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The EXOSAT Interactive Analysis Software System
A.N. Parmar and U. Lammers
(Space Science Department of ESA, ESTEC, The Netherlands)
and L. Angelini (HEASARC)
1. Introduction
The EXOSAT Interactive Analysis, or IA, is the software that is used to access
the original EXOSAT telemetry data to produce spectra, lightcurves, photon
lists and images that can be read into standard analysis packages such as
XSPEC, XIMAGE and XRONOS. For many potential EXOSAT users, the on-line EXOSAT
databases contain suitable products, such as spectra integrated over each
observation and 1-10 keV lightcurves with moderate time resolution, and the
original telemetry data need never be accessed. Since this data is now
available on-line from the HEASARC, we felt that it worthwhile to report on the
capabilities and limitations of the IA software that is available for users
with more specialized requirements.
EXOSAT had three sets of detectors, two Low-energy imaging telescopes (LE1 and
LE2) normally used with channel plate detectors (CMAs), the medium energy
detector array (ME) which provided good temporal and moderate spectral
resolution and the gas scintillation proportional counter (GS) which provided
improved spectral resolution compared to the ME, but with lower effective area.
Good starting points for information on EXOSAT are White and Peacock (1988;
Mem. Ital. Soc. 59, 1) and "The Best of the EXOSAT Express Parts
1 and 2", available from the HEASARC.
2. History of the IA
Following the launch of EXOSAT in 1983, the EXOSAT Observatory and a number of
the groups closely involved in EXOSAT data analysis developed their own
specialized analysis systems. The EXOSAT Observatory's system was developed to
run on (even then) ancient HP1000 computers which used the RTE operating
system. The use of a 16-bit machine and the limited capabilities of the
operating system did not make for easily portable software and the legacy of
this original platform remains even today. However, the IA programs contain
much of the knowledge and expertise concerning the extraction of scientific
information from EXOSAT data and should these programs become unusable, it is
unlikely that this data would ever be fully accessible again. In 1990 SSD
decided to port the IA to a number of UNIX operating systems and make the
resulting software public. At about the same time, ESA (ESRIN/ISD in Frascati)
transcribed all 8340 Telemetry tapes onto optical disks in order to ensure
their survival for posterity. A copy of this archive was deposited with the
HEASARC who have undertaken to convert it to FITS format. Recently SSD, in
collaboration with the HEASARC, has prepared a new release (v 2.0) of the IA,
the characteristics of which are reported here. The new release includes a
number of bug fixes, new plotting capabilities, revised LE image files
compliant with the OGIP standard and the capability of producing LE Photon
Lists in FITS format. In addition, OSF1 and Solaris are now supported as well
as the originally supported HP-UX, SUN-OS and Ultrix.
3. The EXOSAT Interactive Analysis
The EXOSAT IA is written in strict standard Fortran-77 and ANSI-C with the only
exception being the indispensable use of the data type INTEGER*2. The system
uses a UNIX Bourne-shell (sh) script to coordinate all software activities.
The Interactive Analysis system has five major components:
a) User Shell - OP
This provides an environment under which to analyze EXOSAT data. Its
major functions are:
* To register new users and create the required directory structure.
* To control the execution of the IA programs.
* To list available data and products.
* To Provide simple interfaces to XRONOS, XSPEC and XIMAGE
b) Telemetry Filing - FOTF
FOTF reads and transforms FOT data from either tape or disk to a form
suitable for input into the IA. FOTF has a number of functions:
* It checks for data consistency using the internal redundancy on a FOT.
* It divides the telemetry data into files, one for each telemetry stream per
interval of unique spacecraft and instrument configuration and writes them onto
a user area.
* It populates a directory on the user area allowing an easy overview of the
filed data.
* It writes orbit and other data which is not obtained from the EXOSAT
telemetry but is resident on the FOTs onto the user area.
c) The ME Interactive Analysis - MXIA2
This is the program to analyze ME data started by the command IA in
the OP shell. The On board computer modes and data types supported can be found
by typing ??:help in the IA.
One of the major complexities of ME data analysis is background subtraction. To
make this easier a number of macros, or scripts, are available that
automatically produce background subtracted spectra and lightcurves using a
number of different techniques. Comparison of the results allows estimates of
the systematic uncertainties to be made. The available macros can be listed
within the IA by typing ??:mc. More information on a specific macro
can be found by typing ??:xx, where xx is the macro name.
Another complex area is the assignment of absolute times to ME data. To the
best of our knowledge, the necessary corrections are automatically applied when
lightcurves are produced using the `sl' command (for [s]tore [l]ightcurve).
Again, the use of the supplied standard macros is recommended. The major
functions of the ME IA are:
* Decode and display the directory record created by FOTF.
* Display information on the configuration of the ME and available data
streams.
* Allow selection of data by observation, data stream, time, phase and count
rate level.
* Display and plot Housekeeping parameters (via XRONOS).
* Determine pointing directions during EXOSAT slew maneuvers.
* Allow the accumulation of energy spectra in SF format suitable for input to
XSPEC. These can be converted to FITS using the SF2PHA FTOOL.
* Allow the accumulation of lightcurves in a format suitable for XRONOS.
* Allow arrival time correction of lightcurves to the Solar System
barycenter.
* Provide a simple interface to the VIMAT program for the production of XSPEC
response matrices.
* Allow listing of original packet data, spectra and lightcurves and plotting
of spectra.
* Allow results to be corrected for the effects of deadtime, collimator
transmission and known On-board Computer problems.
* Allow the background to be subtracted from spectra and lightcurves.
d) The LE Interactive Analysis - LXIA7
The LE IA is capable of creating images, lightcurves and photon lists. These
can be corrected for the effects of spacecraft `wobble' by first creating a
deblur file and for deadtime and vignetting effects. Images can be produced in
the EXOSAT internal format (which can be read directly into XIMAGE) and FITS.
Lightcurves are produced in a format suitable for XRONOS, while photon lists
can be produced in FITS. Currently, it is not possible to correct LE arrival
times to the Solar System barycenter.
One subtlety in the analysis of data from the LE is that the EXOSAT CMA
detectors were sensitive to UV radiation. The PHA or sum-signal values written
into FITS photon lists are a crude measure of the event energy and can be used
to discriminate between UV and X-ray dominated sources.
The major functions of the LE IA are:
* Decode and display the directory record created by FOTF.
* Display information on the configuration of the LE.
* Allow selection of data by observation, time and exposure fraction.
* Allow the accumulation of lightcurves in a format suitable for XRONOS.
* Allow the accumulation of images in EXOSAT internal or FITS format.
* Allow the production of photon lists in FITS format.
* Allow the examination of the sum-signal distribution by applying standard
FTOOLS to photon lists.
* Allow results to be corrected for the effects of deadtime, spacecraft
`wobble' and vignetting.
e) The GS Interactive Analysis - GXIA7
The GS IA produces lightcurves in a format suitable for use by XRONOS and
spectra that can be read into XSPEC. Currently, it is not possible to correct
GS arrival times to the Solar System barycenter.
Background subtraction in the GS is somewhat tricky. Background spectra can
either be obtained from nearby source-free intervals such as maneuvers or the
standard background spectra which are provided can be used. In either case,
the gain of the source and background spectra should be normalized using
high-energy background lines or the Xe L-edges. The GS IA allows each of these
options to be chosen as well as allowing the quality of fit to the spectral
features to be viewed.
* The major functions of the GS IA are:
* Decode and display the directory record created by FOTF.
* Display information on the configuration of the GS.
* Allow selection of data by observation, time, phase and count rate level.
* Allow the accumulation of energy spectra in SF format suitable for input to
XSPEC. These can be converted to FITS using the SF2PHA FTOOL.
* Allow the accumulation of lightcurves in a format suitable for XRONOS.
* Allow listing of spectra and lightcurves and plotting of spectra.
* Allow results to be corrected for the effects of deadtime, and collimator
transmission.
* Allow background subtraction of spectra using gain normalized spectra.
4. Installation of the IA
The installation is as user-friendly and automated as possible, with little
knowledge of UNIX required. The package configuration is performed by means of
an interactive shell script and the actual building process is driven by a
hierarchy of `makefiles.' The requirements for building and installing the IA
are:
* Operating system either HP-UX (> = 9.01),SunOS (> = 4.1.3), Ultrix
(> =4.3), OSF1 (> = 3.0), or Solaris (> = 2.3).
* Fortran-77 compiler.
* ANSI-C compiler (e.g. gcc (> 2.0)).
* The XANADU package available from heasarc.gsfc.nasa.gov via anonymous ftp.
* Minimum free disk space for installation (excluding XANADU) of 25 Mb.
In the following, expressions in courier font represent machine text.
Expressions in bold courier font represent commands that have
to be typed in by the user. Note that the IA can be currently obtained from
SSD and in the near future from the HEASARC.
- Getting the Archive
mkdir IA && cd IA
ftp astro.estec.esa.nl
...
cd pub/EXOSAT
bin
get IA.tar.Z
bye
- Unpacking the Archive
zcat IA.tar.Z | tar xovf -
This creates the IA subtree under the newly created directory `IA'.
- Making the IA
make config build
This runs first an interactive configuration script which should be
self-explanatory and, subsequently, builds all necessary executables.
- Installing the IA
make install
This initiates the installation of the IA executables and run-time data/help
files to a suitable place specified during the configuration. Note, that write
access to the installation directory <IA_DIR> is needed and, thus,
performing this action may require system administrator privileges.
- Cleaning Up
make clean
This removes all temporary files created during the building stage.
After the package has been successfully built and installed, it is ready to be
used. The only remaining task is to add to the current search path for
executables ($PATH), the location of the IA binaries. This is
<IA_DIR>/bin where <IA_DIR> stands for the IA installation
directory specified during the configuration stage.
Although SSD cannot provide support for users of the IA, questions concerning
installation can be addressed to ulammers@astro.estec.esa.nl.
5. A Typical User Session
Prior to running the IA, FOT data have to be available, either as magnetic
tapes from ESRIN or disk files from the HEASARC on-line service. The default
behavior of the filing program `FOTF' is to read FOT files from a special FOT
disk directory that had been specified during the package configuration reading
data from tape has to be explicitly enforced via a command line switch
(foft -t). Once FOT data are present, the system can be invoked by
typing op at the UNIX shell prompt:
unix> op
Type `?' to get a list of available commands
EEEEEEE X X OOOOO SSSSS A TTTTTTT
E X X O O S S A A T
E X X O O S A A T
EEEEE X O O SSSSS A A T
E X X O O S AAAAAAA T
E X X O O S S A A T
EEEEEEE X X OOOOO SSSSS A A T
Interactive Analysis Software
----------------------------------------------------------
Tue Mar 16 11:36:52 METDST 1994
User name: [uwe]
FOT data area: [/users/uwe/datexo/raw] capacity used: 49
IA data area: [/users/uwe/datexo/ia] capacity used: 49
Current source: [defsrc] Instrument: [ME]
--- Available sources --
defsrc ex2030
OP>
A list of available OP commands can be obtained with ?, the most
important are probably DE, FT and IA. The first
command is used to change the repository directory for the file created during
the analysis (e.g., current source) and/or the instrument. The defaults are
defsrc and ME. For example typing DE,ex2030
changes the current source to EX2030 allowing users to separate files
from different sources. DE,,L1 changes the current instrument to be
L1 which is telescope 1 of the LE. This should be performed before
reading in an L1 FOT. The FT command executes FOTF (described above),
and FT EY8000 would file a FOT called EY8000.fot onto the FOT data
area listed above. The command IA starts the IA program for the
current instrument. In the case of the ME, a welcome message will appear:
-----------------------------------------------------------------------
---- ----
------- Welcome to the EXOSAT Medium-Energy Instrument Analysis -------
---- ----
-----------------------------------------------------------------------
Type `??' to obtain a list of available commands
Version 2.0
There are a number of help facilities within the ME IA. Typing ? lists
the available commands, ??:sl will give information on command or
macro sl etc, ??:mc will give information on the various
macros available while ??:help will provide background information on
the ME IA.
MXS13> ld will list information on the filed data :
Obs Co Start-Stop Main Mech F HT Source Workspace
No. n Times Prog N 12 Cl? Name Parameters [4-8]
59 85 86 0134 0519 HER5 2 -A Y 16 4U1624-49 1 20 256 256 4
60 85 86 0519 0521 HER5 2 ?A Y 8 4U1624-49 1 20 256 256 4
61 85 86 0523 0529 HER5 2 A? Y 8 4U1624-49 1 20 256 256 4
62 85 86 0530 0824 HER5 2 A+ Y 16 4U1624-49 1 20 256 256 4
MXS13> ob:59 defines observation 59 to be current
MXS13> in lists the current data stream
Obs 59 1985 086 01:34 to 086 05:19
Detectors AR 5 to 8 BG 0 to 0
OBC HER5/2 Type= EN t= .31250 s
Chans 5 to 68 [ 32 Bins] ID= **
Sampled/HALF Saved ENV Cartridge XM
No LC Correction
The data stream can be changed with e.g. de,ti to the high time
resolution data stream often present.
MXS12> dc,ti
MXS12> in
Obs 59 1985 086 01:34 to 086 05:19
Detectors BO 1 to 8 BG 0 to 0
OBC HTR3 Type= TI t= .00781 s
Chans 1 to 128 [ 1 Bins] ID= **
Sampled/INST Saved ENV Cartridge XM
No LC Correction
MXS13> oi will provide detailed information about the
EXOSAT and ME configurations during observation 59
POINTING
Source: 4U1624-49
S/C Pointing RA: 246.134 [16:24:32] Dec: -49.061 [-49:03:39]
Source Pos RA: 246.075 [16:24:18] Dec: -49.088 [-49:05:18]
S/C Start Altitude (Km) 163801.
S/C End Altitude 151397.
S/C Roll Angle [degrees] 339
Mean Y Offset (Arc min) -.9
Mean Z Offset 2.0
Beta Angle (degrees) 110
TIMES
Start Time 1985 Day 86 01:34:32 ( 165202472 MJ Secs) on 85/ 3/27
End Time 1985 Day 86 05:19:04 ( 165215944 MJ Secs)
1985 Day 86 1:034:033:016:728 PRT: 57802752 SHF: 165202473
1985 Day 86 5:018:056:978:466 PRT: 278396928 SHF: 165215936
OBC AND SAMPLING
Programs : HER5 HTR3
Output Buffer: 812 268
Slot Number : 0 5
Sampling Rates: Energy: 4096 QE: 128 Det ID: 4096 Time Tag: 0
Time Tag ADC1
ADC Mode CLSD
Ar Xe Sum Select SUM
Reset A1
etc... Now calculate the deadtime for observation 59 :
MXS13> dt:ca
* Record 6700/ 6732
* T3 Cts/sec: 700.174
* Energy correction Factor: 1.1184
* QE correction Factor: 1.0019
Accumulate a spectrum for observation 59 :
MXS13> as
* Record 21000/ 21543
and apply the deadtime correction to this spectrum :
MXS13> dt:sp
* Deadtime: 1.118
Store this spectrum as file `SPEC1'
MXS13> wb,spec1
Now go to observation 62, and select the background detectors :
MXS13> ob:62
MXS13> dc,de:bg,bg:no
MXS13> in
Obs 62 1985 086 05:30 to 086 08:24
Detectors AR 5 to 8 BG 0 to 0
OBC HER5/2 Type= EN t= .31250 s
Chans 5 to 68 [ 32 Bins] ID= **
Sampled/HALF Saved ENV Cartridge XM
No LC Correction
Now determine the deadtime for observation 62 :
MXS13> dt:ca
* Record 5000/ 5084
* T3 Cts/sec: 725.575
* Energy correction Factor: 1.1224
* QE correction Factor: 1.0020
Accumulate a spectrum from the background detectors :
MXS13> as
* Record 16000/ 16268
Apply the deadtime correction to the background spectrum :
MXS13> dt:sp
* Deadtime: 1.122
Store as file `BG1' :
MXS13> wb,bg1
Now subtract the background spectrum from the source one accumulated earlier:
MXS13> op,spec1,su,bg1
Store the result as file `FILE1' :
MXS13> wb,file1
Sum the spectrum between channels 6 and 40 :
MXS13> su,ch:6:40
* Bins 1: 18 or Chans 6: 40 Counts: 74.537 +/- .101 Cts/s
Now check that the background subtraction is good by plotting the current
spectrum :
MXS13> ps
A pgplot window now appears in the currently defined device and the user is
left with the PLT> prompt of the QDP package. When the user is finished
plotting type:
PLT> quit
Now convert the file to SF format for input to XSPEC :
MXS13> xs,file1
This creates a file `file1.pha'. Type LS to see the product files that
you have created. Now run VIMAT to create an XSPEC response file :
MXS13> vm,file1.pha
/users/uwe/datexo/ia/defsrc/spectra/file1.pha
EXOSAT ME AR H2
detector collimatorresponse
5 1.00
6 1.00
7 1.00
8 1.00
* Making ME matrix for detector 5
* Making ME matrix for detector 6
* Making ME matrix for detector 7
* Making ME matrix for detector 8
response file: /users/uwe/datexo/ia/defsrc/spectra/file1.rsp
The user now decides to do some timing analysis by running macro `l2' to
produce lightcurves between channels 6 to 40 for observations 59 and 62. Files
FILE1 and FILE2 are created with 3.1 sec time resolution. See ??:l2
for a description of the calling parameters.
MXS13> ma,l2:59:62:6:40:10,file1,file2
etc... These files are in an internal EXOSAT format and can be converted for
use in XRONOS by typing :
MXS13> xl,file1
MXS13> xl,file2
creating files file1.rbf and file2.rbf. The user now exits the ME IA and starts
an XSPEC session via OP. This opens a dedicated xterm window :
MXS12> exit
OP> xs
When the user has completed the spectral analysis, XSPEC is exited in the usual
way, the xterm disappears and the user decides to do some LE analysis :
OP> de,,l1
EEEEEEE X X OOOOO SSSSS A TTTTTTT
E X X O O S S A A T
E X X O O S A A T
EEEEE X O O SSSSS A A T
E X X O O S AAAAAAA T
E X X O O S S A A T
EEEEEEE X X OOOOO SSSSS A A T
Interactive Analysis Software
----------------------------------------------------------
Tue Mar 14 10:44:01 MET 1995
User name: [uwe]
FOT data area: [/users/uwe/datexo/raw] capacity used: 50
IA data area: [/users/uwe/datexo/ia] capacity used: 50
Current source: [defsrc] Instrument: [L1]
--- Available sources --
bigdip defsrc
OP> ia
LXS17> listd will list information on available data:
obs d1 ut1 ut2 fw det stng zoom pets grt test obc mode pt source id
07 342 1429-1438 3 lx cma 613 39 1 out * comb2 2 GAMMA CASS.
08 342 1442-1726 B cma 613 39 1 out * comb2 2 GAMMA CASS.
09 342 1732-1740 B cma 613 39 1 out * inactive 2 GAMMA CASS.
10 342 1747-1943 Al/P cma 613 39 1 out * comb2 2 GAMMA CASS.
11 342 1947-1956 Al/P cma 613 39 1 out * comb2 3 GAMMA CASS.
Now create a FITS photon list. This is carried out in two stages, first run
program adima and then lcurv. Bold indicates user entries
here.
LXS17> adima
Image type (0=normal, 1=PDF, 2=FITS Image, 3=FITS Photon list): [3]
Enter FITS filename (6 char; w/o extension): [exoimg] fits1
Enter up to 15 observations to chain: [1] 11
Start time: [1984 342 19:47:46]
End time: [1984 342 19:56:58]
Exposure time is 477 seconds
Deblur file name (w/o extension, <return> if none):
GAMMA CASS. star tracker mode: STR2
5" pitch axis rotation performed
Sum signal limits: [1,127]
Processing 683 IM records
Processing small maps 0 0
Image accumulation completed
completed writing header Now use LCURV to complete this FITS file
Normal termination
LXS17> lcurv
Do you want to complete the FITS file started in ADIMA? [Y]
Enter same observation numbers as in ADIMA: [1] 11
Start time: [1984 342 19:47:46]
End time: [1984 342 19:56:58]
Enter DT bin size (8.0 secs): [8.0]
Processing 100% of 785 C2 records
* Record: 700
GAMMA CASS. star tracker mode: STR2
5" pitch axis rotation performed
Enter Xlo, Ylo, Xhi, Yhi for source 1: [1, 1, 1023, 1023]
Enter Xlo, Ylo, Xhi, Yhi for bckgnd 1: [-1023,-1023, 1024, 1024]
Fully overlapping boxes
Another pair of boxes? [N]
Enter ADIMA FITS file name (w/o extension): [exoimg] fits1
Processing 683 IM records
7 7
FITS file Event extension completed
Number of Exposure Bins = 69, Time spanned= 552.000 sec.
FITS file Dead Time extension completed
This file can now be read into XIMAGE or SAOIMAGE, etc. for display or further
processing.
6. Acknowledgments
Almost every member of the EXOSAT Observatory team contributed to the IA in
some way. Particular thanks are due to R. Blissett, L. Chiappetti, T.
Courviosier, P. Giommi, M. Gottwald, F. Haberl, J. Lewis, J. Osborne, L.
Stella, J. Sternberg, G. Tagliaferri and N. White.
References
White, N.E. and Peacock, A. 1988, Memorie della Società Astronomica
Italiana, Vol. 59, 7.
"The Best of the EXOSAT EXPRESS", vol 1-2, NASA/HEASARC publication.
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