Block diagram
Specpr records are fixed format, 1536 bytes/record. Record number counting starts at 0. Binary data are in IEEE format real numbers and non-byte swapped integers (compatiible with all Sun Microsystems, and Hewlett Packard workstations (Intel and some DEC machines are byte swapped relative to Suns and HPs). Each record may contain different information according to the following scheme.
You can get some library of spectra from ftp://ftpext.cr.usgs.gov/pub/cr/co/denver/speclab/pub/spectral.library/splib06.library/
This page hosts a formal specification of SPECtrum Processing Routines Data Format 3/4/88 using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
meta:
id: specpr
title: "SPECtrum Processing Routines Data Format 3/4/88"
file-extension: spec
license: Unlicense
#encoding: "utf-8"
encoding: "ascii"
endian: be
doc: |
Specpr records are fixed format, 1536 bytes/record. Record number
counting starts at 0. Binary data are in IEEE format real numbers
and non-byte swapped integers (compatiible with all Sun
Microsystems, and Hewlett Packard workstations (Intel and some DEC
machines are byte swapped relative to Suns and HPs). Each record may
contain different information according to the following scheme.
You can get some library of spectra from
ftp://ftpext.cr.usgs.gov/pub/cr/co/denver/speclab/pub/spectral.library/splib06.library/
seq:
- id: records
type: record
repeat: eos
types:
icflag:
doc: "it is big endian"
seq:
- id: reserved
type: b26
- id: isctb_type
type: b1
doc: |
=0 ctb is civil time
=1 ctb is universal time
- id: iscta_type
type: b1
doc: |
=0 cta is civil time
=1 cta is universal time
- id: coordinate_mode
type: b1
doc: |
RA, Dec / Long., Lat flag
=0 the array "ira" and "idec" corresponds to the right ascension and declination of an astronomical object.
=1 the array "ira" and "idec" correspond to the longitude and latitude of a spot on a planetary surface.
- id: errors
type: b1
doc: >
flag to indicate whether or not the data for the error bar (1 sigma standard deviation of the mean) is in the next record set.
=0: no errors, =1: errors in next record set.
# - id: type
# type: b2
# enum: record_type
- id: text
type: b1
doc: |
=0 the data in the array "data" is data
=1 the data in the array "data" is ascii text as is most of the header info.
- id: continuation
type: b1
doc: |
=0 first record of a spectrum consists of: header then 256 data channels
=1 continuation data record consisting of:
# bit flags followed by 1532 bytes of
# real data (bit 1=0) (383 channels)
# or 1532 bytes of text (bit 1=1).
# A maximum of 12 continuation records
# are allowed for a total of 4852
# channels (limited by arrays of 4864)
# or 19860 characters of text (bit 1=1).
instances:
type:
value: text.to_i * 1 + continuation.to_i * 2
enum: record_type
identifiers:
seq:
- id: ititle
type: str
size: 40
pad-right: 0x20
doc: "Title which describes the data"
- id: usernm
type: str
size: 8
doc: "The name of the user who created the data record"
coarse_timestamp:
seq:
- id: scaled_seconds
type: s4
instances:
seconds:
value: scaled_seconds * 24000.
illum_angle:
seq:
- id: angl
type: s4
doc: >
(Integer*4 number, in arc-seconds*6000).
(90 degrees=1944000000; -90 deg <= angle <= 90 deg)
instances:
seconds_total:
value: angl / 6000
minutes_total:
value: seconds_total / 60
degrees_total:
value: minutes_total / 60
data_initial:
seq:
- id: ids
type: identifiers
- id: iscta
type: coarse_timestamp
doc: "Civil or Universal time when data was last processed"
- id: isctb
type: coarse_timestamp
doc: "Civil or Universal time at the start of the spectral run"
- id: jdatea
type: s4
doc: "Date when data was last processed. Stored as integer*4 Julian Day number *10"
- id: jdateb
type: s4
doc: "Date when the spectral run began. Stored as integer*4 Julian Day number *10"
- id: istb
type: coarse_timestamp
doc: "Siderial time when the spectral run started. See flag #05."
- id: isra
type: s4
doc: "Right ascension coordinates of an astronomical object, or longitude on a planetary surface (integer*4 numbers in seconds *1000) (RA in RA seconds, Longitude in arc-seconds) See flag #06."
- id: isdec
type: s4
doc: "Declination coordinates of an astronomical object, or latitude on a planetary surface (integer*4 number in arc-seconds *1000). See flag #06."
- id: itchan
type: s4
doc: "Total number of channels in the spectrum (integer*4 value from 1 to 4852)"
- id: irmas
type: s4
doc: "The equivalent atmospheric thickness through which the observation was obtained (=1.0 overhead scaled: airmass*1000; integer*4)."
- id: revs
type: s4
doc: "The number of independent spectral scans which were added to make the spectrum (integer*4 number)."
- id: iband
type: s4
doc: "The channel numbers which define the band normalization (scaling to unity). (integers*4)."
repeat: expr
repeat-expr: 2
- id: irwav
type: s4
doc: "The record number within the file where the wavelengths are found (integer*4)."
- id: irespt
type: s4
doc: "The record pointer to where the resolution can be found (or horizontal error bar) (integer*4)."
- id: irecno
type: s4
doc: "The record number within the file where the data is located (integer*4 number)."
- id: itpntr
type: s4
doc: "Text data record pointer. This pointer points to a data record where additional text describing the data may be found. (32 bit integer)"
- id: ihist
type: str
size: 60
pad-right: 0x20
doc: "The program automatic 60 character history."
- id: mhist
type: str
size: 74
doc: "Manual history. Program automatic for large history requirements."
repeat: expr
repeat-expr: 4
- id: nruns
type: s4
doc: "The number of independent spectral runs which were summed or averaged to make this spectrum (integer*4)."
- id: siangl
type: illum_angle
doc: >
The angle of incidence of illuminating radiation
integrating sphere = 2000000000
Geometric albedo = 2000000001
- id: seangl
type: illum_angle
doc: >
The angle of emission of illuminating radiation
integrating sphere = 2000000000
Geometric albedo = 2000000001
- id: sphase
type: s4
doc: >
The phase angle between iangl and eangl
(Integer*4 number, in arc-seconds*1500).
(180 degrees=972000000; -180 deg <= phase <= 180 deg)
integrating sphere = 2000000000
- id: iwtrns
type: s4
doc: "Weighted number of runs (the number of runs of the spectrum with the minimum runs which was used in processing this spectrum, integer*4)."
- id: itimch
type: s4
doc: "The time observed in the sample beam for each half chop in milliseconds (for chopping spectrometers only). (integer*4)"
- id: xnrm
type: f4
doc: "The band normalization factor. For data scaled to 1.0, multiply by this number to recover photometric level (32 bit real number)."
- id: scatim
type: f4
doc: "The time it takes to make one scan of the entire spectrum in seconds (32 bit real number)."
- id: timint
type: f4
doc: "Total integration time (usually=scatime * nruns) (32 bit real number)."
- id: tempd
type: f4
doc: "Temperature in degrees Kelvin (32 bit real number)."
- id: data
type: f4
doc: "The spectral data (256 channels of 32 bit real data numbers)."
repeat: expr
repeat-expr: 256
instances:
phase_angle_arcsec:
value: sphase / 1500.
doc: "The phase angle between iangl and eangl in seconds"
data_continuation:
seq:
- id: cdata
type: f4
repeat: expr
repeat-expr: 383
doc: "The continuation of the data values (383 channels of 32 bit real numbers)."
text_initial:
seq:
- id: ids
type: identifiers
- id: itxtpt
type: u4
doc: "Text data record pointer. This pointer points to a data record where additional text may be may be found."
- id: itxtch
type: s4
doc: "The number of text characters (maximum= 19860)."
- id: itext
type: str
size: 1476
doc: "1476 characters of text. Text has embedded newlines so the number of lines available is limited only by the number of characters available."
text_continuation:
seq:
- id: tdata
type: str
size: 1532
doc: "1532 characters of text."
record:
seq:
- id: icflag
type: icflag
doc: "Total number of bytes comprising the document."
- id: content
size: 1536 - 4
type:
switch-on: icflag.type
cases:
'record_type::data_initial': data_initial
'record_type::data_continuation': data_continuation
'record_type::text_initial': text_initial
'record_type::text_continuation': text_continuation
enums:
record_type: # if I use 0b notation it doesn't work
0: data_initial
2: data_continuation
1: text_initial
3: text_continuation