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DAWN FC1 RAW (EDR) CRUISE CHECKOUT/CALIBRATION IMAGES V1.0 (PDS)

NSSDCA ID: PSSB-00696

Availability: At NSSDC, Ready for Offline Distribution (or Staging if Digital)

Description

This description was generated automatically using input from the Planetary Data System.

Dataset overview

Framing Camera 1 is one of two identical units flying on Dawn spacecraft. This dataset includes the Experiment Data Record (EDR) version of all available images acquired during the initial checkout and all cruise phases (Earth to Mars, Mars to Vesta and Vesta to Ceres). In addition to the imagery, anciliary information is stored within the image headers. Calibration files needed for further processing are archived as a separate data set. This EDR dataset is the primary record of image data as it was received on Earth. The images in this dataset have not been processed in any way other than by decompressing, extracting header information, and generating and attaching PDS labels. In general, these images contain star fields. In some instances, the field contains a particular star (Canopus, Vega - photometric standard, HR 2290 - solar analog, etc.), a named star cluster like 20 Cephei, or a solar system body (Ceres, Mars). At other times the image just contains whatever stars were in the field of view at the time of the image. For more information on the contents and organization of the volume set refer to the aareadme.txt file located in the root directory of the data volumes.

Parameters

Compression: FC images may optionally be compressed by wavelet transformation. Wavelet compression: Images may be integer or floating point wavelet transform-compressed in the DPU. The integer approach produces lossless compression, while the floating point can induce distortions of +/-1 DN. The encoding of the wavelets ensures that any length of the data starting at the beginning can be decoded, thus allowing to compress further by discarding the trailing part. Windowing: In order to manage downlink resources, up to 10 portions of the image can be selected in the DPU and downlinked as subframes. The subframes are allowed to overlap. During EDR construction each subframe is stored separately and also mosaicked into the original image. Exposure Control: The exposure time of FC images is set by command for each image. Pointing: The Framing Cameras are fix mounted onto the Dawn Instrument deck, with the nominal alignment of the optical axis with the +Z axis of the spacecraft. Deviations from the nominal are documented in the calibration data. Filter selection: The FC has 8 filters at its disposal, numbered from F1 to F8. F1 is a broadband (clear) filter, sensitive in the wavelength interval from 400 to 1100 nm peaking at 700 nm. The narrow-band color filters are of the interference type, and have wavelengths ranging from 430 to 980 nm.

Processing

An FC image downlinked by the spacecraft unpacks into a succession of one or more compressed image subframes with an attached PDS headers containing housekeeping items that include full status of the instrument hardware, software configuration, temperature, voltage and current readings. The data in one EDR consists of one or more reconstructed image frames, with the accompanying header translated into text format in the label. The dimensions and location (pixel coordinates) of each frame are included for proper further processing. Each frame is formatted into one file (suffix *.IMG), with an attached label. Subframes are retained as separate entities and also are reassembled into their original coordinates in the 'summary' image. Parts of the reconstructed image not included in the subframes are given a value of zero. Darks are acquired in a different mode than normal images, leading to different cropping and therefore different image file structure. Darks are acquired as full 1092x1056 pixel images, which are cropped due to operational considerations to include 1088x1056 (Frame 0) and 4x1056 (Frame 6) allowing the complete reconstruction of the original full frame. In contrast, normal images are cropped into several smaller sections (the most prominent of which is the 1024x1024 active area), and therefore have several smaller frames. The label contains all relevant housekeeping information in calibrated form (e.g. degrees Celius, volts, or amperes. For further details on the layout of the data and the possible combinations of frames, please refer to the Software Interface Specification.

These data are available on-line from the Planetary Data System (PDS) at:

https://sbnarchive.psi.edu/pds3/dawn/fc/DWNXFC1_1A/

Alternate Names

  • DAWN-X-FC1-2-EDR-CRUISE-IMAGES-V1.0

Discipline

  • Planetary Science: Small Bodies

Additional Information

Spacecraft

Experiments

Questions and comments about this data collection can be directed to: Dr. David R. Williams

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. Horst Uwe KellerData ProviderMax-Planck-Institut fur Aeronomiekeller@linmpi.mpg.de
Dr. Pablo Gutierrez-MarquesGeneral ContactMax-Planck-Institut fur Sonnensystemforschunggutierrez@mps.mpg.de
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