The MESSENGER mission dictionary contains classes that describe aspects of the MESSENGER mission and related instruments. 1.0.0.0 (2018-05-02) Updated PDS4 model to 1.9.0.0, may want to further update to 1.A.0.0. Corrections and additions by E. Guinness, Geo Node, as noted in comments below. Also changed all DD_Assocation clasess to have identifier_reference instead of local_identifier so that the ingest file works with 1.9.0.0 1.0.1.0 (2018-06-22) S. Slavney: Added orbit_number element. Removed erroneous leading space from mission phase name value "Mercury 4 Cruise". Build with lddtool -lpMs 1.0.2.0 (2018-10-29) T. King: Add ec_factor and make img_id_lsb, img_id_msb, piv_pos_motor and piv_goal nillable as requested by Paul Geissler. Also made mission_phase_name multiple occurrence. 1.1.0.0 (2019-06-07) T. King: Add observation_id, observation_type, data_quality_id, smear_magnitude, dark_strip_mean, missing_pixel_count, saturated_pixel_count and ec_factor as requested by Paul Geissler. The MESSENGER MDIS class is the container for MESSENGER MDIS specific metadata elements. The MESSENGER class is the container for MESSENGER mission-specific metadata elements. This section contains the simpleTypes that provide more constraints than those at the base data type level. The simpleTypes defined here build on the base data types. This is another component of the common dictionary and therefore falls within the common namespace. The background brightness used for MDIS automatic exposure time calculation. In a test image that it analyzed to determine an exposure time using automatic exposure, DPU hardware generates a histogram of the image. The histogram is analyzed by the software to determine if the image is overexposed or underexposed, and the exposure time is adjusted accordingly by analyzing the histogram of raw DN values in different brightness bins. The background or dark current level (mess.mdis.aex_bacb) is taken into account an is assumed to be a constant value. A threshold of number of pixels (mess.mdis.aex_sthr) is allowed to exceed a target brightness (mess.mdis.aex_tgtb). Starting with the maximum value, the number of pixels exceeding the target is counted, and the brightness of the histogram bin in which that threshold is reached (mess.mdis.aex_stat) is reported. The exposure time is scaled back by the ratio of mess.mdis.aex_tgtb/mess.mdis.aex_stat. The maximum allowable exposure time from an MDIS automatic exposure time calculation. In a test image that it analyzed to determine an exposure time using automatic exposure, DPU hardware generates a histogram of the image. The histogram is analyzed by the software to determine if the image is overexposed or underexposed, and the exposure time is adjusted accordingly by analyzing the histogram of raw DN values in different brightness bins. The background or dark current level (mess.mdis.aex_bacb) is taken into account an is assumed to be a constant value. A threshold of number of pixels (mess.mdis.aex_sthr) is allowed to exceed a target brightness (mess.mdis.aex_tgtb). Starting with the maximum value, the number of pixels exceeding the target is counted, and the brightness of the histogram bin in which that threshold is reached (mess.mdis.aex_stat) is reported. The exposure time is scaled back by the ratio of mess.mdis.aex_tgtb/mess.mdis.aex_stat. The minimum allowable exposure time from an MDIS automatic exposure time calculation. In a test image that it analyzed to determine an exposure time using automatic exposure, DPU hardware generates a histogram of the image. The histogram is analyzed by the software to determine if the image is overexposed or underexposed, and the exposure time is adjusted accordingly by analyzing the histogram of raw DN values in different brightness bins. The background or dark current level (mess.mdis.aex_bacb) is taken into account an is assumed to be a constant value. A threshold of number of pixels (mess.mdis.aex_sthr) is allowed to exceed a target brightness (mess.mdis.aex_tgtb). Starting with the maximum value, the number of pixels exceeding the target is counted, and the brightness of the histogram bin in which that threshold is reached (mess.mdis.aex_stat) is reported. The exposure time is scaled back by the ratio of mess.mdis.aex_tgtb/mess.mdis.aex_stat. The bin in a DPU histogram of image brightness used for MDIS automatic exposure time calculation. In a test image that it analyzed to determine an exposure time using automatic exposure, DPU hardware generates a histogram of the image. The histogram is analyzed by the software to determine if the image is overexposed or underexposed, and the exposure time is adjusted accordingly by analyzing the histogram of raw DN values in different brightness bins. The background or dark current level (mess.mdis.aex_bacb) is taken into account an is assumed to be a constant value. A threshold of number of pixels (mess.mdis.aex_sthr) is allowed to exceed a target brightness (mess.mdis.aex_tgtb). Starting with the maximum value, the number of pixels exceeding the target is counted, and the brightness of the histogram bin in which that threshold is reached (mess.mdis.aex_stat) is reported. The exposure time is scaled back by the ratio of mess.mdis.aex_tgtb/mess.mdis.aex_stat. The number of pixels allowed to exceed target brightness during an MDIS automatic exposure time calculation. In a test image that it analyzed to determine an exposure time using automatic exposure, DPU hardware generates a histogram of the image. The histogram is analyzed by the software to determine if the image is overexposed or underexposed, and the exposure time is adjusted accordingly by analyzing the histogram of raw DN values in different brightness bins. The background or dark current level (mess.mdis.aex_bacb) is taken into account an is assumed to be a constant value. A threshold of number of pixels (mess.mdis.aex_sthr) is allowed to exceed a target brightness (mess.mdis.aex_tgtb). Starting with the maximum value, the number of pixels exceeding the target is counted, and the brightness of the histogram bin in which that threshold is reached (mess.mdis.aex_stat) is reported. The exposure time is scaled back by the ratio of mess.mdis.aex_tgtb/mess.mdis.aex_stat. The target brightness used for MDIS automatic exposure time calculation. In a test image that it analyzed to determine an exposure time using automatic exposure, DPU hardware generates a histogram of the image. The histogram is analyzed by the software to determine if the image is overexposed or underexposed, and the exposure time is adjusted accordingly by analyzing the histogram of raw DN values in different brightness bins. The background or dark current level (mess.mdis.aex_bacb) is taken into account an is assumed to be a constant value. A threshold of number of pixels (mess.mdis.aex_sthr) is allowed to exceed a target brightness (mess.mdis.aex_tgtb). Starting with the maximum value, the number of pixels exceeding the target is counted, and the brightness of the histogram bin in which that threshold is reached (mess.mdis.aex_stat) is reported. The exposure time is scaled back by the ratio of mess.mdis.aex_tgtb/mess.mdis.aex_stat. The mission-elapsed-time, or MET, in seconds since MESSENGER launch, of the second during which the spacecraft attitude measurement in the header of an MDIS image was acquired. Attitude quality flag for the spacecraft attitude quaternion in the header of an MDIS image: 7 = Attitude Knowledge OK (At least 1 Star Tracker is available and at least 50% of gyro data is valid) 6 = Attitude Knowledge OK (No Star Tracker is available but at least 50% of gyro data is valid) 5 = Attitude Knowledge OK (No Star Tracker is and between 10% and 50% of gyro data is valid -OR- At least 1 Star Tracker is valid and between 0% and 50% of gyro data valid) 4 = not a legal option 3 = Attitude Knowledge BAD (At least 1 Star Tracker is available and at least 50% of gyro data is valid) 2 = Attitude Knowledge BAD (No Star Tracker is available but at least 50% of gyro data is valid) 1 = Attitude Knowledge BAD (No Star Tracker is available and between 10% and 50% of gyro data is valid -OR- At least 1 Star Tracker is valid and between 0% and 50% of gryo data is valid) 0 = Attitude Knowledge BAD (No Star Tracker data fewer than 10% of gyro data valid). The roll value of the vector component of the attitude quaternion representing spacecraft attitude, in the header of an MDIS image. The pitch value of the vector component of the attitude quaternion representing spacecraft attitude, in the header of an MDIS image. The yaw value of the vector component of the attitude quaternion representing spacecraft attitude, in the header of an MDIS image. The scalar component of the attitude quaternion representing spacecraft attitude, in the header of an MDIS image. The temperature of the focal plane array in raw counts at observation time. The conversion formula to degrees Celsius depends on the camera performing the observation: For WAC: Temperature = -263.2584 + Raw * 0.5022 For NAC: Temperature = -268.8441 + Raw * 0.5130 Where Raw is the raw counts in telemetry (mess.mdis.cam_t1). Camera temperature 2 in raw counts. The meaning depends on whether it is being reported by the WAC or NAC. A single telemetry point is used to return the raw value of filter wheel temperature (WAC), FILTER_TEMPERATURE once converted to units of degrees Celsius, or the raw value of telescope temperature (NAC), OPTICS_TEMPERATURE once converted to units of degrees Celsius, depending on which camera is in use. For the WAC, this is temperature of the filter wheel. Thus, FILTER_TEMPERATURE is 'N/A' if the NAC was used for the observation because the telemetry point will be a measurement of the NAC telescope temperature. For the WAC the conversion from raw counts to degrees Celsius is: T = -292.7603 + Raw * 0.5553 where Raw is the raw counts in MESS:CAM_T2. For the NAC, this is temperature of the NAC telescope. Thus OPTICS_TEMPERATURE is 'N/A' if the WAC was used for observation because the telemetry point will be a measurement of the WAC filter wheel temperature. For the NAC the conversion from raw counts to degrees Celsius is: T = -269.7180 + Raw * 0.4861 where Raw is the raw counts in telemetry (mess.mdis.cam_t2). MDIS CCD temperature in raw counts. The conversion formula to degrees Celsius depends on the camera performing the observation: For WAC: Temperature = -318.4553 + Raw * 0.2718 For NAC: Temperature = -323.3669 + Raw * 0.2737 Where Raw is the raw counts in telemetry (mess.mdis.ccd_temp). 12 to 8 bit image compression enabled or disabled. Which algorithm is used is specified by MESS. 12 to 8 bit compression algorithm (0-7) used to compress images from 12 to 8 bits. Whether this option is enabled is indicated by mess.mdis.comp12_8. The compression is implemented using one of eight lookup tables, which are optimized to the lower WAC CCD read noise and higher NAC read noise, light levels, and bias level (nominal or after inflight drift). Status of lossless Fast compression of MDIS images. This is applied to images by the instrument itself. The images are first uncompressed on the solid-state recorder if lossy wavelet compression is applied. When true, this indicates that the MDIS image is a critical optical navigation image and will be compressed by the MESSENGER Main Processor (MP) before other images. Normally, the MP compresses images in the order that they are received. The dark_strip_mean element provides the mean value of the pixels in the dark strip area of a CCD. The dark strip is an area of the CCD which is covered in such a way as to receive no light. The dark strip provides a measure of the dark current in the CCD. The data_quality_id element provides a numeric key which identifies the quality of data available for a particular time period. The data_quality_id scheme is unique to a given instrument and is described by the associated data_quality_desc element. The value indicates what detector of the GRS instrument measured the observation. Priority for downlink of an MDIS image file from the MESSENGER spacecraft. The identified of the DPU used during acquisition of an MDIS image. The ec_factor element records the empirical correction factor used to process MDIS WAC CDRs. Exposure time mode used for acquisition of an MDIS image. Manual exposure uses a pre-commanded exposure time. Autoexposure determines the exposure time from test images taken before the exposure, targeting a specific brightness value. MDIS exposure time in milliseconds. On-chip image binning option for MDIS. Images may be taken either without on-chip binning or with 2x2 binning, which decreases the size of a full image from 1024x1024 pixels to 512x512 pixels. On-chip binning can be used to manage the size of raw images being stored on the spacecraft solid-state recorder, or to increase CCD sensitivity. If this option is used, sensitivity increases by about a factor of four but read noise is similar. The goal position, in raw counts of the position resolver on the MDIS filter wheel. For each commanded filter number, the instrument software will try to place the filter wheel at the following positions: FILTER_NUMBER mess.mdis.fw_goal 1 17376 2 11976 3 6492 4 1108 5 61104 6 55684 7 50148 8 44760 9 39256 10 33796 11 28252 12 22852 Actual position attained is reported in mess.mdis.fw_pos. The actual position, in raw counts of the position resolver on the MDIS filter wheel. For each commanded filter number, the instrument software will try to place the filter wheel at the following positions: FILTER_NUMBER mess.mdis.fw_goal 1 17376 2 11976 3 6492 4 1108 5 61104 6 55684 7 50148 8 44760 9 39256 10 33796 11 28252 12 22852 Commanded position is reported in mess.mdis.fw_goal. There is a tolerance of 240 resolver counts around mess.mdis.fw_goal for mess.mdis.fw_pos to indicate that the filter wheel is correctly positioned. Validity flag for position of the MDIS filter wheel given in mess.mdis.fw_pos. The raw value from the MDIS filter wheel resolver in resolver counts. It is used by the flight software to compute mess.mdis.fw_pos. For each commanded filter number, the instrument software will try to place the filter wheel at the following positions: FILTER_NUMBER mess.mdis.fw_goal 1 17376 2 11976 3 6492 4 1108 5 61104 6 55684 7 50148 8 44760 9 39256 10 33796 11 28252 12 22852 Commanded position is reported in mess.mdis.fw_goal. There is a tolerance of 240 resolver counts around mess.mdis.fw_goal for mess.mdis.fw_pos to indicate that the filter wheel is correctly positioned. Validity flag for reading of the MDIS filter wheel given in mess.mdis.fw_read. Which of the two cameras was used during acquisition of an MDIS image. The 16 least-significant-bits of the 24-bit unique image identifier from the raw image header. This item was added to images effective with an instrument software update 2009-08-18 and will be set to N/A in images aquired earlier. The 8 most-significant-bits of the 24-bit unique image identifier from the raw image header. This item was added to images effective with an instrument software update 2009-08-18 and will be set to N/A in images aquired earlier. When true, this indicates that an MDIS image is subsampled by jailbars, a subset of all the image columns that are downlinked to save data volume in optical navigation images. The start column, stop column, and column spacing are indicated by mess:jb_x0, mess:jb_x1, and mess:jb_space respectively. Jailbars are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess_fpu_bin and mess:pixelbin. The column spacing for jailbars in an MDIS image, a subset of all the image columns that are downlinked to save data volume in optical navigation images. Jailbars are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess_fpu_bin and mess:pixelbin. The start column for jailbars in an MDIS image, a subset of all the image columns that are downlinked to save data volume in optical navigation images. Jailbars are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess_fpu_bin and mess:pixelbin. The stop column for jailbars in an MDIS image, a subset of all the image columns that are downlinked to save data volume in optical navigation images. Jailbars are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess_fpu_bin and mess:pixelbin. Indicator if MDIS FPU is latched up. If the value is 1 then the image data are probably invalid. The mission-elapsed-time, or MET, in seconds since MESSENGER launch of the second during which an MDIS image completes its exposure. The missing_pixel_count element provides the number of pixels missing from an image or observation. The mission_phase_name attribute provides the mission-defined name of a mission phase. The observation_id element uniquely identifies a scientific observation within a data set. The observation_type element identifies the general type of an observation. The orbit_number attribute identifies the number of the orbital revolution of a spacecraft around a target body. For MESSENGER, the orbit number was incremented at apoapsis. For observations made before the spacecraft was in orbit, orbit_number has no value, and its nilReason attribute is "inapplicable". The offset in measured pivot position applied to mess.mdis.piv_pos and mess.mdis.piv_goal so that zero is as close as possible to true spacecraft nadir (+z axis). The correction is in increments of (180 DEGREES / (2**15)). The commanded position of the MDIS pivot during exposure of an MDIS image, in increments of (180 DEGREES / (2**15)) with zero at nadir. -180 degrees is stowed. This item is not available after an instrument sofware upload 2009-08-18 and will be set to N/A in images acquired later. Status of main processor (MP) control of the MDIS pivot. If this is enabled, then the pivot goes to a position broadcast by the MP that points MDIS to nadir or some other aimpoint. If not enabled then a discrete pivot position is commanded. The actual position of the MDIS pivot during exposure of an MDIS image, in increments of (180 DEGREES / (2**15)) with zero at nadir. -180 degrees is stowed. The actual position of the MDIS pivot during exposure of an MDIS image, in motor step units. This item is not available prior to an instrument software upload 2009-08-18 and will be set to N/A in images taken earlier. Validity flag for position of the MDIS pivot given in mess.mdis.piv_pos. Raw pivot reading from resolver (in units of resolver counts). The pivot platform resolver only covers 45 degrees of motion; the resolver read-out values repeat eight times over the entire 360 degrees that an unconstrained platform could travel. This value is used along with dead-reckoning knowledge of which octant the platform is in to give the value in mess.mdis.piv_pos. Validity flag for reading of the MDIS pivot given in mess.mdis.piv_read. Pivot control state of MDIS. A resolver provides a position reading of the pivot platform. The resolver only covers 45 degrees of motion; the resolver read-out values repeat eight times over the entire 360 degrees that an unconstrained platform could travel. The DPU software must determine in which of the eight octants the platform is located before the resolver reading is meaningful. The software combines the octant with the resolver reading to form a position that covers the entire 360 degrees. To determine the octant the DPU software must be commanded to 'home' the platform. To home the pivot platform, the software drives the motor open loop backwards into the hard stop at -185 degrees. Then the software drives the motor forward, open loop, prepositioning it to -179 degrees. Until homing is completed, the pivot platform is considered 'lost' and all other pivot commands will remain pending. This status item describes that state of the pivot in determining this position knowledge. Pixel binning done to MDIS images by the MESSENGER spacecraft main processor (MP). This is in addition to on-chip binning as described by mess_fpu_bin. The saturated_pixel_count element provides a count of the number of pixels in the array that are at or exceed the maximum DN value. The smear_azimuth element indicates the direction in which an image was smeared. The values of this angle increment in a clockwise direction from a horizontal reference line. The smear_magnitude element indicates how far an image was smeared during an exposure. The name of the software used to generate the product. The version of the software used to generate the product. It usually has the form m.n Source of an MDIS image, either a scene image from the CCD or one of two test patterns. The spacecraft_clock_start_count attribute provides the value of the spacecraft clock at the beginning of a time period of interest. A planned reset of the on-board clock of the MESSENGER spacecraft occurred on January 8, 2013. This was commanded by Mission Operations and was done because the integer seconds part of the on-board mission- elapsed-time (MET) counter is not long enough to contain the larger MET values that would occur due to the extended mission. The MESSENGER team elected to command the clock reset and set MET to a small non-zero value to prevent disruptions in on-board timekeeping and other effects (that might have occurred if the clock were allowed to automatically rollover to 0 in early 2013) and to ensure that the MET counter would accomodate the remaining extended mission. As a result of the spacecraft clock reset, a discontinuity was introduced and MET values are no longer guaranteed to be unique throughout the mission. This ambiguity is resolved in ground processing by the use of SPICE 'clock partitions' (partition 1 for pre-reset METs and partition 2 for post-reset METs) in the Spacecraft Clock (SCLK) kernel (which supports mapping MET to other time forms using SPICE routines as described below) and with MET values stored in PDS products, labels, and for some instruments, product file names. For MET values in products or labels, a '1/' or '2/' preceding MET indicates the partition, as in: SPACECRAFT_CLOCK_START_COUNT = '1/265485874' SPACECRAFT_CLOCK_STOP_COUNT = '2/000100005' When using SPICE routines, clock partition numbers should be included with MET input values. METs expressed without an explicit partition number are associated with clock partition 1 by default. Use of clock partition numbers in file names for some MDIS products is described in the MDIS EDR and CDR/RDR SIS documents with those data sets. The spacecraft_clock_stop_count attribute provides the value of the spacecraft clock at the beginning of a time period of interest. A planned reset of the on-board clock of the MESSENGER spacecraft occurred on January 8, 2013. This was commanded by Mission Operations and was done because the integer seconds part of the on-board mission- elapsed-time (MET) counter is not long enough to contain the larger MET values that would occur due to the extended mission. The MESSENGER team elected to command the clock reset and set MET to a small non-zero value to prevent disruptions in on-board timekeeping and other effects (that might have occurred if the clock were allowed to automatically rollover to 0 in early 2013) and to ensure that the MET counter would accomodate the remaining extended mission. As a result of the spacecraft clock reset, a discontinuity was introduced and MET values are no longer guaranteed to be unique throughout the mission. This ambiguity is resolved in ground processing by the use of SPICE 'clock partitions' (partition 1 for pre-reset METs and partition 2 for post-reset METs) in the Spacecraft Clock (SCLK) kernel (which supports mapping MET to other time forms using SPICE routines as described below) and with MET values stored in PDS products, labels, and for some instruments, product file names. For MET values in products or labels, a '1/' or '2/' preceding MET indicates the partition, as in: SPACECRAFT_CLOCK_START_COUNT = '1/265485874' SPACECRAFT_CLOCK_STOP_COUNT = '2/000100005' When using SPICE routines, clock partition numbers should be included with MET input values. METs expressed without an explicit partition number are associated with clock partition 1 by default. Use of clock partition numbers in file names for some MDIS products is described in the MDIS EDR and CDR/RDR SIS documents with those data sets. The standard_data_product_id keyword is used to identify data products of the same processing level that are not otherwise indentified by being in different collections within the bundle. The number of columns in the FIRST rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess_subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess:fpu_bin and mess:pixelbin. The number of columns in the SECOND rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess_subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess:fpu_bin and mess:pixelbin. The number of columns in the THIRD rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess_subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess:fpu_bin and mess:pixelbin. The number of columns in the FOURTH rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess_subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess:fpu_bin and mess:pixelbin. The number of columns in the FIFTH rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess_subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess:fpu_bin and mess:pixelbin. The number of rows in the FIRST rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess_subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess:fpu_bin and mess:pixelbin. The number of rows in the SECOND rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess_subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess:fpu_bin and mess:pixelbin. The number of rows in the THIRD rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess_subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess:fpu_bin and mess:pixelbin. The number of rows in the FOURTH rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess_subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess:fpu_bin and mess:pixelbin. The number of rows in the FIFTH rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess_subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess:fpu_bin and mess:pixelbin. The zero-based starting column of the FIRST rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess:subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess_fpu_bin and mess:pixelbin. The zero-based starting column of the SECOND rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess:subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess_fpu_bin and mess:pixelbin. The zero-based starting column of the THIRD rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess:subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess_fpu_bin and mess:pixelbin. The zero-based starting column of the FOURTH rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess:subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess_fpu_bin and mess:pixelbin. The zero-based starting column of the FIFTH rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess:subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess_fpu_bin and mess:pixelbin. The zero-based starting row of the FIRST rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess:subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess_fpu_bin and mess:pixelbin. The zero-based starting row of the SECOND rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess:subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess_fpu_bin and mess:pixelbin. The zero-based starting row of the THIRD rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess:subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess_fpu_bin and mess:pixelbin. The zero-based starting row of the FOURTH rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess:subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess_fpu_bin and mess:pixelbin. The zero-based starting row of the FIFTH rectangular subframe within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). There may be up to five subframes per image as defined by mess:subframe. Subframes are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess_fpu_bin and mess:pixelbin. Number of rectangular subframes within an MDIS image to be retained after image compression by the MESSENGER spacecraft main processor (MP). Subframes may overlap each other, and are defined in the original 1024x1024 pixel MDIS coordinate system before pixel binning as described by mess:fpu_bin and mess:pixelbin. Either a full image may be specified, or up to five discrete regions within the full image. In all cases, the first four columns of the original 1024x1024 image, which are physically masked and serve as a dark current reference, are downlinked as subframe 0, even if the full image case is described. Within the subframes, pixel binning as described by mess:fpu_bin and mess:pixelbin is performed. Source of the 1 Hz time pulse used in time-tagging MDIS images. Commanded (lossy) wavelet compression ratio for an MDIS image.