Data Set Information
DATA_SET_NAME IMAGES OF COMET 19P/BORRELLY FROM 9/21-23, 2001 V1.0
DATA_SET_ID EAR-C-I0065-2-IMGBORRELLYKPNO-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview : The data set consists of ground-based images of comet 19P/Borrelly in the R filter taken at the Kitt Peak 2.1m for three nights from September 21-23, 2001, bracketing the Deep Space 1 encounter. The Kitt Peak 2.1m telescope at f/7.5 with the T2KA (2kx2k) chip was used for all observations. The Harris broad band R filter optimized for the Landolt broad band colors was used. The Harris R filter is very close to the Cousins R filter. All nights were photometric. All objects were tracked at the sidereal rate. Raw, as well as reduced images are included. Corresponding calibration frames (dome flats and bias frames) are included. Twilight flats are included for September 23 but were not used in our reduction. All the data were trimmed, bias subtracted and flat fielded with the dome flats. Dithered object frames were combined and smoothed. These frames were used as illumination correction as the illumination for the dark sky is different from that of the white spot in the dome. The resulting reduced images are smaller than the raw images due to the trimming. Landolt standard fields PG0231+051 and PG22213-006 (Landolt 1992) are available with tables listing the centers (x,y) of the standard stars in the reduced images. The centers of comet 19P/Borrelly are also tabulated for the reduced images. Note that the origin in the frames is (1,1), not (0,0). All the standard stars were measured with the same aperture with a diameter of 30 pixels (approximately 9'). The size of the aperture is large enough to include 99% of the measured flux of the star and is at least 3 times larger than the seeing. As the nights were photometric, tables relating the counts/second of individual images to calibrated flux density units (f) are also included. f : counts/sec * f0 * 10^(-0.4*(m0-ZP-coeff*airmass)) where m0:25mag is the zero point offset of the magnitude scale, ZP the zero point, coeff the airmass coefficient, and counts/sec is the DN value read from the image / exposure time. Therefore f : DN value * f0 * conversion factor where the conversion factor is 1/exptime * 10^(-0.4*(m0-ZP-coeff*airmass)) These conversion factors are given in tables and f0:2.23E-09 erg s^-1 cm^-2 Angstrom^-1 for the R-band (converted from Bessel 1989). The error in f0 is 0.02E-09 due to the difference in effective wavelength between the Cousins Filter and the Harris filter. The filter response curves however look very similar to each other. The data were used in part to put constraints on the direction of the angular momentum vector (Samarasinha and Mueller 2002). Although the data were not explicitly taken to support the Deep Space 1 mission, they complement the spacecraft data as well as other space- and ground-based data for comet 19P/Borrelly. References ----------- Bessell, M. S. 1979. UBVRI Photometry II: The Cousins VRI System, its Temperature and Absolute Flux Calibration, and Relevance for Two-dimensional Photometry. PASP 91, 589-607. Landolt, A. U. 1992. UBVRI Photometric Standard Stars in the Magnitude Range 11.5
DATA_SET_RELEASE_DATE 2011-09-20T00:00:00.000Z
START_TIME 2001-09-20T11:40:49.000Z
STOP_TIME 2001-09-23T12:23:23.000Z
MISSION_NAME SUPPORT ARCHIVES
MISSION_START_DATE 2004-03-22T12:00:00.000Z
MISSION_STOP_DATE N/A (ongoing)
TARGET_NAME CALIBRATION
19P/BORRELLY 1 (1904 Y2)
PG 0231+051
PG 2213-006
TARGET_TYPE CALIBRATION
COMET
STAR
INSTRUMENT_HOST_ID OBS321T3
INSTRUMENT_NAME CFIM+T2KA
INSTRUMENT_ID I0065
INSTRUMENT_TYPE IMAGER
NODE_NAME Small Bodies
ARCHIVE_STATUS ARCHIVED
CONFIDENCE_LEVEL_NOTE Confidence Level Overview : The conversion factors to relate counts to flux densities have an error of about 2E-13 The error in f0 is 0.02E-09 due to the difference in the effective wavelength between the Cousins Filter and the Harris filter. The filter response curves however look very similar to each other.
CITATION_DESCRIPTION Mueller, B.E.A. and Samarasinha, N.H., Images of comet 19P/Borrelly from 9/21-23, 2001 V1.0. EAR-C-I0065-2-IMGBORRELLYKPNO-V1.0. NASA Planetary Data System, 2011.
ABSTRACT_TEXT The data set consists of ground-based images of comet 19P/Borrelly in the R filter taken at the Kitt Peak 2.1m for three nights from September 21-23, 2001, bracketing the Deep Space 1 encounter. Raw, as well as reduced images are included.
PRODUCER_FULL_NAME BEATRICE MUELLER
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