Retrieve ChaRT Rays

Overview

Synopsis:

After running ChaRT, you will be sent an email pointing to the directory on the FTP server where you can download a compressed tarfile containing the results of the run. This thread illustrates how to retrieve, unpack, and view the output data.

The data used here were created by running ChaRT with the following parameters:

  theta   = 5.949 arcmin  
  phi     = 197.74 degrees 
  energy  = 1.7 keV
  density = 2
  seed    = 96969267

Last Update: 26 Oct 2012 - screen output text updated for the Linux version of the SAOTrace backend, after transition from Solaris version of SAOTrace/ChaRT.

Email from ChaRT

Once your job has finished, ChaRT will send you an email which looks similar to this:

Your data are now available for download. You can retrieve them here:
        ftp://saotrace.cfa.harvard.edu/pub/ChaRT//HRMA_theta5.949_phi197.74_en1.7_den2.fits

        File size: 42307200 bytes
The data will be deleted automatically after two days.

The ChaRT threads explain how to analyze this ray file.
http://cxc.harvard.edu/chart/threads/index.html

With the location of the simulated ray file.

Download the Ray File

The name of the rayfile (HRMA_theta5.949_phi197.74_en1.7_den2.fits) appends the mirror-coordinate position and energy/ray density or spectrum/exposure time information. There are two simple ways to retrieve the file from the server:

Paste the URL from the email (ftp://saotrace.cfa.harvard.edu/pub/ChaRT/HRMA_theta5.949_phi197.74_en1.7_den2.fits) into your web browser and a "Save As..." box should be launched.

From the command line, it is possible to use wget (most users have this tool installed on the system):

unix% wget ftp://saotrace.cfa.harvard.edu/pub/ChaRT/HRMA_theta5.949_phi197.74_en1.7_den2.fits

or to FTP to saotrace.cfa.harvard.edu:

unix% ftp saotrace.cfa.harvard.edu
Connected to saotrace.cfa.harvard.edu (131.142.198.54).
220 ProFTPD 1.3.2 Server (ChaRT FTP Service) [131.142.198.105]
Name (saotrace.cfa.harvard.edu:chartusr): anonymous
331 Anonymous login ok, send your complete email address as your password
Password:
230 Anonymous access granted, restrictions apply
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> cd /pub/ChaRT
250 CWD command successful
ftp> get HRMA_theta5.949_phi197.74_en1.7_den2.fits
local: HRMA_theta5.949_phi197.74_en1.7_den2.fits remote: HRMA_theta5.949_phi197.74_en1.7_den2.fits
227 Entering Passive Mode (131,142,198,54,223,135)..
150 Opening BINARY mode data connection for HRMA_theta5.949_phi197.74_en1.7_den2.fits (42307200 bytes)
226 Transfer complete
42307200 bytes received in 4.04 secs (1e+04 Kbytes/sec)
ftp> quit
221 Goodbye.

Columns and Header Keywords

There are many columns in the output rayfile:

unix% dmlist HRMA_theta5.949_phi197.74_en1.7_den2.fits cols
 
--------------------------------------------------------------------------------
Columns for Table Block PSFRAYS
--------------------------------------------------------------------------------
 
ColNo  Name                 Unit        Type             Range
   1   rt_cosx              none         Real8          -0.99978059776498:   -0.99440812340341 Label for field
   2   rt_cosy              none         Real8          -0.06685644634982:    0.07914464045537 Label for field
   3   rt_cosz              none         Real8          -0.07996208257243:    0.10212248230860 Label for field
   4   rt_kev               KeV          Real8          1.70:        1.70    Label for field
   5   rt_graze             radians      Real8          0.00515173170542:    0.04639439521712 Label for field
   6   rt_id                none         UInt4          1:236042             Label for field
...
  20   rt_x                 mm           Real8          -10079.7716668160:   -10079.7716668160 Label for field
  21   rt_y                 mm           Real8          -294.5379545577:      634.5264797508 Label for field
  22   rt_z                 mm           Real8          -565.9773700636:      545.5865192870 Label for field
  23   rt_srfms             none         UInt4          0:2                  Label for field
  24   rt_norm_x            none         Real8          -0.99926784828577:    0.99927332103941 Label for field
  25   rt_norm_y            none         Real8          -0.99935442736250:    0.99930348502744 Label for field
  26   rt_norm_z            none         Real8          0.00779889642402:    0.04506851436049 Label for field
  27   theta                             Real8          -0.04031009147342:    0.02488942993832 Label for field
  28   rt_time              sec          Real8          0.0003458911558:      199.8319193666 Label for field
  29   rt_wght              none         Real8          0.08414399651754:    0.89017727798276 Label for field

rt_x, rt_y, rt_z: ray position in telescope coordinates [mm]
rt_cosx, rt_cosy, rt_cosz: cosine of the ray direction
rt_kev: energy of the ray [keV]
rt_wght: fractional probability that this ray will reach the focal plane
rt_id: ray id
rt_graze: grazing angle at point of last reflection from an optic [radians]
rt_srfms: code indicating which surfaces had been missed
rt_normx, rt_normy, rt_normz: surface normal at point of last reflection from an optic
rt_time: arrival time of ray at entrance of telescope [s]. The first ray arrives at time zero.

There are also some header keywords that should be highlighted; to view the complete header, use:

unix% dmlist HRMA_theta5.949_phi197.74_en1.7_den2.fits header

The ChaRT input parameters used to create the PSF are written as keywords:

unix% dmlist HRMA_theta5.949_phi197.74_en1.7_den2.fits header | egrep 'CREATOR|SRC_|CONFFILE|PSFSEED1'
0003 SRC_E                        1.70 [keV]             Real8        Energy used to generate rays
0004 SRC_DENS             2 [r/mm^2]                     Int4         Ray density
0005 SRC_THET                     5.9490 [arcmin]        Real8        input THETA
0006 SRC_PHI                    197.740 [degrees]        Real8        input PHI
0010 CREATOR              saotrace-1.0.2rc3              String       Software that created
0023 CONFFILE             orbit-200809-01f               String       HRMA config. file

The CONFFILE keyword lists the name of the raytrace configuration file used in the simulation. If a spectral model is used to create the PSF, different "SRC_" keywords are added to the header to record the filename and exposure time:

unix% dmlist HRMA_theta5.949_phi197.74_ensource_flux_chart.dat_exp15.fits \
      header | egrep 'SRC_'

0003 SRC_SPEC             0                              Int4         home/cxc_rays/tmp/runrays/tmp52EpLa/source_flux_
0004 SRC_EXPT             15 [ksec]                      Int4         Livetime time
0005 SRC_THET                     5.9490 [arcmin]        Real8        input THETA
0006 SRC_PHI                    197.740 [degrees]        Real8        input PHI

Examining the PSF data

HRMA_theta5.949_phi197.74_en1.7_den2.fits is a FITS file with the data stored in the PSFRAYS block of the file. Using dmlist shows that this file contains approximately 192,000 rays:

unix% dmlist HRMA_theta5.949_phi197.74_en1.7_den2.fits blocks
 
--------------------------------------------------------------------------------
Dataset: HRMA_theta5.949_phi197.74_en1.7_den2.fits
--------------------------------------------------------------------------------
 
     Block Name                          Type         Dimensions
--------------------------------------------------------------------------------
Block    1: PRIMARY                        Null        
Block    2: PSFRAYS                        Table        29 cols x 192160   rows

The total counts in the PSF image is also recorded in the TOTCTS header keyword:

unix% dmkeypar HRMA_theta5.949_phi197.74_en1.7_den2.fits totcts echo+
192160.0

Summary

The output from ChaRT (i.e. HRMA_theta5.949_phi197.74_en1.7_den2.fits) cannot be used directly in your analysis. It first needs to be projected onto the detector and have the detector response applied to it to create a simulated event file. The Using MARX to Create an Event File thread describes how to do this.

History

27 Jun 2003	original version, updated for CIAO 3.0: layout
13 Jul 2004	created Columns and Header Keywords section
16 Feb 2005	reviewed for CIAO 3.3: no changes
18 Aug 2008	updated for CIAO 4.0: minor changes to screen output
17 Feb 2010	reviewed for CIAO 4.2: no changes
15 Dec 2010	reviewed for CIAO 4.3: no changes
24 Sep 2012	thread renamed
26 Oct 2012	screen output text updated for the Linux version of the SAOTrace backend, after transition from Solaris version of SAOTrace/ChaRT.