Data Set Overview  :   This data set contains Calibrated data taken by New Horizons  Alice Ultraviolet Imaging Spectrograph  instrument during the PLUTO mission phase.   PERSI-Alice (P-ALICE; also ALICE) is a spectrograph on the New Horizons  spacecraft that is sensitive to extreme and far UltraViolet (UV) light  (520-1870 Angstroms). The ALICE instrument comprises a telescopic optics section and a spectrograph section that includes a diffraction grating  and a photosensitive two-dimensional (2-D) detector. The optics and  diffraction grating physical arrangement configure one detector  dimension as a spatial dimension and the other as spectral. ALICE has  two separate entrance apertures that feed light to the telescope section of the instrument: the AirGlow Channel (AGC) aperture; the Solar  Occultation Channel (SOCC) aperture. Both apertures pass light to the  detector through a lollipop-shaped slit comprising two contiguous  sections: a narrow, rectangular slit with a Field Of View (FOV) of 0.1  by 4.0 degrees; a fat, square slit with FOV 2.0 x 2.0 degrees. ALICE has two data-taking modes: pixel list mode records each detector/photon  event location (pixel i.e. spectral and spatial), interleaved with time  sequence events (hacks), allowing sub-second resolution of the photon  events; histogram mode summarizes the per-pixel photon event counts into a 2-D histogram over all detector pixels, collected over an extended  time which can range from a few seconds to several days. From both  modes, the common data product is the histogram (derived on the ground  in the pixel list case), which is functionally equivalent to a  spectral-by-spatial spectrogram (2-D image); other data products are  also provided and described in this data set.  During the Pluto mission phase starting in January, 2015, there were  several sub-phases: three Approach sub-phases, (AP1, AP2 and AP3); a  CORE sequence for the Pluto flyby on 14 July, 2015 (Day Of Year 195),  sometimes also referred to as NEP (Near-Encounter Phase); three  Departure sub-phases (DP1, DP2, DP3). For this first MVIC delivery for  the Pluto mission phase, this data set includes only the Approach data  plus the subset of the CORE sequence data that was downlinked through  the end of July, 2015. The rest of the Pluto data will be delivered in  future versions of this data set according to the schedule worked out  by the Project and NASA.   The first Pluto dataset delivery for the P-Alice instrument covers the  data on the ground between 1/15/2015 and 7/31/2015. It includes  functional testing and preliminary observations made during approach,  as well as a selected few observations from the few days up to the  Pluto encounter closest approach. Rho_Leo and Alice_Func are instrument  functional and calibration tests. PC_AIRGLOW is an observation that was  repeated regularly over the 2 months leading up to the CORE sequence.  The VISUV_MAP, Multi_Map, Airglow_Appr, and Airglow_Held observations  are part of the prime science data sets that meet specific objectives  of the mission.   *--- Alice_Rho_Leo  This observation points the P-Alice airglow boresight to the sky  location of Rho Leo to meet the following objectives:  1) Quick flux sensitivity verification,  2) Airglow pointing verification,  3) Detector PHD determination.  There are the two observations included:  Unsaturated PHD observation, a single 30 second Histogram, and a  Rho-Leo observation, another single 300 second Histogram.   *--- Alice_Func_080  This observation is the standard functional wake up Check (HK-TM,  Modes, Checksums and Selftest) with the following objectives:  1) Verify some very basic operations after the instrument has been  deactivated for some period of time (>month),  2) Verify unchanged code (PROM and EEPROM),  3) Verify succesful parameter load and values,  4) Verify succesful completion of internal selftest,  5) Verify unchanged behavior of the pixelhack problem  6) Perform a standard door performance test run   *--- PC_AIRGLOW 2.1-1.4  This set of observations is the P-Alice airglow observation of Pluto in  histogram mode. Each observation includes 6, 600 second histograms with  Pluto and Charon in the slot. They meet a goal to determine the time  variability of Pluto's surface and atmosphere, and the airglow  variability over several rotations. The long-time base of this  observation is to look for variability in Pluto's atmosphere or  excitation mechanisms. Deep histograms are obtained roughly daily over  a few set intervals on approach to document and study the variability  of atmospheric airglow emissions from H, O, and N atoms/ions, N2 and CO  band emissions, and to search for other emissions such as from S, Ar,  and Ne atoms. Pluto will not be resolved, but it is possible that  extended emission in the system could be seen, though model brightness  estimates indicate this is unlikely. Models predict emission  brightnesses of 0.01 to a few Rayleighs.   *--- PC_PIXELLIST  Functional test of P-Alice, with a few minutes of data using Pixel  list.   *--- UNOCC_SUN  Unocculted sun observation.  A series of different exposures, 1 histogram for each, at 1, 10, 100,  and 1000 seconds. This is a histogram instead of pixellist, but  otherwise, it uses the same orientation, observation setup, and same  instrument parameters (voltage, etc) as P_OCC, which will be delivered  in a future dataset.   *--- PC_VISUV_MAP  PEAL_01_PC_VISUV_MAP_B_12 is a 40 minute P-Alice Histogram on Pluto and  Charon in the P-Alice box, taken 15 days before closest approach. For  these types of observations taken less than 10 days before closest  approach, Pluto and Charon are targeted in the slot. The goal is: Color  and Composition of Non-Encounter Hemispheres of Pluto & Charon. The  scientific motivation is to document the rotational disk-integrated UV  lightcurves of Pluto and Charon, primarily for surface composition, and  to search for spectral features indicative of surface materials such as  H2O-ice. It is expected that only the longer wavelengths will have  small enough opacity to see Pluto's surface, based on current  (1992-2007) gaseous CH4 observations.   *--- PC_Multi_Map_A/B  Multi_Map_A5 has 4, 600 second P-Alice Airglow histograms with Pluto in  the box, similar to PC_VISUV_MAP. These observations are all multiple  300 second Airglow histograms, similar to PC_VISUV_MAP. For the  Multi_Map_B observations, Pluto is aligned in the center of the slot.  All of the PC_Multi_Map observations have the same goals as  PC_VISUV_MAP.   *--- PC_Airglow_Appr  There were 5 total of these observations, with Appr_3 and Appr_4 being  the last 2, taken a few hours before closest approach.  PC_Airglow_Appr_3 has 10, 300 second histograms, and PC_Airglow_Appr_4  has 18, 150 second histograms. They meet a number of primary mission  goals. In addition to the goals for PC_VISUV_MAP and PC_Multi_Map,  these measurements also can be used for Pluto/Charon Hemisphere Surface  Composition Maps, to determine Pluto's Atmospheric Composition (N2, CO,  CH4, Ar), and the secondary goal of searching for emissions from minor  species (e.g., H, or perhaps C) in the airglow spectra.  The observations provide the best practical S/N on the airglow and  information on its spatial distribution with both dayglow and  nightglow. Airglow observations from Pluto are very weak, but are  expected to provide the primary means for detecting certain minor  atmospheric species, including Ar and CO. Typical expected limb  brightnesses are a few Rayleighs or less, with the exception of H Lyman  alpha, which is expected to be 50-100 Rayleighs (note that this should  be darker than the background interplanetary signal from H Lyman alpha,  which should be ~100-200 Rayleighs). Most of these emissions are  excited by photoelectron impact (peaking in emission rate at ~1000 km  altitude), and modeling the observed emissions will yield density  estimates for the parent species. It is important to note that N+  emissions result from dissociation/ionization/excitation of N2, and  provide no information regarding Pluto's ionosphere.  The observations can also be used to generate Pluto- and  Charon-resolved UV surface maps. P-Alice is used for surface  composition studies of the sunlit face of Pluto, mostly looking for  H2O, and the instrument is used as a backup for LEISA composition  mapping. Water ice and certain other frosts have FUV absorption bands  that could be detected by making albedo maps. These observations can  also provide the disk-integrated rotationally resolved UV light curves  of Pluto and Charon, in support of surface composition studies.  Any additional Alice airglow or H Lyman alpha coronal data would be  useful for investigating atmospheric composition. Most of the near  encounter observations are designed for high-resolution surface  studies. Although the Alice instrument has poor spatial resolution, its  time-tagging ability makes it very flexible at taking useful data  whenever there is an opportunity (i.e., whenever MVIC, LEISA, or REX  are making primary observations).   *--- P_Alice_Airglow_Held  These observations are Alice airglow observations of Pluto in held  histogram mode, taken just before closest approach. Held_1 is 180  seconds, and Held_2 is 65 seconds. In addition to the goals from  PC_Airglow_Appr, these observations see the Pluto airglow at the limb.  As with the near-encounter airglow observations, these limb  observations are to ensure we obtain spatially-resolved airglow data.  At the bright limb, Pluto's airglow emissions should be ~10x brighter  due to the extended path length.   Every observation provided in this data set was taken as a part of a  particular sequence. A list of these sequences has been provided in  file DOCUMENT/SEQ_ALICE_PLUTO.TAB.  N.B. Some sequences provided may have no corresponding observations.   For a list of observations, refer to the data set index table. This  is typically INDEX.TAB initially in the INDEX/ area of the data set.  There is also a file SLIMINDX.TAB in INDEX/ that summarizes key  information relevant to each observation, including which sequence  was in effect and what target was likely intended for the  observation.    Version  :   This is VERSION 1.0 of this data set.    Processing  :   The data in this data set were created by a software data  processing pipeline on the Science Operation Center (SOC) at  the Southwest Research Institute (SwRI), Department of Space Studies.  This SOC pipeline assembled data as FITS files from raw telemetry  packets sent down by the spacecraft and populated the data labels  with housekeeping and engineering values, and computed geometry  parameters using SPICE kernels. The pipeline did not resample  the data.    Data  :   The observations in this data set are stored in data files using  standard Flexible Image Transport System (FITS) format. Each FITS  file has a corresponding detached PDS label file, named according  to a common convention. The FITS files may have image and/or table  extensions. See the PDS label plus the DOCUMENT files for a  description of these extensions and their contents.   This Data section comprises the following sub-topics:   - Filename/Product IDs  - Instrument description  - Other sources of information useful in interpreting these Data  - Visit Description, Visit Number, and Target in the Data Labels    Filename/Product IDs  --------------------   The filenames and product IDs of observations adhere to a  common convention e.g.   ALI_0123456789_0X4B0_ENG.FIT  ^^^ ^^^^^^^^^^ ^^^^^ ^^^\__/  | | | | ^^  | | | | |  | | | | +--File type (includes dot)  | | | | - .FIT for FITS file  | | | | - .LBL for PDS label  | | | | - not part of product ID  | | | |  | | | +--ENG for CODMAC Level 2 data  | | | SCI for CODMAC Level 3 data  | | |  | | +--Application ID (ApID) of the telemetry data  | | packet from which the data come  | |  | +--MET (Mission Event Time) i.e. Spacecraft Clock  |  +--Instrument designator    Note that, depending on the observation, the MET in the data filename  and in the Product ID may be similar to the Mission Event Time (MET)  of the actual observation acquisition, but should not be used as an  analog for the acquisition time. The MET is the time that the data are  transferred from the instrument to spacecraft memory and is therefore  not a reliable indicator of the actual observation time. The PDS label  and the index tables are better sources to use for the actual timing of  any observation. The specific keywords and index table column names for which to look are   * START_TIME  * STOP_TIME  * SPACECRAFT_CLOCK_START_COUNT  * SPACECRAFT_CLOCK_STOP_COUNT    Instrument Instrument designators ApIDs  : : :  ALICE ALI 0X4B0 - 0X4B7 *   * Not all values in this range are in this data set   There are other ApIDs that contain housekeeping values and  other values. See SOC Instrument ICD (/DOCUMENT/SOC_INST_ICD.*)  for more details.    Here is a summary of the types of files generated by each ApID  along with the instrument designator that go with each ApID:    ApIDs Data product description/Prefix(es)  : :  0x4b0 - ALICE Pixel List Lossless (CDH 1)/ALI  0x4b1 - ALICE Pixel List Packetized (CDH 1)/ALI  0x4b4 - ALICE Pixel List Lossless (CDH 2)/ALI  0x4b5 - ALICE Pixel List Packetized (CDH 2)/ALI  0x4b2 - ALICE Histogram Lossless (CDH 1)/ALI  0x4b3 - ALICE Histogram Packetized (CDH 1)/ALI  0x4b6 - ALICE Histogram Lossless (CDH 2)/ALI  0x4b7 - ALICE Histogram Packetized (CDH 2)/ALI    Notes:  ------  1) CDH 1 and CDH 2 refer to the spacecraft redundant Command and Data  Handling systems in general, and here specifically to their  respective Solid State Recorders (SSRs) 1 and 2, where ALICE data  be sretored and prepared for downlink. ALICE can send data to SSR  1 or to SSR 2, or, for mission-critical data, to both redundantly.  ALICE shares its channel to the SSRs with the Long-Range  Reconaissance Imager (LORRI), so both instruments cannot store  data simultaneously. ALICE has the capabilty to store histogram  data to instrument-internal storage, and to transfer it to the  SSR(s) later; such an operation is called a Held Historgram, and  it allows ALICE to take data at the same time that LORRI is taking  and writing data to the SSR(s).   2) Packetized and Lossless refer to the method used on-board to  convert raw, high-speed instrument data on the SSR to low-speed  data ready for downlink. The conversion process is generally  referred to as compression, even though Packetized conversion does  not reduce the data volume In practice, Pixel List data always  use Packetized compression. Histogram data may use Packetized or  Lossless compression. Depending on the actual data contents,  Lossless compression reduces data volume by 60 to 90% or more;  for nominal science data a factor of 3 or more is normal.  Lossless compression is used whenever possible to reduce downlink  data volume. There is no difference, between Packetized and  Lossless compression, in the resultant FITS files after processing  by the Science Operation Center (SOC) data pipeline.     Instrument description  ----------------------   Refer to the following files for a description of this instrument.   CATALOG   ALICE.CAT   DOCUMENTS   ALICE_SSR.*  SOC_INST_ICD.*  NH_ALICE_V###_TI.TXT (### is a version number)    Other sources of information useful in interpreting these Data  --------------------------------------------------------------   Refer to the following files for more information about these data   NH Trajectory tables:   /DOCUMENT/NH_MISSION_TRAJECTORY.* - Heliocentric   ALICE Field Of View definitions:   /DOCUMENT/NH_FOV.*  /DOCUMENT/NH_ALICE_V###_TI.TXT     Visit Description, Visit Number, and Target in the Data Labels  ---------------------------------------------------------------   The observation sequences were defined in Science Activity Planning  (SAP) documents, and grouped by Visit Description and Visit Number.  The SAPs are spreadsheets with one Visit Description & Number per row.  A nominal target is also included on each row and included in the data  labels, but does not always match with the TARGET_NAME field's value in  the data labels. In some cases, the target was designated as RA,DEC  pointing values in the form ``RADEC:123.45,-12.34'' indicating Right  Ascension and Declination, in degrees, of the target from the  spacecraft in the Earth Equatorial J2000 inertial reference frame.  This indicates either that the target was either a star, or that the  target's ephemeris was not loaded into the spacecraft's attitude and  control system which in turn meant the spacecraft could not be pointed  at the target by a body identifier and an inertial pointing value had  to be specified as Right Ascension and Declination values. The PDS  standards do not allow putting a value like RADEC:... in the PDS  TARGET_NAME keyword's value. In those cases the PDS TARGET_NAME value  is set to CALIBRATION.    Ancillary Data  :   The geometry items included in the data labels were computed  using the SPICE kernels archived in the New Horizons SPICE  data set, NH-X-SPICE-6-PLUTO-V1.0.   Every observation provided in this data set was taken as a part of a  particular sequence. A list of these sequences has been provided in  file DOCUMENT/SEQ_ALICE_PLUTO.TAB. In addition, the  sequence identifier (ID) and description are included in the PDS label  for every observation. N.B. While every observation has an associated  sequence, every sequence may not have associated observations; that is,  some sequences may have failed to execute due to spacecraft events  (e.g. safing) and there will be observations associated with those  sequences. No attempt has been made during the preparation of this  data set to identify if any, or how many, such empty sequences there  are, so it is up to the user to compare the times of the sequences  to the times of the available observations from the INDEX/INDEX.TAB  table to identify such sequences.    Time  :   There are several time systems, or units, in use in this dataset:  New Horizons spacecraft MET (Mission Event Time or Mission Elapsed  Time), UTC (Coordinated Universal Time), and TDB Barycentric  Dynamical Time.   This section will give a summary description of the relationship  between these time systems. For a complete explanation of these  time systems the reader is referred to the documentation  distributed with the Navigation and Ancillary Information  Facility (NAIF) SPICE toolkit from the PDS NAIF node, (see  http://naif.jpl.nasa.gov/).   The most common time unit associated with the data is the spacecraft  MET. MET is a 32-bit counter on the New Horizons spacecraft that  runs at a rate of about one increment per second starting from a  value of zero at   19.January, 2006 18:08:02 UTC   or   JD2453755.256337 TDB.   The leapsecond adjustment (DELTA_ET : ET - UTC) over this dataset  is 65.184s.   The data labels for any given product in this dataset usually  contain at least one pair of common UTC and MET representations  of the time at the middle of the observation. Other portions  of the products, for example tables of data taken over periods  of up to a day or more, will only have the MET time associated  with a given row of the table.   For the data user's use in interpreting these times, a reasonable  approximation (+/- 1s) of the conversion between Julian Day (TDB)  and MET is as follows:   JD TDB : 2453755.256337 + ( MET / 86399.9998693 )   For more accurate calculations the reader is referred to the  NAIF/SPICE documentation as mentioned above.    Reference Frame  :    Geometric Parameter Reference Frame  -----------------------------------   Earth Mean Equator and Vernal Equinox of J2000 (EMEJ2000) is the  inertial reference frame used to specify observational geometry items  provided in the data labels. Geometric parameters are based on best  available SPICE data at time of data creation.    Epoch of Geometric Parameters  -----------------------------   All geometric parameters provided in the data labels were computed at  the epoch midway between the START_TIME and STOP_TIME label fields.     Software  :   The observations in this data set are in standard FITS format  with PDS labels, and can be viewed by a number of PDS-provided  and commercial programs. For this reason no special software is  provided with this data set.    Contact Information  :   For any questions regarding the data format of the archive,  contact   New Horizons ALICE Principal Investigator:   Alan Stern, Southwest Research Institute   S. Alan Stern   Southwest Research Institute  Department of Space Studies  1050 Walnut Street, Suite 400  Boulder, CO 80302  USA

Confidence Level Overview  :  During the processing of the data in preparation for  delivery with this volume, the packet data associated with each  observation were used only if they passed a rigorous verification  process including standard checksums.   In addition, raw (Level 2) observation data for which adequate  contemporary housekeeping and other ancillary data are not available  may not be reduced to calibrated (Level 3) data. This issue is raised  here to explain why some data products in the raw data set,   NH-P-ALICE-2-PLUTO-V1.0,   may not have corresponding data products in the calibrated data set,   NH-P-ALICE-3-PLUTO-V1.0.    Data coverage and quality  :   The lollipop-shaped fuzz in images of calibrated spectra, seen as  high signal levels at the box end of the slit around Hydrogen  Lyman-alpha (H Lya) wavelengths, is due to a design characteristic of  the detector and aperture. To make the Micro Channel Plate (MCP)  more sensitive to UV light, it was coated with potassium bromide  (KBr) photocathodes from 520 to 1180 Angstrom and with cesium iodide  (CsI) photocathodes from 1250 to 1870 Angstrom. A vertical strip - a  spectral band of 70 Angstrom centered at ~1216 Angstrom - of the MCP  was masked and left uncoated to reduce the sensitivity of the  detector to H Lya radiation. In the slit portion of the aperture  (0.1deg wide x 4deg high), the diffraction grating keeps the strong H  Lya line within that uncoated band. However, in the 2x2 degree box  portion of the aperture designed to capture the Sun during  occultations, the H Lya spreads out beyond the uncoated 70-Angstrom  band over another ~110 Angstroms of photocathode-coated, more  sensitive detector on either side. The quantum efficiencies of the  photocathode-coated surfaces are about an order of magnitude more  sensitive to H Lya wavelengths than the bare, uncoated MCP glass,  which gives rise to high signal levels from the box area of the slit  i.e. the lollipop fuzz.    Caveat about TARGET_NAME in PDS labels and observational intent  :    A fundamental truth of managing data from some spacecraft missions  is that the intent of any observation is not suitable for insertion  into the command stream sent to the spacecraft to execute that  observation. As a result, re-attaching that intent to the data  that are later downlinked is problematic at best. For New Horizons  that task is made even more difficult as the only meta-data that  come down with the observation is the unpredictable time of the  observation. The task is made yet even more difficult because  uplink personnel, who generate the command sequences and initially  know the intent of each observation, are perpetually under  deadlines imposed by orbital mechanics and can rarely be spared for  the time-intensive task of resolving this issue.   To make a long story short, the downlink team on New Horizons has  created an automated system to take various uplink products, decode  things like Chebyshev polynomials in command sequences representing  celestial body ephemerides for use on the spacecraft to control  pointing, and infer from those data what the most likely intended  target was at any time during the mission. This works well during  flyby encounters and less so during cruise phases and hibernation.   The point to be made is that the user of these PDS data needs to  be cautious when using the TARGET_NAME and other target-related  parameters stored in this data set. This is less an issue for the  plasma and particle instruments, more so for pointing instruments.  To this end, the heliocentric ephemeris of the spacecraft, the  spacecraft-relative ephemeris of the inferred target, and the  inertial attitude of the instrument reference frame are provided  with all data, in the J2000 inertial reference frame, so the user  can check where that target is in the Field Of View (FOV) of the  instrument. Furthermore, for pointing instruments with one or more  spatial components to their detectors, a table has been provided  in the DOCUMENT/ area with XY (two-dimensional) positions of each  inferred target in the primary data products. If those values are  several thousand pixels off of a detector array, it is a strong  indication that the actual target of that observation is something  other than the inferred target, or no target at all e.g. dark sky.    Review  :  This dataset was peer reviewed and certified for scientific use on  TBD.