iLat Tutorial - Part 1: Setup

Notice: The Fermi code has not been released to the public and is for use by members of the LAT Collaboration only!

A powerful interface for analyzing LAT data, iLat is a python software wrapper currently installed and running on SLAC's linux batch farm.

The core of the iLAT wrapper uses the Automated Science Processing (ASP) scripts, Science Tools, and FTOOLS. The matplotlib (pylab) module provides plotting capabilities, and the standalone script used by the catalog pipeline is used to perform likelihood analysis.

Using iLat, you can – with a single command (getdcft):

• get the data using normal calendar dates;
• convert the FT1 file dates to MET;
• merge all FT1 files to produce another output file with good time intervals (e.g., outfile="ft1merge_gti.fits"); and
• perform cuts on the data using the merged FT1 file as input.

You can also:

• generate a counts map;
• perform source finding (e.g., run likelihood);
• perform a spectral analysis;
• generate a light curve; and
• change the binning to get a new light curve.

Assumptions

This tutorial is based on the assumption that you are running the PROD(uction) version of iLat on a SLAC Public unix machine with a tcsh shell available, and that you will be running ScienceTools v9r7, or above.

Note: This tutorial was vetted by Andrea Tramacere on Nov. 4, 2008 using non-optimized (rh9_gcc32) ScienceTools-v9r8p1.

Preliminary Steps:

Note: If you wish to run ilat from your desktop, see:
iLat Desktop Installation (preliminary).

1. Perform all steps related to the Science Tools software setup for using SLAC's Public Installation;see:
   • Prerequisites: Basic
   • Modify Your SLAC Public Environment

2. Log in to a SLAC Public machine.

3. Create a work directory in NFS user space (see SLAC's Public Installation: Using the NFS User Space, then change to that directory:

cd /afs/slac/g/glast/users/<your directory>
mkdir myiLat
cd myiLat

4. Verify that it has a tcsh shell available by entering echo $SHELL at the command prompt. If it is not the default shell, enter tcsh at the command prompt to change shells.

   You should get the following answerback: /bin/tcsh

5. Determine which optimized Linux version of ScienceTools you wish to use, and then set the ScienceTools environment variable:

setenv ST_INST /nfs/farm/g/glast/u30/builds/rh9_gcc32/ScienceTools/ScienceTools-v9r8p1

Note: The optimized version of ScienceTools reportedly runs approximately five times faster than the debug version; however, all examples used in this tutorial were produced when running the non-optimized version (rh9_gcc32) .

If you wish to run the optimized version (rh9_gcc32opt), set the ScienceTools environment variable to:

setenv ST_INST /nfs/farm/g/glast/u30/builds/rh9_gcc32opt/ScienceTools/ScienceTools-v9r8p1

Tip: Set your CMTCONFIG environment variable accordingly:

	setenv CMTCONFIG rh9_gcc32
or
	setenv CMTCONFIG rh9_gcc32opt

6. Set the ILATROOT environment variable:

setenv ILATROOT /afs/slac.stanford.edu/g/glast/applications/iLat/PROD/

7. Run the iLat setup scripts for the current production version:

source $ILATROOT/setup.csh

8. Run the following setup script so you can run HEADAS software:

source $GLASTROOT/applications/astroTools/astrotools_setup.csh

source /afs/slac.stanford.edu/g/ki/software/etc/csh.login.xray

9. You are now ready to perform the step-by-step procedure described in: Part 2: Analysis of 3C454.3 Using iLat.

Note: This procedure provides detailed instructions on how to use iLat to:

• Get the data.
• Merge the FT1 and FT2 .fits files.
• Set the:
  • irfs
  • energy boundaries
  • ROI
• Generate an xml model.
• Perform a preliminary source detection using PGWave.
• Generate a livetime cube.
• Determine source location using Likelihood.