DRAFT info from AIA – not JSOC adopted as of 10 Mar 07.

 

AIA/SDO FITS Keywords for Scientific Usage and Data Processing at Levels 0.0, 0.5, 0.9, and 1.0

 

(A document in progress)

Keyword Nomenclature:

(Telemetry keywords are bold italic; derived keywords are bold; & potential keywords are italic)

{#  = Integer (~ 0-999); @ = Optional single character A-Z; & = Alpha-numeric}

LL@#                          Lower Left corner pixel for row (X) / column (Y) for ROI # on CCD

NAXIS@#                   Dimension (in pixels) along row (X) / column (Y) for ROI # on CCD

A@&&&&&&            Originating from telemetry data (@: H = HDR, F = FRB, I = ISP)

 

(Note: The definitions of the output data levels included below have been extracted from the Stanford SDO DRMS and SUMS computer database data to a certain level.)

 

1. Basic Image Information for Level 0 (and Above)

 

Definition of Level 0

    1.  Image Header

Generated from metadata consists only of keywords derived directly from the image camera header data and its characteristics, such as image size, date of observation, telescope, instrument, etc.

    2.  Image Data

Decompressed raw data recompressed using gzip (see http://www.gzip.org/).

 

From science data packet image header (HDR) information (definition in Doc. AIA02019):

 

AHAPID = Packet APID (11b; from HDR)

AHTCS   = Time Code Seconds (32b; from HDR)

AHTCSS = Time Code Sub Seconds (32b; from HDR)

AHFSN   = Frame Serial Number (32b; from HDR)

AHT1RN   = Target 1 Row Number (7b; from HDR) for center pixel (to nearest 32nd row or column)

AHT1CN   = Target 1 Column Number (7b; from HDR) for center pixel

AHT2RN   = Target 2 Row Number (7b; from HDR) for center pixel

AHT2CN   = Target 2 Column Number (7b; from HDR) for center pixel

AHFDBID = Frame Definition Block ID (8b; from HDR)

AHTAPC = TAP Code (4b; from HDR)

AHBITID = Bit Select ID (4b; from HDR)

AHCPIDN = Compression parameter n (4b; from HDR)

AHCPIDK = Compression parameter k (4b; from HDR)

AHLUTID = Lookup Table ID (8b; from HDR)

 

It is proposed to utilize the 2 highest order bits in the Frame Serial Number to specify the AIA telescope number,  TELESCOP , associated with the data image, such that

 

AHFSN   = ATLID (2b; telescope # -1) + AFSN [Frame Serial Number (least significant 30b)],

where ATLID = [0, 1, 2, 3] = TELESCOP – 1, or TELESCOP = ATLID + 1 = [1, 2, 3, 4].

 

From Frame Definition Block (generated and stored in database (GDB) on the ground):

 

AFDBID = Frame Definition Block ID (8b; from GDB)

AFCRM = CCDReadoutMode (4b; from GDB) for number of ports: 1, 2, 4 (= 3, 2, 1)

AFDBSM   = SummingMode (4b; from GDB) for summing: 1x1, 2x2, 4x4 (= 0, 1, 2)

AFDBNW  = NumWindows (4b; from GDB) for number of ROI windows (= 0, 1, 2)

AFNR1 = NumRows1 (16b; from GDB) for length of region 1 in pixels

AFNC1 = NumCols1 (16b; from GDB) for height of region 1 in pixels

AFNR2 = NumRows2 (16b; from GDB) for length of region 2 in pixels

AFNC2 = NumCols2 (16b; from GDB) for height of region 2 in pixels

AFDBRL    = RowLength (16b; from GDB) for length of row for extracted regions

 

Using the basic keywords above for the center pixel of the 2 target regions of interest (ROI) and for the lengths and heights of the regions, together with the following figure from the AIA Sequence Control Document (#AIA02019), the derived keywords below can be determined for each of the ROI, 1, 2, and ROI 3 in between if the first two are overlapping in columns but not rows, as shown.

 

 

Derived Keywords:

 

NUMWIN = AFDBNW  + TBD                               [number of window regions of interest:

= 0 for full (4kx4k) CCD

                                                                        = 1 for 1 ROI;

                                                                        = 2 for 2 ROI;

                                                                        = 3 for extra region when first 2 regions have overlapping columns but not rows, as in the figure.]

LLX1 = AHT1RN * 32 – AFNR1 / 2            [region 1 (R1) lower left corner, X variable]

LLY1 = AHT1CN * 32 – AFNC1 / 2            [R1 lower left corner, Y variable]

LLX2 = AHT2RN * 32 – AFNR2 / 2            [R2 lower left corner, X variable]

LLY2 = AHT2CN * 32 – AFNC2 / 2            [R2 lower left corner, Y variable]

LLX3 = LLX1 + AFNR1                               [gray region (R3) lower left corner, X variable]

LLY3 = LLY1                                     [R3 lower left corner, Y variable]

NAXISX1 = AFNR1                                      [R1 number of pixels along X axis]

NAXISY1 = AFNC1                                     [R1 number of pixels along Y axis]

NAXISX2 = AFNR2                                      [R2 number of pixels along X axis]

NAXISY2 = AFNC2                                      [R2 number of pixels along Y axis]

NAXISX3 = AFDBRL – AFNR1 – AFNR2  [R3 number of pixels along X axis]

NAXISY3 = LLY2 + AFNC2 – LLY1           [R3 number of pixels along Y axis]

NAXIS = 2, 2, 1, 1                                          [corresponds to number of axes of images for NUMWIN = 0, 1, 2, 3 to not confuse simple FITS  file readers.]

NAXIS1 = 4096, NAXISX1, total number of pixels in area, total number of pixels in area

NAXIS2 = 4096, NAXISX2, 0, 0                  

[both correspond to the axis length for NUMWIN = 0, 1 and NAXIS1 to total number of pixels for NUMWIN = 2, 3 with NAXIS2 = 0 to not confuse simple FITS  file readers.]

 

Quality/Sanity Check of FDB ID:

 

Does AHFDBID = AFDBID ?

 

Reconstructing the acquired image requires in addition the appropriate use of AHCPIDN, AHCPIDK, AHTAPC, AHBITID, AHLUTID, AFDBSM, and AFCRM. The observation time can be determined (TBD) from AHTCS and AHTCSS.

 

----------

INSTRUME = AIA                Name of instrument

SIMPLE                                  True if conforming FITS file                              (HMI uses as T in L0)

BITPIX                                    Bits/pixel, negative for floating point                   (HMI uses as 16 in L0)

DATE-END                             End date/time of observation

DATE-OBS                            Date of observation, usually start time

DATE_OBS                             DATE-OBS with light travel correction

MJD                                       Modified Julian Day    (long interger used in conjunction with TIME

                                                to provide efficient binary time representation in SSW)

MJD-OBS                                Modified Julian Date of observation

TIME                                      Milliseconds of day                                          

 

 

2.  Additional Information for Level 0.5 (and Above)

 

Definition of Level 0.5      (Note: The intended use of this level is for the planner in near-real time.)

    1.  Image Header

Metadata for Level 0 plus that generated from the associated image status packet.  (See accompanying/latest image status packet (ISP) list)

    2.  Image Data

Decompressed raw data recompressed using gzip. (Same as that for Level 0)

 

More Basic Keywords for ROI Quality/Sanity Check:

 

AICRE = A8390 = AIA_IMG_CCD_ROW_END (16b; from ISP)

AICRS = A838F = AIA_IMG_CCD_ROW_START (16b; from ISP)

AIR1CE = A839A = AIA_IMG_ROI_1_COL_END (16b; from ISP)

AIR1CS = A8396 = AIA_IMG_ROI_1_COL_START (16b; from ISP)

AIR2CE = A839B = AIA_IMG_ROI_2_COL_END (16b; from ISP)

AIR2CS = A8397 = AIA_IMG_ROI_2_COL_START (16b; from ISP)

 

ROI Quality/Sanity Check (using ISP & FDB keywords to obtain the same derived keywords as above):

 

LLX1 = AICRS                                                          [R1 lower left corner, X variable]

LLY1 = AIR1CS                                                        [R1 lower left corner, Y variable]

LLX2 = AGCRE – AFNR2                                       [R2 lower left corner, X variable]

LLY2 = AIR2CS                                                        [R2 lower left corner, Y variable]

LLX3 = LLX1 + AFNR1                                           [R3 lower left corner, Y variable]

LLY3 = LLY1                                                             [R3 lower left corner, Y variable]

NAXISX1 = AFNR1                                                  [R1 number of pixels along X axis]

NAXISY1 = AIR1CE – LLY1                                   [R1 number of pixels along Y axis]

NAXISX2 = AFNR2                                                  [R2 number of pixels along X axis]

NAXISY2 = AIR2CE – LLY2                                   [R2 number of pixels along Y axis]

NAXISX3 = LLX2 – LLX1 – AFNR1                      [R3 number of pixels along X axis]

NAXISY3 = AIR2CE – LLY1                                   [R3 number of pixels along Y axis]

 

 

AICNTC = A8317 = AIA_IMG_CENTER_COL (16b; from ISP)

AICNTR = A8316 = AIA_IMG_CENTER_ROW (16b; from ISP)

AICSFT = A8319 = AIA_IMG_COL_SHIFT (16b; from ISP)

AIRSFT = A8318 = AIA_IMG_ROW_SHIFT (16b; from ISP)

 

CCD Information

 

AIPSM = A838B = AIA_IMG_PAR_SUM_MODE (8b; from ISP)

AISSM = A8388 = AIA_IMG_SER_SUM_MODE (8b; from ISP)

 

Quality/Sanity Check with FDB Summing Mode (TBD)

 

 

2.1 Instrument, Mechanisms, & Observable Information

 

AISTATE = A8284 = AIA_IMG_STATE (3b; from ISP)  

from which the telescope number, TELESCOP, can be sanity checked and the ISS status bit on,  ISS, can be obtained.

AIASEN = A82BF = AIA_IMG_AS_ENCODER (16b; from ISP)     

AIFWEN = A8292 = AIA_IMG_FW_ENCODER (8b; from ISP)    

AIAECTYP = (?) (2b; from ISP [TBD])

WAVELNTH = (?) (8b; from ISP [TBD])       Wavelength of observation (character or Angstroms)

Exposure Information:

 

AIMGSHEN = A8296 = AIA_IMG_SH_ENCODER (8b; from ISP)

AIMGOTS = A8285 = AIA_IMG_OBT_TIME_SH_SEC (32b; from ISP)  

AIMGOTSS = A8286 = AIA_IMG_OBT_TIME_SH_SS (16b; from ISP)  

AIMGSHCE = A8213 = AIA_IMG_SH_CMDED_EXPOSURE (16b; from ISP)  

AIMSHOBC = A853E = AIA_IMG_SH_OPEN_BOT_CENTR (24b; from ISP)  

AIMSHOBE = A853F = AIA_IMG_SH_OPEN_BOT_EDGE (24b; from ISP)  

AIMSHOTC = A8540 = AIA_IMG_SH_OPEN_TOP_CENTR (24b; from ISP)  

AIMSHOTE = A8541 = AIA_IMG_SH_OPEN_TOP_EDGE (24b; from ISP)  

AIMSHCBC = A8214 = AIA_IMG_SH_CLOSE_BOT_CENTR (24b; from ISP)  

AIMSHCBE = A8291 = AIA_IMG_SH_CLOSE_BOT_EDGE (24b; from ISP)  

AIMSHCTC = A853C = AIA_IMG_SH_CLOSE_TOP_CENTR (24b; from ISP)  

AIMSHCTE = A853D = AIA_IMG_SH_CLOSE_TOP_EDGE (24b; from ISP)  

 

-------------

EXPTIME                               Exposure time in seconds

 

 

2.2 Time Information

 

ATCSO27 = APID027_TIMECODE_SECONDS (32b; from ISP) 

ATCSS027 = APID027_TIMECODE_SUBSECS (32b; from ISP)  

 

Another Quality/Sanity Check can be performed for the observation time

 

Sequence/State Information

 

ASQFGSN = AIA_SEQ_FRAME_SN (32b; from ISP)  

ASQFGID = AIA_SEQ_FRAME_ID (32b; from ISP)  

AIFCPS = A8225 = AIA_IMG_FC_POSITION (16b; from ISP)  

AIFDBID = A8315 = AIA_IMG_FDB_ID (16b; from ISP)  

AIAECDL = A82F6 = AIA_IMG_AEC_DELAY (16b; from ISP)  

AIAECTI = A82CA = AIA_IMG_AEC_TABLE_ID (16b; from ISP)  

AIAECST = A8215 = AIA_IMG_AEC_STATUS (8b; from ISP)  

TBD = AIA_SEQ_EXP

TBD = AIA_SEQ_FL_REL_TIME

TBD = AIA_SEQ_FRLIST_POS

TBD = AIA_SEQ_FTSID

TBD = AIA_SEQ_FLID

TBD = AIA_SEQ_STATE

TBD = AIA_SEQ_FRAME_COUNT

TBD = Target type for AEC

 

Quality/Sanity Check of FDB ID:

 

Does AIMFDBID = AFDBGID ?

 

 

3. Other Keywords

 

Coordinate Information (including instrument & spacecraft pointing)

 

CD#_#@                                 Dimensioned transformation matrix                   

CDELT#@                              Pixel spacing along axis #

CROTA#                                  Coordinate rotation (see footnote 1)                 

CRPIX#@                               Reference pixel along axis #

CRVAL#@                              Reference value along axis #

CTYPE#@                              Type of coordinate axis #

CUNIT#@                              Units along axis #

PC#_#@                                 Transformation matrix

XCEN                                      X co-ordinate of array center (float)

YCEN                                      Y co-ordinate of array center (float)

 

Observation Planning Information

 

OBJECT                                  Name of object

OBJ_ID                                   Object identifier, e.g. active region number

OBSERVER                             Name of observer

OBS_PROG                             Name of the observing program

SCI_OBJ                                 The science objective of the observation

 

Temperature Information:

 

AIMCCTP1 = A8282 = AIA_IMG_CEB_CCD_TEMP1 (8b; from ISP)  

AIMCCTP2 = A8283 = AIA_IMG_CEB_CCD_TEMP2 (8b; from ISP)  

 

Data and Image Data Information

 

AIMGCPPR = A838C = AIA_IMG_COMPR_PAR (32b; from ISP)  

AIMPCGT1 = A830C = AIA_IMG_PIX_COUNT_GT_TH1 (16b; from ISP)  

AIMPCGT2 = A830D = AIA_IMG_PIX_COUNT_GT_TH2 (16b; from ISP)  

AIMPCGT3 = A830F = AIA_IMG_PIX_COUNT_GT_TH3 (16b; from ISP)  

AIMPCGT4 = A8310 = AIA_IMG_PIX_COUNT_GT_TH4 (16b; from ISP)  

AIMPCLT1 = A8311 = AIA_IMG_PIX_COUNT_LT_TH1 (16b; from ISP)  

AIMPCLT2 = A8312 = AIA_IMG_PIX_COUNT_LT_TH2 (16b; from ISP)  

AIMPCLT3 = A8313 = AIA_IMG_PIX_COUNT_LT_TH3 (16b; from ISP)  

AIMPCLT4 = A8314 = AIA_IMG_PIX_COUNT_LT_TH4 (16b; from ISP)  

 

 

 

 

---------------

EXTEND                                 FITS file may contain extensions                      

COMMENT                             ASCII comment (can be multiple)                    

HISTORY                                 ASCII history record (can be multiple)

FILENAME                             Name of the data file

 

TBD: keywords for focus, GT statistics, H/K packet #, S/C info., orbit info., etc., when available and derived keywords, e.g., statistics, bad pixels, flat fielding, image center, etc.

 

Reformatter Information

 

DATE                                      FITS creation date

ORIGIN                                   Responsible organization or institution

 

VERSION

QUALITY

LEVEL NUMBER

PIPELINE VERSION

 

 

More level definitions

 

Definition of Level 0.9

    1.  Header

Metadata for Level 0.0 plus that generated from the associated image status packet and from the spacecraft and other ancillary metadata, such as roll angle, orbital information, fine-pointing information, etc., to provide the lowest level of  scientifically-useful data, expressed in terms of the accompanying AIA/SDO FITS keyword names list, where applicable.

    2.  Data

Decompressed raw data recompressed using gzip. (Same as that for Level 0.0)

 

Definition of Level 1.0

    1.  Header

Metadata for Level 0.0 plus that generated from the associated image status packet and from spacecraft and other ancillary metadata, such as roll angle, orbital information, fine-pointing information, calibration information on flat field used and missing pixel correction value, etc., to provide the lowest level of scientifically-useful data, expressed in terms of the accompanying AIA/SDO FITS keyword names list, where applicable. Additional keywords will be added, when needed.

    2.  Data

Decompressed raw data (level 0) calibrated for exposure time and flat field plus corrected for missing pixels. Possible other corrections may be added where needed. Recompress processed data using gzip.