**Combined Release and Radiation Effects Satellite (CRRES)**

**High Energy Electron Fluxmeter (HEEF)**

**and**

**Proton Telescope** (**PROTEL)**

**The HEEF and PROTEL databases have been generated by the**

**US Air Force Research Laboratory (AFRL), Space Vehicles Directorate
(AFRL/VS)**

**16 October 2001**

**For further information, contact**

**Dr. Donald Brautigam**

**AFRL/VSBXR**

**Hanscom AFB, MA 01731**

**email: Donald.Brautigam@hanscom.af.mil**

**phone: (781) 377-3890**

**CRRES HEEF and PROTEL Databases**

The Combined Release and Radiation Effects Satellite (CRRES) was
launched on 25 July 1990 and returned data up through 11 October 1991.
The CRRES orbit was 350 km x 36000 km, 18^o^ inclination, with an
orbital period of \~10 hours. Data from the Air Force High Energy
Electron Fluxmeter (HEEF) and Proton Telescope (PROTEL) are organized
into two primary databases per instrument, with separate files for each
orbit. The CRRES magnetometer data were used for the determination of
local pitch angles. One database (with the file extension \'.min\')
provides 1-minute average local pitch angle distributions at the
satellite\'s local spatial coordinates. A second database (with the file
extension \'.pad\') is derived from the first, and provides pitch angle
distributions mapped to the equator as a function of the McIlwain L
parameter (also referred to simply as L-shell or L). The McIlwain L used
for sorting the data was calculated using the combined IGRF85 and
Olson-Pfitzer quiet magnetic field \[1\].

There are several orbits for which no data files exists for one of the
following various reasons: (a) the spacecraft spin rate was decreasing
from its initial rate to its final spin rate of \~2 rpm, (b) there were
no magnetometer data to permit pitch angle identification and binning,
(c) particle data existed but were flagged as bad, or (d) particle data
were not available. These orbits are listed in sections I (HEEF) and II
(PROTEL). There is also an interval of orbits for which a subset of
PROTEL channels are bad and should be avoided. These are also mentioned
in section II.

The HEEF instrument is briefly described in section I, followed by a
description of its \'.min\' (section IA) and \'.pad\' (section IB)
files. The PROTEL instrument is briefly described in section II,
followed by a description of its \'.min\' (section IIA) and \'.pad\'
(section IIB) files.

**I. High Energy Electron Fluxmeter (HEEF)**

The HEEF electron telescope design includes two solid state detectors
(SSDs),a bismuth germanate (BGO) crystal scintillator, and an
anti-coincidence plastic scintillator surrounding the BGO crystal.
Normal HEEF operation requires a triple coincidence between the two
SSD\'s and the BGO, and an anti-coincidence with the plastic
scintillator (to veto particles which exit the BGO without depositing
all of their energy). Assuming a particle trajectory triggers the
particle identification logic, the energy deposition signature (in the
SSDs and BGO) will determine the particle specie (electron, proton) and
energy.

For each SSD, two energy deposition windows (W1,W2) are defined by the
energy thresholds S0, S1, and S2 (W1=S0-S1, W2=S0-S2). For the BGO
crystal, there are 11 energy deposition thresholds which define 10
channel windows. Because of uncertainties in the lowest energy channel,
that channel has been omitted from the database. An electron passing
through HEEF which produces a pulse within a front SSD energy window
(W1F or W2F), a back SSD window (W1B or W2B), and a BGO window, is
assigned to the appropriate differential energy channel. A trajectory
which deposits energy exceeding the thresholds in the front SSD (S1F or
S2F) or the back SSD (S1B or S2B) can be used to determine an
appropriate integral energy channel. In regions where there are no
energetic protons, it is possible to use the (S1F-S2F) and (S1B-S2B)
integral flux differences to provide two electron differential energy
channels (0.65 and 0.95 MeV). A more detailed instrument description is
provided by elsewhere \[2\]. The final set of mid-channel energies
(MeV), determined following a temperature correction mentioned below,
are as follows:

> 1 - 0.65 7 - 3.15 12 - \>0.80 (S2F) 16 - \>1.05 (S2B)

2 - 0.95 8 - 3.75 13 - \>0.50 (S1F) 17 - \>0.85 (S1B)

3 - 1.60 9 - 4.55 14 - \>0.30 (W1F) 18 - \>0.75 (W1B)

4 - 2.00 10 - 5.75 15 - \>0.30 (W2F) 19 - \>0.75 (W2B)

5 - 2.35 11 - 7.50

6 - 2.75

Channels 3-11 are directly measured differential energy channels
\[(cm^2^ sec sr keV)^-1^\] and channels 12-19 are integral energy
channels \[(cm^2^ sec sr)^-1^\]. Channels 1 and 2 are differential
channels computed from integral channels (12,13) and (16,17),
respectively. One note of caution: although the energies are given in
MeV, the energy unit used in the differential flux is keV.

Though this telescope design led to a very \"clean\" measurement of
electrons, the count rates were quite low (maximum of \~100/s for the
lowest energy BGO channel, and \< \~10/s for the higher energy
channels), resulting in significant statistical scatter in the data
(particularly notable in the pitch angle distributions for the higher
energy channels during \"quiet\" periods).

Corrections applied to the HEEF data are briefly mentioned below (A
detailed discussion is found in an AFRL technical report \[3\] available
from AFRL upon request.) :

1\. Temperature correction: There was an unanticipated requirement to
shut off one of the heaters in the satellite compartment where HEEF was
located, causing the temperature to drop from 2^o^ C to -12^o^ C over
the course of the mission. Unfortunately, the BGO crystal response is
strongly temperature dependent. Laboratory modeling was performed on a
second \'backup\' HEEF to determine the necessary temperature
corrections (a factor up to \~50).

2\. Dead-time corrections: Because of the finite temporal response of
the system, the counting logic was \'paralyzed\' under very intense
(\~100 keV) electron fluxes, requiring a correction factor up to \~10
(largest in the front SSD integral energy channels).

The data set is restricted to L \>= 2.5 because fluxes within the inner
belt are contaminated by energetic protons. The integral channels are
unreliable within and below the slot region because of low count rates.
The differential channels (0.65 MeV and 0.95 MeV) derived from the
integral channels are undefined because they often compute to negative
flux values.

The HEEF flux data have been cross-calibrated with CRRES dosimeter flux
data. Fully corrected HEEF differential spectra were convolved with
dosimeter geometric factors to predict dosimeter count rates which
agreed with observed count rates to within a factor of 2 \[3\].

The following orbits are missing from the database:

ORBIT# COMMENTS

001 - 014 Satellite spin decreasing

163 - 164 No Magnetometer data

231 - 236 Data flagged as bad

272 No Magnetometer data

366 - 409 No Magnetometer data

555 No HEEF data

842 - 843 No HEEF data

**IA. HEEF one minute averaged pitch angle data files (\*.min)**

Input for creating this database is the raw data at 0.512 s time
resolution. At 1-minute increments, the high resolution data is sorted
and averaged into 5^o^ local pitch angle bins (19 bins ranging from 0^o^
to 90^o^). The resulting average count rates are corrected for deadtime
and temperature effects, and then converted to flux units. Each 1-minute
record is tagged with two sets of 8 ephemeris values - the first set is
associated with the beginning of the 1-minute interval, the second with
the averaged UT.

There is one file per orbit, with the naming convention:
\'d04xxxx.min\'. The \'d04\' refers to \'data(d) from the HEEF(04)
instrument, and \'xxxx\' is the orbit number (\'0015\' is orbit 15). The
range of orbits is 15 to 1067. The \'.min\' extension designates the
database type. The files are binary and were created as direct access
files using a FORTRAN 77 compiler on a non-DEC UNIX machine ( SGI) so
the byte order in each word may need to be reversed if transporting to a
DEC machine or a PC. The records are a fixed length of 2232 bytes. The
last 2 bytes are zero filled. Some systems require that you define a
record length in 4-byte words. This makes the record length compatible
with 4-byte words. This is easily read with other program languages
since there are no control words etc., added to the end of records or
the file itself. The record structure is described below:

RECORD \# 1 consists of a HEADER. The values in the header are as
follows:

> VALUE 1: ORBIT number - 4 byte integer (10-1067)
>
> VALUE 2: YEAR number - 4 byte integer, should be 90 or 91
>
> VALUE 3: DAY number - 4 byte integer, day of year at start of orbit
> (1-365)
>
> VALUE 4: BSEC - 4 byte integer, UT at beginning of orbit file.
> (0-86399)
>
> VALUE 5: ESEC - 4 byte integer, UT at end of orbit file . (1-\~115000)
>
> VALUE 6: IBR - 4 byte integer, Beginning Record of data ( always 2)
>
> VALUE 7: IER - 4 byte integer, Ending Record of data ( approx. 500 for
> L \>= 2.5 )
>
> VALUE 8-26: ENERGY - 4 byte REAL, 19 mid-channel energies (MeV)
>
> VALUE 27-558: ZEROS, 532- 4 BYTE ZEROS

RECORD #IBR to #IER (defined in record 1 header above)

> VALUE 1-8: 4 byte reals, Ephemeris at beginning of one-minute average.
>
> VALUE 1: UT
>
> VALUE 2: X km (ECI), ECI = Earth Centered Inertial coord. system
>
> VALUE 3: Y km (ECI)
>
> VALUE 4: Z km (ECI)
>
> VALUE 5: SMLAT (Solar Magnetic Latitude)
>
> VALUE 6: SMLT (Solar Magnetic Local Time)
>
> VALUE 7: L-SHELL
>
> VALUE 8: B/B0 - Model
>
> VALUE 9-16: 4 byte reals, Ephemeris for average UT
>
> VALUE 17-377: FLUX(19,19) 4 byte real, 19 channels by 19 pitch angles.
>
> VALUE 17: FLUX(1,1)
>
> VALUE 18: FLUX(2,1)

. . .

> VALUE 377: FLUX(19,19)
>
> VALUE 378-738: NOBS(19,19) 2 byte integer, Number of observations in
> the average FLUX
>
> VALUE 739: DUMMY 2 byte integer

NOTES:

A. ECI = Earth Centered Inertial coord. system

B. Magnetic coordinates computed using IGRF85 + Olson-Pfitzer quiet
static model (1974)

C. L-shell is the McIlwain L-parameter. The single value of L given here
is computed for the case of locally mirroring particles (90^o^ at the
spacecraft location).

D. If there is no data for the 1-minute interval, all the ephemeris
values are set to -1.

E. The last record of every file (# IER) has no data. It provides
ephemeris for the end of the one minute average for the previous record.

F. The pitch angle bins are: 1(0^o^), 2(5^o^) \... 19(90^o^), where the
angle is the middle of the pitch angle bin.

G. A FLUX value of ZERO is a valid FLUX if the corresponding NOBS value
is greater than ZERO.

For further clarification, the following FORTRAN code is provided to
create a listing of flux for each data record for a given channel. This
should be a useful starting point for reading the files.

C HEEF - One minute average sorted by local pitch angle

C Input file = \'d04xxxx.min\' ; Output file = \'d04xxxx.lis\'\'

PROGRAM READ_MIN

REAL\*4 EPHEMA(8),EPHEMB(8),FLUX(19,19),ENERGY(19)

INTEGER\*2 NOBF(19,19),IDUM

INTEGER\*4 IORBIT,IYEAR,IDAY,IBSEC,IESEC,IBR,IER

CHARACTER\*11 INFILE,OUTFILE

DATA inFILE/\'d04xxxx.min\'/

PRINT\*,\'ENTER ORBIT NUMBER:\'

READ(\*,\*)JORBIT

PRINT\*,\'ENTER CHANNEL NUMBER:(1-19)\'

READ(\*,\*)ICH

WRITE(INFILE(4:7),\'(I4.4)\')JORBIT

OUTFILE=INFILE(1:8)//\'lis\'

OPEN(1,FILE=inFILE,ACCESS=\'DIRECT\',RECL=558,ERR=100)

OPEN(2,FILE=OUTFILE)

C HEADER FILE

READ(1,REC=1)IORBIT,IYEAR,IDAY,IBSEC,IESEC,IBR,IER,ENERGY

WRITE(2,21) IYEAR,IDAY,ENERGY(ICH)

21 FORMAT(\' YEAR=\',I4,\' DAY=\',I4,\' ENERGY=\',F5.2,\' MEV\')

WRITE(2,22)IORBIT,IBSEC,IESEC,IER

22 FORMAT(\' ORBIT=\',I4,\' BSEC=\',I6,\' ESEC=\',I6,\' NO. RECORDS=\',

\+ I4)

DO 10 NREC=ibr,ier

WRITE(2,\*)

READ(1,REC=NREC,ERR=100)EPHEMB,EPHEMA,FLUX,NOBF,IDUM

WRITE(2,23)EPHEMB

23 FORMAT(\' BEG EPHEM. \',4F9.1,4F8.3)

write(2,24)EPHEMA

24 FORMAT(\' AVE EPHEM. \',4F9.1,4F8.3)

WRITE(2,25)

25 FORMAT(/,\' Pitch Angle Flux Obs\')

DO 20 IPA=1,19

WRITE(2,26)IPA\*5-5,FLUX(ICH,IPA),NOBF(ICH,IPA)

20 CONTINUE

26 FORMAT(I8,4X,E10.4,i8)

10 CONTINUE

100 CONTINUE

END

**IB. HEEF pitch angle dependent L-shell data files (\*.pad)**

Input for this data set is the 1-minute average database described in
section IA which has been sorted into 5^o^ local pitch angle bins. For
every 1-minute interval (with average UT and local spatial coordinates),
the 19 pitch angles are assigned a McIlwain L from a previously
generated look-up table. The L\'s in the look-up table were computed
using a combined IGRF85 and Olson-Pfitzer quiet static magnetic field
model \[1\]. The local pitch angle distribution is then mapped to the
equator, assuming the conservation of the first adiabatic invariant,
into 0.05 wide L bins. Data determined to be in the loss-cone are
excluded. This procedure is applied to both leg one (first half of
orbit) and leg two ( second half of the orbit).

There is one file per orbit, with the naming convention:
\'d04xxxx.pad\'. The \'d04\' refers to \'data(d) from the HEEF(04)
instrument, and \'xxxx\' is the orbit number (\'0015\' is orbit 15). The
range of orbits is 15 to 1067. The \'.pad\' extension designates the
database type. The files are binary and were created as direct access
files using a FORTRAN 77 compiler on a non-DEC UNIX machine ( SGI) so
the byte order in each word may need to be reversed if transporting to a
DEC machine or a PC. The records are a fixed length of 2176 bytes. The
last 2 bytes are zero filled. Some systems require that you define a
record length in 4-byte words. This makes the record length compatible
with 4-byte words. This format is easily read with other program
languages since there are no control words, etc., added to the end of
records or the file itself. The record structure is described below:

RECORD \# 1 consists of a HEADER. The values in the header are as
follows:

> VALUE 1: ORBIT number - 4-byte integer (15-1067)
>
> VALUE 2: YEAR number - 4-byte integer, should be 90 or 91
>
> VALUE 3: DAY number - 4-byte integer, day of year at start of orbit
> (1-365)
>
> VALUE 4: NREC - 4-byte integer, number of data records after the
> header record, (\<260)
>
> VALUE 5: MAXBIN - 4-byte integer, MAXBIN\*.05+2.45 = Max L-shell
>
> VALUE 6-24: ENERGY - 4-byte REAL, 19 mid-channel energies (MeV)
>
> VALUE 25-544: ZEROS, 520- 4-BYTE ZEROS.

RECORD \# 2 to NREC+1.

> VALUE 1: LEG number - 2-byte integer, 1 for first half of orbit, 2 for
> second half of orbit.
>
> VALUE 2: LSH number - 2-byte integer, represents the beginning of the
> 1/20th of an L-shell bin.
>
> L-shell=LSH\*.05+2.45
>
> VALUE 3: KSEC - 4 byte integer, nearest value of average UT in the LSH
> bin for that LEG.
>
> VALUE 4-364: FLUX(19,19) - 4-byte real, 19 channels by 19 pitch
> angles.
>
> VALUE 4: FLUX(1,1)
>
> VALUE 5: FLUX(2,1)

. . .

> VALUE 364: FLUX(19,19)
>
> VALUE 365-725: NOBS(19,19) 2-byte integer, Number of observations in
> the average FLUX
>
> VALUE 726: DUMMY 2-byte integer

NOTES:

A. UT is from beginning day of orbit, so that if there is a cross-over
from one day to the next within a given orbit, KSEC will exceed the
total number of seconds in a day (86400). That is, the full range of
KSEC can be 0 - \~115,000.

B. If there is no data for the 1-minute interval, all the ephemeris
values are set to -1.

C. The pitch angle bins are: 1(0^o^), 2(5^o^) \... 19(90^o^), where the
angle is the middle of the pitch angle bin.

D. A FLUX value of ZERO is a valid FLUX if the corresponding NOBS value
is greater than ZERO.

For further clarification, the following FORTRAN code is provided to
create a listing of flux for each data record for a given channel. This
should be a useful starting point for reading the files.

C HEEF - One minute average sorted by pitch angle dependent L (derived
from \*.min files).

C Input file = \'d04xxxx.pad\' ; Output file = \'fort.2\'\'

PROGRAM READ_PAD

INTEGER\*2 NOBF(19,19),KLEG,KSH

INTEGER\*4 IORBIT,ICH,JORBIT,IYEAR,IDAY,NREC,MAXBIN,KSEC

REAL\*4 ENERGY(19),FLUX(19,19)

CHARACTER\*11 INFILE

DATA INFILE/\'d04xxxx.pad\'/

iorbit=600

ich=5

C

C ORBIT 600 AND CHANNEL=5 ARE HARDWIRED

C

write(infile(4:7),\'(i4.4)\')iorbit

C

C NOTE THAT THE RECORD LENGTH IS DEFINED IN 4-BYTE WORDS, I\'VE USED

C OTHER UNIX SYSTEMS THAT NEED TO BE IN BYTES.

C

OPEN(1,FILE=inFILE,ACCESS=\'DIRECT\',RECL=544,ERR=100)

C HEADER

READ(1,REC=1,err=100)JORBIT,iyear,iday,nrec,maxbin,ENERGY

WRITE(2,22)JORBIT,IYEAR,IDAY,ENERGY(ICH)

22 FORMAT(/,\' ORBIT=\',I4,\' YEAR=\',I2,\' DAY=\',I3,\' MeV=\',F6.2)

DO 10 iREC=2,nrec+1

READ(1,REC=iREC,ERR=100)kleg,ksh,ksec,FLUX,NOBF

SH=KSH\*.05+2.45

WRITE(2,23)KLEG,SH,KSEC

23 FORMAT(/,\' LEG=\',I2,\' L-SHELL=\',F5.2,\' UT=\',I7,/)

WRITE(2,24)

24 FORMAT(\' PITCH ANGLE FLUX OBS\')

DO 20 IPA=1,19

WRITE(2,25)IPA\*5-5,FLUX(ICH,IPA),NOBF(ICH,IPA)

25 FORMAT(I8,E13.4,I6)

20 CONTINUE

10 CONTINUE

100 CONTINUE

END

**II. Proton Telescope (PROTEL)**

The Proton Telescope (PROTEL) was designed to make well calibrated, high
resolution measurements of high energy protons from the heart of the
inner belts out to geosynchronous altitudes. PROTEL has two detector
heads which combine to measure the differential flux \[cm^2^sec sr
MeV)^-1^\] spectrum of protons from 1 to 100 MeV in 24 channels with the
following mid-channel energies (MeV) :

1 - 1.5 9 - 6.8 17 - 26.3

2 - 2.1 10 - 8.5 18 - 30.9

3 - 2.5 11 - 9.7 19 - 36.3

4 - 2.9 12 - 10.7 20 - 42.3

5 - 3.6 13 - 13.2 21 - 47.5

6 - 4.3 14 - 15.2 22 - 57.0

7 - 5.7 15 - 16.9 23 - 67.5

8 - 8.4 16 - 19.4 24 - 82.9

The low energy head (LEH) has channels 1-8 and covers a range of 1 - 9
Mev. The high energy head (HEH) has the remaining channels 9-24 and
covers a range of 6 - 100 Mev. Channel 8 ( the highest energy in the
LEH) may be ignored because of its overlap of channels 9 and 10 of the
HEH. This avoids any discontinuity in the display of the spectra or
complicated integration. Channel 14 has been determined to have a
significantly lower sensitivity than the other channels and as a result
has been left out of any calculations in the PROTEL flux models
(CRRESPRO) \[4\]. The instrument contains silicon solid state detector
arrays with both anti-coincidence and multiple coincidence requirements
to reduce contamination. A more detailed description of the
instrument\'s proton detection scheme has been published elsewhere
\[5\].

PROTEL showed no response to electrons, including the \>10 MeV electrons
found in the slot region following the March 1991 storm. However, in
calibration measurements made prior to flight, and in computer
simulations of the detector, it was found that \>100 MeV protons could
enter the telescope off-axis and be counted as lower-energy protons.
This contamination is important in regions where \>100 MeV protons
greatly exceed the flux of lower-energy protons, namely, for L \< 1.7 at
pitch angles near the loss cone. For L \< 1.4 the correction can be
comparable to or greater than the residual value, and these data should
be used with caution. A description of the loss cone subtraction (made
on the \*.pad files, but not the \*.min files) may be found in the
literature \[4\].

The following orbits are missing from the database:

ORBIT# COMMENTS

001 - 014 Satellite spin decreasing

026 Bad time tag in PROTEL THDB

163 - 164 No Magnetometer data

272 No Magnetometer data

351 No PROTEL data

366 - 409 No Magnetometer data

For orbits 231-255, the LEH (channels 1-8) was operated in a mode that
resulted in bad flux data. The channels have been included to maintain
the data structure, but they should be excluded from any study.

**IIA. PROTEL one minute averaged pitch angle data files (\*.min)**

Input for creating this database is the raw data at 1.024 s time
resolution. At 1-minute increments, the high resolution data is sorted
and averaged into 5^o^ local pitch angle bins (19 bins ranging from 0^o^
to 90^o^).

Spike removal is implemented by passing through the data a second time,
throwing out individual count rates within each 1-minute interval which
were outside a +/- 3 sigma window for that minute\'s average value. The
resulting average count rates are converted to flux units. Each 1-minute
record is tagged with two sets of 8 ephemeris values - the first set is
corresponds to the beginning of the 1-minute interval, the second with
the interval\'s average UT. The loss cone subtraction described in
section II is not applied to this database of local pitch angle
distributions; it is used only for the equatorial pitch angle
distribution database described in section IIB.

There is one file per orbit, with the naming convention:
\'d08xxxx.min\'. The \'d08\' refers to \'data(d) from the PROTEL(08)
instrument, and \'xxxx\' is the orbit number (\'0015\' is orbit 15). The
range of orbits is 15 to 1067. The \'.min\' extension designates the
database type. The files are binary and were created as direct access
files using a FORTRAN 77 compiler on a non-DEC UNIX machine ( SGI) so
the byte order in each word may need to be reversed if transporting to a
DEC machine or a PC. The records are a fixed length of 2800 bytes. This
is easily read with other program languages since there are control
words etc., added to the end of records or the file itself. The record
structure is described below:

RECORD \# 1 consists of a HEADER. The values in the header are as
follows:

> VALUE 1: ORBIT number - 4 byte integer (10-1067)
>
> VALUE 2: YEAR number - 4 byte integer, should be 90 or 91
>
> VALUE 3: DAY number - 4 byte integer, day of year at start of orbit
> (1-365)
>
> VALUE 4: BSEC - 4 byte integer, UT at beginning of orbit. (0-86399)
>
> VALUE 5: ESEC - 4 byte integer, UT at end of orbit. (1-\~115000)
>
> VALUE 6: IBR - 4 byte integer, Beginning Record of data ( always 2)
>
> VALUE 7: IER - 4 byte integer, Ending Record of data ( approx.
> 595-625)
>
> VALUE 8-31: ENERGY - 4 byte REAL, 24 mid-channel energies (MeV)
>
> VALUE 32-700: ZEROS, 669 - 4 BYTE ZEROS

RECORD #IBR to #IER (defined in record 1 header above)

> VALUE 1-8: 4 byte reals, Ephemeris at beginning of one-minute average.
>
> VALUE 1: UT
>
> VALUE 2: X km (ECI), ECI = Earth Centered Inertial coord. system
>
> VALUE 3: Y km (ECI)
>
> VALUE 4: Z km (ECI)
>
> VALUE 5: SMLAT (Solar Magnetic Latitude)
>
> VALUE 6: SMLT (Solar Magnetic Local Time)
>
> VALUE 7: L-SHELL
>
> VALUE 8: B/B0 - Model
>
> VALUE 9-16: 4 byte reals, Ephemeris for average UT
>
> VALUE 17-472: FLUX(24,19) 4 byte real, 24 channels by 19 pitch angles.
>
> VALUE 17: FLUX(1,1)
>
> VALUE 18: FLUX(2,1)
>
> . . .
>
> VALUE 472: FLUX(24,19)
>
> VALUE 473-928: NOBS(24,19) 2 byte integer, Number of observations in
> the average FLUX
>
> VALUE 739: DUMMY 2 byte integer

NOTES:

A. ECI = Earth Centered Inertial coord. system

B. Magnetic coordinates computed using IGRF85 + Olson-Pfitzer quiet
static model (1974)

C. L-shell is the McIlwain L-parameter. The single value of L given here
is computed for the case of locally mirroring particles (90^o^ at the
spacecraft location).

D. If there is no data for the 1-minute interval, all the ephemeris
values are set to -1.

E. The last record of every file (# IER) has no data. It provides
ephemeris for the end of the one minute average for the previous record.

F. The pitch angle bins are: 1(0^o^), 2(5^o^) \... 19(90^o^), where the
angle is the middle of the pitch angle bin.

G. A FLUX value of ZERO is a valid FLUX if the corresponding NOBS value
is greater than ZERO.

For further clarification, the following FORTRAN code is provided to
create a listing of flux for each data record for a given channel. This
should be a useful starting point for reading the files.

C PROTEL - One minute average sorted by local pitch angle

C Input file = \'d08xxxx.min\' ; Output file = \'d08xxxx.lis\'\'

C

PROGRAM READ_MIN

REAL\*4 EPHEMA(8),EPHEMB(8),FLUX(24,19),ENERGY(24)

INTEGER\*2 NOBF(24,19)

INTEGER\*4 IORBIT,IYEAR,IDAY,IBSEC,IESEC,IBR,IER

CHARACTER\*11 INFILE,OUTFILE

DATA inFILE/\'d08xxxx.min\'/

PRINT\*,\'ENTER ORBIT NUMBER:\'

READ(\*,\*)JORBIT

PRINT\*,\'ENTER CHANNEL NUMBER:(1-24)\'

READ(\*,\*)ICH

WRITE(INFILE(4:7),\'(I4.4)\')JORBIT

OUTFILE=INFILE(1:8)//\'lis\'

OPEN(1,FILE=inFILE,ACCESS=\'DIRECT\',RECL=700,ERR=100)

OPEN(2,FILE=OUTFILE)

C HEADER FILE

READ(1,REC=1)IORBIT,IYEAR,IDAY,IBSEC,IESEC,IBR,IER,ENERGY

WRITE(2,21) IYEAR,IDAY,ENERGY(ICH)

21 FORMAT(\' YEAR=\',I4,\' DAY=\',I4,\' ENERGY=\',F5.2,\' MEV\')

WRITE(2,22)IORBIT,IBSEC,IESEC,IER

22 FORMAT(\' ORBIT=\',I4,\' BSEC=\',I6,\' ESEC=\',I6,\' NO. RECORDS=\',

\+ I4)

DO 10 NREC=ibr,ier

WRITE(2,\*)

READ(1,REC=NREC,ERR=100)EPHEMB,EPHEMA,FLUX,NOBF

WRITE(2,23)EPHEMB

23 FORMAT(\' BEG EPHEM. \',4F9.1,4F8.3)

write(2,24)EPHEMA

24 FORMAT(\' AVE EPHEM. \',4F9.1,4F8.3)

WRITE(2,25)

25 FORMAT(/,\' Pitch Angle Flux Obs\')

DO 20 IPA=1,19

WRITE(2,26)IPA\*5-5,FLUX(ICH,IPA),NOBF(ICH,IPA)

20 CONTINUE

26 FORMAT(I8,4X,E10.4,i8)

10 CONTINUE

100 CONTINUE

END

**IIB. PROTEL pitch angle dependent L-shell data files (\*.pad)**

Input for this data set is the 1-minute average database described in
section IIA which has been sorted into 5^o^ local pitch angle bins. For
every 1-minute interval (with average UT and local spatial coordinates),
the 19 pitch angles are assigned a McIlwain L from a previously
generated look-up table. The L\'s in the look-up table were computed
using a combined IGRF85 and Olson-Pfitzer quiet static magnetic field
model \[1\]. The local pitch angle distribution is then mapped to the
equator, assuming the conservation of the first adiabatic invariant,
into 0.05 wide L bins. The loss cone subtraction mentioned in section II
is performed on the equatorial pitch angle distribution. This equatorial
mapping procedure is applied to both leg one (first half of orbit) and
leg two ( second half of the orbit).

There is one file per orbit, with the naming convention:
\'d08xxxx.pad\'. The \'d08\' refers to \'data(d) from the PROTEL(08)
instrument, and \'xxxx\' is the orbit number (\'0015\' is orbit 15). The
range of orbits is 15 to 1067. The \'.pad\' extension designates the
database type. The files are binary and were created as direct access
files using a FORTRAN 77 compiler on a non-DEC UNIX machine ( SGI) so
the byte order in each word may need to be reversed if transporting to a
DEC machine or a PC. The records are a fixed length of 2744 bytes. This
format is easily read with other program languages since there are no
control words, etc., added to the end of records or the file itself. The
record structure is described below:

RECORD \# 1 consists of a HEADER. The values in the header are as
follows:

> VALUE 1: ORBIT number - 4-byte integer (15-1067)
>
> VALUE 2: YEAR number - 4-byte integer, should be 90 or 91
>
> VALUE 3: DAY number - 4-byte integer, day of year at start of orbit
> (1-365)
>
> VALUE 4: NREC - 4-byte integer, number of data records after the
> header record, (\<320)
>
> VALUE 5: MAXBIN - 4-byte integer, MAXBIN\*.05+.95 = Max L-shell
>
> VALUE 6-29: ENERGY - 4-byte REAL, 24 mid-channel energies (MeV)
>
> VALUE 30-686: ZEROS, 657 4-BYTE ZEROS.

RECORD \# 2 to NREC+1.

> VALUE 1: LEG number - 2-byte integer, 1 for first half of orbit, 2 for
> second half of orbit.
>
> VALUE 2: LSH number - 2-byte integer, represents the beginning of the
> 1/20th of an L-shell bin.
>
> VALUE 3: KSEC - 4 byte integer, nearest value of average UT in the LSH
> bin for that LEG.
>
> VALUE 4-459: FLUX(24,19) - 4-byte real, 24 channels by 19 pitch
> angles.
>
> VALUE 4: FLUX(1,1)
>
> VALUE 5: FLUX(2,1)
>
> . .
>
> VALUE 459: FLUX(24,19)
>
> VALUE 460-915: NOBS(24,19) 2-byte integer, Number of observations in
> the average FLUX

NOTES:

A. UT is from beginning day of orbit, so that if there is a cross-over
from one day to the next within a given orbit, KSEC will exceed the
total number of seconds in a day (86400). That is, the full range of
KSEC can be 0 - \~115,000.

B. The pitch angle bins are: 1(0^o^), 2(5^o^) \... 19(90^o^), where the
angle is the middle of the pitch angle bin.

C.FLUX channels 1-24 are differential flux \[(cm^2^ sec sr MeV)^-1^\].

D. A FLUX value of ZERO is a valid FLUX if the corresponding NOBS value
is greater than ZERO.

For further clarification, the following FORTRAN code is provided to
create a listing of flux for each data record for a given channel. This
should be a useful starting point for reading the files.

C Input file = \'d08xxxx.pad\' ; Output file = \'fort.2\'

C PROTEL - One minute average sorted by pitch angle dependent L (derived
from \*.min files)

C

PROGRAM READ_PAD

INTEGER\*2 NOBF(24,19),KLEG,KSH

INTEGER\*4 IORBIT,ICH,JORBIT,IYEAR,IDAY,NREC,MAXBIN,KSEC

REAL\*4 ENERGY(24),FLUX(24,19)

CHARACTER\*11 INFILE

DATA INFILE/\'d08xxxx.pad\'/

iorbit=600

ich=5

C

C ORBIT 600 AND CHANNEL=5 ARE HARDWIRED

C

write(infile(4:7),\'(i4.4)\')iorbit

C

C NOTE THAT THE RECORD LENGTH IS DEFINED IN 4-BYTE WORDS, I\'VE USED

C OTHER UNIX SYSTEMS THAT NEED TO BE IN BYTES.

C

OPEN(1,FILE=inFILE,ACCESS=\'DIRECT\',RECL=686,ERR=100)

C HEADER

READ(1,REC=1,err=100)JORBIT,iyear,iday,nrec,maxbin,ENERGY

WRITE(2,22)JORBIT,IYEAR,IDAY,ENERGY(ICH)

22 FORMAT(/,\' ORBIT=\',I4,\' YEAR=\',I2,\' DAY=\',I3,\' MeV=\',F6.2)

DO 10 iREC=2,nrec+1

READ(1,REC=iREC,ERR=100)kleg,ksh,ksec,FLUX,NOBF

SH=KSH\*.05+.95

WRITE(2,23)KLEG,SH,KSEC

23 FORMAT(/,\' LEG=\',I2,\' L-SHELL=\',F5.2,\' UT=\',I7,/)

WRITE(2,24)

24 FORMAT(\' PITCH ANGLE FLUX OBS\')

DO 20 IPA=1,19

WRITE(2,25)IPA\*5-5,FLUX(ICH,IPA),NOBF(ICH,IPA)

25 FORMAT(I8,E13.4,I6)

20 CONTINUE

10 CONTINUE

100 CONTINUE

END

**References**

\[1\] Olson, W.P., and K. A. Pfitzer, A quantitative model of the
magnetospheric magnetic field, *Journal of Geophysical Research*, (79),
3739, 1974.

\[2\] Dichter, B.K., Hanser, F.A., Sellers, B., Hunerwadel, J.L., High
Energy Electron Fluxmeter, *IEEE Transactions on Nuclear Science* 40
(2), 242-245, 1993.

\[3\] Hanser, F., Analyze data from CRRES payloads AFGL-701-2/Dosimeter
and AFGL-701-4/HEEF, #PL-TR-95-2103, 1995.

\[4\] Gussenhoven, M.S., E.G. Mullen, M.D. Violet, C. Hein, J. Bass and
D. Madden, CRRES high energy proton flux maps, *IEEE Transactions on
Nuclear Science* 40 (6), 1450-1457, 1993.

\[5\] Violet, M.D., Lynch, K., Redus, R., Riehl, K., Boughan, E., Hein,
C., Proton Telescope (Protel) on the CRRES spacecraft, *IEEE
Transactions on Nuclear Science* 40 (2), 242-245, 1993.