SUMER USERS GUIDE

D. M. Zarro (Space Applications Corporation)




CONTENTS


1. INTRODUCTION

1.1 Getting SUMER Software
1.2 Getting SUMER Data
1.3 Updating SUMER Software

2. ANALYZING SUMER DATA


1. INTRODUCTION

SUMER IDL software is now SolarSoft (SSW) compliant. This means that many useful SUMER display and analysis programs are maintained and distributed as part of a general package that incorporates software from other SOHO instruments (e.g. CDS, EIT, MDI ), other solar missions ( Yohkoh, TRACE ), and many ground-based observatories.

1.1 Getting SUMER Software

The SSW software is already installed on most EOF and EAF UNIX systems at GSFC. To check, type: 

printenv SSW
which should return the "top" or root directory in which SSW is installed. If $SSW is not defined, check with your systems administrator for the root directory (usually /solarsoft) in which SSW may have been installed. If you don't already have SSW installed at your site, then you can download it from the Lockheed mirror site at:

http://www.lmsal.com/solarsoft/ssw_install_howto.html.

At this site, you will complete a form to request the SUMER software package, and (optionally) software for additional instruments. The SUMER SSW package is currently optimized for running on a UNIX system.

Here are some useful     for installing the package.

Once you have successfully installed the package, it will be useful to make the following definitions in your .login file: 

setenv SSW top
alias sidl $SSW/gen/ssw_load
where top is the directory name in which SSW is installed. The definition sidl is an alias that you can use to run IDL without conflicting with existing IDL setups on your system. In addition, there is a useful WWW interface for searching all the software (including SUMER) contained within SSW.

1.2 Getting SUMER Data

If you are at Goddard Space Flight Center, then you will find SUMER FITS files stored locally on the SOHO_ARCHIVE disks. To check whether this is the case, type: 

printenv SUMER_FITS_DATA
which should return the top directory containing SUMER FITS files. You can access the files on these disks using IDL procedures described in section 2.. If the SOHO-ARCHIVE disks are not available locally then you can use the SOHO main catalog interface at:

http://sohowww.nascom.nasa.gov/data/catalogues/main.htm.

to download FITS files to a local directory.

1.3 Updating SUMER Software

The master (and, hence, most current) versions of SUMER software and accompanying database and catalog files are maintained at the SOHO Archive at GSFC. In order to obtain the latest versions of these files, it is recommended that you frequently update your local software copy with the master version. The slow way to do this is to reinstall the software over the network as described in section 1.1. A faster, more efficient method is to use the PERL mirror program that comes installed with the SUMER SSW package. This program will update only newer versions of files. To run it, type the following: 

IDL> ssw_upgrade,/spawn

The /spawn keyword is necessary to actually "spawn" the mirror command. Note that PERL version 5 needs to be installed on your system for the mirror upgrade to work.

2. ANALYZING SUMER DATA

The following is a set of examples illustrating useful SUMER IDL access and analysis programs. It is assumed that you have already downloaded the pertinent FITS data files to your local directory. If you are working at GSFC, then the software will attempt to search the SOHO-ARCHIVE for the relevant files.

search and browse SUMER files in the SOHO-ARCHIVE:

IDL> sumer_search

quickly locate files in SOHO-ARCHIVE:

IDL> filenames=get_sumer_files(tstart,tend,[/flat,/nearest])

where tstart and tend are the search times. This routine will return FITS filenames between the input search times (inclusive). If an end time is not entered, then all the files for the day corresponding to start time will be returned. The optional keyword /nearest can be used to locate the filename that is nearest to the start time. The optional keyword /flat can be used to locate only flatfield files.

The use of these keywords is described in these  
quicklook interface to rasters and spectra:

IDL> sumer_tool,filename

read FITS file:

IDL> rd_sumer,filename,index,data

where index and data are structures described in this  

If the input filename does not contain a directory pathname, then the rd_sumer will search your local directory first and then the SOHO-ARCHIVE for the file.

flatfield SUMER data:

IDL> sumer_flatfield,index,data,[flat=flatfield_filename]

where index and data are structures returned by rd_sumer. The keyword flatfield_filename is the (optional) name of the SUMER flatfield file to be used. If the latter is not entered, sumer_flatfield will search for the flatfield file that is nearest in time to the input data.

destretch SUMER data:

IDL> sumer_destretch,index,data

Note that flatfielding must be performed before destretching.

process SUMER data:

Reading, flatfielding, and destretching are combined in the program sumer_calib:

IDL> sumer_calib,file,index,data,[flat=flatfield_name]

If you have already read the data file, then you can input the index and data structures directly:

IDL> sumer_calib,index,data,[flat=flatfield_name]

A user-specified flatfield file can be entered via the flat keyword.

Here is a run of sumer_calib.
save processed SUMER data:

The data structures produced by the above processing routines can be saved into machine portable XDR-format file via:

IDL> wrt_sumer,index,data,[file=file,dir=dir]

where file and dir are optional names for the output file and directory location, respectively. By default, the output file will be written to the current directory with the same original FITS file name but with a .genx extension. For example, an original file named sum_960516_052729.fits would become sum_960516_052729.genx. The latter file can be read back using rd_sumer.

Here is a example of reading, processing, and writing SUMER data.
make a SUMER image map:

IDL>smap=mk_sumer_map(index,data,[/peak])

The output variable is a map structure that contains a SUMER image created by summing over wavelength. Setting the keyword /peak creates an image based on the peak intensity of the selected line. The image can be plotted by using the procedure plot_map:

IDL> plot_map,smap

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