From: IOWASP::DVORSKY 26-JUN-1992 17:11:14.41 To: NCF::KAYSER CC: Subj: MAFCRD formats ############################################################ # # # # # CONTENTS OF THIS FILE # # # # 1.0 SAI MISSION ANALYSIS FILE # # 1.1 DESCRIPTION # # 1.2 FORMATS # # 1.3 READING A MAF # # 1.4 DISPLAYING AN IMAGE # # # # 2.0 SAI GEOGRAPHIC COORDINATE FILE # # 2.1 DESCRIPTION # # 2.2 FORMATS # # 2.3 READING A .GEO FILE # # # # 3.0 SAI CORRECTED GEOMAGNETIC COORDINATE FILE # # 3.1 DESCRIPTION # # 3.2 FORMATS # # 3.3 READING A .CGM FILE # # # # 4.0 CONVERTING COMPRESSED TELEMETRY COUNTS TO # # KILORAYLEIGHS # # 4.1 COMPRESSED COUNTS TO TRUE COUNTS # # 4.2 TRUE COUNTS TO KILORAYLEIGHS # # # # 5.0 MISCELLANEOUS INFORMATION # # 5.1 UT OF A PIXEL # # 5.2 DEFAULT ALTITUDES USED FOR # # CALCULATING COORDINATES # # # # # ############################################################ 1.0*****SAI MISSION ANALYSIS FILE (.MAF)**************** 1.1 DESCRIPTION An SAI MISSION ANALYSIS FILE contains the pixels of one image from one photometer. An image is made up of all consecutive scans of the photometer without changes in mirror stepping direction. Consecutive images in time will be stepping in opposite directions. The MAF is organized with a header record describing the file and the spacecraft position during the image, followed by one record for each scan containing the mirror position and the pixels collected during that scan. Most MAFs have been reduced to show a thirty-five degree region containing the Earth rather than including all the pixels of the nominal 120 or 360 degrees of scan. The number of pixels left off at the start of the scan and the number of pixels included are given in each scan line record. The data in single byte fields have values 0 to 255. All others are two's complement integers. 1.2 FORMATS HEADER RECORD FORMAT BYTE# DESCRIPTION DEC TYPE 1-2 RECORD LENGTH (16-BIT WORDS) I*2 3-4 FILE TYPE*256 + BLOCKING FACTOR " 5-6 RECORD LENGTH (BYTES-4) " 7-8 ZEROS " 9-12 FILE TYPE I*4 13-16 YEAR " 17-20 DAY OF YEAR " 21-24 MILLISECONDS OF DAY " 25-28 PHOTOMETER ID (1,2,3) " 29-32 FILTER WHEEL VOLTAGE (IN UNITS OF 0.02V) " 33-36 EBCDIC FILTER WHEEL CODE " 37-40 FILTER WHEEL TEMPERATURE " 41-44 FIRST MIRROR LOCATION COUNTER " 45-48 LAST MIRROR LOCATION COUNTER " 49-52 NUMBER OF SCAN LINE RECORDS IN MAF " 53-56 NUMBER OF PIXELS IN MAF " 57-60 MAXIMUM NUMBER OF PIXELS IN EACH SCAN LINE " 61-64 MINIMUM DIN " 65-68 6% DIN " 69-72 50% DIN " 73-76 94% DIN " 77-80 MAXIMUM DIN " 81-84 GREY SCALE MIN DIN " 85-88 GREY SCALE MAX DIN " 89-92 PHOTOMETER DIGITAL HOUSEKEEPING (FIRST FOUR BYTES) " 93-96 PHOTOMETER DIGITAL HOUSEKEEPING (3 BYTES) + RELAY STATUS " 97-100 DCU MINOR-MODE-COMMAND BYTES " 101-116 ANALOG SUBCOM (PACKED ONE VALUE PER BYTE) " 117-120 ORBIT NUMBER " 121-124 X \ " 125-128 Y > S/C POSITION IN GEI COORDINATES (METERS) " 129-132 Z / " 133-136 X(SPIN) \ " 137-140 Y(SPIN) > IN GEI COORD. (UNIT VECTOR * 1.E6) " 141-144 Z(SPIN) / " 145-148 X(NORMAL TO ORBIT) \ " 149-152 Y(NORMAL TO ORBIT) > GEI (UNIT VECTOR * 1.E6) " 153-156 Z(NORMAL TO ORBIT) / " 157-160 UI PROCESSING DATE YDDD (BCD) SECONDS (BINARY) " 161-164 VX \ " 165-168 VY > S/C VELOCITY IN GEI (MILLIMETERS/SECOND) " 169-172 VZ / " 173-176 SX \ " 177-180 SY > GEI UNIT VECTOR TOWARD SUN (* 1.E6) " 181-184 SZ / " 185-188 S/C SPIN RATE (W/R/T NADIR, MICRORADIANS/SECOND) " 189-192 MILLISECONDS OF DAY FOR ORBIT/ATTITUDE DATA ABOVE " 193-196 NADIR SCAN LINE AVERAGE SPIN PERIOD (MILLISECONDS) " 197-200 MINIMUM RUNNING AVERAGE SPIN PERIOD (MILLISECONDS) " 201-204 MAXIMUM RUNNING AVERAGE SPIN PERIOD (MILLISECONDS) " 205-206 LSB = 1 IF NADIR CORRECTIONS HAVE BEEN DONE I*2 207-372 SPARE 373-380 RESERVED \ BYTE 381-388 ASCII FILE NAME \ " 389-390 IMSYNC VERSION NUMBER (*64) + LEVEL NUMBER \ I*2 391-392 HIGH-ORDER CHAR OF INPUT FILE NAME \ for " 393-394 HIGH-ORDER CHAR OF OUTPUT FILE NAME (THIS FILE) / IOWA " 395-396 SCAN LINE OFFSET (FOR MAF DIRECTORY) / use " 397-400 INPUT FILE NAME (FOR MAF DIRECTORY) / " 401-404 OUTPUT FILE NAME (FOR MAF DIRECTORY) (THIS FILE)/ " SCAN LINE RECORD FORMAT BYTE# DESCRIPTION DEC TYPE 1-2 RECORD LENGTH (16-BIT WORDS) I*2 3-4 RECORD LENGTH (BYTES-2) " 5-8 UT (MILLISECONDS) AT LAST MINOR FRAME 0 MOD 16 I*4 9 DIGITAL MIRROR LOCATION COUNTER BYTE 10 ANALOG MIRROR LOCATION " 11 ANALOG FILTER WHEEL POSITION " 12 S/C CLOCK SUBCOM COUNTER (0,8,16,...,112,120) " 13-14 DCU COUNT (FULL 16 BITS) I*2 15-16 OFFSET FROM NADIR TO START OF SCAN (IN PIXELS) " 17-18 BMHS PIXEL CORRECTION " 19-20 SUN SENSOR PIXEL CORRECTION " 21-22 MANUAL PIXEL CORRECTION " 23-24 ORDER OF PIXEL CORRECTION ***for IOWA use " 25 PIXEL 1 IMAGE DATA BYTE 26 PIXEL 2 IMAGE DATA " . . . . . . . . . n+24 PIXEL n IMAGE DATA " 1.3 READING A MAF The header record, length 404 bytes, may be read into a byte array in a common block with other data types equivalenced to it, as shown below. The header record gives the number of scan line records (LINES below, bytes 49-52), and a maximum number of pixels per scan line (MAXPIX, bytes 57-60). MAXPIX + 24 is the maximum size of a scan line. You may wish to retain the header record while reading each scan line consecutively into another byte array. Each scan line contains LBYTES - 22 pixels (LBYTES from bytes 3-4 of the scan line record). COMMON /MAFIN/IHEAD,ISCAN !minimum ISCAN dimension: BYTE IHEAD(404),ISCAN(174) ! 174 for 35 degree MAFs, ! 600 for 120 degree MAFs, ! 1600 for 360 degree MAFs. INTEGER*2 IWORDS,IBLOCK,IBYTES,NCFLAG,IMSYNC,IDIRCT(7) BYTE MRSRV(8),MNAME(8) INTEGER*4 NTYPE,NYEAR,NDAY,MSEC,ID,NFWV,NFWC,NFWT,MLCA,MLCZ,LINES, & NPIXM,MAXPIX,NDIN(5),NDINGR(2),NDGHSK(2),MMC,NANSUB(4),NORBIT, & NSCGEI(3),NSPIN(3),NORMAL(3),NUIPRO,NVEL(3),NSUN(3),NSPRAT, & MSECOA,NSPNP,MNSPNP,MXSPNP EQUIVALENCE (IHEAD( 1),IWORDS ), (IHEAD( 97), MMC ), & (IHEAD( 3),IBLOCK ), (IHEAD(101),NANSUB(1)), & (IHEAD( 5),IBYTES ), (IHEAD(117),NORBIT ), & (IHEAD( 9), NTYPE ), (IHEAD(121),NSCGEI(1)), & (IHEAD(13), NYEAR ), (IHEAD(133), NSPIN(1)), & (IHEAD(17), NDAY ), (IHEAD(145),NORMAL(1)), & (IHEAD(21), MSEC ), (IHEAD(157),NUIPRO ), & (IHEAD(25), ID ), (IHEAD(161), NVEL(1)), & (IHEAD(29), NFWV ), (IHEAD(173), NSUN(1)), & (IHEAD(33), NFWC ), (IHEAD(185),NSPRAT ), & (IHEAD(37), NFWT ), (IHEAD(189),MSECOA ), & (IHEAD(41), MLCA ), (IHEAD(193), NSPNP ), & (IHEAD(45), MLCZ ), (IHEAD(197),MNSPNP ), & (IHEAD(49), LINES ), (IHEAD(201),MXSPNP ), & (IHEAD(53), NPIXM ), (IHEAD(205),NCFLAG ), & (IHEAD(57),MAXPIX ), (IHEAD(373), MRSRV(1)), & (IHEAD(61), NDIN(1)), (IHEAD(381), MNAME(1)), & (IHEAD(81),NDINGR(1)), (IHEAD(389),IMSYNC ), & (IHEAD(89),NDGHSK(1)), (IHEAD(391),IDIRCT(1)) INTEGER*4 LMSEC INTEGER*2 LWORDS,LBYTES,LDCU,LOFFST,LNCORR(3),LORDER BYTE MLC,MLAN,LFWP,LSUBCM,LPIXEL(150) !minimum LPIXEL dimension: ! 150 for 35 degree MAFs, ! 576 for 120 degree MAFs, ! 1576 for 360 degree MAFs. EQUIVALENCE (ISCAN( 1),LWORDS), (ISCAN(12),LSUBCM ), & (ISCAN( 3),LBYTES), (ISCAN(13), LDCU ), & (ISCAN( 5), LMSEC), (ISCAN(15),LOFFST ), & (ISCAN( 9), MLC), (ISCAN(17),LNCORR(1)), & (ISCAN(10), MLAN), (ISCAN(23),LORDER ), & (ISCAN(11), LFWP), (ISCAN(25),LPIXEL(1)) OPEN statement: OPEN(UNIT=n,NAME='XXXXXX.MAF',FORM='UNFORMATTED',TYPE='OLD') 1.4 DISPLAYING AN IMAGE Successive pixels within a scan line are conventionally displayed from top to bottom on the view screen. The mirror location counter (MLC) gives the scan line's relative position left to right, as shown in the following table. leftmost center rightmost MLC MLC MLC photometer A 141 80 21 photometer B 133 73 13 photometer C 28 90 148 Each scan line has three pixel correction fields, bytes 17-18, 19-20, and 21-22 (LNCORR above). Added together these give a correction in eighths of pixels for irregularities in S/C nadir determination. A negative total correction indicates the scan line should be shifted up on the screen by that amount, positive indicates a shift down. An additional correction for an early processing problem should be done if the UI PROCESSING DATE (header record bytes 157-158) is before 84/039. If the DCU count (scan line record bytes 13-14) modulo 32 is 0 the scan line should be shifted up one pixel, as in the following algorithm: IF (ISHFT(NUIPRO,-16).LT.16441.AND.MOD(LDCU,32).EQ.0) shift scan line up one pixel Note: If you are using a GEOGRAPHIC or CORRECTED GEOMAGNETIC COORDINATE FILE (.GEO or .CGM) in connection with the MAF, you may align scan lines up and down with the offset in tenths of pixels to the nadir crossing given in bytes 9-10 of each .GEO or .CGM scan line record. If you use that offset for alignment, don't apply either the pixel correction or the additional correction described immediately above as they are already included in the offset. For color table settings the pixel histogram values given in header record bytes 61-88 may be helpful. Pixel values above 127 have the guardian tripped and are usually shown as saturated or blacked out. 2.0*****SAI GEOGRAPHIC COORDINATE FILE (.GEO)**************** Version 1.0, 02-AUG-85 2.1 DESCRIPTION The SAI GEOGRAPHIC COORDINATE FILE contains geographic coordinates for each pixel in one SAI MISSION ANALYSIS FILE (.MAF). The first record in the file is a header record of 200 bytes giving the number of scan line coordinate records following it, the maximum length of those records, and pertinent positional data from the .MAF header record. For each scan line record in the .MAF there is a corresponding coordinate record containing UT and S/C position at the nadir crossing and for each pixel the geographic north latitude and east longitude. When pixels are not on the earth or coordinates cannot be computed for some other reason, latitude and longitude are both set to -300 degrees. All records except the header record are of variable length. All data values are two's complement integers. 2.2 FORMATS HEADER RECORD FORMAT (.GEO) BYTE# DESCRIPTION DEC TYPE 1-2 HEADER RECORD LENGTH (16-BIT WORDS) I*2 3-4 FILE TYPE (.GEO = 10) * 256 + BLOCKING FACTOR " 5-6 HEADER RECORD LENGTH (BYTES) " 7-8 MAXIMUM RECORD LENGTH IN THIS FILE (BYTES) " 9-12 FILE TYPE (.GEO = 10) I*4 13-16 YEAR \ " 17-20 DAY OF YEAR > AT APPROXIMATE START OF IMAGE " 21-24 MILLISECONDS OF DAY / " 25-28 PHOTOMETER ID (1,2,3) " 29-32 FIRST MIRROR LOCATION COUNTER " 33-36 LAST MIRROR LOCATION COUNTER " 37-40 NUMBER OF SCAN LINE COORDINATE RECORDS " 41-44 MILLISECONDS OF DAY FOR ORBIT/ATTITUDE DATA BELOW " 45-48 ORBIT NUMBER " 49-52 X \ " 53-56 Y > S/C POSITION IN GEI COORDINATES (METERS) " 57-60 Z / " 61-64 X(SPIN) \ " 65-68 Y(SPIN) > IN GEI COORD. (UNIT VECTOR * 1.E6) " 69-72 Z(SPIN) / " 73-76 X(NORMAL TO ORBIT) \ " 77-80 Y(NORMAL TO ORBIT) > GEI (UNIT VECTOR * 1.E6) " 81-84 Z(NORMAL TO ORBIT) / " 85-88 VX \ " 89-92 VY > S/C VELOCITY IN GEI (MILLIMETERS/SECOND) " 93-96 VZ / " 97-100 SX \ " 101-104 SY > GEI UNIT VECTOR TOWARD SUN (* 1.E6) " 105-108 SZ / " 109-112 S/C SPIN RATE (W/R/T NADIR, MICRORADIANS/SECOND) " 113-116 NADIR SCAN LINE AVERAGE SPIN PERIOD (MILLISECONDS) " 117-120 MINIMUM RUNNING AVERAGE SPIN PERIOD (MILLISECONDS) " 121-124 MAXIMUM RUNNING AVERAGE SPIN PERIOD (MILLISECONDS) " 125-128 ALTITUDE OF PIXEL COORDINATES (METERS) " 129-176 SPARE 177-184 RESERVED \ BYTE 185-192 ASCII FILE NAME \ " 193-194 MAFCRD VERSION NUMBER >for IOWA use I*2 195-196 HIGH-ORDER CHAR OF INPUT FILE NAME/ " 197-200 INPUT FILE NAME / " SCAN LINE RECORD FORMAT (.GEO) BYTE# DESCRIPTION DEC TYPE 1-2 RECORD LENGTH (16-BIT WORDS) I*2 3-4 RECORD LENGTH (BYTES) " 5-6 NUMBER OF PIXELS IN IMAGE SCAN LINE " 7-8 DIGITAL MIRROR LOCATION COUNTER " 9-10 OFFSET IN TENTHS OF PIXELS FROM START OF SCAN LINE TO NADIR " 11-12 SPARE 13-16 UT (MILLISECONDS) AT NADIR POSITION I*4 17-20 X \ " 21-24 Y > S/C POSITION GEI AT NADIR POSITION (METERS) " 25-28 Z / " 29-30 GEOGRAPHIC NORTH LATITUDE FOR PIXEL 1 (DEGREES*100) (-90 TO 90) I*2 31-32 GEOGRAPHIC EAST LONGITUDE FOR PIXEL 1 (DEGREES*100) (-180 TO 180) " 33-34 GEOGRAPHIC NORTH LATITUDE FOR PIXEL 2 " 35-36 GEOGRAPHIC EAST LONGITUDE FOR PIXEL 2 " . . . . . . . . . (n*4)+25,+26 GEOGRAPHIC NORTH LATITUDE FOR PIXEL n " (n*4)+27,+28 GEOGRAPHIC EAST LONGITUDE FOR PIXEL n " 2.3 READING A .GEO FILE The header record, length 200 bytes, may be read into a byte array in a common block with other data types equivalenced to it, as shown below. The header record gives the number of scan line records (KLINES below, bytes 37-40), and the maximum number of bytes per scan line record (MAXBYT, bytes 7-8). You may wish to retain the header record while reading each scan line coordinate record consecutively into another byte array. Each scan line coordinate record contains coordinates for KBYTES/4 - 2 pixels (KBYTES from bytes 3-4 of the record). COMMON /COORDS/KHEAD,KSCAN !minimum KSCAN dimension: BYTE KHEAD(200),KSCAN(628) ! 628 for 35 degree MAFs, ! 2332 for 120 degree MAFs, ! 6332 for 360 degree MAFs. INTEGER*2 KWORDS,KBLOCK,KBYTES,MAXBYT,MAFCRD,KDIRCT(3) BYTE KRSRV(8),KNAME(8) INTEGER*4 KTYPE,KYEAR,KDAY,KMSEC,KPHOT,KMLCA,KMLCZ,KLINES, & KMSOA,KORBIT,KSCGEI(3),KSPIN(3),KNRMAL(3),KVEL(3),KSUN(3), & KSPRAT,KNSPNP,K1SPNP,K2SPNP,KALTTD EQUIVALENCE (KHEAD( 1),KWORDS), (KHEAD( 49),KSCGEI(1)), & (KHEAD( 3),KBLOCK), (KHEAD( 61), KSPIN(1)), & (KHEAD( 5),KBYTES), (KHEAD( 73),KNRMAL(1)), & (KHEAD( 7),MAXBYT), (KHEAD( 85), KVEL(1)), & (KHEAD( 9), KTYPE), (KHEAD( 97), KSUN(1)), & (KHEAD(13), KYEAR), (KHEAD(109),KSPRAT ), & (KHEAD(17), KDAY), (KHEAD(113),KNSPNP ), & (KHEAD(21), KMSEC), (KHEAD(117),K1SPNP ), & (KHEAD(25), KPHOT), (KHEAD(121),K2SPNP ), & (KHEAD(29), KMLCA), (KHEAD(125),KALTTD ), & (KHEAD(33), KMLCZ), (KHEAD(177), KRSRV(1)), & (KHEAD(37),KLINES), (KHEAD(185), KNAME(1)), & (KHEAD(41), KMSOA), (KHEAD(193),MAFCRD ), & (KHEAD(45),KORBIT), (KHEAD(195),KDIRCT(1)) INTEGER*2 KWRDS,KBYTS,KPIX,KMLC,KOFFST INTEGER*4 NDUTMS,NDPGEI(3) INTEGER*2 KPAIRS(2,150) !minimum KPAIRS dimensions: ! (2, 150) for 35 degree MAFs, ! (2, 576) for 120 degree MAFs, ! (2,1576) for 360 degree MAFs. EQUIVALENCE (KSCAN(1),KWRDS), (KSCAN( 9),KOFFST ), & (KSCAN(3),KBYTS), (KSCAN(13),NDUTMS ), & (KSCAN(5), KPIX), (KSCAN(17),NDPGEI(1) ), & (KSCAN(7), KMLC), (KSCAN(29),KPAIRS(1,1)) OPEN statement: OPEN(UNIT=n,NAME='XXXXXX.GEO',FORM='UNFORMATTED',TYPE='OLD') 3.0*****SAI CORRECTED GEOMAGNETIC COORDINATE FILE (.CGM)**************** Version 1.0, 02-AUG-85 3.1 DESCRIPTION The SAI CORRECTED GEOMAGNETIC COORDINATE FILE contains the corrected geomagnetic latitude, interpolated from the table by Georg Gustafsson, Kiruna Geophysical Institute, Sweden (Epoch 1980), and the magnetic local time in degrees for each pixel in one SAI MISSION ANALYSIS FILE (.MAF), where those coordinates are available. Where corrected geomagnetic latitude is not available, between the geographic latitudes of approximately twelve degrees south and twenty-four degrees north, it is set to -300 degrees. When the pixel is not on the Earth, the corrected geomagnetic latitude and magnetic local time are both set to -300 degrees. Several points near magnetic south in the Gustafsson table have been adjusted to provide a smoother function for interpolation. The first record in the file is a header record of 200 bytes in the same format as the header of the geographic coordinate file above with file type 11. For each scan line record in the .MAF there is a corresponding coordinate record containing UT and S/C position at the nadir crossing and for each pixel the corrected geomagnetic north latitude and magnetic local time. All records except the header record are of variable length. All data values are two's complement integers. 3.2 FORMATS HEADER RECORD FORMAT (.CGM) same as for .GEO file shown above except FILE TYPE = 11 SCAN LINE RECORD FORMAT (.CGM) BYTE# DESCRIPTION DEC TYPE 1-2 RECORD LENGTH (16-BIT WORDS) I*2 3-4 RECORD LENGTH (BYTES) " 5-6 NUMBER OF PIXELS IN IMAGE SCAN LINE " 7-8 DIGITAL MIRROR LOCATION COUNTER " 9-10 OFFSET IN TENTHS OF PIXELS FROM START OF SCAN LINE TO NADIR " 11-12 SPARE 13-16 UT (MILLISECONDS) AT NADIR POSITION I*4 17-20 X \ " 21-24 Y > S/C POSITION GEI AT NADIR POSITION (METERS) " 25-28 Z / " 29-30 CORRECTED GEOMAGNETIC NORTH LATITUDE FOR PIXEL 1 I*2 (DEGREES*100) (-90 TO 90) 31-32 MAGNETIC LOCAL TIME FOR PIXEL 1 (DEGREES*100) (-180 TO 180) " 33-34 CORRECTED GEOMAGNETIC NORTH LATITUDE FOR PIXEL 2 " 35-36 MAGNETIC LOCAL TIME FOR PIXEL 2 " . . . . . . . . . (n*4)+25,+26 CORRECTED GEOMAGNETIC NORTH LATITUDE FOR PIXEL n " (n*4)+27,+28 MAGNETIC LOCAL TIME FOR PIXEL n " 3.3 READING A .CGM FILE Because the formats are nearly identical, a .CGM file may be read into the same equivalenced variable structure as a .GEO file (see 2.3 above). OPEN statement: OPEN(UNIT=n,NAME='XXXXXX.CGM',FORM='UNFORMATTED',TYPE='OLD') 4.0*****CONVERTING COMPRESSED TELEMETRY COUNTS TO KILORAYLEIGHS***** Converting to kilorayleighs requires that the compressed telemetry counts be first converted to true counts per pixel, and that the true counts be multiplied by a sensitivity factor for the filter used for the image, as described below. 4.1 CONVERTING COMPRESSED TELEMETRY COUNTS TO TRUE COUNTS PER PIXEL The compressed telemetry count is r = 16y + x where x and y are the decimal equivalents of the four low-order and four high-order bits, respectively. The true number of counts per image pixel is R, where / x y=0 / R = \ y-1 \ (x+16)2 y>0 If r > 127 the protective circuit has been activated and the data are to be ignored. The following function may be used to convert pixel telemetry counts to true counts. FUNCTION ICOUNT(I) C C ICOUNT RETURNS THE TRUE UNCOMPRESSED COUNT FOR THE GIVEN C TELEMETRY COUNT. C IF (I.LT.128) GO TO 3 ICOUNT = -1 !!!overflow!!! GO TO 99 C 3 IF (I.GT.32) GO TO 40 ICOUNT = I GO TO 99 C 40 IX = MOD(I,16) IY = I/16 ICOUNT = (IX+16) * 2**(IY-1) C 99 RETURN END 4.2 CONVERTING TRUE COUNTS PER PIXEL TO KILORAYLEIGHS True counts can be converted to line-of-sight intensities in kilorayleighs with the sensitivity factors in the tables below. (See Frank et al., Space Science Instrumentation, 5, 369-395, 1981.) The conversion factors used here are based upon pre-launch laboratory calibrations. No corrections are made here for long term changes in sensitivity which have occurred in flight. PHOTOMETER A filter filter analog filter wheel sensitivity in number code position range (counts) counts/(kilorayleigh-pixel) -4 1 360Z 101-107 2.3x10 -4 2 317Z 119-125 5.7x10 3 630W 137-143 0.88 4 557W 155-161 2.40 5 391W 173-179 3.31 6 394B 191-197 1.96 7 626B 209-215 1.08 8 630W 227-233 0.78 9 557N 245 1.30 10 391N 47-53 2.33 11 630N 64-70 0.66 12 557N 82-88 1.60 PHOTOMETER B filter filter analog filter wheel sensitivity in number code position range (counts) counts/(kilorayleigh-pixel) -4 1 629C 62-68 3.2x10 2 630N 82-88 1.31 3 557N 102-109 2.40 4 391N 122-130 4.49 5 630N 143-150 1.19 -4 6 317Z 164-171 4.5x10 7 482M 185-191 7.40 8 554B 204-211 3.85 9 557W 224-231 4.85 10 390W 2-9 5.84 11 630W 22-29 2.00 12 557W 42-48 4.64 PHOTOMETER C filter filter analog filter wheel sensitivity in number code position range (counts) counts/(kilorayleigh-pixel) 1 136W 91-97 1.65 2 123W 110-116 3.08 3 120W 129-135 3.10 4 140N 148-154 1.27 5 136W 167-173 2.05 6 125N 186-193 1.71 7 123W 205-211 3.08 8 117N 224-230 0.84 9 140N 242-245 1.26 10 125N 37-42 1.80 11 117N 54-60 0.91 12 117A 73-79 10.5 5.O*****MISCELLANEOUS INFORMATION*************************************** 5.1 UT OF A PIXEL The UT of each pixel may be calculated from the UT of the nadir crossing (.GEO or .CGM scan line record bytes 13-16) plus 3.90625 milliseconds per pixel times the distance of the pixel from the nadir position in the scan line (.GEO or .CGM scan line record bytes 9-10). 5.2 DEFAULT ALTITUDES USED FOR CALCULATING COORDINATES The coordinates in .GEO and .CGM files are calculated at the following altitudes: photometer filter filter altitude in ID number code kilometers A 4 557W 120.0 5 391W 100.0 6 394B 100.0 7 626B 300.0 8 630W 300.0 B 8 554B 120.0 9 557W 120.0 10 390W 100.0 11 630W 300.0 C 1 136W 100.0 2 123W 200.0 3 120W 200.0 12 117A 200.0 --------------------<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>---------------------