Data set overview  :  This data set includes the Experiment Data Record (EDR) version of all  available images acquired during the Ceres Prime Mission (Approach,  Transfer to Survey, Survey, HAMO, and LAMO),and extended missions 1  (XMO1, XMO2, XMO3, XMO4) and 2 (XMO6, XMO7). In addition to the imagery, ancillary information is stored within the image headers. Calibration  files needed for further processing are archived as a separate data set. This data set is the primary record of image data as it was received  on Earth. The images in this data set have not been processed in any  way other than by decompressing, extracting header information, and  generating and attaching PDS labels.   This data set includes individual dark and calibration lamp images.  These images are the inputs to the composite calibration files which  are needed for further processing of the raw images. The composite  calibration files are archived as a separate data set.   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.   For further details on the layout of the data and the possible  combinations of frames, please refer to the Software Interface  Specification.   The label contains all relevant housekeeping information in calibrated  form (e.g. degrees Celsius, volts, or amperes).   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 characters.  : Dawn Ceres Prime Mission 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 232 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 + 103 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 115 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 551 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 249 RC3 North lit side clear+color images  15-05-05 CSR RC3 249 RC3 Equator lit side clear+color images 15-05-07 CSR RC3 249 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  15-06-08 CSS CYCLE2 193 nadir clear + color + 45 limb clear  15-06-11 CSS CYCLE3 212 nadir clear + color images  15-06-14 CSS CYCLE4 190 nadir clear + color + 73 limb clear  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 observations 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 204 off-nadir clear images (12 orbits)  15-09-20 CSH CYCLE4 598 off-nadir clear images (12 orbits)  15-10-01 CSH CYCLE5 2422 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 observations in this phase  ------------------------------------------------------------------------ 15-12-16 CSL LAMO Ceres Science LAMO Phase (range ~850 km)  ------------------------------------------------------------------------ 15-12-16 CSL CYCLE0 436 nadir clear (1 seg)  15-12-18 CSL CYCLE1 3957 nadir clear (5 segs)  16-01-10 CSL CYCLE2 3795 nadir clear (5 segs)  16-02-02 CSL CYCLE3 3579 nadir clear (5 segs)  16-02-25 CSL CYCLE4 1638 nadir clear (5 segs)  16-03-19 CSL CYCLE5 1364* nadir clear+color(5 segs)  16-04-11 CSL CYCLE6 2778 nadir clear (5 segs)  16-05-04 CSL CYCLE7 2716 nadir clear (5 segs)  16-05-27 CSL CYCLE8 4065 nadir clear+color (5 segs)  : Dawn Ceres Extended Mission 1 Science Observations  ------------------------------------------------------------------------ 16-06-19 CXL XMO1** Ceres Extended LAMO Phase (range ~850 km)  ------------------------------------------------------------------------ 16-06-19 CXL CYCLE9 4486 nadir clear+color (5 segs)  16-07-16 CXL CYCLE10 5142 nadir clear+color (6 segs)  16-08-10 CXL CYCLE11 4189 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 1879 nadir clear+color (9 orbits)  16-10-24 CXJ CYCLE2 1050 nadir clear+color (7 orbits)  ------------------------------------------------------------------------ 16-11-03 CTG TRANSFER_ Ceres Transfer to GRaND Phase  TO_GRAND  ------------------------------------------------------------------------ No FC science observations in this phase  ------------------------------------------------------------------------ 16-12-14 CXG XMO3 Ceres Extended GRaND Phase (range ~8000-9500 km)  ------------------------------------------------------------------------ 16-12-14 CXG CYCLE1 no images acquired (6 orbits)  17-01-21 CXG CYCLE2 989 FC2 nadir clear+color (3 orbits)  17-02-17 CXG CYCLE3 307 FC2~nadir clear+color (1 orbit)  107 FC1~nadir clear+color  ------------------------------------------------------------------------ 17-02-23 CTO TRANSFER_ Ceres Transfer to Opposition Phase  TO_OPPOSITION  ------------------------------------------------------------------------ 17-03-28 OpNav1 43 Ceres/Star exposure images  17-04-15 OpNav2 43 Ceres/Star exposure images  17-04-17 OpNav3 43 Ceres/Star exposure images  ------------------------------------------------------------------------ 17-04-28 CXO XMO4 Ceres Extended Opposition Phase (range 14-55E3 km) ------------------------------------------------------------------------ 17-04-29 CX0 Opposition 205 FC2~nadir clear+color (range ~20,000 km) 199 FC1~nadir clear+color  17-05-17 OpNav4 43 Ceres/Star exposure images  : Dawn Ceres Extended Mission 2 Science Observations  ------------------------------------------------------------------------ 17-07-01 CX2 XMO5 Ceres Extended Mission 2 Phase (range ~15000 km)  ------------------------------------------------------------------------ 18-01-09 Checkout 65 non-pointed clear and color  ------------------------------------------------------------------------ 18-04-15 CTI TRANSFER_ Ceres Transfer to Intermediate Orbit  TO_INTERMEDIATE  ------------------------------------------------------------------------ No FC science observations in this phase  ------------------------------------------------------------------------ 18-05-15 C2I XMO6 Ceres Extended 2 Intermediate (range ~1950 km)  ------------------------------------------------------------------------ 18-05-15 C2I XMO6 1333 nadir clear+color (10 orbits)   ------------------------------------------------------------------------ 18-05-31 CTE TRANSFER_ Ceres Transfer to Elliptical Phase  TO_ELLIPTICAL  ------------------------------------------------------------------------ No FC science observations in this phase  ------------------------------------------------------------------------ 18-06-09 C2E XMO7 Ceres Extended 2 Elliptical (peri range ~35 km)  ------------------------------------------------------------------------ 18-06-09 C2E da942 899 nadir clear only (5 orbits)  18-06-15 C2E da942 903 nadir clear only (5 orbits)  18-06-21 C2E da942 550 nadir Cerelia at Periapsis (3 orbits)  18-06-25 C2E da942 960 nadir clear only (5 orbits)  18-07-02 C2E da942 983 nadir clear only (5 orbits)  18-07-08 C2E da943 799 nadir clear only (5 orbits)  18-07-15 C2E da943 1006 nadir clear only (5 orbits)  18-07-22 C2E da943 708 nadir clear only (5 orbits)  18-07-29 C2E da943 879 nadir clear and color (5 orbits)  18-08-05 C2E da944 595 nadir clear only (5 orbits)  18-08-11 C2E da944 813 nadir and limb clear only (5 orbits)  18-08-18 C2E*** da944 416 nadir clear only (5 orbits)  18-08-25 C2E da944 530 nadir clear and color (5 orbits)  18-09-01 C2E da945 149 ~nadir clear only (1 orbit)  18-09-29 C2E da946 136 star calibration (1 orbit)  ------------------------------------------------------------------------ * 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  dark side of Ceres and color images missed their intended targets.  *** Missing 104 images from orbit 65 on Aug 21(233) to unknown ground  system (GDS) error.   Comment on Extended Mission 2 (XM2)Observations  :  The XM2 orbits were highly elliptical and the argument of periapses  evolved rapidly during orbits. In particular, the periapsis latitude  drifted to the south by a few tenths of a degree/orbit in XMO6 and  by 1.7 degree/orbit in XMO7. Eventually periapsis crossed the south  pole and on to the dark side of Ceres in late August. As a result,  there is a gradual decrease in the number of images acquired in each  XMO7 partition. Another peculiarity of XMO7 is that the orbit was  designed to be 3:1 resonant with the Ceres rotation period such that  the observed longitude band would cover the Occator crater. Small  forces acting on the spacecraft created a slight east-west oscillation of the ground track, with a general eastward drift, that allowed a  swath of longitudes near Occator to be observed. In addition, this  swath covers the Urvara crater in the south so it was imaged in detail as well. There are no images acquired in XMO7 orbit 11 as this time  period was used to do a trajectory correction manuever (TCM) that  targeted Cerealia Facula at periapsis in orbit 13. Orbits 12 and 14  also cover this region extending the high resolution coverage. Images  from these three orbits are included in their own subdirectory for  the users.   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.

Image Processing  :  Through the analysis of Ceres Approach images it was determined that  there was a mean offset of 2.05 FC pixels in the FC2 boresight between  Vesta and Ceres. The reason for or source of this change in pointing  is unknown.   Exposure times  :  Due to an idiosyncrasy of the proximity electronics, that takes  approximately 193 milliseconds from the commanding of the image  acquisition to the actual start of the exposure, the images report the  commanding time and the end of exposure. This results in a difference of 193 milliseconds between the usual calculation of exposure time  (STOP_TIME - START_TIME) and the reported EXPOSURE_DURATION, which is  always shorter than the difference of the other two.   Data Coverage  :  There were very few major losses of FC2 data as of the end of  the Ceres HAMO mission phase. A DSN station problem resulted in the  loss of 77 images from the OpNav5 satellite search observation and an  unexpected transition between 1-way and 2-way communication during  the R2 playback resulted in the loss of 11 images (5 color, 6 clear).  At the LAMO/XMO1 altitude, the spacecraft small forces were  unpredictable and the spacecraft was often far from the expected ground  track. XMO1 was the most highly impacted part of the mission, partly  because the project expected to leave LAMO at the end of Cycle 9 and so  no course correction maneuver was planned. By the time the Cycle 11 was  being planned, the spacecraft was no longer following the predicted  trajectory, introducing significant gaps in coverage. In addition,  starting in HAMO and continuing thereafter, FC2 began to reset  unexpectedly while imaging. Images acquired before the camera reset  were not lost, but those that were expected to be acquired after the  reset were frequently lost or corrupted.   Data Quality  :   The following table contains a list of known lost or corrupted images.  ---------------------------------------------------------------------  Lost or Corrupted Images  ---------------------------------------------------------------------  Phase/Obs Image # Notes  ---------------------------------------------------------------------  Approach OpNav5 77 of 220 images lost to DSN outage  Survey Cycle 8 660 of 660 images lost to instrument reset  HAMO Cycle 2 1 of 432 images lost to DSN issues  HAMO Cycle 3 257 of 462 images lost to instrument reset  LAMO Cycle 0 6 of 442 images lost to DSN issues  LAMO Cycle 1 26 of 3983 images lost to instrument reset  LAMO Cycle 2 171 of 3976 images lost to instrument reset  LAMO Cycle 3 25 of 3604 images lost to DSN issues  LAMO Cycle 4 167 of 1804 images lost to instrument reset  LAMO Cycle 5 30 of 1394 images lost to DSN issues  LAMO Cycle 6 0 of 2778 images lost  LAMO Cycle 7 0 of 2716 images lost  LAMO Cycle 8 1 of 4066 images lost to DSN issues  XMO1 Cycle 9 121 of 4650 images lost to instrument reset  XMO1 Cycle 10 11 of 5153 images lost to instrument reset  XMO1 Cycle 11 1056 of 5234 images lost to instrument reset  XMO2 Cycle 1 0 of 1879 images lost  XMO2 Cycle 2 160 of 1337 images lost to instrument reset  XMO3 Cycle 1 0 of 969 images lost  XMO3 Cycle 2 0 of 307 images lost  XMO4 OpNav001-004 0 of 43 images/observation lost  XMO4 Opposition 0 of 205 images lost  XMO6 5 of 1338 images lost to DSN issues  XMO7 da942 18 of 4321 images lost to DSN issues  XMO7 da943 0 of 3403 images lost  XMO7 da944 105 of 2470 images lost to unknown GDS issue  XMO7 da945 0 of 160 images lost  XMO7 da946 0 of 147 star cal images lost   DSN issues associated with  1) Dawn ephemeris errors resulting in not being pointed directly  at the DSN (C1),  2) Ephemeris errors altering occultation timing (C0),  3) Mountains in the way at low elevation angles at Canberra (C2, C3),  4) Wind at Goldstone (C3).   Most of the color images in XMO1 missed their planned targets because  the spacecraft was not on the predicted trajectory. In addition, many  of the clear images are either dark or have exposure durations that  were set for phase angles very different than those observed.   During XMO1 Cycle 10, segment 3, FC2 reset with a warm reboot.  Although the FEE was restarted by the onboard sequence, the camera  flight software came up with compression turned off. This greatly  increased the size of each image as well as the raw telemetry format  and these images could not be processed using the normal processing  pipeline. Images in the internal processing queue (color filter) and  those acquired after the reset (mix of filters) may be partially  corrupted.   During XMO2 (Juling), FC2 reset just before the start of the final orbit of segment 2. This reset resulted in the loss of 276 planned high angle  views of Occator and Juling in all filters.