Data Set Information
DATA_SET_NAME MMT OBSERVATORY 6.5M CLIO CALIBRATED OBSERVATIONS OF LCROSS
DATA_SET_ID EAR-L-MMTO_CLIO-3-CDR-LCROSS-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview : The LRO/LCROSS spacecraft was launched on June 18, 2009, and crashed into the Cabeus crater near the Moon's south pole on October 9, 2009. The spent upper stage, called the Centaur, impacted the moon at 11:31:19.51 UTC at -84.68 deg latitude, -48.69 deg longitude, Mean Earth frame, and the LCROSS shepherding spacecraft impacted the surface at 11:35:34 UTC. This data set includes the observations made on UT October 9, 2009, of the Moon and ancillary supporting data during the LCROSS observations at the MMTO 6.5-meter telescope with the Clio imager and spectrograph. These data are the observations with the bias counts removed, and corrected for differences in gain among the four amplifiers used to read out the data on the array. The Clio camera is designed for use with the MMTO 6.5-meter telescope and the f/15 adaptive secondary AO system. It incorporates an InSb 9809 ROIC 256 x 320 array of 30-micron pixels. These pixels were not binned during the LCROSS observations. The detector reads out using 4 amplifiers, providing a readout rate of 400 kHz. Readout noise is ~ 350e-. The camera has a 12 arcsecond x 16 arcsecond field of view. The camera used L' filter imaging to place the 10 arcsecond slit on the lunar surface, and a low-resolution direct vision prism with the 10 arcsecond slit to produce spectra from ~ 2.5 - 4.5 microns. Due to the optical nature of the prism, the resolving power is not linear with respect to wavelength, thus resolution will vary with wavelength. The camera is cryogenically cooled. Further descriptions of Clio can be found in Freed et al. (2004). Description of the corrections for amplifier gain differences can be found in Kenworthy and Hinz (2009). The observations were obtained at the MMT 6.5-meter telescope on Mt. Hopkins in Arizona. The facility is owned and operated jointly by the Smithsonian Astrophysical Observatory and the University of Arizona. This is an altitude-azimuth telescope. Adaptive optics designed and developed for the MMT incorporate an adaptive secondary mirror with incoming focal ratio of f/15. During the LCROSS observations, the f/15 adaptive optics secondary was used with the MMT natural guide star top box and the Clio imager and coronagraph. Inside the top box, a beamsplitter divides the incoming light into visible and infrared components, routing light of wavelength > 1.1 micron to the Clio imager. The Clio camera was attached externally to the top box to receive the near-infrared light (higher wavelength range) signal from the beamsplitter. These observations were taken concurrently with the visible observations taken using the CCD47 camera. The visible observations taken using the CCD47 are described in the DATASET.CAT file for the data set EAR-L-MMTO_CCD47-2-EDR-LCROSS-V1.0. Observing conditions were photometric with seeing measured by wavefront sensor to be 0.38 arcseconds. The night of the LCROSS impact event was the only night we were able to take preparatory observations (other practice time allocated for observations was lost to bad weather). Processing : These data have been processed to remove a 'bias' frame and to correct for nonuniformities among the four Clio readout ampifiers. Starting with a raw Clio multi-extension fits file, the first step is to subtract a 'bias' frame to each fits extension. Clio is not capable of taking a zero second exposure. M. Kenworthy manufactured a bias frame (extrapolating backwards from a short exposure) that is included in the calibration directory (CLIO_bias_0msec.fits). This is described in detail in Kenworthy and Hinz (2010). The bias frame needs to be horizontally inverted in order to match the target frames, due to the way the array is read out. The bias-subtracted frame then needs to be corrected for variations in the gain settings of the four Clio readout amplifiers. The four amplifiers are interleaved on a column-by-column basis such as A, B, C, D, A, B, C, D etc. Corrections are done on a pixel-by-pixel basis using a lookup table (clio_lookup_091007.dat) calculated by M. Kenworthy (Kenworthy and Hinz, 2010). Before applying the lookup table, zero and maximum value (65000 ADU) clipping of the pixel values should be done to facilitate proper results from the lookup table. The bias subtraction and gain correction is carried out on all frames including target, sky, calibration, and standard stars. Extraction of the spectra can then be executed however the astronomer wishes. Data : The sequence of observations includes images of the Moon taken before the impact occurred using the L' filter, 2-D spectra taken covering a spectral interval of ~ 2.5 - 4.5 microns of the Cabeus crater, observations of two A0 stars (HD22859, HD43607) used for wavelength calibration (http://irtfweb.ifa.hawaii.edu/), observations of solar analogue star HD28099 (Hya 64: e.g., Farnham et al., 2000; Hardorp, 1978) for data analysis of the lunar reflectance spectra, and images of the slit on the Clio chip. For observations of standard stars, the AO system was used. About 0.33 hr prior to the LCROSS impact, the AO secondary system was triggered on a bright star near the Moon; the secondary mirror was frozen in corrected figure to remove gross aberrations caused by the atmospheric fluctuations; and the telescope was then pointed on the Cabeus crater target area. Observations covered a time range of 8 minutes before the first impact to 36 minutes after the second impact when twilight stopped observations. Spectra were taken of the Cabeus crater of the Moon where the impact was predicted to occur. The impact observations did not show any discernible effect from the impact. Quick-and-dirty spectral ratioing immediately following the event did not show any signature of the event. Based upon the observed brightness of the impact by the LCROSS shepherding satellite, we expect that we would have been able to see the event had we not had unshadowed, illuminated portions of the lunar surface in the same field of view. The observations are described in Hastie et al. (2010). Media/Format : All data are stored in FITS format.
DATA_SET_RELEASE_DATE 2010-02-05T00:00:00.000Z
START_TIME 2009-10-09T07:39:03.000Z
STOP_TIME 2009-10-09T12:57:39.000Z
MISSION_NAME LUNAR CRATER OBSERVATION AND SENSING SATELLITE
MISSION_START_DATE 2009-04-27T12:00:00.000Z
MISSION_STOP_DATE 2009-10-09T12:00:00.000Z
TARGET_NAME BIAS
FLAT FIELD
SKY
MOON
HD 22859
HD 28099
HD 43607
TARGET_TYPE CALIBRATION
SATELLITE
STAR
INSTRUMENT_HOST_ID MMTO
INSTRUMENT_NAME CLIO
INSTRUMENT_ID CLIO
INSTRUMENT_TYPE CAMERA
NODE_NAME Geosciences
ARCHIVE_STATUS LOCALLY_ARCHIVED
CONFIDENCE_LEVEL_NOTE Review : This data set has been subjected to peer review according to Planetary Data System standards.
CITATION_DESCRIPTION Vilas, F., MMT Observatory 6.5m CLIO Calibrated Observations of LCROSS, NASA Planetary Data System, EAR-L-MMTO_CLIO-3-CDR-LCROSS-V1.0, 2010.
ABSTRACT_TEXT This archive contains calibrated observations of the 2009-10-09 impact of the LCROSS spacecraft on the moon by the CLIO instrument on the MMT Observatory 6.5m telescope. The archive consists of calibrated FITS images of the event. This is one of several data sets of Earth-based observations of the impact.
PRODUCER_FULL_NAME FAITH VILAS
SEARCH/ACCESS DATA
  • LCROSS Analysts Notebook
  • LCROSS MMTO/CLIO-3-CDR FTP Resource
  • GEOSCIENCES WEB SERVICES
    		•