File Naming Conventions

where

VVVV = the vehicle mission number

NNNNN = the orbit number

SS = the segment number
Example: ULI_5007_00013_00.PREP

SDF1 Files: ULI_VVVV_NNNNN.SDF1

where

VVVV = the vehicle mission number

NNNNN = the orbit number
Example: ULI_5007_00013.SDF1

SDF2 Files: ULI_VVVV_FFF_NNNNN.SDF2

where

VVVV = the vehicle mission number

FFF = the spectral feature that the file contains

NNNNN = the orbit number
Example: ULI_5007_834_00013.SDF2

EDF Files: ULI_VVVV_SS_NNNNN.EDF

where

VVVV = the vehicle mission number

SS = the species that the file contains

NNNNN = the orbit number
Example: ULI_5007_N2_00013.EDF

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SDF and EDF Data Types

The SDFs and EDFs are stored in ASCII format for ease of viewing and ease of transport between systems. All values are named, and the names given in the "Item" column will appear in the file, as specified in the tables for each file's format. All values with associated uncertainties are listed as a pair of floating/fixed point reals, in ASCII.

The following table lists some of the common formats used within the sensor and environmental data files:

Table 1. Common Data Formats

Data Type	Description
	Sample Format	Sample Entry
Raw ASCII Text	Straight ASCII text without a field name. This format is used only for the file type identifiers on the first line of each file.
	N/A	SSULI SDF2
Text String	Textual data. This format indicates the data value is specified as a string of characters. The number of characters never exceeds 63, by arbitrary decree.
	Text String	LBH1
	Text string	Dayside Ionosphere Algorithm v2.01
Integer	Simple integer data. The format gives the maximum width require by the item, though fewer characters may be present. There is no uncertainty value paired with values which are formatted as Integers.
	Integer 4	-124
	Integer 2	3
Fixed point	Fixed-point data. This format first gives the (maximum) width of the portion of the number to the left of the decimal point, followed by the decimal point itself, ".", followed by the width of the fractional part of the number (the part to the right of the decimal point). A space character, " ", is then given, followed by formatting information for the number's uncertainty. The uncertainty format is specified like the number itself.
	Fixed 4.2 1.2	-125.34 0.67
	Fixed 4.2 2.1	123.45 6.7
Floating point	Floating-point data. This format first gives a mandatory "1.", followed by a width (indicating the number of digits following the decimal point), followed by "E", followed finally by the width of the exponent. The uncertainty format is specified like the number itself.
	Float 1.5E2 1.2E2	-1.34000E-10 3.67E-11
	Float 1.3E2 1.1E2	3.452E10 2.5E08
Time	Date & time data. This format specifies the time in a single fixed format: "YYYY.MM.DD hh:mm:ss.HH uuuu.uu". "YYYY" is the four-digit year, "MM" is the month (starting with January = 01), "DD" is the day of the month (01-31), "hh" is the hour in the 24-hour day (00-23), "mm" is the minute (00-59), "ss" is the second (00-60, where 60 is used for leap seconds, if necessary), "HH" is the hundredth of a second, and "uuu.uu" is the uncertainty in the time, in seconds. All of these values are numeric and are 0-padded (except for the seconds portion of the uncertainty, which may or may not be padded).
	November 20th of 1990, 1:30 pm, +/- eleven minutes	1990.11.20 13:30:00.00 660.00
Quality Level	Quality level (integer) number, 0 .. 100, where 100 is the highest quality.
	Quality Level	85
Scan Mode	Instrument mode when the scan was taken, ranging from 0 to 7. The modes associated with the numbers are: Number Mode Name Description 0 Primary Two segments in 90s with a 5.1s flyback. I. -10.0° to -18.5° in 30s (.2834 °/s) II. -18.5° to -27.0° in 60s (.1417 °/s) 1 Overlap Three Segments in 120s with a 9s flyback. I. -10.0° to -18.5° in 30s (.2834 °/s) II. -18.5° to -27.0° in 60s (.1417 °/s) III. -27.0° to -40.0° in 30s (.4333 °/s) 2 Reduced A One segment in 45s with a 2.55s flyback. I. -18.5° to -27.0° in 45s (.1889 °/s) 3 Reduced B One segment in 60s with a 2.55s flyback. I. -18.5° to -27.0° in 60s (.1417 °/s) 4 Dither Two segments in 90s with a 1s flyback I. -18.5° to -27.0° in 45s (.1889 °/s) II. -27.0° to -18.5° in 45s (-.1889 °/s) 5 Ground Site Track Six segments in XXs with a YYs flyback . I. II. III. IV. V. VI. 6 Stellar Track One segment in 90s with a Xs flyback. I. 7 Stare One segment in 90s with a 1s flyback I. 25° for 90s (.0000 °/s)
	Scan Mode	3
Feature String	Feature string. The following are valid feature strings: 834 911 1304 1356 LBH1 LBH2
	Feature String	LBH1
Solar Region	An indication of the scan's tangent location with respect to the sun. One of: Day Night Terminator
	Solar Region	Day
Boolean	A Boolean flag. One of: TRUE FALSE
	Boolean	FALSE
Datatype String	Species datatype string. The following are valid environmental species strings: N2 O2 O O+ T (temperature)
	Datatype String	O+

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Prepfile Format

The SSULI Prepfile acts as the bridge between the database, which receives data from the SSULI instrument, and the Mission Algorithm, which provides the necessary files for the SSULI GDAS application. It is a binary file consisting of the Prepfile Information Record and a number of Seconds Information data (the number of Seconds data is indicated in the first 4 bytes of the Prepfile). Each Seconds data record consists of 52 bytes of Spacecraft Information and a 315 byte Data Frame.

Prepfile Information Record Contains basic information about the entire file structure.
Byte	Description	Data Type
0-3	Number of "second" records in prepfile	unsigned integer
4-7	Mission ID	char[4]
8-11	First year of start record	unsigned integer
12-15	First Julian Day of start record	unsigned integer
16-19	First Second of start record	double
Seconds Information Each second of data in the prepfile contains both a Spacecraft Information and Data Frame data structure.
Spacecraft Information
0-7	Spacecraft x-axis position	double
8-15	Spacecraft y-axis position	double
16-23	Spacecraft z-axis position	double
24-31	Spacecraft x-axis orientation	double
32-39	Spacecraft y-axis orientation	double
40-47	Spacecraft z-axis orientation	double
48-51	Spacecraft orbit number	unsigned integer
Data Frame
The SSULI prepfile distinguishes between 3 data frame formats dependent upon the mode of operation. One full scan consists of around 90 scan angles in addition to the mirror flyback. The 90 scan angles are encoded as Type 1A frames whereas a Type 1B frame is generated at the beginning of the mirror flyback frame. Type 1C frames are generated for the remainder of the mirror flyback time or if SSULI is not in mirror scan mode. Each frame consists of 315 bytes. Type 1A - Wavelength Data Type 1B - Pulse Height and Atypical Information Type 1C - Fill Data

Table 2. Prepfile Information Record

SSULI Data Frame Types

Byte	Description
	Type 1A Frame	Type 1B Frame	Type 1C Frame
0	Frame Type Low	Frame Type Low	Frame Type Low
1	Frame Type High	Frame Type High	Frame Type High
2	Encoder Low	Reserved	Reserved
3	Encoder High	Reserved	Reserved
4	Total Event Count Low	Reserved	Reserved
5	Total Event Count High	Reserved	Reserved
6	Location 0	Location 0 Low	Location 0
.	Location 1	Location 0 High	Location 1
.	Location 2	Location 1 Low	Location 2
.	256 9-Bit Location Counts 288 Bytes Wavelength Data 5 Mantissa/4 Exponent	144 16-Bit Locations Pulse Height & Atypical Data 11 Mantissa/5 Exponent	288 8-Bit Location Counts Fill Data = 01 hex
.	Location 254	Location 143 Low	Location 286
293	Location 255	Location 143 High	Location 287
294	Telemetry Count	Telemetry Count	Telemetry Count
295	Point 1	Point 1	Point 1
.	Point 2	Point 2	Point 2
.	16 Bytes of Telemetry	16 Bytes of Telemetry	16 Bytes of Telemetry
.	Point 15	Point 15	Point 15
310	Point 16	Point 16	Point 16
311	Reserved	Reserved	Reserved
312	Reserved	Reserved	Reserved
313	Checksum Low	Checksum Low	Checksum Low
314	Checksum High	Checksum High	Checksum High

Table 3. SSULI Data Frame Types

Type 1 Data Frame Specifications

Data Element	Specification
Header: Type 1A Type 1B Type 1C	1AC3 hex 1BC3 hex 1CC3 hex
ENCODER: Type 1A Type 1B & 1C	Mirror Position (referenced to the beginning of the sample period relative to the data contained within the same frame). 0 to 22.5 degrees (3.433E-4 degree/bit) 0000 hex
TOTAL EVENT COUNT: Type 1A Type 1B & 1C	Total Event Count is in the same compressed format as pulse height data Reserved (0000 hex)
LOCATION 0-255: TYPE 1A TYPE 1B TYPE 1C	Wavelength Data - 5 LSBs of a 6-bit mantissa (MSB always equals 1) and a 4-bit exponent. Location(0) corresponds to Wavelength Accumulator 0. Pulse Height and Atypical Information - 11 LSBs of a 12-bit mantissa (MSB always equals 1) and a 5-bit exponent. ** Location[0] = Pulse Height[0], Location[127] = Pulse Height[127], Location[128] = Atypical[0], Location[143] = Atypical[15] Fill Data = 0000 0001 binary
TELEMETRY COUNT	8-Bit Incrementing Counter. Counts ending in 00 contain bytes 0-15 of the telemetry table Counts ending in 01 contain bytes 16-31 of the telemetry table Counts ending in 10 contain bytes 32-47 of the telemetry table Counts ending in 11 contain bytes 48-63 of the telemetry table
TELEMETRY DATA	Refer to the Telemetry Array Format table.
CHECKSUM	16-Bit Checksum of bytes 0-312 (initial value of 0).

Telemetry Array Format

Telemetry Count = 0
Byte	Description	Measurement Range (Binary Range)
0	USA HV A Supply	0 to -8333 Vdc (00h to FFh)
1	USA HV B Supply	0 to -8333 Vdc (00h to FFh)
2	Mirror Motor Temp	-30C to +80C (87h to C0h)
3	Detector Temp	-30C to +80C (87h to C0h)
4	Detector Electronics Temp	-30C to +80C (87h to C0h)
5	Mirror Temp	-30C to +80C (87h to C0h)
6	USA HV A Current	0 to 25mA (80h to FFh)
7	USA HV B Current	0 to 25mA (80h to FFh)
8	Sun Sensor A	0 to 15mA (80h to FFh)
9	Sun Sensor B	0 to 15mA (80h to FFh)
10	+13.5 Vdc Voltage	0 to 33.7 Vdc (80h to FFh)
11	+5 Vdc Voltage	0 to 13.3 Vdc (80h to FFh)
12	SCE Temp A	-30C to +70C (87h to C0h)
13	-13.5 Vdc Voltage	0 to -33.7 Vdc (80h to 00h)
14	Input current Monitor	0 to 2 Amps (80h to FFh)
15	SCE Temp B	-30C to +70C (87h to C0h)
Telemetry Count = 1
Byte	Description	Measurement Range (Binary Range)
16	+15 Vdc Voltage	0 to 20 Vdc (80h to FFh)
17	-15 Vdc Voltage	0 to -20 Vdc (80h to FFh)
18	Mirror Motor Drive Voltage	-15 to +15V (00h to FFh)
19	Mirror Motor Drive Current	-1500 to +1500 mA (00h to FFh)
20	Mirror Motor DAC	-10 Vdc to +10 Vdc (00h to FFh)
21	HVPS Temp A	-30C to +70C (87h to C0h)
22	HVPS Temp B	-30C to +70C (87h to C0h)
23	Grating Temp	-30C to +70C (87h to C0h)
24	3.7 Vdc Reference	0 to +5V (80h to FFh)
25	+HVPSA TLM	0 to 33.7 Vdc (80h to FFh)
26	-HVPSA TLM	0 to -33.7 Vdc (80h to 00h)
27	+HVPSV TLM	0 to 33.7 Vdc (80h to FFh)
28	-HVPSV TLM	0 to -33.7 Vdc (80h to 00h)
29	Spare
30	Spare
31	0 Volt Reference	-5V to +5V (00h to FFh)
Telemetry Count = 2
Byte	Description	Bit Definition
32	SCE State Code: bit 0 - bit 1 - bit 2- bit 3 - bit 4 - bit 5 - bit 6 - bit 7 -	SCE operational state code register: SCE State Code 0 SCE State Code 1 SCE State Code 2 SCE State Code 3 SCE State Code 4 undefined undefined undefined
33	Scan Profile Register: bit 2:0 - bit 4 - bit 5 - bit 6 - bit 7 -	0 to 7 Scan Select Overflow Status Command Overflow Status BIT Error New Scan Flag
34	Operational Error Reg: bit 0 - bit 1 - bit 2 - bit 3 - bit 4 - bit 5 - bit 6 - bit 7 -	OLS Overflow Self-Test Error Command Error ADC Timeout MDI Interface Overflow OLS Interface Underflow Command Interface Overflow Mirror Motor Error
35	Self-Test Error Reg Low: bit 0 - bit 1 - bit 2 - bit 3 - bit 4 - bit 5 - bit 6 - bit 7 -	CPU Fail spare Data RAM Test Fail Real-time Interrupt Fail Motor Drive Voltage Fail Motor R to D Error Voltage Fail Motor DAC Motor Control Loop Fail
36	Self-Test Error Reg High: bit 0 - bit 1 - bit 2 - bit 3 - bit 4 - bit 5 - bit 6 - bit 7 -	MDI Not Reply Fail MDI Data Mismatch Fail ADC Conversion Timeout Fail ADC Ref Voltage Fail OLSI Byte Not Sent Fail OLSI Byte Not Received Fail OLSI Data Mismatch Pwr Fail
37	Mirror Motor State Register	State Code (bits 2-0)
38	HiV Register: bit 0 - bit 1 - bit 2 - bit 3 - bit 4 - bit 5 - bit 6 - bit 7 -	Adjust 0 Adjust 1 Adjust 2 Adjust 3 HV B On HV A On HV B ARM HV A ARM
39	Discrete Status Reg Low: bit 0 - bit 1 - bit 2 - bit 3 - bit 4 - bit 5 - bit 6 - bit 7 -	HVB RPI HVA RPI Dust Closed Dust Open spare Dust Activated Door Closed Door Open
40	Discrete Status Reg High: bit 0 - bit 1 - bit 2 - bit 3 - bit 4 - bit 5 - bit 6 - bit 7 -	WDT SP4 spare spare spare spare spare spare
41	Flag Register Low: bit 0 - bit 1 - bit 2 - bit 3 - bit 4 - bit 5 - bit 6 - bit 7 -	Mirror Motor ON Flag Dust Cover Actuate Flag Door/Dust ARM Flag Door OPEN Flag Door CLOSE Flag Dust Operate Flag Door Operate Flag Simulated Data Flag
42	Flag Register High: bit 0 - bit 1 - bit 2 - bit 3 - bit 4 - bit 5 - bit 6 - bit 7 -	Park Mirror Flag Forward Scan Flag Flyback Flag State Mode Flag Any Dump Memory Flag Wavelength Array A/B Flag *flag Comp. Direction Flag
43	Sun A Threshold Register	Commanded Sun Sensor A threshold (bits 2-0)
44	Sun B Threshold Register	Commanded Sun Sensor B threshold (bits 2-0)
45	Dump Memory Register: bit 0 - bit 1 - bit 2 - bit 3 - bit 4 -	Dump I/O Map Dump program PROM Dump program RAM Dump data RAM Dump EEPROM
46	Mirror Motor Error Low	Current mirror position error (bits 7-0)
47	Mirror Motor Error High	Current mirror position error (bits 15-8)
Telemetry Count = 3
Byte	Description	Bit Definition
48	Scan Profile Pointer Low	Scan profile pointer (bits 7-0)
49	Scan Profile Pointer High	Scan profile pointer (bits 15-8)
50	Sequence Velocity low	Sequence velocity (bits 7-0)
51	Sequence Velocity High	Sequence velocity (bits 15-8)
52	Sequence Position Low	Sequence position (bits 7-0)
53	Sequence Position High	Sequence position (bits 15-8)
54	Computed Velocity Low	Computed velocity (bits 7-0)
55	Computed Velocity High	Computed velocity (bits 15-8)
56	Max Mirror Motor Error Low	Max mirror position error per scan (bits 7-0)
57	Max Mirror Motor Error High	Max mirror position error per scan (bits 15-8)
58	Max Command Current Low	Max command current (bits 7-0)
59	Max Command Current High	Max command current (bits 15-8)
60	Computed Reference Position Low	Computed reference position (bits 7-0)
61	Computed Reference Position High	Computed reference position (bits 15-8)
62	Valid Command Count:	Number of valid commands received
63	Command Byte	Last command received

Table 4. Telemetry Array Format

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Sensor Data Records (SDRs)

There are two types of Sensor Data Records (SDRs). The first type, SDR1, consists of the sensor data for all of the wavelength bins in the instrument. The second type, SDR2, contains similar sensor data, but extracted for one of six particular spectral features: 834 Angstroms (A), 911 A, 1304 A, 1356 A, and Lyman/Birge/Hopfield Bands 1 and 2 (LBH1 and LBH2). The sensor data in both SDF1s and SDF2s are calibrated and are measured in rayleighs, as opposed to the photon counts contained in the SSULI Prepfile .

SDR Calibration

SSULI sensor data are calibrated before being written to SDFs. This means that properties of the instrument itself, which have been measured either in the laboratory before launch or during calibration periods on orbit, are used to adjust the photon counts as read out of the SSULI Prepfile. The major elements of the calibration process are:

• Convert lookangles to altitudes using ephemeris information.
• Change pixel (bin) to wavelength.
• Convert photon counts to rayleighs.
• Subtract background.
• Adjust for differences over lookangle and wavelength.
• Fit to the linearity of the detector.
• Star extraction.

For SDF2s, there is an additional step of feature extraction, which deconvolutes the specific spectral features from raw spectral data.

The specifics of SDR calibration can be found in the SSULI Calibration Algorithm document.

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SDF1 File Format

The SDF1 file contains all of the calibrated sensor data from the instrument.

Item	Description	Type		Format			Units	Nominal Value	Min Value	Max Value
Header Record Format
SSULI SDF1	File type identifier. The first SDF1 line contains the raw ASCII text SSULI SDF1 followed by a line delimiter. This should allow quick identification of the file type by eye as well as by machine.	Raw ASCII		Verbatim			-	-	-	-
instrument	The instrument number, according to its mission ID.	Text String		Valid Mission Ids			-	-	-	-
calibration	Calibration file used.	Text String		Valid VMS filename			-	-	-	-
orbit	The number of the current orbit [readout rev?].	Integer		nnnnn			-	-	1	99999
scans	The number of scans contained in this file. Each scan is then listed along with its data (see scan, below).	Integer		nn			-	67	0	99
Sensor Data Record (SDR1) Format (Repeats for the number of scans specified)
scan	The scan record number. Signifies the start of a new sensor data record.	Integer		nn			-	-	1	scans
quality	The quality of the input data for this scan, as a summary of estimations derived from each phase of calibration and preparation.	Integer		Valid Quality Level nnn			-	-	0	100
mode	The instrument mode for this scan.	Integer		Valid scan mode n			-	-	1	7
time	The date and time (Universal Time) at the lowest point of the scan. The uncertainty includes any adjustments from the most recent time given in the ephemeris record.	Date & Time		YYYY.MM.DD hh:mm:ss.HH uuuu.uu			-	-	-	-
lookangles	The number of lookangles in the scan.	Integer		nnn			-	Near 90	0	999
obs radius	The radius of the earth at the satellite's latitude and longitude followed by the radius variant.	Fixed	Fixed	Value nnnn.n		Variant nn.n	km	-	6300.0	6500.0
obs lat	The satellite latitude at the lowest point of the scan followed by the latitude variant.	Fixed	Fixed	Value nn.nnnnnn		Variant nn.nnnnn	Degrees	-	-90.000000	90.000000
obs lon	The satellite longitude at the lowest point of the scan followed by the longitude variant.	Fixed	Fixed	Value nnn.nnnnnn		Variant n.nnnnnn	Degrees	-	-179.000000	180.000000
obs alt	The satellite altitude at the lowest point of the scan followed by the altitude variant.	Fixed	Fixed	Value nnnn.nnn		Variant nnnn.nnn	km	875.000	0.000	1000.000
tangent radius	The radius of the earth at the tangent latitude and longitude followed by the radius variant.	Fixed	Fixed	Value nnnn.n		Variant nn.n	km	-	6300.0	6500.0
tangent lat	The tangent latitude at the lowest point of the scan followed by the latitude variant.	Fixed	Fixed	Value nn.nnnnnn		Variant n.nnnnnn	Degrees	-	-90.000000	90.000000
tangent lon	The tangent longitude at the lowest point of the scan followed by the longitude variant.	Fixed	Fixed	Value nnn.nnnnnn		Variant n.nnnnnn	Degrees	-	-179.000000	180.000000
tangent alt	The tangent altitude at the lowest point of the scan followed by the altitude variant.	Fixed	Fixed	Value nnnn.nnn		Variant nnnn.nnn	km	875.000	0.000	1000.000
tangent sza	The solar zenith angle at the lowest point of the scan followed by the angle variant.	Fixed	Fixed	Value nnn.nnn		Variant n.nnn	Degrees	-	0.000	180.000
obs orient	The satellite's orientation unit vector, indicating which direction the satellite is facing in [TBD] coordinates followed by the orientation variant. The obsdir keyword is followed by three values for the three components of the vector.	Fixed	Fixed	Value n.nnnnn		Variant n.nnnnn	-	-	-1.00000	1.00000
lookangle	Following this keyword are the lookangles different lookangles for the scan.	Fixed	Fixed	Value nnn.nn	Variant n.nnn		-	108.00-128.00	0.00	359.99
bins	The number of detector bins represented in the scan.	Integer		nnn			-	-	-	-
sample	Current sample number for the scan. A sample is a single sweep of the detector, which occurs once per second (which is the same as once per lookangle, since lookangles are measured at each sweep through the detector, too). Following the sample keyword and its integer value are the 256 samples from the detector.	Integer		nnn			-	-	1	lookangles
	The calibrated intensity measured in each of the 256 detector bins for the current sample (lookangle) of the scan.	Float	Float	Value n.nnnnEn	Variant n.nnEn		-	-	0.0000E+00	-

Sample SDF1

Due to the large size of SDF1 files (29MB), the following SDF1 file contains the header and scan data down to the bins of the first lookangle. It contains each field identified in Table 5, but the numbers of a couple items (scans and samples) are atypical.

Sample SDF1 File: ULI_5007_00013.SDF1

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SDF2 File Format

The SDF2 file contains all of the calibrated sensor data from the instrument for a single spectral feature. The possible features extracted are "834", "911", "1304", "1356", "LBH1" and "LBH2". The feature is specified in the first data item of each SDF2.

The nominal, minimum, and maximum values fields apply to the value specified not the variant.

Item	Description	Type		Format			Units	Nominal Value	Min Value	Max Value
Header Record Format
SSULI SDF2	File type identifier. The first SDF2 line contains the raw ASCII text SSULI SDF2 followed by a line delimiter. This should allow quick identification of the file type by eye as well as by machine.	Raw ASCII		Verbatim			-	-	-	-
instrument	The instrument number, according to its mission ID.	Text String		Valid Mission Ids			-	-	-	-
calibration	Calibration file used.	Text String		Valid VMS filename			-	-	-	-
orbit	The number of the current orbit [readout rev?].	Integer		nnnnn			-	-	1	99999
feature	Valid SSULI spectural features.	Text String		Valid features			-	LBH1	-	-
scans	The number of scans contained in this file. Each scan is then listed along with its data (see scan, below).	Integer		nn			-	67	0	99
Sensor Data Record (SDR2) Format (Repeats for the number of scans specified)
scan	The scan record number. Signifies the start of a new sensor data record.	Integer		nn			-	-	1	scans
quality	The quality of the input data for this scan, as a summary of estimations derived from each phase of calibration and preparation.	Integer		Valid Quality Level nnn			-	-	0	100
mode	The instrument mode for this scan.	Integer		Valid scan mode n			-	-	1	7
time	The date and time (Universal Time) at the lowest point of the scan. The uncertainty includes any adjustments from the most recent time given in the ephemeris record.	Date & Time		YYYY.MM.DD hh:mm:ss.HH uuuu.uu			-	-	-	-
lookangles	The number of lookangles in the scan.	Integer		nnn			-	Near 90	0	999
obs radius	The radius of the earth at the satellite's latitude and longitude followed by the radius variant.	Fixed	Fixed	Value nnnn.n		Variant nn.n	km	-	6300.0	6500.0
obs lat	The satellite latitude at the lowest point of the scan followed by the latitude variant.	Fixed	Fixed	Value nn.nnnnnn		Variant nn.nnnnn	Degrees	-	-90.000000	90.000000
obs lon	The satellite longitude at the lowest point of the scan followed by the longitude variant.	Fixed	Fixed	Value nnn.nnnnnn		Variant n.nnnnnn	Degrees	-	-179.000000	180.000000
obs alt	The satellite altitude at the lowest point of the scan followed by the altitude variant.	Fixed	Fixed	Value nnnn.nnn		Variant nnnn.nnn	km	875.000	0.000	1000.000
tangent radius	The radius of the earth at the tangent latitude and longitude followed by the radius variant.	Fixed	Fixed	Value nnnn.n		Variant nn.n	km	-	6300.0	6500.0
tangent lat	The tangent latitude at the lowest point of the scan followed by the latitude variant.	Fixed	Fixed	Value nn.nnnnnn		Variant n.nnnnnn	Degrees	-	-90.000000	90.000000
tangent lon	The tangent longitude at the lowest point of the scan followed by the longitude variant.	Fixed	Fixed	Value nnn.nnnnnn		Variant n.nnnnnn	Degrees	-	-179.000000	180.000000
tangent alt	The tangent altitude at the lowest point of the scan followed by the altitude variant.	Fixed	Fixed	Value nnnn.nnn		Variant nnnn.nnn	km	875.000	0.000	1000.000
tangent sza	The solar zenith angle at the lowest point of the scan followed by the angle variant.	Fixed	Fixed	Value nnn.nnn		Variant n.nnn	Degrees	-	0.000	180.000
obs orient	The satellite's orientation unit vector, indicating which direction the satellite is facing in [TBD] coordinates followed by the orientation variant. The obsdir keyword is followed by three values for the three components of the vector.	Fixed	Fixed	Value n.nnnnn		Variant n.nnnnn	-	-	-1.00000	1.00000
lookangle	Following this keyword are the lookangles different lookangles for the scan.	Fixed	Fixed	Value nnn.nn	Variant n.nnn		-	108.00-128.00	0.00	359.99
bins	The number of detector bins represented in the scan.	Integer		nnn			-	-	-	-
sample	Current sample number for the scan. A sample is a single sweep of the detector, which occurs once per second (which is the same as once per lookangle, since lookangles are measured at each sweep through the detector, too). Following the sample keyword and its integer value are the 256 samples from the detector.	Integer		nnn			-	-	1	lookangles
	The calibrated intensity measured in each of the 256 detector bins for the current sample (lookangle) of the scan.	Float	Float	Value n.nnnnEn	Variant n.nnEn		-	-	0.0000E+00	-

 

Sample SDF2

The following is a sample SDF2 file. It contains each field identified in Table 6, but the numbers of scans and samples are atypical.

Sample SDF2 File: ULI_5007_834_00013.SDF2

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Environmental Data Files (EDFs)

The Naval Research Laboratory (NRL) has developed a set of science algorithms which are used to determine the temperature and the neutral and ionic composition of the upper atmosphere given the observations made by SSULI. The resulting densities (and temperatures) are called Environmental Data Records (EDRs) and are stored in Environmental Data Files (EDFs).

The file format outlined below includes the EDF header block followed by a single environmental data record (EDR). The EDF header block ends with the SCANS field and the EDR block begins with the SCAN field. The value of SCANS denotes how many EDRs there are in an EDF.

EDF File Format

Each EDF contains profiles along an altitude grid of a single species (or temperature): "N2", "O2", "O", "O+" and "Temperature" (temperature).

The nominal, minimum, and maximum values fields apply to the value specified not the variant.