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From: aszostek@slac.stanford.edu
Subject: Filtering of filter wheel closed data
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2 followups: 1 2

Private message: yes  no

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Date: Fri, 16 Sep 2011 23:03:05 GMT
From: aszostek@slac.stanford.edu
To: xmmhelp@sciops.esa.int
Cc: aszostek@slac.stanford.edu
Subject: Filtering of filter wheel closed data
Full_Name: anna szostek
Submission from: (NULL) (198.129.217.162)


Hi,
I would like to use filter wheel closed data as an instrumental background for
my extended source. I analyzed my extended source with ESAS package. Currently I
cut the same region of the detector in FWC and mask the regions of point sources
from the source observation. I also remove the same CCDs. I create spectrum
using xselect. Next I calculate a ratio of count rates in 10-12 keV band in both
spectrum of the source and FWC to scale the rates to properly account for
different exposures. When I plot the source spectrum and background in xspec
they look ok, background is lower than source region. But when I want to use FWC
spectrum as background to the source, I run into problems in that the data after
subtraction has negative rate - background is over subtracted. I think it is
something related to backscale keyword which is very small in FWC spectrum and
large (several orders of magnitude) in source spectrum. What am I missing here?
Should I do some special filtering of the FWC data? Should I set backscale
keyword by hand? I tried to use backscale script of SAS but the script
complains:

** backscale::arfgen: error (blockNotFound), Could not find block with qualified
name 'test.pha:REGION' in dataset with name 'test.pha'

How can I fix it?
Best regards
Anna




Reply 1

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From: Matthias Ehle <xmmhelp@sciops.esa.int>
To: aszostek@slac.stanford.edu
Subject: Re: Filtering of filter wheel closed data (PR#48686)
Date: Mon Sep 19 10:05:01 2011
Dear Anna,

yes, if you used the same spatial extraction filtering to create
your source and FWC spectra, the backscale factor should roughly
agree. So as a test you could 'manually' edit the value of the
BACKSCAL keyword in the FWC spectrum.

Did you run the SAS backscale task on the FWC spectrum?
(you need to do so in case you create the spectrum with evselect;
if you did it with xmmselect, this is done automatically, see
http://xmm.esac.esa.int/sas/current/documentation/threads/PN_spectrum_thread.shtml
).

As a comment: if you use ESAS, the background is automatically modelled,
based on FWC templates that are part of the ESAS related calibration files.
So there actually is no need for you to create a FWC spectrum yourself.
But of course you might have a good reason why you prefer to create
it with your own method - I just thought to mention to you this possibility.

Regards,
   Matthias

--
   Dr Matthias Ehle 
   XMM-Newton User Support Group
   European Space Astronomy Centre


Followup 1

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From: "Szostek, Anna" <aszostek@slac.stanford.edu>
To: Matthias Ehle <xmmhelp@sciops.esa.int>
Date: Mon, 19 Sep 2011 10:42:09 -0700
Subject: Re: Filtering of filter wheel closed data (PR#48686)
Dear Matthias,
Thank you vary much for your reply. I just have two more small questions.




On Sep 19, 2011, at 3:05 AM, Matthias Ehle wrote:

> Dear Anna,
> 
> yes, if you used the same spatial extraction filtering to create
> your source and FWC spectra, the backscale factor should roughly
> agree. So as a test you could 'manually' edit the value of the
> BACKSCAL keyword in the FWC spectrum.
> 

ASZ: Ok


> Did you run the SAS backscale task on the FWC spectrum?

ASZ: I tried but it complains

asz ~/Projects/Cooling_flows/XMM/0610980201/FWC_files > backscale
spectrumset=test.pha
** backscale::arfgen: error (blockNotFound), Could not find block with qualified
name 'test.pha:REGION' in dataset with name 'test.pha'


> (you need to do so in case you create the spectrum with evselect;
> if you did it with xmmselect, this is done automatically, see
> http://xmm.esac.esa.int/sas/current/documentation/threads/PN_spectrum_thread.shtml
> ).
> 


I created my spectra with xselect instead of xmmselect. Could this be the reason
for my problems? I will redo my spectra with xmmselect.


> As a comment: if you use ESAS, the background is automatically modelled,
> based on FWC templates that are part of the ESAS related calibration files.
> So there actually is no need for you to create a FWC spectrum yourself.
> But of course you might have a good reason why you prefer to create
> it with your own method - I just thought to mention to you this
possibility.
> 


ASZ: I tried this and I was successful with MOS background spectra. But ESAS did
not want to work for PN (in sas v11). Is it already fixed to work with PN?

Best regards,
Anna






Reply 2

Resend
From: Matthias Ehle <xmmhelp@sciops.esa.int>
To: aszostek@slac.stanford.edu
Subject: Re: Filtering of filter wheel closed data (PR#48686)
Date: Tue Sep 20 07:46:29 2011
Dear Anna,
 
you wrote:
> I created my spectra with xselect instead of xmmselect. Could this be the
reason
> for my problems? I will redo my spectra with xmmselect.

Yes, this could be the case: xmmselect should be used as it makes sure that
keywords and extensions of FITS files are created such that the further
processing in SAS works fine. Please give it a try - and do not hesitate 
to contact us again in case of remaining problems.


>> As a comment: if you use ESAS, the background is automatically
modelled,
>> based on FWC templates that are part of the ESAS related calibration
files.
>> So there actually is no need for you to create a FWC spectrum
yourself.
>> But of course you might have a good reason why you prefer to create
>> it with your own method - I just thought to mention to you this
possibility.
>> 
> 
> 
> ASZ: I tried this and I was successful with MOS background spectra. But
ESAS
did
> not want to work for PN (in sas v11). Is it already fixed to work with PN?

Yes, ESAS is embedded into the SAS environment and since SAS version 11
it actually works for pn, too. There was an issue with SAS v11 if downloaded 
before 24/3/2011: in this case a patch is needed, see 
http://xmm.esac.esa.int/sas/current/sas_news.shtml
But if you downloaded SAS v11 later, all is ready to go.

Note that ESAS was originally invented by our colleagues from the NASA
Guest observer facility, see
http://heasarc.gsfc.nasa.gov/docs/xmm/xmmhp_xmmesas.html
Also they invite you to report to them any problem with ESAS; so in case you
have detailed questions or comments, feel free to contact them directly at
xmmhelp@athena.gsfc.nasa.gov

Regards,
   Matthias


Followup 2

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From: "Szostek, Anna" <aszostek@slac.stanford.edu>
To: Matthias Ehle <xmmhelp@sciops.esa.int>
Date: Tue, 20 Sep 2011 18:19:01 -0700
Subject: Re: Filtering of filter wheel closed data (PR#48686)
Hi,
Thank you for the followup.


> 
> Yes, ESAS is embedded into the SAS environment and since SAS version 11
> it actually works for pn, too. There was an issue with SAS v11 if
downloaded 
> before 24/3/2011: in this case a patch is needed, see 
> http://xmm.esac.esa.int/sas/current/sas_news.shtml
> But if you downloaded SAS v11 later, all is ready to go.
> 
> Note that ESAS was originally invented by our colleagues from the NASA
> Guest observer facility, see
> http://heasarc.gsfc.nasa.gov/docs/xmm/xmmhp_xmmesas.html
> Also they invite you to report to them any problem with ESAS; so in case
you
> have detailed questions or comments, feel free to contact them directly at
> xmmhelp@athena.gsfc.nasa.gov

Indeed I tried the new esas and pn-spectra worked great. But pn-back has
problems. It says a file pnS001-4obj.pi is missing while it is there in the
directory. I am not sure how to proceed. See below the screen output.

Anna

asz ~/Projects/Cooling_flows/XMM/0610980201/annulus11 > pn_back prefix=S001
caldb=$SAS_CCFPATH diag=0 elow=400 ehigh=7200 quad1=1 quad2=1 quad3=1 quad4=1
 xmmdir: /Users/aszostek/Projects/Cooling_flows/XMM/0610980201/../ccf           
        
 Quiescent particle background data file:
 /Users/aszostek/Projects/Cooling_flows/XMM/0610980201/../ccf/pn-qpb.fits.gz    

 diag:  0
 prefix: S001
 el, eh:  400 7200
 Quadrant selection 1 1 1 1
   
 Create the OOT subtracted spectrum
  
 Observed spectrum: pnS001-obj.pi                                               
                   
  
 PN Mode: PrimeFullWindow          
 OOT Scale:   0.0630
  
 Spectrum RMF: pnS001.rmf                                                       
              
  
 OOT spectrum: pnS001-obj-oot.pi                                                
              
  
 Exposure:   12168.8 s
  
 Process the individual quadrant observation data and create OOT 
 subtracted spectra and exposures which are area and exposure normalized.
  
 READ_PHA POSITION 11
 Missing EXPOSURE keyword
 PN_BACK POSITION 04
 missing file: pnS001-4obj.pi           

asz ~/Projects/Cooling_flows/XMM/0610980201/annulus11 > ls pnS001-4obj.pi
pnS001-4obj.pi











Reply 3

Resend
From: Matthias Ehle <xmmhelp@sciops.esa.int>
To: aszostek@slac.stanford.edu
Subject: Re: Filtering of filter wheel closed data (PR#48686)
Date: Wed Sep 21 07:18:53 2011
Dear Anna,

I actually have no clue...
Can you, please, re-submit this ticket to the NASA Guest Observer HelpDesk
(xmmhelp@athena.gsfc.nasa.gov). I think for this issue the advise from the
ESAS developers is needed.

Sorry that I have no better thing to offer.

Cheers,
  Matthias

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