This document contains the high-level overview of the DRACO Calibrated Data Collection. Data Set Overview =============================================================================== This collection consists of DRACO calibrated images contained in FITS files and of files used by the calibration pipeline in order to generated calibrated images. Calibration files used by the calibration pipeline come in two types: FITS files and ASCII csv files. Their formats are described in the jhuapl_dart_draco_uncalibrated_calibrated_sis. Instrument Overview =============================================================================== DRACO is a narrow-angle, panchromatic, visible light imager consisting of an optical telescope assembly, a focal plane array with associated electronics, and image processing software. DRACO has a Ritchey-Chretien telescope with an aperture of 208 mm, operates at f/12.6, and has a field of view of 0.29 deg. The focal plane array is a 2560 x 2160 pixel, panchromatic, front-side illuminated complementary metal–oxide–semiconductor (CMOS) sensor with 6.5 micrometer pixels with digital output. The instantaneous field of view (IFOV) is 2.48 microradian unbinned, or 4.96 microradian binned. The detector is sensitive to light from 400–1000 nm. DRACO was designed to support optical navigation of the spacecraft and ensure impact with Dimorphos (the secondary member of the Didymos system), to refine system properties (e.g., orbit, rotation rate, pole), to characterize the surface characteristics and shape of Dimorphos during the Terminal and Final mission phases, and to constrain the location of the impact site. The latter observations will allow insight into target properties, presence or absence of blocks at the impact site, and impact angle, which will feed into the estimation of dynamical changes in the Didymos system resulting from the DART impact. The DRACO detector runs in both global and rolling shutter readout modes and has dual high and low gain output, although only one output can be recorded at a time. There are four possible gain settings: low gain amplification can be set to 1x or 2x; high gain amplification can be set to 10x or 30x. DRACO typically employs high gain, 30x when operating in rolling shutter mode to maximize the SNR, and low gain, 1x when operating in global mode during the Terminal and Final mission phases to prevent saturation and maximize the dynamic range of the images. Data =============================================================================== Raw data products are processed through a calibration pipeline to create calibrated data. Some raw images will not be turned into calibrated images (e.g., in-flight bias and dark current images; test patterns; images taken around detector reconfigurations). Each calibrated PDS4 data product will consist of: 1) A 32-bit float fits file with a single Header Data Unit (HDU) containing header metadata records and a data unit of the radiometrically calibrated windowed array (1024 pixels x 1024 pixels 2x2 binned from the original 2048 x 2048 window). The data are represented in radiance (W m-2 nm-1 sr-1) for files ending in _rad.fits The data are represented in reflectance (I/F, unitless) for files ending in _iof.fits A given DRACO raw fits image will only be converted into either a calibrated image in radiance or a calibrated image in I/F, not both. 2) A browse PNG created from the raw FITS file. Pixel values indicating “outside of window”, “missing data”, or identified as a "bad pixel" will be set to zero in the browse PNG. Saturated pixel values will be set to 255 in the browse PNG. The calibrated DRACO fits image is created by the DRACO Calibration Pipeline, which is described in detail in the jhuapl_dart_draco_calibration_pipeline_description document. This document also describes the format of the calibration files used by the DRACO Calibration Pipeline. DRACO calibrated data products are identified with file names in the format of: dart_SSSSSSSSSS_sssss_##_. SSSSSSSSSS 10-digit value of IMGTMSEC sssss 5-digit value of IMGTMSUB ## two digit version number, e.g., “01” defines product as one of the following types: rad (calibrated image converted to radiance) iof (calibrated image converted to I/F) the file extension: .fits for fits file format .png for PNG files