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From: Dong-Woo Kim <kim@head.cfa.harvard.edu>
Subject: question on blank sky event files
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2 followups: 1 2

Private message: yes  no

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Date: Wed, 18 Oct 2006 17:59:03 -0400
From: Dong-Woo Kim <kim@head.cfa.harvard.edu>
Subject: question on blank sky event files
To: xmmhelp@sciops.esa.int, Steve Snowden <snowden@milkyway.gsfc.nasa.gov>,
Cc: "kim@head.cfa.harvard.edu" <kim@head.cfa.harvard.edu>
Hi,

I am trying to rescale the blank sky event files based
on the count rates taken  from the whole FOV in high energies (> 10keV).
I got the blank sky data from the XMM web site.

Since I have screened the data for background flares,
based on the light curve made at the same high energies,
I would expect to have ~10% difference between those count rates of my two  
observations
and blank sky data. However, I got a wide range, 1-1.5 for mos and 2.5-3.
In all cases, the rates from the blank sky data are higher.

My first question is whether the blank sky data are really screened for  
the background flares, as described in Read & Ponman (2003 AA section 3.2,  
ie., 0.35 cnt/s and 1 cnt/s for mos and pn).  In fact, I see some time  
intervals with higher rate up to 1 cnt/s for MOS.

Any idea? thanks.
- dw


------------------------------
obsid=0302780101
                                    ontime   livetime cnt(10-12keV)  
(12-14keV)

M1.T.FF.EVLIRP.FIT             2218894.00 2194330.00  270612.00  158093.00
mos1-filt-time.fits              84651.17   83610.21    9478.00    5355.00
ratio                               26.21      26.24      28.55      29.52
                                      1.00       1.00       1.09       1.12

M2.T.FF.EVLIRP.FIT             2110414.00 2087800.00  257612.00  169417.00
mos2-filt-time.fits              83644.41   82630.32   10400.00    6740.00
ratio                               25.23      25.27      24.77      25.14
                                      1.00       1.00       0.98       0.99

PN.T.FF.EVLIRA.FIT              594669.00  536349.00  431623.00  357720.00
pn-filt-time.fits                52330.53   45703.30   14327.00   12576.00
ratio                               11.36      11.74      30.13      28.44
                                      0.97       1.00       2.57       2.42
-----------------------------
obsid=0149240101

M1.M.FF.EVLIRP.FIT             1602610.00 1583390.00  217089.00  126988.00
mos1-filt-time.fits              39344.35   38956.34    3451.00    2073.00
ratio                               40.73      40.65      62.91      61.26
                                      1.00       1.00       1.55       1.51

M2.M.FF.EVLIRP.FIT             1699170.00 1679920.00  221125.00  147114.00
mos2-filt-time.fits              39578.93   39215.60    3437.00    2301.00
ratio                               42.93      42.84      64.34      63.93
                                      1.00       1.00       1.50       1.49

PN.T.FF.EVLIRA.FIT              594669.00  536349.00  431623.00  357720.00
pn-filt-time.fits                36574.47   33152.29    7995.00    7278.00
ratio                               16.26      16.18      53.99      49.15
                                      1.00       1.00       3.34       3.04

---------------------------
-- 
========
Dong-Woo Kim                              Harvard-Smithsonian Center
kim@cfa.harvard.edu                                 for Astrophysics
Phone:  617-496-7852                          60 Garden Street, MS 6
Fax:    617-495-7356                       Cambridge, MA  02138  USA


Reply 1

Resend
From: Maria Diaz Trigo <xmmhelp@sciops.esa.int>
To: kim@head.cfa.harvard.edu
Subject: Re: question on blank sky event files (PR#23575)
Date: Thu Oct 19 13:34:05 2006
Dear Dong-Woo,

indeed, the blank sky data are screened for the background flares, but in a
different way as the 1 ct/s limit. You should screen both your data and the
blank sky data with the same parameters. So, if you are using the 1 ct/s limit
for your data, you should screen the blank sky data with the same criterium.

Best regards,

Maria

Maria Diaz Trigo
XMM-Newton Users Support Group

> Hi,
> 
> I am trying to rescale the blank sky event files based
> on the count rates taken  from the whole FOV in high energies (>
10keV).
> I got the blank sky data from the XMM web site.
> 
> Since I have screened the data for background flares,
> based on the light curve made at the same high energies,
> I would expect to have ~10% difference between those count rates of my two 

> observations
> and blank sky data. However, I got a wide range, 1-1.5 for mos and 2.5-3.
> In all cases, the rates from the blank sky data are higher.
> 
> My first question is whether the blank sky data are really screened for  
> the background flares, as described in Read & Ponman (2003 AA section
3.2,  
> ie., 0.35 cnt/s and 1 cnt/s for mos and pn).  In fact, I see some time  
> intervals with higher rate up to 1 cnt/s for MOS.
> 
> Any idea? thanks.
> - dw
> 
> 
> ------------------------------
> obsid=0302780101
>                                     ontime   livetime cnt(10-12keV)  
> (12-14keV)
> 
> M1.T.FF.EVLIRP.FIT             2218894.00 2194330.00  270612.00  158093.00
> mos1-filt-time.fits              84651.17   83610.21    9478.00    5355.00
> ratio                               26.21      26.24      28.55      29.52
>                                       1.00       1.00       1.09      
1.12
> 
> M2.T.FF.EVLIRP.FIT             2110414.00 2087800.00  257612.00  169417.00
> mos2-filt-time.fits              83644.41   82630.32   10400.00    6740.00
> ratio                               25.23      25.27      24.77      25.14
>                                       1.00       1.00       0.98      
0.99
> 
> PN.T.FF.EVLIRA.FIT              594669.00  536349.00  431623.00  357720.00
> pn-filt-time.fits                52330.53   45703.30   14327.00   12576.00
> ratio                               11.36      11.74      30.13      28.44
>                                       0.97       1.00       2.57      
2.42
> -----------------------------
> obsid=0149240101
> 
> M1.M.FF.EVLIRP.FIT             1602610.00 1583390.00  217089.00  126988.00
> mos1-filt-time.fits              39344.35   38956.34    3451.00    2073.00
> ratio                               40.73      40.65      62.91      61.26
>                                       1.00       1.00       1.55      
1.51
> 
> M2.M.FF.EVLIRP.FIT             1699170.00 1679920.00  221125.00  147114.00
> mos2-filt-time.fits              39578.93   39215.60    3437.00    2301.00
> ratio                               42.93      42.84      64.34      63.93
>                                       1.00       1.00       1.50      
1.49
> 
> PN.T.FF.EVLIRA.FIT              594669.00  536349.00  431623.00  357720.00
> pn-filt-time.fits                36574.47   33152.29    7995.00    7278.00
> ratio                               16.26      16.18      53.99      49.15
>                                       1.00       1.00       3.34      
3.04
> 
> ---------------------------
> -- 
> ========
> Dong-Woo Kim                              Harvard-Smithsonian Center
> kim@cfa.harvard.edu                                 for Astrophysics
> Phone:  617-496-7852                          60 Garden Street, MS 6
> Fax:    617-495-7356                       Cambridge, MA  02138  USA
> 
> 


Followup 1

Compose reply
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Date: Thu, 19 Oct 2006 10:25:26 -0400
From: Dong-Woo Kim <kim@head.cfa.harvard.edu>
Subject: Re: question on blank sky event files (PR#23575)
To: Maria Diaz Trigo <xmmhelp@sciops.esa.int>
Cc: Steve Snowden <snowden@milkyway.gsfc.nasa.gov>,
On Thu, 19 Oct 2006 09:34:05 -0400, Maria Diaz Trigo  
<xmmhelp@sciops.esa.int> wrote:

> Dear Dong-Woo,
>
> indeed, the blank sky data are screened for the background flares, but  
> in a
> different way as the 1 ct/s limit. You should screen both your data and  
> the
> blank sky data with the same parameters. So, if you are using the 1 ct/s  
> limit
> for your data, you should screen the blank sky data with the same  
> criterium.
>
> Best regards,
>
> Maria
>
> Maria Diaz Trigo
> XMM-Newton Users Support Group
>

Hi Maria,

The 1 ct/s limit is what I am seeing in MOS data.
How about PN? I see as high as 10 ct/s.

thanks.
- dw


>> Hi,
>>
>> I am trying to rescale the blank sky event files based
>> on the count rates taken  from the whole FOV in high energies (>
10keV).
>> I got the blank sky data from the XMM web site.
>>
>> Since I have screened the data for background flares,
>> based on the light curve made at the same high energies,
>> I would expect to have ~10% difference between those count rates of my 

>> two
>> observations
>> and blank sky data. However, I got a wide range, 1-1.5 for mos and  
>> 2.5-3.
>> In all cases, the rates from the blank sky data are higher.
>>
>> My first question is whether the blank sky data are really screened for
>> the background flares, as described in Read & Ponman (2003 AA
section  
>> 3.2,
>> ie., 0.35 cnt/s and 1 cnt/s for mos and pn).  In fact, I see some time
>> intervals with higher rate up to 1 cnt/s for MOS.
>>
>> Any idea? thanks.
>> - dw
>>
>>
>> ------------------------------
>> obsid=0302780101
>>                                     ontime   livetime cnt(10-12keV)
>> (12-14keV)
>>
>> M1.T.FF.EVLIRP.FIT             2218894.00 2194330.00  270612.00   
>> 158093.00
>> mos1-filt-time.fits              84651.17   83610.21    9478.00     
>> 5355.00
>> ratio                               26.21      26.24      28.55       
>> 29.52
>>                                       1.00       1.00       1.09       

>> 1.12
>>
>> M2.T.FF.EVLIRP.FIT             2110414.00 2087800.00  257612.00   
>> 169417.00
>> mos2-filt-time.fits              83644.41   82630.32   10400.00     
>> 6740.00
>> ratio                               25.23      25.27      24.77       
>> 25.14
>>                                       1.00       1.00       0.98       

>> 0.99
>>
>> PN.T.FF.EVLIRA.FIT              594669.00  536349.00  431623.00   
>> 357720.00
>> pn-filt-time.fits                52330.53   45703.30   14327.00    
>> 12576.00
>> ratio                               11.36      11.74      30.13       
>> 28.44
>>                                       0.97       1.00       2.57       

>> 2.42
>> -----------------------------
>> obsid=0149240101
>>
>> M1.M.FF.EVLIRP.FIT             1602610.00 1583390.00  217089.00   
>> 126988.00
>> mos1-filt-time.fits              39344.35   38956.34    3451.00     
>> 2073.00
>> ratio                               40.73      40.65      62.91       
>> 61.26
>>                                       1.00       1.00       1.55       

>> 1.51
>>
>> M2.M.FF.EVLIRP.FIT             1699170.00 1679920.00  221125.00   
>> 147114.00
>> mos2-filt-time.fits              39578.93   39215.60    3437.00     
>> 2301.00
>> ratio                               42.93      42.84      64.34       
>> 63.93
>>                                       1.00       1.00       1.50       

>> 1.49
>>
>> PN.T.FF.EVLIRA.FIT              594669.00  536349.00  431623.00   
>> 357720.00
>> pn-filt-time.fits                36574.47   33152.29    7995.00     
>> 7278.00
>> ratio                               16.26      16.18      53.99       
>> 49.15
>>                                       1.00       1.00       3.34       

>> 3.04
>>
>> ---------------------------
>> --
>> ========
>> Dong-Woo Kim                              Harvard-Smithsonian Center
>> kim@cfa.harvard.edu                                 for Astrophysics
>> Phone:  617-496-7852                          60 Garden Street, MS 6
>> Fax:    617-495-7356                       Cambridge, MA  02138  USA
>>
>>
> ================================================================================================
> This message and any attachments are intended for the use of the  
> addressee or addressees only. The
> unauthorised disclosure, use, dissemination or copying (either in

Message of length 5699 truncated


Reply 2

Resend
From: Maria Diaz Trigo <xmmhelp@sciops.esa.int>
To: kim@head.cfa.harvard.edu
Subject: Re: question on blank sky event files (PR#23575)
Date: Fri Oct 20 08:27:24 2006
Dear Dong-Woo,

the recommended rates to screen EPIC data are ~1 ct/s for the pn, and ~0.35 ct/s
for the MOS. However, depending on the kind of analysis that you want to do, you
may be more restrictive or relax a bit your constraints. In any case, if you
were going to apply 1 ct/s to your pn data, you should apply the same cut to the
blank sky fields, independently on how big the flares are. That's what the
screening is for, to remove flares...

Best regards,

Maria 

Maria Diaz Trigo
XMM-Newton Users Support Group

> On Thu, 19 Oct 2006 09:34:05 -0400, Maria Diaz Trigo  
> <xmmhelp@sciops.esa.int> wrote:
> 
>> Dear Dong-Woo,
>>
>> indeed, the blank sky data are screened for the background flares, but 

>> in a
>> different way as the 1 ct/s limit. You should screen both your data and
 
>> the
>> blank sky data with the same parameters. So, if you are using the 1
ct/s  
>> limit
>> for your data, you should screen the blank sky data with the same  
>> criterium.
>>
>> Best regards,
>>
>> Maria
>>
>> Maria Diaz Trigo
>> XMM-Newton Users Support Group
>>
> 
> Hi Maria,
> 
> The 1 ct/s limit is what I am seeing in MOS data.
> How about PN? I see as high as 10 ct/s.
> 
> thanks.
> - dw
> 
> 
>>> Hi,
>>>
>>> I am trying to rescale the blank sky event files based
>>> on the count rates taken  from the whole FOV in high energies (>
10keV).
>>> I got the blank sky data from the XMM web site.
>>>
>>> Since I have screened the data for background flares,
>>> based on the light curve made at the same high energies,
>>> I would expect to have ~10% difference between those count rates of
my  
>>> two
>>> observations
>>> and blank sky data. However, I got a wide range, 1-1.5 for mos and 

>>> 2.5-3.
>>> In all cases, the rates from the blank sky data are higher.
>>>
>>> My first question is whether the blank sky data are really screened
for
>>> the background flares, as described in Read & Ponman (2003 AA
section  
>>> 3.2,
>>> ie., 0.35 cnt/s and 1 cnt/s for mos and pn).  In fact, I see some
time
>>> intervals with higher rate up to 1 cnt/s for MOS.
>>>
>>> Any idea? thanks.
>>> - dw
>>>
>>>
>>> ------------------------------
>>> obsid=0302780101
>>>                                     ontime   livetime
cnt(10-12keV)
>>> (12-14keV)
>>>
>>> M1.T.FF.EVLIRP.FIT             2218894.00 2194330.00  270612.00   
>>> 158093.00
>>> mos1-filt-time.fits              84651.17   83610.21    9478.00    

>>> 5355.00
>>> ratio                               26.21      26.24      28.55    
  
>>> 29.52
>>>                                       1.00       1.00       1.09   
    
>>> 1.12
>>>
>>> M2.T.FF.EVLIRP.FIT             2110414.00 2087800.00  257612.00   
>>> 169417.00
>>> mos2-filt-time.fits              83644.41   82630.32   10400.00    

>>> 6740.00
>>> ratio                               25.23      25.27      24.77    
  
>>> 25.14
>>>                                       1.00       1.00       0.98   
    
>>> 0.99
>>>
>>> PN.T.FF.EVLIRA.FIT              594669.00  536349.00  431623.00   
>>> 357720.00
>>> pn-filt-time.fits                52330.53   45703.30   14327.00   

>>> 12576.00
>>> ratio                               11.36      11.74      30.13    
  
>>> 28.44
>>>                                       0.97       1.00       2.57   
    
>>> 2.42
>>> -----------------------------
>>> obsid=0149240101
>>>
>>> M1.M.FF.EVLIRP.FIT             1602610.00 1583390.00  217089.00   
>>> 126988.00
>>> mos1-filt-time.fits              39344.35   38956.34    3451.00    

>>> 2073.00
>>> ratio                               40.73      40.65      62.91    
  
>>> 61.26
>>>                                       1.00       1.00       1.55   
    
>>> 1.51
>>>
>>> M2.M.FF.EVLIRP.FIT             1699170.00 1679920.00  221125.00   
>>> 147114.00
>>> mos2-filt-time.fits              39578.93   39215.60    3437.00    

>>> 2301.00
>>> ratio                               42.93      42.84      64.34    
  
>>> 63.93
>>>                                       1.00       1.00       1.50   
    
>>> 1.49

Message of length 7000 truncated


Followup 2

Compose reply
Download message
Date: Fri, 20 Oct 2006 10:16:51 -0400
From: Dong-Woo Kim <kim@head.cfa.harvard.edu>
Subject: Re: question on blank sky event files (PR#23575)
To: Maria Diaz Trigo <xmmhelp@sciops.esa.int>
Cc: "kim@head.cfa.harvard.edu" <kim@head.cfa.harvard.edu>
>> Hi Maria,
>>
>> The 1 ct/s limit is what I am seeing in MOS data.
>> How about PN? I see as high as 10 ct/s.
>>
>> thanks.
>> - dw
>

Maria,

I looks like I was not quite clear in my response.
My question was about the blank sky data in the XMM ftp site.
As you said in the previous email, the MOS blank sky data were screened at
the 1 ct/s limit. How were PN blank sky data screened?
I am seeing the rate as high as 10 ct/s in PN blank sky data.

BTW, after screening my data and blank sky data at the same rate,
now I am getting much more consistent results.
thanks.
- dw



On Fri, 20 Oct 2006 04:27:23 -0400, Maria Diaz Trigo  
<xmmhelp@sciops.esa.int> wrote:

> Dear Dong-Woo,
>
> the recommended rates to screen EPIC data are ~1 ct/s for the pn, and  
> ~0.35 ct/s
> for the MOS. However, depending on the kind of analysis that you want to  
> do, you
> may be more restrictive or relax a bit your constraints. In any case, if  
> you
> were going to apply 1 ct/s to your pn data, you should apply the same  
> cut to the
> blank sky fields, independently on how big the flares are. That's what  
> the
> screening is for, to remove flares...
>
> Best regards,
>
> Maria
>
> Maria Diaz Trigo
> XMM-Newton Users Support Group
>
>> On Thu, 19 Oct 2006 09:34:05 -0400, Maria Diaz Trigo
>> <xmmhelp@sciops.esa.int> wrote:
>>
>>> Dear Dong-Woo,
>>>
>>> indeed, the blank sky data are screened for the background flares,
but
>>> in a
>>> different way as the 1 ct/s limit. You should screen both your data
and
>>> the
>>> blank sky data with the same parameters. So, if you are using the 1
 
>>> ct/s
>>> limit
>>> for your data, you should screen the blank sky data with the same
>>> criterium.
>>>
>>> Best regards,
>>>
>>> Maria
>>>
>>> Maria Diaz Trigo
>>> XMM-Newton Users Support Group
>>>
>>
>> Hi Maria,
>>
>> The 1 ct/s limit is what I am seeing in MOS data.
>> How about PN? I see as high as 10 ct/s.
>>
>> thanks.
>> - dw
>>
>>
>>>> Hi,
>>>>
>>>> I am trying to rescale the blank sky event files based
>>>> on the count rates taken  from the whole FOV in high energies
(>  
>>>> 10keV).
>>>> I got the blank sky data from the XMM web site.
>>>>
>>>> Since I have screened the data for background flares,
>>>> based on the light curve made at the same high energies,
>>>> I would expect to have ~10% difference between those count
rates of my
>>>> two
>>>> observations
>>>> and blank sky data. However, I got a wide range, 1-1.5 for mos
and
>>>> 2.5-3.
>>>> In all cases, the rates from the blank sky data are higher.
>>>>
>>>> My first question is whether the blank sky data are really
screened  
>>>> for
>>>> the background flares, as described in Read & Ponman (2003
AA section
>>>> 3.2,
>>>> ie., 0.35 cnt/s and 1 cnt/s for mos and pn).  In fact, I see
some time
>>>> intervals with higher rate up to 1 cnt/s for MOS.
>>>>
>>>> Any idea? thanks.
>>>> - dw
>>>>
>>>>
>>>> ------------------------------
>>>> obsid=0302780101
>>>>                                     ontime   livetime
cnt(10-12keV)
>>>> (12-14keV)
>>>>
>>>> M1.T.FF.EVLIRP.FIT             2218894.00 2194330.00  270612.00
>>>> 158093.00
>>>> mos1-filt-time.fits              84651.17   83610.21    9478.00
>>>> 5355.00
>>>> ratio                               26.21      26.24      28.55
>>>> 29.52
>>>>                                       1.00       1.00      
1.09
>>>> 1.12
>>>>
>>>> M2.T.FF.EVLIRP.FIT             2110414.00 2087800.00  257612.00
>>>> 169417.00
>>>> mos2-filt-time.fits              83644.41   82630.32   10400.00
>>>> 6740.00
>>>> ratio                               25.23      25.27      24.77
>>>> 25.14
>>>>                                       1.00       1.00      
0.98
>>>> 0.99
>>>>
>>>> PN.T.FF.EVLIRA.FIT              594669.00  536349.00  431623.00
>>>> 357720.00
>>>> pn-filt-time.fits                52330.53   45703.30   14327.00
>>>> 12576.00
>>>> ratio                               11.36      11.74      30.13
>>>> 28.44
>&g

Message of length 9128 truncated


Reply 3

Resend
From: Maria Diaz Trigo <xmmhelp@sciops.esa.int>
To: kim@head.cfa.harvard.edu
Subject: Re: question on blank sky event files (PR#23575)
Date: Mon Oct 23 12:42:58 2006
Dear Dong-Wo,

the 1 ct/s and 0.35 ct/s that I mentioned in the previous mail for the pn and
MOS were for the data. I don't know currently which are the equivalent numbers
for the blank sky fields, but I have forwarded this question to the experts who
generated them and I will come back to you as soon as possible. However, for
your analysis, use the same screening for the source and the background, this
should be fine.

Best regards,

Maria

Maria Diaz Trigo
XMM-Newton Users Support Group

> >> Hi Maria,
>>>
>>> The 1 ct/s limit is what I am seeing in MOS data.
>>> How about PN? I see as high as 10 ct/s.
>>>
>>> thanks.
>>> - dw
>>
> 
> Maria,
> 
> I looks like I was not quite clear in my response.
> My question was about the blank sky data in the XMM ftp site.
> As you said in the previous email, the MOS blank sky data were screened at
> the 1 ct/s limit. How were PN blank sky data screened?
> I am seeing the rate as high as 10 ct/s in PN blank sky data.
> 
> BTW, after screening my data and blank sky data at the same rate,
> now I am getting much more consistent results.
> thanks.
> - dw
> 
> 
> 
> On Fri, 20 Oct 2006 04:27:23 -0400, Maria Diaz Trigo  
> <xmmhelp@sciops.esa.int> wrote:
> 
>> Dear Dong-Woo,
>>
>> the recommended rates to screen EPIC data are ~1 ct/s for the pn, and 

>> ~0.35 ct/s
>> for the MOS. However, depending on the kind of analysis that you want
to  
>> do, you
>> may be more restrictive or relax a bit your constraints. In any case,
if  
>> you
>> were going to apply 1 ct/s to your pn data, you should apply the same 

>> cut to the
>> blank sky fields, independently on how big the flares are. That's what 

>> the
>> screening is for, to remove flares...
>>
>> Best regards,
>>
>> Maria
>>
>> Maria Diaz Trigo
>> XMM-Newton Users Support Group
>>
>>> On Thu, 19 Oct 2006 09:34:05 -0400, Maria Diaz Trigo
>>> <xmmhelp@sciops.esa.int> wrote:
>>>
>>>> Dear Dong-Woo,
>>>>
>>>> indeed, the blank sky data are screened for the background
flares, but
>>>> in a
>>>> different way as the 1 ct/s limit. You should screen both your
data and
>>>> the
>>>> blank sky data with the same parameters. So, if you are using
the 1  
>>>> ct/s
>>>> limit
>>>> for your data, you should screen the blank sky data with the
same
>>>> criterium.
>>>>
>>>> Best regards,
>>>>
>>>> Maria
>>>>
>>>> Maria Diaz Trigo
>>>> XMM-Newton Users Support Group
>>>>
>>>
>>> Hi Maria,
>>>
>>> The 1 ct/s limit is what I am seeing in MOS data.
>>> How about PN? I see as high as 10 ct/s.
>>>
>>> thanks.
>>> - dw
>>>
>>>
>>>>> Hi,
>>>>>
>>>>> I am trying to rescale the blank sky event files based
>>>>> on the count rates taken  from the whole FOV in high
energies (>  
>>>>> 10keV).
>>>>> I got the blank sky data from the XMM web site.
>>>>>
>>>>> Since I have screened the data for background flares,
>>>>> based on the light curve made at the same high energies,
>>>>> I would expect to have ~10% difference between those count
rates of my
>>>>> two
>>>>> observations
>>>>> and blank sky data. However, I got a wide range, 1-1.5 for
mos and
>>>>> 2.5-3.
>>>>> In all cases, the rates from the blank sky data are
higher.
>>>>>
>>>>> My first question is whether the blank sky data are really
screened  
>>>>> for
>>>>> the background flares, as described in Read & Ponman
(2003 AA section
>>>>> 3.2,
>>>>> ie., 0.35 cnt/s and 1 cnt/s for mos and pn).  In fact, I
see some time
>>>>> intervals with higher rate up to 1 cnt/s for MOS.
>>>>>
>>>>> Any idea? thanks.
>>>>> - dw
>>>>>
>>>>>
>>>>> ------------------------------
>>>>> obsid=0302780101
>>>>>                                     ontime   livetime
cnt(10-12keV)
>>>>> (12-14keV)
>>>>>
>>>>> M1.T.FF.EVLIRP.FIT             2218894.00 2194330.00 
270612.00
>>>>> 158093.00

Message of length 10779 truncated


Reply 4

Resend
From: Maria Diaz Trigo <xmmhelp@sciops.esa.int>
To: kim@head.cfa.harvard.edu
Subject: Re: question on blank sky event files (PR#23575)
Date: Wed Feb 28 17:09:48 2007
Dear Dong-Woo,

sorry that I come back to you so late, but the information on the screening of
the blank sky data that you were requesting is finally in the web page. Maybe
you have seen it already, but in case you haven't, please go to the following
page:

http://xmm.esac.esa.int/external/xmm_sw_cal/background/blank_sky.shtml

All the best,

Maria


Maria Diaz Trigo
XMM-Newton Users Support Group

> >> Hi Maria,
>>>
>>> The 1 ct/s limit is what I am seeing in MOS data.
>>> How about PN? I see as high as 10 ct/s.
>>>
>>> thanks.
>>> - dw
>>
> 
> Maria,
> 
> I looks like I was not quite clear in my response.
> My question was about the blank sky data in the XMM ftp site.
> As you said in the previous email, the MOS blank sky data were screened at
> the 1 ct/s limit. How were PN blank sky data screened?
> I am seeing the rate as high as 10 ct/s in PN blank sky data.
> 
> BTW, after screening my data and blank sky data at the same rate,
> now I am getting much more consistent results.
> thanks.
> - dw
> 
> 
> 
> On Fri, 20 Oct 2006 04:27:23 -0400, Maria Diaz Trigo  
> <xmmhelp@sciops.esa.int> wrote:
> 
>> Dear Dong-Woo,
>>
>> the recommended rates to screen EPIC data are ~1 ct/s for the pn, and 

>> ~0.35 ct/s
>> for the MOS. However, depending on the kind of analysis that you want
to  
>> do, you
>> may be more restrictive or relax a bit your constraints. In any case,
if  
>> you
>> were going to apply 1 ct/s to your pn data, you should apply the same 

>> cut to the
>> blank sky fields, independently on how big the flares are. That's what 

>> the
>> screening is for, to remove flares...
>>
>> Best regards,
>>
>> Maria
>>
>> Maria Diaz Trigo
>> XMM-Newton Users Support Group
>>
>>> On Thu, 19 Oct 2006 09:34:05 -0400, Maria Diaz Trigo
>>> <xmmhelp@sciops.esa.int> wrote:
>>>
>>>> Dear Dong-Woo,
>>>>
>>>> indeed, the blank sky data are screened for the background
flares, but
>>>> in a
>>>> different way as the 1 ct/s limit. You should screen both your
data and
>>>> the
>>>> blank sky data with the same parameters. So, if you are using
the 1  
>>>> ct/s
>>>> limit
>>>> for your data, you should screen the blank sky data with the
same
>>>> criterium.
>>>>
>>>> Best regards,
>>>>
>>>> Maria
>>>>
>>>> Maria Diaz Trigo
>>>> XMM-Newton Users Support Group
>>>>
>>>
>>> Hi Maria,
>>>
>>> The 1 ct/s limit is what I am seeing in MOS data.
>>> How about PN? I see as high as 10 ct/s.
>>>
>>> thanks.
>>> - dw
>>>
>>>
>>>>> Hi,
>>>>>
>>>>> I am trying to rescale the blank sky event files based
>>>>> on the count rates taken  from the whole FOV in high
energies (>  
>>>>> 10keV).
>>>>> I got the blank sky data from the XMM web site.
>>>>>
>>>>> Since I have screened the data for background flares,
>>>>> based on the light curve made at the same high energies,
>>>>> I would expect to have ~10% difference between those count
rates of my
>>>>> two
>>>>> observations
>>>>> and blank sky data. However, I got a wide range, 1-1.5 for
mos and
>>>>> 2.5-3.
>>>>> In all cases, the rates from the blank sky data are
higher.
>>>>>
>>>>> My first question is whether the blank sky data are really
screened  
>>>>> for
>>>>> the background flares, as described in Read & Ponman
(2003 AA section
>>>>> 3.2,
>>>>> ie., 0.35 cnt/s and 1 cnt/s for mos and pn).  In fact, I
see some time
>>>>> intervals with higher rate up to 1 cnt/s for MOS.
>>>>>
>>>>> Any idea? thanks.
>>>>> - dw
>>>>>
>>>>>
>>>>> ------------------------------
>>>>> obsid=0302780101
>>>>>                                     ontime   livetime
cnt(10-12keV)
>>>>> (12-14keV)
>>>>>
>>>>> M1.T.FF.EVLIRP.FIT             2218894.00 2194330.00 
270612.00
>>>>> 158093.00
>>>>> mos1-filt-time.fits              84651.17   83610.21   
9478.00
>

Message of length 10689 truncated

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