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DAWN FC2 CALIBRATED CERES IMAGES V1.0 (PDS)

NSSDCA ID: PSSB-00705

Availability: Archived at NSSDC, accessible from elsewhere

Description

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

Dataset overview

Framing Camera 2 is one of two identical units flying on Dawn spacecraft. This dataset includes the Reduced Data Record (RDR) version of all available images acquired during the Ceres Encounter (Approach, Survey, HAMO, and LAMO. In addition to the imagery, anciliary information is stored within the image headers, as well as a detailed account of all the reference files used for the calibration. Calibration files needed for further processing are archived as a separate data set. The images in this dataset have been radiometrically calibrated by means of fully reversible procedures, transforming the value of the pixels from digital units to applicable engineering units without modification of the geometry. Color filter data have been calibrated to units of spectral irradiance and the clear filter data to radiance. 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 RDR 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. The label contains all relevant housekeeping information in calibrated form (e.g. degrees Celsius, volts, or amperes). The calibration process is divided into several steps that aim to remove the effect of different source of noise: conversion from 16-bit integer to 32-bit floating point, read-out bias, dark current, read-out smear, flat field non-uniformity, correction of under-sensitive pixels, exposure normalization, radiometric calibration. For more detailed informatin on the calibration process, please refer to [SCHROEDER&GUTIER2011]. For a discussion of which calibration images to use for a given activity, please refer to the data set catalog file for DAWN-CAL-FC2-2-EDR-CALIB-IMAGES-V1.0.

Summary of Observations

The following table contains a listing of FC2 observations at Ceres. Note that the abbreviation Sat. is used for Satellite in the table below to keep the width within the allowable number of charaters. -----------------------------------------------------------------------Dawn Science Observations -----------------------------------------------------------------------Start Mission Activity Activity Date Phase Name Description ======================================================================== 14-12-26 CSA APPROACH Ceres Science Approach Phase -----------------------------------------------------------------------15-01-13 CSA OPNAV_001 40 FC OpNav images 15-01-25 CSA OPNAV_002 40 FC OpNav images 15-02-04 CSA SAT_SEARCH_1 192 Sat. search images - Off-Ceres Pointing 15-02-04 CSA OPNAV_003 40 OpNav images + 180 Sat. search images 15-02-04 CSA SAT_SEARCH_2 256 Sat. search images - Off-Ceres Pointing 15-02-12 CSA RC1 171 FC rotational char #1 clear+color imgs 15-02-19 CSA RC2 237 FC rotational char #2 clear+color imgs 15-02-25 CSA OPNAV_004 40 OpNav images + 180 Sat. search images 15-03-01 CSA OPNAV_005 40 OpNav images + 180 Sat. search images 15-04-10 CSA OPNAV_006 40 OpNav images + 180 Sat. search images 15-04-15 CSA OPNAV_007 40 OpNav images + 180 Sat. search images ======================================================================== 15-04-24 CSR RC3 Ceres Science Rot Char 3 (range ~14030 km) -----------------------------------------------------------------------15-04-25 CSR RC3 104 RC3 Eq. Limb 1 (South) high phase imgs 15-04-26 CSR RC3 54 HighPhaseSouth_001 clear images 15-04-26 CSR RC3 180 HighPhaseSouth_002 clear images 15-04-27 CSR RC3 363 HighPhaseSouth_003 clear images 15-04-29 CSR RC3 540 HighPhaseNorth_001 clear images 15-04-29 CSR RC3 270 HighPhaseNorth_002 clear images 15-04-30 CSR RC3 114 HighPhaseNorth_003 clear images 15-04-30 CSR RC3 42 RC3 Eq. Limb 2 (North) high phase imgs 15-05-01 CSR RC3 120 RC3 Eq. Limb 3 (North) high phase imgs 15-05-04 CSR RC3 238 RC3 North lit side clear+color images 15-05-05 CSR RC3 238 RC3 Equator lit side clear+color images 15-05-07 CSR RC3 238 RC3 South lit side clear+color images -----------------------------------------------------------------------15-05-09 CTS TRANSFER_ Ceres Transfer to Survey Phase TO_Survey -----------------------------------------------------------------------15-05-16 CTS OPNAV_008 40 FC OpNav images 15-05-22 CTS OPNAV_009 40 FC OpNav images -----------------------------------------------------------------------15-06-04 CSS SURVEY Ceres Science Survey Phase (range ~4870 km) -----------------------------------------------------------------------15-06-05 CSS CYCLE1 191 nadir clear+color +71 limb clear images 15-06-08 CSS CYCLE2 193 nadir clear+color +45 limb clear images 15-06-11 CSS CYCLE3 212 nadir clear+color images 15-06-14 CSS CYCLE4 190 nadir clear+color +73 limb clear images 15-06-17 CSS CYCLE5 207 nadir clear+color images 15-06-21 CSS CYCLE6 210 nadir clear+color images 15-06-24 CSS CYCLE7 230 nadir clear+color images 15-06-27 CSS CYCLE8 Data lost to instrument reset -----------------------------------------------------------------------15-07-01 CTH TRANSFER_ Ceres Transfer to HAMO Phase TO_HAMO -----------------------------------------------------------------------No science observation in this phase -----------------------------------------------------------------------15-08-17 CSH HAMO Ceres Science HAMO Phase (range ~1950 km) -----------------------------------------------------------------------15-08-18 CSH CYCLE1 2640 nadir clear+color images (12 orbits) 15-08-29 CSH CYCLE2 431 off-nadir clear images (12 orbits) 15-09-09 CSH CYCLE3 205 off-nadir clear images (12 orbits) 15-09-20 CSH CYCLE4 598 off-nadir clear images (12 orbits) 15-10-01 CSH CYCLE5 2421 nadir clear+color images (12 orbits) 15-10-12 CSH CYCLE6 408 off-nadir clear images (12 orbits) -----------------------------------------------------------------------15-10-23 CTL TRANSFER_ Ceres Transfer to LAMO Phase TO_LAMO -----------------------------------------------------------------------No science observation in this phase -----------------------------------------------------------------------15-12-16 CSL LAMO Ceres Science LAMO Phase (range ~850 km) -----------------------------------------------------------------------15-12-16 CSL CYCLE0 425 nadir clear images (1 seg) 15-12-18 CSL CYCLE1 3946 nadir clear images (5 segs) 16-01-10 CSL CYCLE2 3783 nadir clear images (5 segs) 16-02-02 CSL CYCLE3 3411 nadir clear images (5 segs) 16-02-25 CSL CYCLE4 1626 nadir clear images (5 segs) 16-03-19 CSL CYCLE5 1353 nadir clear+color images (5 segs) 16-04-11 CSL CYCLE6 2775 nadir clear images (5 segs) 16-05-04 CSL CYCLE7 2705 nadir clear images (5 segs) 16-05-27 CSL CYCLE8 4054 nadir clear+color images (5 segs) ---------------------------------------------------------16-06-19 CXL XMO1** Ceres Extended LAMO Phase (range ~850 km) -----------------------------------------------------------------------16-06-19 CXL CYCLE9 4475 nadir clear+color (5 segs) 16-07-16 CXL CYCLE10 5131 nadir clear+color (6 segs) 16-08-10 CXL CYCLE11 4178 nadir clear+color (5 segs, seg 5 lost) -----------------------------------------------------------------------16-09-02 CTJ TRANSFER_ Ceres Transfer to Juling Phase TO_JULING -----------------------------------------------------------------------No FC science observations in this phase -----------------------------------------------------------------------16-10-10 CXJ XMO2 Ceres Extended Juling Phase (range ~1950 km) -----------------------------------------------------------------------16-10-10 CXJ CYCLE1 1868 nadir clear+color (9 orbits) 16-10-24 CXJ CYCLE2 1050 nadir clear+color (7 orbits) -----------------------------------------------------------------------* Data volume in LAMO Cycle 5 was perferentially assigned to the VIR instrument. Clear images were taken in selected orbits with lossless compression so that compression artifacts in other nadir cycles could be assessed by comparison. ** Instrument resets and other issues resulted in the loss of many images in XMO1, and some raw images that are included in the archive could not be routinely processed. Since the project did not know if it would be staying at Ceres or departing for Adeona, expensive orbit maintenance maneuvers were not performed. As a result, the s/c was far off the predicted trajectory. Many images were acquired on the Coordinate System ================= The geometry items SC_SUN_POSITION_VECTOR, SC_TARGET_POSITION_VECTOR and SC_TARGET_VELOCITY_VECTOR provided in the label of the data product are relative to the Earth Mean Equator frame of J2000. SUB_SPACECRAFT_LATITUDE, SUB_SPACECRAFT_LONGITUDE are given in the IAU PLANETOCENTRIC coordinate system. These parameters are corrected for planetary and stellar aberrations. Distances are given in km, angles in degrees.

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

https://sbnarchive.psi.edu/pds3/dawn/fc/DWNC1FC2_1B/

Alternate Names

  • DAWN-A-FC2-3-RDR-CERES-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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