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From: h.oti@crya.unam.mx
Subject: RGS spectra: is it actually there?
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1 followups: 1

Private message: yes  no

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Date: Sat, 23 May 2015 01:21:15 GMT
From: h.oti@crya.unam.mx
To: xmmhelp@sciops.esa.int
CC: h.oti@crya.unam.mx
Subject: RGS spectra: is it actually there?
Full_Name: Hector Oti-Floranes
Submission from: (NULL) (177.243.39.192)


Hello.
I'm currently analysing NGC 1808 RGS data included in XMM-Newton observation
0110980801. I've got some queries:

+ Attending to the XDSP_CORR vs. M_LAMBDA plot, there is no trace of a strong
signal, and source and background regions apparently show the a similar number
of counts per pixel. If I'm not wrong, RGS FOV is large enough to contain the
source, and I've re-run rgsproc with NED coordinates of the object. Despite
that, after loading the obtained spectra in XSPEC, some emission lines are seen.
Is everything all right? Did I do something wrong? Actually, Jim.nez-Bail.n et
al. 2005, A&A 442, 861 showed and analysed these spectra.

You can take a look at the XDSP_CORR vs. M_LAMBDA and banana plots (PI vs.
M_LAMBDA) here:
https://www.dropbox.com/s/vjr3nr139eh3z98/images_0110980801_rgs.tgz?dl=0



+ Also, attending to the "Users Guide to the XMM-Newton Science Analysis System"
Issue 11.0 (18.12.2014), files *SRSPEC* represent source+background spectrum.
However, in this thread

http://xmm.esac.esa.int/sas/current/documentation/threads/xspec_thread.shtml

it is mentioned that those files have been background subtracted. Which one is
correct?



Thanks a lot.


Cheers,

H.ctor



Reply 1

Resend
From: Ignacio de la Calle <xmmhelp@sciops.esa.int>
To: h.oti@crya.unam.mx
Subject: Re: RGS spectra: is it actually there? (PR#76584)
Date: Mon May 25 09:49:40 2015
Dear Hector,

> Hello.
> I'm currently analysing NGC 1808 RGS data included in XMM-Newton
observation
> 0110980801. I've got some queries:
> 
> + Attending to the XDSP_CORR vs. M_LAMBDA plot, there is no trace of a
strong
> signal, and source and background regions apparently show the a similar
number
> of counts per pixel. If I'm not wrong, RGS FOV is large enough to contain
the
> source, and I've re-run rgsproc with NED coordinates of the object.
Despite
> that, after loading the obtained spectra in XSPEC, some emission lines are
seen.
> Is everything all right? Did I do something wrong? Actually, Jim.nez-Bail.n
et
> al. 2005, A&A 442, 861 showed and analysed these spectra.
> 
> You can take a look at the XDSP_CORR vs. M_LAMBDA and banana plots (PI vs.
> M_LAMBDA) here:
> https://www.dropbox.com/s/vjr3nr139eh3z98/images_0110980801_rgs.tgz?dl=0

You can have a look at what using the BiRD browser for RGS data:

http://xmm.esac.esa.int/BiRD/

Put your obsid in the obsid list to get the results for your observation. You
can see the XDSP_CORR vs. M_LAMBDA plot that you should be getting.

If you get an spectra in XSPEC, then you are probably doing things right. But
with the information you provide I cant tell you more. Maybe there is something

wrong in the way you produce the XDSP_CORR vs. M_LAMBDA plot (?). Im guessing
you
are using the latest version of SAS.

> + Also, attending to the "Users Guide to the XMM-Newton Science Analysis
System"
> Issue 11.0 (18.12.2014), files *SRSPEC* represent source+background
spectrum.
> However, in this thread
> 
> http://xmm.esac.esa.int/sas/current/documentation/threads/xspec_thread.shtml
> 
> it is mentioned that those files have been background subtracted. Which one
is
> correct?

This is something that we will clarify in the thread. The files you get when
you
run rgsproc should be *SRSPEC* source+background spectrum. However the PPS
products
provide two files, source+background spectrum (*SBSPEC*) and source-background
spectrum (*SRSPEC*).

Thanks,

Ignacio de la Calle
XMM-Newton SOC


Followup 1

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Date: Mon, 25 May 2015 08:34:34 -0500
From: =?windows-1252?Q?H=E9ctor_Ot=ED_Floranes?= <h.oti@crya.unam.mx>
To: Ignacio de la Calle <xmmhelp@sciops.esa.int>
Subject: Re: OutSRV Re: RGS spectra: is it actually there? (PR#76584)
Thanks a lot for the response, Ignacio.


+ I executed thsese commands to obtain the plots


evselect table='P0110980801R1S004EVENLI0000.FIT:EVENTS' 
imageset='my_spatial_R1.fits' xcolumn='M_LAMBDA' ycolumn='XDSP_CORR'


evselect table='P0110980801R1S004EVENLI0000.FIT:EVENTS' 
imageset='my_pi_fit_R1.fits' xcolumn='M_LAMBDA' ycolumn='PI' yimagemin=0 
yimagemax=3000 
expression='REGION(P0110980801R1S004SRCLI_0000.FIT:RGS1_SRC3_SPATIAL,M_LAMBDA,XDSP_CORR)'


rgsimplot endispset='my_pi_fit_R1.fits' spatialset='my_spatial_R1.fits' 
srcidlist='3' srclistset='P0110980801R1S004SRCLI_0000.FIT' device=/xs




evselect table='P0110980801R2S005EVENLI0000.FIT:EVENTS' 
imageset='my_spatial_R2.fits' xcolumn='M_LAMBDA' ycolumn='XDSP_CORR'


evselect table='P0110980801R2S005EVENLI0000.FIT:EVENTS' 
imageset='my_pi_fit_R2.fits' xcolumn='M_LAMBDA' ycolumn='PI' yimagemin=0 
yimagemax=3000 
expression='REGION(P0110980801R2S005SRCLI_0000.FIT:RGS2_SRC3_SPATIAL,M_LAMBDA,XDSP_CORR)'


rgsimplot endispset='my_pi_fit_R2.fits' spatialset='my_spatial_R2.fits' 
srcidlist='3' srclistset='P0110980801R2S005SRCLI_0000.FIT' device=/xs




where the source 3 is the one including the NED coordinated of NGC 1808.



+ I didn't know this BiRD tool. Thanks for the info! I've checked that 
there is what I believe to be background emission in my XDSP_CORR vs. 
M_LAMBDA plot, in the range lambda > 30 A, which does not appear in the 
BiRD plot. What do you think of that? You can take a look at my plots 
(see previous e-mail).


+ Having said that, my spectrum does look similar to the one shown in 
BiRD. I guess S/N of the spectrum continuum is very low, but indeed the 
emission lines are there.



+ "This is something that we will clarify in the thread. The files you 
get when you run rgsproc should be *SRSPEC* source+background spectrum. 
However the PPS products provide two files, source+background spectrum 
(*SBSPEC*) and source background spectrum (*SRSPEC*)".

	-> Check!



	Thanks again.


		Cheers,

				H.ctor



On 5/25/15 4:49 AM, Ignacio de la Calle wrote:
> Dear Hector,
>
>> Hello.
>> I'm currently analysing NGC 1808 RGS data included in XMM-Newton
observation
>> 0110980801. I've got some queries:
>>
>> + Attending to the XDSP_CORR vs. M_LAMBDA plot, there is no trace of a
strong
>> signal, and source and background regions apparently show the a similar
> number
>> of counts per pixel. If I'm not wrong, RGS FOV is large enough to
contain the
>> source, and I've re-run rgsproc with NED coordinates of the object.
Despite
>> that, after loading the obtained spectra in XSPEC, some emission lines
are
> seen.
>> Is everything all right? Did I do something wrong? Actually,
Jim.nez-Bail.n
> et
>> al. 2005, A&A 442, 861 showed and analysed these spectra.
>>
>> You can take a look at the XDSP_CORR vs. M_LAMBDA and banana plots (PI
vs.
>> M_LAMBDA) here:
>> https://www.dropbox.com/s/vjr3nr139eh3z98/images_0110980801_rgs.tgz?dl=0
>
> You can have a look at what using the BiRD browser for RGS data:
>
> http://xmm.esac.esa.int/BiRD/
>
> Put your obsid in the obsid list to get the results for your observation.
You
> can see the XDSP_CORR vs. M_LAMBDA plot that you should be getting.
>
> If you get an spectra in XSPEC, then you are probably doing things right.
But
> with the information you provide I cant tell you more. Maybe there is
something
>
> wrong in the way you produce the XDSP_CORR vs. M_LAMBDA plot (?). Im
guessing
> you
> are using the latest version of SAS.
>
>> + Also, attending to the "Users Guide to the XMM-Newton Science
Analysis
> System"
>> Issue 11.0 (18.12.2014), files *SRSPEC* represent source+background
spectrum.
>> However, in this thread
>>
>> http://xmm.esac.esa.int/sas/current/documentation/threads/xspec_thread.shtml
>>
>> it is mentioned that those files have been background subtracted. Which
one
> is
>> correct?
>
> This is something that we will clarify in the thread. The files you get
when
> you
> run rgsproc should be *SRSPEC* source+background spectrum. However the PPS
> products
> provide two files, source+background spectrum (*SBSPEC*) and
source-background
> spectrum (*SRSPEC*).
>
> Thanks,
>
> Ignacio de la Calle
> XMM-Newton SOC
>
> This message and any attachments are intended for the use of the addressee
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> The unauthorised disclosure, use, dissemination or copying (either in whole
or in part) of its
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-- 
========================================================

Message of length 5413 truncated


Reply 2

Resend
From: Ignacio de la Calle <xmmhelp@sciops.esa.int>
To: h.oti@crya.unam.mx
Subject: Re: RGS spectra: is it actually there? (PR#76584)
Date: Thu May 28 09:50:09 2015
Dear Hector,

Sorry for the late reply. We had a look at the data. 

The SAS commands you run are fine. 

> + I didn't know this BiRD tool. Thanks for the info! I've checked that 
> there is what I believe to be background emission in my XDSP_CORR vs. 
> M_LAMBDA plot, in the range lambda > 30 A, which does not appear in the

> BiRD plot. What do you think of that? You can take a look at my plots 
> (see previous e-mail).

The filtering used by the SAS task and the one used to create the plots in BiRD

and different. So it is not unexpected that you see differences in this plot.
What you see in your plot is likely due to noise. The BiRD plots have some 
filtering applied to them to account for these things and make the plots
cleaner
that the SAS task does not apply. So this is expected. The spectra is extracted
in the same way, so you should get the same result.

Regards,

Ignacio de la Calle
XMM-Newton SOC

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