Using the HEASARC

INSTRUCTIONS FOR USING HEASARC X-RAY DATA FILES DIRECTLY

by James Humphreys

updated by James Lochner

What You Need

This is not necessarily the least that you need, but to easily and effectively use the public information data files through NASA, you should have:

direct internet access, or access through a server allowing you to download large files
a fast modem (baud rate >2400 bps)
a graphics printer
at least 4k of RAM to be able to use (not download) analysis software

The files can be downloaded as ASCII or binary files, and files and software are accessible by Mac or DOS platforms. However, most of the files are very large (several megabytes or even gigabytes!!), so a desktop computer is not going to have the power necessary to store these files. You will need in most cases to delimit certain parameters of the files to isolate the information you need before attempting to download.

Getting To The HEASARC

The HEASARC (High Energy Astrophysics Science Archive Research Center) is the location for all these wonderful data products, representing over 145 databases. It is housed at NASA's Goddard Space Flight Center, Office for Guest Investigator Programs (OGIP) and is a collaborative effort of the Astrophysics ScienceDivision (ASD) and the National Space Sciences Data Center (NSSDC).

Access to the data bases and software is available via two methods:

Using World Wide Web, http://heasarc.gsfc.nasa.gov

Use the menu near the top to select W3BROWSE
Choose the desired mission (or Master Catalog), and select Coordinates or Object Name under Search by.
Select one or more catalogues and specify the desired object (or coordinates).

Note: This method does not allow yet allow on-line analysis of data files. There are instructions on these screens to allow users with adequately powerful computers to download files, but in general teacher users will not find this route very useful for this purpose. However, HEASARC homepage has other features and links that are worth looking at.

Using anonymous FTP or Gopher to legacy.gsfc.nasa.gov

login as XRAY
then use BROWSE to search

Note that this option is also available via the HEASARC home page (http://heasarc.gsfc.nasa.gov). Scroll down to the choice "Login to HEASARC On-line Service", found under the FTP, Gopher, Email and Telnet heading.

Also note that the x-ray account on legacy is currently the most useful route to access the features described below. It is from this starting point that the instructions below refer.

Sample Session

xtelab:/home/lhea3/jhumphre(32) telnet legacy
Trying 128.183.8.233 ...
Connected to legacy.
Escape character is '^]'.


OSF/1 (legacy.gsfc.nasa.gov) (ttyp7)

login: xray
'
*************************THE HEASARC ONLINE SERVICE****************************
To access the HEASARC Archive of catalogs and high-energy astrophysics 
data, type `browse ?`  when you reach the HEASARC prompt. To find out about 
other available applications, type `la`. To access the on-line help, type 
`help` (except type `fhelp ftools` to display help information for all FTOOLS 
tasks).
*******************************************************************************

*                          Current Announcements                              *
*******************************************************************************

In June 1995 the following databases have been added or revised to our 
archive:

    MPCRAW        New      The catalog and data files of the Einstein MPC
                           (complete 2.56-second time-resolution dataset)
    MESSIER       New      The Messier Catalog of Extended Objects
    OPENCLUST     New      The Lynga Catalog of Galactic Open Clusters
    IRASZSURV     New      The Strauss et al. IRAS 1.2 Jy Redshift Survey

DECNET type E-mail address is no longer supported.

BROWSE application now supports two name-to-coordinate resolver commands:
Press  to continue ...
Enter your HEASARC username (? for help): jhumphre

Type email to change the e-mail address
Type cpd to change the graphics plot device
Type address to change the postal address

Welcome to the XOBSERVER software system v1.0.3
Type help for help (? for internal help)
HEASARC> browse
BROWSE 6.1o: 18-Aug-95 14:50:21 Address=jamesh@umdd5.umd.edu (xray)
Session initialization, please wait

Database name:

At any time you can type help at the HEASARC> prompt for additional information.

When using WWW, the BROWSE program will present a graphical interface. Gopher or FTP will get BROWSE in command line mode.

Finding Files: Useful search commands are:

sn - to search by name
sc - to search by coordinates

Using files: The results of your search will be listed with information such as the name (or other designation) of the object, the coordinates of the observation, date and time, exposure, and event count rates. (Note: the date is given in [year.day.decimal portion of day] format, and the time may be in time periods after launch or in time periods of the current observation) Each observational database has a number on this list. It is to this number that the program responds.

Database name: cma


For further information type ?, HELP, or DBHELP (to end use EXIT)

Current equinox year: 1950
Current plot device: /XTERM
Loading CMA database sample SOURCES indexed on DEC
Catalog/Images/Lightcurves

CMA_SOURCES_DEC > sn GX5-1

     Name     Seq OFF  Expos  Time      Cts    FILT RA(1950) DEC(1950) Inst
                  (m)  (sec) (yy.d)    (/s)         (hh mm ) (o  '  ")
  ----------+----+---+------+------+----------+----+--------+---------+----
1 GX5-1       164  53   3960 83.257  0.172E+00    7 18 00 39 -24 22 56 L1
2 GX5-1       164  23   3960 83.257  0.178E-01    7 17 57 38 -24 40 49 L1
3 GX5-1       164    1   3960 83.257  0.261E+00    7 17 58 03 -25 04 46 L1
4 GX5-1       164    1   3960 83.257  0.623E-02    7 17 58 00 -25 03 34 L1
5 GX5-1       164    8   5591 83.257  0.205E+00    6 17 58 04 -25 04 35 L2
CMA_SOURCES_NAM 5>

Once you have found a database that you want, You may wish to plot selected files, using:

cpd - change plot device (to current terminal emulation)
pp/im - plot data product/image
pp/li - plot data product/lightcurve
pp/sp - plot data product/spectrum

CMA_SOURCES_NAM 5> pp/li 3
Loading ZZFNAME and ZZFILES, please wait...
Plotting to /XTERM
File cma_c07998.lc LIGHTCURVE FITS 0.04-2.0 keV in current directory
 Nampa error: Parameter not found - EXPOSURE

Accessing EXOSAT CMA FITS LIGHTCURVE file cma_c07998.lc 0.04-2.0 keV

You can place selected files into a temporary directory in HEASARC by typing xp (extract product) followed by the number of the database. This will cause the computer to query you for the number of the database, and whether you want all the files. If you respond in the negative, each file will be listed separately and you will be asked for each file whether or not you want it.

CMA_SOURCES_NAM 5> xp 3
Do you want to select all [N]:
Extract EXOSAT CMA 0.04-2.0 keV IMAGE IMAGE [N]:
Extract EXOSAT CMA matrix RESPONSE RSP [N]:
Extract EXOSAT CMA 0.04-2.0 keV BGLIGHTCURVE BGLC [N]:
Extract EXOSAT CMA 0.04-2.0 keV LIGHTCURVE LC [N]: y
Extract EXOSAT CMA 0.04-2.0 keV SPECTRUM SP [N]:
File cma_c07998.lc LIGHTCURVE FITS 0.04-2.0 keV in current directory

CMA_SOURCES_NAM 5> quit
HEASARC> ls
total 4712
drwxrwxr-x   2 xray     dbase       1024 Aug 18 14:50 .
drwxrwxr-x2177 xray     dbase      36864 Aug 17 09:09 ..
-rwxr-xr-x   1 xray     dbase        768 Aug 18 14:50 .xobserver
-rw-rw-r--   1 xray     dbase      13056 Aug 18 14:57 browse.hty
-rw-rw-r--   1 xray     dbase       1634 Aug 18 14:57 browse.log
-rw-rw-r--   1 xray     dbase     112320 Aug 17 09:56 cma_c07998.lc

To view this directory once you have selected your files, type ls at the HEASARC> prompt.

HEASARC> put cma_c07998.lc
Enter file transfer e-mail address [jhumphre@rosserv.gsfc.nasa.gov]: 
Enter file transfer directory [jhumphre]: 
Do you want this transfer in binary mode [Y]?
Connected to rosserv.
220-
220-  
####################################################################
220-
220-                                  WARNING
220-
220-
220-  THIS UNITED STATES GOVERNMENT COMPUTING SYSTEM IS FOR AUTHORIZED USE 
ONLY.
220-  USING IT FOR OTHER THAN OFFICIAL U.S. GOVERNMENT BUSINESS IS A 
VIOLATION
220-  OF FEDERAL LAW.
220-
220-  INDIVIDUALS USING THIS COMPUTER SYSTEM ARE SUBJECT TO HAVING ALL OF 
THEIR
220-  ACTIVITIES MONITORED AND RECORDED WITHOUT FURTHER NOTICE. KEYSTROKE
220-  MONITORING AS WELL AS OTHER FORMS OF MONITORING MAY BE USED.
220-
220-  ANY INDIVIDUAL WHO USES THIS SYSTEM EXPRESSLY CONSENTS TO SUCH 
MONITORING
220-  AND IS ADVISED THAT IF THIS MONITORING REVEALS POSSIBLE EVIDENCE OF 
CRIMINAL
220-  ACTIVITY, THIS EVIDENCE MAY BE PROVIDED TO FEDERAL LAW ENFORCEMENT 
OFFICIALS
220-  FOR POSSIBLE PROSECUTION.
220-
220-  
#####################################################################
220-
220 rosserv FTP server (Version wu-2.4(1) Thu Oct 20 00:13:16 EDT 1994) 
ready.
331 Password required for jhumphre.
Password:
230 User jhumphre logged in.
200 Type set to I.
Local directory now /online/xray/users/jhumphre
550 jhumphre: No such file or directory.
200 PORT command successful.
150 Opening BINARY mode data connection for cma_c07998.lc.
226 Transfer complete.
112320 bytes sent in 0.23 seconds (4.8e+02 Kbytes/s)
221 Goodbye.
HEASARC>

To download these files onto your machine (or server), type put , and answer the resulting queries. Please be cautious of the very large size of most of these files! To see the file size, type ls at the HEASARC> prompt. File size, date, time and name will appear.

	Logout.

Downloading Data Analysis Tools

The most useful analysis software tools are XANADU and FTOOLS. These are available for on-line use through the xray account on the legacy annex, and on HEASARC through WWW. Mainframe users can download these files through mission pages accessible from the WWW homepage, or via menu through ftp or Gopher. They are compressed files so must be handled accordingly. The pages give good instructions on downloading. Again be aware of the computing requirements for these programs.

Using The Data Analysis Tools

While in an xray account on the legacy annex, HEASARC> help, or help at any of the tool's prompts will give an extensive menu of specific help items. The most useful tools will be

fdump - used to convert files to ASCII format

fplot - plots files and allows interactivity with plots

xspec - for producing and analyzing spectrum plots; also allows statistical comparison to models that you choose along with relevant parameters
xronos - for producing and analyzing lightcurve plots.

These tools are not available on the WWW pages.

By using the transfer tools in your communications package, you can bring an ASCII or binary version of files you've selected onto your local machine (you may need to limit the file size by selecting only certain lines). You can then use your graphics program to plot and analyze the data within the limits of that program.

Getting Help

E-mail to James Humphreys at jamesh@umd5.umd.edu

Addendum

To copy files from hard drive into Excel: drag from HD directly to the Excel icon open Excel from Excel File menu, select go to beginning of data enlarge columns B and C to about 14 select series of items in column A (To select a large series in a column, holding down the open apple and shift keys, use the down arrow to highlight the items you want to select.) select Parse from the Data menu (It may be necessary to select data in pieces, since the memory may be inadequate to handle all the rows at once.) NB: The maximum number of data points that can be plotted in Excel is 4000!

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This file was last modified on Thursday, 07-Sep-2006 14:02:43 EDT