETAL2003] are reproduced here. Additional observing conditions, such as the mid-IR (MIR) seeing, are provided in Fernandez et al. 2003 [FERNANDEZETAL2003]. 20 Aug 2000 ---------------------------------------- Heliocentric distance 2.547 AU Geocentric distance 1.667 AU Phase angle 13.93 degrees MIR wavelengths 8.9, 10.7, 11.7, 12.5, 17.9, 20.0 micron Sky condition Cirrus When displaying a FITS image from this data set using the directions provided by the LINE_DISPLAY_DIRECTION and SAMPLE_DISPLAY_DIRECTION keywords in the PDS labels, North is approximately down and East is to the right. Media/Format : Data are supplied as electronic files in a PDS standard volume structure. Filenames follow the ISO 9660 level 2 Interchange Standard so that a variety of computer systems can access the data.
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| DATA_SET_RELEASE_DATE |
2004-05-21T00:00:00.000Z
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| START_TIME |
2000-08-21T10:51:19.920Z
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| STOP_TIME |
2000-08-21T03:53:05.340Z
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| MISSION_NAME |
DEEP IMPACT
SUPPORT ARCHIVES
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| MISSION_START_DATE |
2005-01-12T12:00:00.000Z
2004-03-22T12:00:00.000Z
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| MISSION_STOP_DATE |
2005-07-13T12:00:00.000Z
N/A (ongoing)
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| TARGET_NAME |
9P/TEMPEL 1 (1867 G1)
BETA ANDROMEDAE
PHI 1 CETI
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| TARGET_TYPE |
COMET
STAR
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| INSTRUMENT_HOST_ID |
KECK1
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| INSTRUMENT_NAME |
KECK I LONG WAVELENGTH SPECTROGRAPH (IR)
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| INSTRUMENT_ID |
KECK1LWS
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| INSTRUMENT_TYPE |
IMAGING SPECTROMETER
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| NODE_NAME |
Small Bodies
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| ARCHIVE_STATUS |
ARCHIVED
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| CONFIDENCE_LEVEL_NOTE |
Confidence Level Overview : Standard techniques were used for the reduction of the data and are documented in Fernandez et al. 2003 [FERNANDEZETAL2003]. In the data labels, START_TIME + EXPOSURE_TIME/2 is not the mid-time of an observation. This information is not availalbe and not readily calculable. See the Parameters section of this file for more detail. The raw and reduced FITS filename have a prefix of 'FOCUS'. These are the original names provided by the observers. None of the raw or reduced images in this data set are focus frames. Review : This data set was reviewed in May 2004 and was approved for ingestion into the PDS Data Archive, pending the resolution of liens. Liens were resolved in December 2004.
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| CITATION_DESCRIPTION |
Fernandez, Y.R., C.M. Lisse, M.F. A'Hearn, and M.J.S. Belton, KECK I LWS MID-IR IMAGES AND PHOTOMETRY OF 9P/TEMPEL 1, DI/EAR-C-KECK1LWS-3-9P-IMAGES-PHOT-V1.0, NASA Planetary Data System, 2004.
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| ABSTRACT_TEXT |
This data set contains raw and reduced mid-infrared images and photometry of comet 9P/Tempel 1, the target of the Deep Impact mission. Images were acquired on the night of 21 August 2000, about 7.5 months after perihelion, by Y. Fernandez, C. Lisse, M. A'Hearn and M. Belton using the Long Wavelength Spectrometer instrument at the Keck I telescope.
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| PRODUCER_FULL_NAME |
YAN R. FERNANDEZ
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| SEARCH/ACCESS DATA |
SBN Online Comet Archives
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