National Aeronautics and Space Administration
NASA Space Science Data Coordinated Archive

Lunar Data Project: Apollo 15/16 X-Ray Flourescence Spectrometer Data

These data were restored and made available as part of the Lunar Data Project at the NASA Space Science Data Coordinated Archive with assistance from Michael Bielefeld.

This set of four tables holds the event counts from the Apollo 15 and 16 X-Ray Flourescence Spectrometers (XRFS) for all channels of the three proportional counters (unfiltered, magnesium filter, aluminum filter) and the solar monitor. The XRFS instruments were carried on-board the Apollo 15 and 16 Command and Service Modules and took measurements from lunar orbit. They also had magnesium K alpha and Fe55 calibration sources. For more on the instrument, see the NSSDCA Master Catalog. The data are also available as PDS data sets.

The Data

The four tables are all in the same format, as described below. The tables hold the following data:

A15C_XRFS_71_NORMAL_1.TAB (7.5M)

Data from the Apollo 15 XRFS set to normal modes [NFLAG = 14 or 96 as described below] with all three counters measuring the same energy ranges.

A15C_XRFS_71_EXTENDED_2.TAB (2.0M)

Data from the Apollo 15 XRFS set to extended mode [NFLAG = 144 or 224 as described below] with detector 1 (unfiltered) measuring with the energy boundaries for each channel doubled.

A16C_XRFS_72_NORMAL_1.TAB (6.9M)

Data from the Apollo 16 XRFS set to normal modes [NFLAG = 14 or 96 as described below] with all three counters measuring the same energy ranges.

A16C_XRFS_72_EXTENDED_2.TAB (2.0M)

Data from the Apollo 16 XRFS set to extended mode [NFLAG = 144 or 224 as described below] with detector 1 (unfiltered) measuring with the energy boundaries for each channel doubled.

The Format

The values give the measurement mode of the instrument, the time, orbit, spacecraft position and orientation, and the event counts, normally for 8-s intervals, for the three proportional counters and the solar monitor. The normal energy range for the first seven channels of the first three counters (detector 1 unfiltered, detector 2 magnesium filter, and detector 3 aluminum filter) was between 0.75-2.75 keV, broken into seven equal energy ranges: 0.75-1.04, 1.04-1.32, 1.32-1.61, 1.61-1.89, 1.89-2.18, 2.18-2.46, and 2.46-2.75 keV. The solar monitor measured the range from approximately 1-3 keV, divided into seven equal intervals. An eighth channel recorded all x-ray events with energies higher than the upper level. However the solar monitor data for Apollo 15 was not usable due to saturation effects.

Each row in the table represents one set of measurements and contains 45 numbers in the order: one integer (I3) designated NFLAG; eight real numbers (F11.2,7F9.2) designated ANS(1) through ANS(8); and 36 integers (36I6) forming an array designated ISPEC(I,J), where I ranges from 1 to 4 and represents the counter used, and J ranges from 1 to 9 and represents the energy channel.

I=1 detector 1, beryllium windowed counter, no filter 
I=2 detector 2, beryllium windowed, magnesium filtered counter 
I=3 detector 3, beryllium windowed, aluminum filtered counter 
I=4 solar monitor 
J=1-7 seven energy regions into which the energy readings were divided, 
J=8 all x-ray events above the upper level discriminator 
J=9 all non X-ray events

The ISPEC values are ordered in each row as ISPEC(1,1), ISPEC(1,2), ISPEC(1,3), etc.

Specifically, the values in each row are:

(1) NFLAG [I3] - Measurement mode of the X-Ray Spectrometer, where:
NFLAG = 14 indicates normal mode, three detectors measuring external
input of energies above 0.75 keV, solar monitor measuring external input
above 1.0 keV.
NFLAG = 96 indicates calibration mode, the magnesium K alpha and Fe55 
calibration sources have been rotated into the field of view of detectors 
1, 2, and 3. 
NFLAG = 144 indicates same as normal mode except the energy range and 
all range boundaries for detector 1 channels have been doubled. 
NFLAG = 224 indicates same spectral range as NFLAG=144 but detectors 
1, 2, and 3 are measuring K alpha and Fe55 calibration sources.
(2) ANS(1) [F11.2] - Ground elapsed time in seconds (time since launch 
of Apollo 15 at 13:34:00 UT on 26 July 1971 or Apollo 16 at 17:54:00 UT 
on 16 April 1972) of the midpoint of the count accumulation period. 
(3) ANS(2) [F9.2] - Lunar orbit number, to the nearest tenth of an orbit.  
(4) ANS(3) [F9.2] - Subspacecraft selenographic latitude in degrees
from 90 to -90 at the midpoint of the accumulation period.
(5) ANS(4) [F9.2] - Subspacecraft selenographic longitude in degrees
east from 180 to -180 at the midpoint of the accumulation period.
(6) ANS(5) [F9.2] - Spacecraft altitude in km assuming mean circular 
Moon (i.e. no terrain corrections).  The equatorial radius of the moon 
is roughly 1738 km.
(7) ANS(6) [F9.2] - Spacecraft pitch angle in degrees.     
(8) ANS(7) [F9.2] - Spacecraft yaw angle in degrees.   
(9) ANS(8) [F9.2] - Spacecraft roll angle in degrees.
(10) ISPEC(1,1) [I6] - Event count for channel 1 (0.75-1.04 keV) of
detector 1 (unfiltered). In modes 144 and 224 the energy range is
1.50-2. keV.
(11) ISPEC(1,2) [I6] - Event count for channel 2 (1.04-1.32 keV) of
detector 1 (unfiltered). In modes 144 and 224 the energy range is 
2.08-2.64 keV.
(12) ISPEC(1,3) [I6] - Event count for channel 3 (1.32-1.61 keV) of
detector 1 (unfiltered). In modes 144 and 224 the energy range is 
2.64-3.22 keV.
(13) ISPEC(1,4) [I6] - Event count for channel 4 (1.61-1.89 keV) of
detector 1 (unfiltered). In modes 144 and 224 the energy range is 
3.22-3.78keV.
(14) ISPEC(1,5) [I6] - Event count for channel 5 (1.89-2.18 keV) of
detector 1 (unfiltered). In modes 144 and 224 the energy range is 
3.78-4.36 keV.
(15) ISPEC(1,6) [I6] - Event count for channel 6 (2.18-2.46 keV) of
detector 1 (unfiltered). In modes 144 and 224 the energy range is 
4.36-4.92 keV.
(16) ISPEC(1,7) [I6] - Event count for channel 7 (2.46-2.75 keV) of
detector 1 (unfiltered). In modes 144 and 224 the energy range is 
4.92-5.50 keV.
(17) ISPEC(1,8) [I6] - Event count for channel 8 (above 2.75 keV) of
detector 1 (unfiltered). In modes 144 and 224 the energy range is above
5.50 keV.
(18) ISPEC(1,9) [I6] - Event count of all non X-ray events for 
detector 1 (unfiltered)
(19) ISPEC(2,1) [I6] - Event count for channel 1 (0.75-1.04 keV) of
detector 2 (magnesium filter).
(20) ISPEC(2,2) [I6] - Event count for channel 2 (1.04-1.32 keV) of
detector 2 (magnesium filter).
(21) ISPEC(2,3) [I6] - Event count for channel 3 (1.32-1.61 keV) of
detector 2 (magnesium filter).
(22) ISPEC(2,4) [I6] - Event count for channel 4 (1.61-1.89 keV) of
detector 2 (magnesium filter).
(23) ISPEC(2,5) [I6] - Event count for channel 5 (1.89-2.18 keV) of
detector 2 (magnesium filter).
(24) ISPEC(2,6) [I6] - Event count for channel 6 (2.18-2.46 keV) of
detector 2 (magnesium filter).
(25) ISPEC(2,7) [I6] - Event count for channel 7 (2.46-2.75 keV) of
detector 2 (magnesium filter).
(26) ISPEC(2,8) [I6] - Event count for channel 8 (above 2.75 keV) of
detector 2 (magnesium filter).
(27) ISPEC(2,9) [I6] - Event count of all non X-ray events for 
detector 2 (magnesium filter).
(28) ISPEC(3,1) [I6] - Event count for channel 1 (0.75-1.04 keV) of
detector 3 (aluminum filter).
(29) ISPEC(3,2) [I6] - Event count for channel 2 (1.04-1.32 keV) of
detector 3 (aluminum filter).
(30) ISPEC(3,3) [I6] - Event count for channel 3 (1.32-1.61 keV) of
detector 3 (aluminum filter).
(31) ISPEC(3,4) [I6] - Event count for channel 4 (1.61-1.89 keV) of
detector 3 (aluminum filter).
(32) ISPEC(3,5) [I6] - Event count for channel 5 (1.89-2.18 keV) of
detector 3 (aluminum filter).
(33) ISPEC(3,6) [I6] - Event count for channel 6 (2.18-2.46 keV) of
detector 3 (aluminum filter).
(34) ISPEC(3,7) [I6] - Event count for channel 7 (2.46-2.75 keV) of
detector 3 (aluminum filter).
(35) ISPEC(3,8) [I6] - Event count for channel 8 (above 2.75 keV) of
detector 3 (aluminum filter).
(36) ISPEC(3,9) [I6] - Event count of all non X-ray events for 
detector 3 (aluminum filter).
(37) ISPEC(4,1) [I6] - Event count for channel 1 (1.00-1.29 keV) of
the solar monitor.
(38) ISPEC(4,2) [I6] - Event count for channel 2 (1.29-1.57 keV) of
the solar monitor.
(39) ISPEC(4,3) [I6] - Event count for channel 3 (1.57-1.86 keV) of
the solar monitor.
(40) ISPEC(4,4) [I6] - Event count for channel 4 (1.86-2.14 keV) of
the solar monitor.
(41) ISPEC(4,5) [I6] - Event count for channel 5 (2.14-2.43 keV) of
the solar monitor.
(42) ISPEC(4,6) [I6] - Event count for channel 6 (2.43-2.71 keV) of
the solar monitor.
(43) ISPEC(4,7) [I6] - Event count for channel 7 (2.71-3.00 keV) of
the solar monitor.
(44) ISPEC(4,8) [I6] - Event count for channel 8 (above 3.00 keV) of
the solar monitor.
(45) ISPEC(4,9) [I6] - Event count of all non X-ray events for the
solar monitor.
 
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