Oberon Version

Ian M George: Spectral Analysis

These pages are unofficial in all respects. They are primarily simply notes to myself. The information is not guaranteed to be correct or up-to-date.

Last Updated: 2004 Jul 17

Starting Point... The steps below assume (require) that you have successfully completed all steps up to and including the sep_hetg.csh command in Extract Standard files from the EVT2

Compute HETGS/ACIS-S Grating ARFs

[Updated 04jul05]

We are going to make "ARFS" for the dispersed spectra. At the present time, this (unfortunately) involves copying and editing a script. However first we must extract a file from cleaned.evt2 which the script will need

punlearn tgextract
tgextract infile=cleaned.evt2 outfile=acis_pha2.fits outfile_type=pha_typeII tg_srcid_list=all tg_part_list=header_value tg_order_list=default ancrfile=none respfile=none clobber=yes

OK, so now copy the script:

cp /data/oberon5/george/data/axaf/scripts/do_fullgarf.csh ./

Now edit this this, eg

emacs do_fullgarf.csh &

such as to replace every occurance of the string
badpix="../primary/acisf00335_000N002_bpix1.fits"
with the OBSID-specific {bpix}

Now run the script (which may take some time)

punlearn mkarf       
./do_fullgarf.csh

A number of files will be produce, including

  meg_p1.arf
  meg_n1.arf
  heg_p1.arf
  heg_n1.arf

(hereafter refered to as the +ve & -ve 1^storder ARFS for the MEG & HEG). These files (along with the event files containing the corresponding +ve & -ve 1^storder event data for the MEG & HEG) will be read into some of the forthcoming spectral scripts.

Make some Standard Spectra

[Updated 2004 Jul 08]
Extract some standard spectra using

/data/oberon5/george/data/axaf/scripts/tg_bkg acis_pha2.fits

and then

/data/oberon5/george/data/axaf/scripts/do_split_type2.csh

(Scott, this script has now been corrected [2004 Jul 08]) These led to file such as

    coadd_MEG_1_NONE.pha
    coadd_MEG_1.arf
    .... etc ...

Take a quick look by

cp /data/oberon5/george/data/axaf/scripts/megheg_data_nogrp.xcm ./

and then going into xspec, and

xspec>@megheg_data_nogrp.xcm

Make a Standard (Quick-look) Broad-band Spectrum

[Updated 2004 Jul 10]

grppha infile=coadd_MEG_1_NONE.pha outfile=coadd_MEG_1_grp50.pha comm="bad 1-3433 8038-8192 & gr min 50 & exit" clobber=yes
grppha infile=coadd_HEG_1_NONE.pha outfile=coadd_HEG_1_grp50.pha comm="bad 1-1508 8070-8192 & gr min 50 & exit" clobber=yes

Get some standard xcm files:

cp /data/oberon5/george/data/axaf/scripts/megheg_data_grp50.xcm ./
cp /data/oberon5/george/data/axaf/scripts/megheg_data_grp50_2posmedgengal_mo.xcm ./

(Scott, this xcm should now be OK [2004 Jul 08]) and then going into xspec, and

xspec>@megheg_data_grp50.xcm
xspec>@megheg_data_grp50_2posmedgengal_mo.xcm

(Scott, this script has now been corrected [2004 Jul 10]) Then we must decide on the correct value to set the 'Galactic column density'
(due to the ISM in our Galaxy) which will be parameter #2
(wabs nH, with units of 10²² cm^-2 in xspec).
I will have to tell you this value for each object...
But then we should perform a fit, and store the result

xspec>ignore bad
xspec>new 2 {wotever}
xspec>freeze 2 
xspec>fit 100000
xspec>sav mo megheg_data_grp50_2posmedgengal_mo.xcm
 megheg_data_grp50_2posmedgengal_mo.xcm exists, reuse it? y

Quick Search for Features

[New 2004 Jul 17] Make 'grp20' spectral files

grppha infile=coadd_MEG_1_NONE.pha outfile=coadd_MEG_1_grp20.pha comm="bad 1-3433 8038-8192 & gr min 20 & exit" clobber=yes
grppha infile=coadd_HEG_1_NONE.pha outfile=coadd_HEG_1_grp20.pha comm="bad 1-1508 8070-8192 & gr min 20 & exit" clobber=yes

Get some standard xcm files:

cp /data/oberon5/george/data/axaf/scripts/megheg_data_grp20.xcm ./
cp /data/oberon5/george/data/axaf/scripts/megheg_data_grp20_2powabsngal_search_setup.xcm ./
cp /data/oberon5/george/data/axaf/scripts/megheg_data_grp20_2powabsngal_run_search.xcm ./

Now load these new data files into xspec, along with the model we obtained from the previous step,
and then run the first (setup) script just copied..

xspec>@megheg_data_grp20.xcm
xspec>@megheg_data_grp50_2posmedgengal_mo.xcm
xspec>@megheg_data_grp20_2powabsngal_search_setup.xcm
xspec>ignore bad

[Note 2004 Jul 23] Scott, when I changed the script a while back, I forgot to tell you that I had
changed the numbering of the parameters, so redshift is now 7 (sorry) !!!!
Important, the following tasks require that the redshift of the source be entered correctly
(as parameter 7). At the present time, this must be done by hand, e.g.

xspec>new 7 0.01234

I will have to tell you this value for each object...
Now we are ready to run the search script

xspec>@megheg_data_grp20_2powabsngal_run_search.xcm

This will take a long [long.....] time, and dump information to the screen. None of this information is useful
(unless it starts spewing error messages of course). The task will write two ASCII o/p files (just log files actually)

megheg_data_grp20_2posmedgengal_emis.log
megheg_data_grp20_2posmedgengal_abso.log

these contain the basic results. I will describe these to you, and how to further process these files
once you get this far...

Ian M George: Spectral Analysis

Compute HETGS/ACIS-S Grating ARFs

Make some Standard Spectra

Make a Standard (Quick-look) Broad-band Spectrum

Quick Search for Features

Incomplete