February 10, 2000

                            ===== SUMMARY =====

HEASOFT 5.0 is a software suite consisting of FTOOLS 5.0, FV 2.6,
XIMAGE 3.0, XRONOS 5.16, XSPEC 11.0, and XSTAR 2.0. This document
contains information about the form and function of all these
packages, with emphasis on changes to each since the last major
release of each. All this software now shares common build,
installation and initialization procedures. These procedures
are different than in previous releases. Please see the files
for details.

                        ===== SUPPORT FOR WINDOWS =====

At present, only FV 2.6 is supported on MS Windows 95/98/NT.

                    ===== YEAR 2000 (Y2K) COMPLIANCE =====

Great efforts were made to render HEASOFT 5.0 Y2K compliant, but
since the year is still young, is is possible there are problems
which have not yet been reported. For convenience, here are the
detailed notes regarding Y2K compliance of the FTOOLS, reprinted
from the Release Notes to FTOOLS 4.2 (December, 1998):

        "As of release 4.2, we believe that the FTOOLS are ready for
    2000. In particular, we have transitioned them to the new format
    for FITS dates, YYYY-MM-DD.  All programs and library routines
    should now understand both this and the old DD/MM/YY format
    (which in accordance with the FITS standard will be interpretted
    as 19YY, usually), but in general they will write only new-format
    dates.  Our intention is that old data files should be usable
    without conversion; please let us know if you run into trouble.

        "Date/time keyword pairs (e.g., DATE-OBS/TIME-OBS,
    DATE-END/TIME-END) have *not* been combined into the full FITS
    date/time format ("yyyy-mm-ddThh:mm:ss.s"); they will remain as
    separate keywords for the date and the time.  However, the file-
    creation DATE keywords and many HISTORY keywords *do* now use the
    combined format.

        "Date keywords that are merely copied from an input file are
    not usually converted to the new format, so in some cases it is
    possible to have, for instance, DATE-OBS in the old format and
    DATE-END in the new one.  A few FTOOLS will write old-format
    dates for 1900 <= year <= 1998, and new-format ones for other
    years; these include sf2pha, ascii2pha, eaddmap, fesdb2rdf,
    fbbft2pha, and fbdrm2rmf.  ascalin will write HISTORY keywords
    with old-format dates until we can wean its author off CFITSIO
    version 1.

        "FTOOLS for some old, long-inactive missions, such as
    Vela-5B, will continue to write old-format DATE-OBS and DATE-END
    strings (although new-format file-creation dates).  This is so
    that users' seldom-used, non-FTOOL, analysis programs will not
    have to be changed.  Since these missions ended long before 2000,
    we believe that there is no possibility of misinterpretation or
    an overflow.  Where these FTOOLS take user-input dates, either
    format may be used.

        "These changes required modifications in many source files
    throughout the FTOOLS.  While we think we found them all, it is
    possible that we missed some.  If you find any incompatibilities
    or stray old-format dates, please send the details to us at, and we wish you an enjoyable

                         ===== SPECIFIC CHANGES =====

For each of the HEASOFT subpackages below are listed tools
and/or features which are new in version 5.0. More information
on FTOOLS 5.0, XRONOS 5.16 and XSTAR 2.0 can be obtained using
the fhelp utility. Type "fhelp ftools" to obtain a full listing
of all the tools available, or "fhelp " to list
all of the tools in a particular subpackage, e.g., "fhelp asca".
Finally, type "fhelp " for more detailed help on a
particular tool. FV 2.6, XIMAGE 3.0, and XSPEC 11.0 all have
online help available from within the program. In addition,
XIMAGE 3.0, XSPEC 11.0, and XSTAR 2.0 have TeX formatted manuals
for their usage.

                              ===== FV =====

See for the latest
information about fv.

===> New since FTOOLS 4.2 (December, 1998) <===

   * Ported to MacOS and LinuxPPC
   * FTP access added to Windows/MacOS versions
   * The Open File browser now lists file sizes and dates 
   * The windows management has been improved to reduce clutter 
   * layout of user buttons and menu items is more ergonomic
   * New scripting capabilities have been added via the XPA Public 
     Access (XPA) mechanism (developed by the SAO/HEAD R&D group)
   * Replaced Options menu with a unified Preferences window 
   * Added preference to "Auto-Plot Primary Image" when opening a file.
   * Added preference to turn off the Desktop Manager
   * Accepts and opens multiple files from the command line
   * All HDU-level modifications (Cut/Paste/Append HDUs) affect a temporary 
     file.  Original file now affected only by the "Save" command.
   * Can edit multiple extensions simultaneously. 
   * Revert command added which reloads last-saved version of file.  
   * Tables of 1D images are displayed vertically instead of horizontally.
   * Histogram function records axis coordinate information in image's
   * New plots can be added to a pre-existing graph
   * Curves can be created from arithmetic expressions, not just column data. 
   * Calculator engine replaced with one which is faster and more powerful
   * Images with 'CD' style WCS keywords are now supported
   * The size and location of the scope window in POW are user configurable
   * A histogram-equalization image display option has been added
   * Publication-quality annotation labels can be added to the graphs
   * Graph selection buttons have been eliminated and graph titles added
   * Full font control over all labels has been added
   * Many new configuration options for graphs, images, and curves added...
   * Logarithmic axes and tick labels supported.
   * Tick marks and/or labels can be turned off on either axis.
   * For curves, points and lines can have separate colors.  Histogram 
     curves can be drawn as solid boxes instead of outlines.
   * Line colors (for curves or grid lines) selected via a 27-element 
     visual color table instead of a list of color names.
   * Graphs use different colors for each curve.
   * New "Dot" point shape can be drawn much faster than the others.  This 
     shape is the default for curves with more than 10000 points.
   * More than 20 colormaps are available for images.
   * Most graph/curve/image options can be saved as the defaults 
     for use in new graphs.
   * Most Color menu items change the settings for all the images in the 
     current graph.  Settings for individual images can also be changed.
   * Images with large aspect ratios (eg, 1D images) will be expanded along 
     their narrow axes if they would otherwise be "pencil thin".

                             ===== ASCA =====

(*) For complete details and up-to-date information on using
    HEASOFT 5.0 to analyze ASCA data, please refer to:

ascaarf: Added the option to take as input the results of ray-tracing a 
         source distribution.

make_ascaray_images: Create a set of ray-tracing images by running
         "ascaray" seqentially.  The output ray-tracing images may
         be read by "ascaarf" to create corresponding ARFs (will be 
        useful for  extedned source analysis).  Please see:

        for more details.

mkgisbgd: Create "pure" GIS blank sky images and spectra
          taking out point sources. Please see:

          for more details.

corpileup: For SIS observation affected by the event pile-up, 
           "guess" the amount of pile-up, and create new spectra
           in which pile-up effects are corrected as much as possible.

  temp2gain: Make a GIS gain history FITS file from FRF file.


                           ===== CALTOOLS =====

===> New since FTOOLS 4.2 (December, 1998) <===

    NEW!!! REMOTE ACCESS of files in the HEASARC CALDB - FTOOLS users
    can now access files in the HEASARC CALDB, without having to download 
    and install the CALDB.  To do this do the following:

        1) download the file 


           and set the environment $CALDBCONFIG to point to that file.  For
           example if you download the file to /local/user/caldb.config, then

                % setenv CALDBCONFIG /local/user/caldb.config
        2) download the file 


           and set the environment variable $CALDBALIAS to point
           to that file.  For example, if you download the file to
           /local/user/alias_config.fits, then
                % setenv CALDBALIAS /local/user/alias_config.fits

        3) set the environment variable $CALDB to

           setenv CALDB

        Now, whenever an ftool task which needs a file from the CALDB (for
        example ascaarf or pcarf), if the key CALDB is given for the
        filename, the task will connect to the HEASARC CALDB via ftp check
        the appropriate caldb.indx file for the name of the appropriate
        file, download the file to the current working directory, and
        continue the task.

    Changes to CALTOOLS tasks:

All tools which manipulate response matrix files now use compressed
form internally so they can handle the large matrices required for
Chandra, XMM, Astro-E. (These use new callib routines wdrmf4 and

   addarf, addrmf, dmprmf, gcorrmf, marfrmf, rbnrmf
             -- The limits of the dimensions of data arrays are removed. 
                These arrays are generated dynamically now.

      genrsp -- The user can now input an rmf instead of just assuming a 
                gaussian response with some relation between sigma and energy.

      rsp2rmf -- Now supports the OGIP RMF version 1.3.0.

    udcif --         now does more rigorous checking for duplications of good
                quality files in the caldb.indx file being updated.  If a
                duplication is found, udcif will ask the user to change the
                quality value of the entry which already exists in the
                caldb.indx file; if the user does not change the quality
                value of the entry which already exists in the caldb.indx
                file, udcif halts.  This ensures that no duplications (and
                hence no ambiguities) exist in the caldb.indx file.

===> Bug fixes <===

  quzcif  -- fixed uninitialized variable which caused problems under IRIX
  rbnrpsf -- change PIX_SIZE to PIXSIZE in error message

                            ===== EXOSAT =====

===> Bug fixes <===

 cmadead  -- fixed the exposure calculation when multiple event files 
             are used to extract a lightcurve. 
                            ===== FIMAGE =====

===> New since FTOOLS 4.2 (December, 1998) <===

fimg2tab:  Copy the image pixel values into a table extension. 
 fimgpar:  Copy the value of a FITS image pixel to a parameter file.
 fparimg:  Write a parameter value to a FITS image pixel 

===> Major revision <===
fregcon: Added a new parameter called factor. If this parameter is set then 
         fregcon just multiplies all dimensions in the region by this factor. 
         If positions are in pixels then these are multiplied as well.

                            ===== FUTILS =====

===> New since FTOOLS 4.2 (December, 1998) <===

  fdelete:  Delete a FITS file.
  fmodtab:  [P}Modify the values in multiple rows of a table column.
  fsumrows: Sum or average values from list of table columns over spec.
  ovferify: Orignal fverify in v4.2 release.

===> Major changes since FTOOLS 4.2 (December, 1998) <===
     * Newly re-written in C and comforms to the latest FITS Standard. 
     * Added options to control the amount of information  
       and levels of the reported errors. 
     * The number of errors and warnings are also stored in parameter 
     * Added supports for comparing the data units (images and
     * Changed the default output format of bit columns from integer to 
       bit string. Added an parameter xdisp to specify the format of 
       bit columns. 
     * Added an option to specify the coordinate system for the 
       histogram bin (WCS or raw).

                             ===== GRO =====

    bodgetvp -- The viewing period list for this ftool has been
                updated through CGRO Cycle 8.

    bod2rmf  -- This ftool creates RMF FITS files in XSPEC
                format for BATSE occultation data (NHIS type).
                To be used with ftools bod2pha and bodgetvp.

                            ===== HEAO1 =====

These are new tools which allow to extract lightcurves from the raw rate data 
taken with the HEAO1 A2 detector. These tools work on the fits HEAO1 A2 data
files as available in the HEASARC archive.  Further information about the 
HEAO1 mission, archive and software is available from :

===> New since FTOOLS 4.2 (December, 1998) <===

 a2source    - Find HEAO1 A2 raw rate files for a given sky position
 a2lcurve    - Extract lightcurve from HEAO1 A2 raw rate data
 dsdlcurve   - Extract scanning profile from HEAO1 A2 DSDISK data

                            ===== HEASARC =====

Extractor changes

Changed WMAP output from integer to real.

Added ability to use multiple event files with different WCS keywords. The
output uses the WCS keywords of the first file and events from later files
are remapped by using FITSIO routines to transform pixels to sky coordinates
and then back again.

Added support for PIE regions.

Increased the maximum number of GTIs allowed.

Changed the temporary files from formatted to unformatted to save space.

The OPTIC keywords are now modified for the effects of any binning or
extraction of a sub-image.

Added wtmapfix parameter to determine whether WMAP pixels outside the
selected region should be set to -1.

Added CXC data model keywords to output GTI extensions.

If there is no GTI extension in an event file then extractor now uses
TSTART and TSTOP to define a single good time interval.

Bug fixes :
  Rotation on BOX regions was being ignored ! Fixed this.
  Fixed bug that caused regions not to work correctly when XYCENTER/XYSIZE
    were set.
  Added check for TIMEZERO in events extension and added its value to
    event times.
  Fixed bug that caused regions with negative declinations to be handled
  Fixed incorrect value of PIXSIZE in output WMAP.

Mathpha changes

Added a new option errmeth='poiss-0' which causes no STAT_ERR column
to be written and the POISSERR keyword in the output file to be set
to 'T'.

                             ===== OSO8 =====

===> Bug fixes <===

 osopha & osorat -- fixed bug which causes differences in the output
                    files on different platforms.

                             ===== ROSAT =====

===> Bug fixes <===

  ao    -- changed upper case input filenames to lower case
  calcbgdcor -- added POINT, ELLIPSE, and ANNULUS to supported regions;
                fixed seg fault under some OSes
  castpart -- changed upper case input filenames to lower case
  lte   -- changed upper case input filenames to lower case
  pcparpha -- fixed "array dimensions too small" problem
  rate  -- changed upper case input filenames to lower case
  tilt  -- changed upper case input filenames to lower case

                             ===== TIME =====

===> New since FTOOLS 4.2 (December, 1998) <===

  makefilter:  Create a filter file from housekeeping files.  

                           ===== XIMAGE =====

For full documentation on XIMAGE, refer to:

===> Major changes since XIMAGE v2.53 <===

   * Dynamically allocated image maps
   * Linux support
   * Internal image header accessed by keywords
   * Mission database defining mission-specific settings
   * Increased color resolution (Up to 83 levels)
   * Readline capability allows command recall and filename completion
   * New commands
      + centroid - Centroid calculation
      + chheader - Change internal header
      + chmdb - Change mission database
      + colors - Show and manipulate available colors
      + counts - Sum counts in selected area
      + excess - Find excesses (background + excess + search = detect)
      + flip - Flip image (horizontal, vertical, +/-90 degrees)
      + free_saved - Free memory of saved image
      + keywords - List help keywords
      + levels - Manipulate image levels
      + offset - Calculate angular offset between two points
      + powplot - Spawn POWplot image viewer
      + search - Slide-cell search (background + excess + search = detect)
      + surface - Plot pseudo-3d surface
      + timestamp - Print the time on the image plot
      + value - Print pixel values, an alias for polygon
      + viewport - Set configuration for multiple plots on page
      + vplabel - Label the viewport

===> Other changes since XIMAGE v2.53 <===

For complete details on command changes and new features see:

                            ===== XRONOS =====

===> Bug Fixes & Minor changes since xronos 5.15  <===
     lcurve - fixed bug that causes a crash, on OSF platform, when use 
              multiple time series as input 

             fixed labels in the default plot files
             fixed warnings seen at building time due to incorrect parsing 
                 in routines that print messages

                            ===== XSPEC =====

1) Miscellaneous issues:

       Y2K compliance. XSPEC had only one substantive Y2K related
       issue, which arose when creating data simulations (using the
       fakeit command). This new version produces fake data files in
       FITS format with a DATE keyword compliant with the FITS standard
       for files created after January 1, 2000. Cosmetic issues include
       the printing of the date by commands such as "show", which  now
       produces 4 rather than 2 digits for the year.

       The implementation of user models is now performed by the
       construction of a shared library. As a result, users may now
       simply use the XSPEC build routines to compile their own model
       library to be used by the site-installed xspec binary rather
       than having to build a personal copy of the xspec binary.
       However, this feature is very new, and should be considered
       a "beta" option. It is still possible to build local models
       directly into the site-installation, in a way similar to
       previous releases. Full details of both approaches may be
       found in the file INSTALL.SOURCE.

2) User Interface. Some of these issues may affect 'undocumented features'
   of XSPEC that users have learnt to take advantage of. Please note carefully!

       a) Interrupt (Ctrl-C) handling has been added for interactive
          sessions.  XSPEC will now not terminate on a Ctrl-C added at
          the prompt. However, we have retained interrupt handling from
          scripts: Ctrl-C during script execution will kill the program.
          We considered allowing interrupt handling during the execution of
          long-running commands such as 'fit' or 'steppar'. However,
          there is presently no way of restoring the state of the program
          (parameter values) before the command was entered, and thus the
          program would be left in an undefined state. We will reconsider
          this issue in future releases.

       b) In version 10's implementation of the tcl interface, XSPEC 
          would process any valid XSPEC/tcl command at the prompt
          provided  during commands requiring user input (e.g. newpar,
          model, addmod, editmod, gain, and fakeit). This had a serious
          potential for leaving the program in an undefined and
          producing erroneous results. This has now been disallowed.
       c) XSPEC now uses tcl version 8.2.2 as its command processing shell. 
          tcl 8.x introduced a bytecode compiler, such that command
          scripts are compiled the first time they are invoked and then
          reused on subsequent calls.
       d) XSPEC will now correctly process tcl scripts entered at the prompt. 
          In version 10, XSPEC did not correctly process looping instructions. 
       e) There are some changes in the recommended usage for calling 
          scripts (avoid 'source script.xcm' and use @script instead).
          See the online help and the manual for details. No loss of
          functionality is implied.
       f) A new command, tclout, is available to write XSPEC internal 
          information (such as data arrays, models) to tcl variables.
          tclout writes its output to a Tcl variable called
          $xspec_tclout, which can then be manipulated using Tcl
          commands.  The v10.0 method of returning variables to  tcl
          (i.e.  writing to the result string for a command) is deprecated
          and will be withdrawn in the next release.
       g) The single character abbreviations for XSPEC commands have
          been  withdrawn owing to many clashes with commands
          recognized by tcl's command interpreter.  XSPEC commands must
          be at least two characters in length, apart from "renorm" which
          clashes with "rename" and thus needs at least 4 characters.
          Users may, however, define their own aliases (see manual for
          details). It is, however, not advisable to alias commands such
          as "rename" or "unknown" that are used extensively by tcl's
          internal processing.
       h) XSPEC now loads tk, tcl's companion graphical toolkit library 
          at startup.  Scripts for XSPEC can therefore be written using
          tcl and tk commands.  For more information  about tcl/tk, see

       i) XSPEC now sets up a directory, $XSPEC_HOME, in which the user
          can place tcl/tk scripts that are indexed on start up. This
          allows users to create their own composite command procedures in
          tcl/tk as augmented by XSPEC commands.  $XSPEC_HOME defaults to
          $HOME/.xspec .

3)  Changes to existing procedures. Please note the first item in particular:
        a) The default setup for V.11 will not exactly reproduce V10
           numerical results.  This is because the default table of
           photoelectric absorption cross sections is a newer version.
           For testing purposes etc. one may recover the earlier
           numerical results by restoring the older cross-section
           tables using the new 'xsect' command:
           XSPEC>xsect obcm        ! ("Old Balucinska-Church and McCammon") 
           For further details of xsect, see below.
        b) The data command  now accepts wildcards and simple ranges
           for multispectra OGIP Type II files, allowing the user to
           read multiple spectra with a single command. Additionally,
           one can modify the TypeII file such that XSPEC will read
           multiple spectra with different {response, background,
           ancilliary,correction} files. See the data command
           documentation for details.  Additionally, the limit of
           number of datasets that can be read into the program has
           been increased from 100 to 500. It is expected that future
           versions will remove this limit altogether.
        c) During parameter setting, if more than one parameter is to be 
           modified, XSPEC now displays a text string prompt indicating 
           the data group  number (if there is more than one data group),
           model component, and parameter name.

        d) In specifying parameter linking [using newpar  and 
           {model, addmod, editmod}], one may now specify linking operations 
           between parameters x and y of the form 
           newpar y = x * a {/b} (+|-) c
           where a, b and c are real numbers. This allows simple fractional 
           relationships as well as straight multiplicative factors.

        e) User-defined models may now specify a computed uncertainty as part
           of the calculation. This is added in quadrature with the uncertainty in the data. 
           Currently, this is only implemented in the XSPEC model library for 
           the ascac cluster mixing model.
        f) When using the  C-statistic, the  Akaike and Bayesian Information 
           Criteria are printed.
        g) For the steppar command, the default  option is now "best" rather 
           than "current".
        h) The error command now allows the user to restart the calculation 
           if a new  minimum is found. This can be made an automatic option.
        i) setplot rebin can now take a plot group argument to allow plots 
           to be rebinned independently.
        j) new option 'show free'  shows only free parameters.

        k) Convolution components now operate on model*area rather than
           just model. This allows pile-up to be modelled as a convolution

        l) The goodness command now  works for spectra with background
           and for the chi-squared statistic, provided the only source of
           variance is counting statistics.
        m) Local models that use the cgabnd, cgdatd, or cgsolr routines
           should be changed to use fgabnd, fgdatd, and fgsolr,
           respectively. The argument lists are identical - only
           the first letter of the routine name has changed.

4) New commands and techniques:

        a) xsect command changes the photoelectric absorption
           cross-sections used in all the absorption models with the
           exception of wabs. The other options are the older
           Balucinska-Church & McCammon cross-sections used before and a
           newer compilation by Verner et al.
        b) bayes command sets up Bayesian inference including
           specifying priors for model parameters. This is valid for data
           with background even when both source and background spectrum
           have too few counts to be in the gaussian regime.

        c) mdefine command allows the user to define a new model
           component as an algebraic expression.
        d) identify command lists possible line identifications in the
           energy range requested.
        e) extend command extends the energy range over which a model
           is calculated.  This is useful for convolution models.
        f) ftest command  calculates F-statistic and probability to aid
           in comparing alternative fits.
        g) genetic global optimization scheme can now be chosen with
           `method genetic'.  The genetic command  can be used to modify
           the parameters of the fitting algorithm.
5) New Models:  

       apec, vapec:    emission spectrum from collisionally ionized
                       diffuse gas: versions for fixed and variable 
       bexrav, bexriv: E-folded broken power law reflected from neutral
                       and ionized matter.
       bmc:            comptonization by relativistically moving matter.
       equil, vequil:  ionization equilibrium collisional plasma model in
                       fixed and variable abundance versions.
       lorentz:        lorentzian line profile
       nei, vnei:      Simple non-equilibrium ionization plasma model
                       (fixed and variable abundance versions).
       gnei, vgnei:    generalized non-equilibrium ionization plasma model
                       (fixed and variable abundance versions).
       npshock,vnpshock: plane-parallel shock with ion and 
                       electron temperatures (fixed and variable abundance 
       pshock,vpshock: constant-temperature plane-parallel shock model 
                       (fixed and variable abundance versions).
       redden:         IR/optical/UV extinction from Cardelli et al 1998.
       refsch:         E-folded powerlaw reflected from an ionized 
                       relativistic disk. 
       sedov, vsedov:  Sedov model with electron and ion temperatures
                       (fixed and variable abundance versions). 
       srcut:          synchrotron radiation from cutoff electron distribution.
       sresc:          synchrotron radiation from escape-limited electron

6) The following models have been removed:


                           ===== XSELECT =====

The latest version of the Xselect user's guide is available
online at:

Changes for xselect v2.0

There are now three versions of xselect. The standard interface is still
called xselect. xseltcl is xselect with a Tcl interface - several commands
are renamed to avoid conflicts with Tcl commands. ixselect is a preliminary
version of a GUI for xselect. Please try it out and let us know what you

A new command "select chip" has been added for Chandra and XMM data. This
selects all events for the requested chip(s) and constructs the appropriate
GTI extension. It also sets the xycenter and xysize to minimize the size of
any extracted image.

When a region selection has been made the extract fullimage parameter 
determines whether any created image will cover the entire field-of-view
or just a box bounding the selected region.

Added mission database entries for all Astro-E instruments and updated
entries for Chandra and XMM. Switched SAX default sky coordinates to X,Y.

Added the wtmapfix variable to the mission database to determine whether
extractor will attempt to set to -1 all pixels outside the selected region.
If this variable is set to false then pixels outside the selected region
will have value 0.

Modified the mission database to allow spectra to be truncated both at the
low and high ends.

Fixed bug for XTE PCA - now correctly passes INDEF for chmin and chmax to 
saextract when no PHA cuts are specified.

XYCENTER and XYSIZE should now always be given in unbinned coordinates.

Set xybinsize now automatically resizes any region filters that have been
given so that they are valid with the new binning.

Suppressed the prompt for the size keyword after set XYNAME to a coordinate
system other than the standard three in the mdb. Assume that the TLMAX
keywords will be used, which should always be the case now.

If event files from different instruments are read together the program
now issues a warning rather than refusing to read the offending files.

                               ===== XSTAR =====

 This marks the first time that xstar has been included as part of the 
 Lheasoft distribution. 
 For complete details and up-to-date information on using Xstar, see
  the xstar home page at:
                              ===== XTE =====

For complete details and up-to-date information on using FTOOLS to
analyze RXTE data, please refer to:

===> New since FTOOLS 4.2 (December, 1998) <===

         hxtrsp -- Produces a response matrix for an input HEXTE
                   spectrum (.pha file) using calibration data stored in
                   the OGIP calibration database (CALDB). (Already
                   released as part of the patch to FTOOLS v4.2.)

            rex -- A script designed to run through all of the basic
                   data reduction steps for multiple observations of
                   a given target. Rex has been available since March
                   1999 via the RXTE-GOF web site but is included
                   in a FTOOLS release for the first time here.

        rebinlc -- Rebins lightcurves by integer multiple of TIMEDEL.
                   Designed for rebinning of HEXTE lightcurves to 
                   facilitate background subtraction and is used by
                   the latest version of rex.

===> Major changes since FTOOLS 4.2 (December, 1998) <===

     These two tools have been withdrawn from FTOOLS v5.0 for
     extensive renovation.

     This tool has been completely rewritten as a compiled program rather
     than a Perl script and, as such, the interface now uses a standard
     FTOOLS parameter file. The tool takes an input lightcurve which
     covers periods during which PCUs turn on or off and places it onto
     a constant scale. By default the RATE/ERROR columns are scaled up
     to the maximum number of PCUs on at any time during the observation
     but alternate behavior may be selected to scale to one average PCU
     throughout or to any user-specified set of PCUs. This rewrite has
     made correctlc considerably faster and more robust.

     This tool has been removed from FTOOLS v5.0 for extensive renovation.


     Response matrix generation now includes Epoch 4.  Energy-to-channel
     information has been updated for all epochs.  Parameters in the
     parameter file have also evolved.  The latest version of pcarmf,
     combined with the latest energy-to-channel table (included with this
     FTOOLS release) and parameter file generate response matrices which
     minimize (but do not eliminate) features near 5 keV.  Corrections for
     Gain drift are included.  The default behavior has been changed so
     that the latest energy-to-channel information is searched for in
     $LHEA_DATA, as opposed to CALDB.

===> Bug Fixes and Minor changes since FTOOLS 4.2 (December, 1998) <===

     Fixed bug related to long strings in CPIX keywords.

     Bug fixed so that output files include necessary

     Fixed calculation of exposure for fast pulsars.

     fdpath parameter can now accept either path or a named file.
     In the former case it expects to find a file named "FMI"; in 
     the latter the named file can be anything that begins with "FMI".

     TDISP keyword format corrected to conform to FITS standard.

     Now properly handles rare cases where files from multiple
     appids exist in the same column in a subsystem index file.

     Fixed minor bug affecting reads from output file.

     Documentation updated slightly related to hidden/prompted parameters.

     Now allows ".gz" suffix when checking existence of input file.

     Handles MJDREF vs MJDREFI/F properly. Modified to match new 
     FSTRUCT parameter list.

     FTOOLS v5.0 includes the newest versions of these tools as provided 
     by the HEXTE team at UCSD. These are identical to the versions which 
     were previously released as a patch to FTOOLS v4.2.

     Checks SAA dose history file validity

     Bugs fixed in handling null input rates.
     Accumulation of quaternions handled better.

     Now more robust in checking for errors in input file list. 

     Case-sensitivity removed for "INDEF" vs. "indef".

     Fixed bugs related to timemin/max and timeint merging with gtiand/gtior
     which led to loss of the first GTI in some circumstances.

     Screen output modified slightly to reflect timeint/timemin/timemax.

     Fixed dropped leading digit in screen output for bright sources.

     Fixed bug in call to Check_Time subroutine which could cause an
     error in rare cases for events separated by very small amounts of time.

     Fixed bug which caused crashes in rare circumstances.

     Transparent change to interface with fcollect (see above).

===> Known Bugs in v5.0 RXTE FTOOLS <===

     The extractors may bail out complaining about number of GTIs. 
     Workaround is to run standalone binaries rather than dispatch.
     (Affects only IRIX-based systems (ie, SGIs) running the "dispatch" 

     Large light curve files have a problem such that the first entry
     in the TIME column for every new processing cycle (by default every
     100000 rows) incorrectly repeats the last time from the previous cycle.
     Subsequent rows are all correct. This does not appear to affect the
     RATE or other columns.