Up to top level
AO11   AO12   AO13   AO14   Backgrounds   Calibration   Conference   Data   Docs   EPICMOS   EPICpn   Feedback   Gallery   Misc   OM   Pending   PhD_Theses   Publications   RGS   RadMonitor   SAS_Hardware   SAS_WS   SASv12.0   SASv12.0_Installation   SASv13.0   SASv13.0_Installation   SASv13.5   SASv13.5_Installation   SciSim   Simulators_other   Suggestions   Trash   Visibility   XMM-bouncing   XMM-news   XRPS   XSA   XSA_old   esas   incoming  

Logged in as guest

Viewing Backgrounds/5916
Full headers

From: SSC.SPR.system@star.le.ac.uk
Subject: Response to SSC SPR SSC-SPR-2977
Compose reply
Move To:
0 replies:
0 followups:

Private message: yes  no

Notes:

Notification:


Date: Tue, 17 Sep 2002 11:07:19 +0100 (BST)
From: SSC.SPR.system@star.le.ac.uk
To: xmmhelp@xmm.vilspa.esa.es
Cc: md@star.le.ac.uk, mim@star.le.ac.uk, sasdev@xmm.vilspa.esa.es
Subject: Response to SSC SPR SSC-SPR-2977
Your SPR entitled

"attcalc does not properly put sky coords of source image into background image"

has been rejected. Please see the response section for further details.

-----------------------------------------------------------------------------
SPR no.:    SSC-SPR-2977
Date:        6th September 2002
Task:       attcalc (version 4.27.1)
Title:      attcalc does not properly put sky coords of source image into
background image
Originator: P. Rodriguez on behalf of D. Buote (xmmhelp@xmm.vilspa.esa.es)
Priority:   normal

Description:


I am analyzing an extended source & would therefore like to
use the standard background templates provided by D. Lumb
for background subtraction. I would like to do this in sky
coordinates if possible. As Pedro explained to me, it is
possible to fill the (X,Y) columns of the background template using
"attcalc"
which I have attempted to do with the following command:
buote@nephos: attcalc eventset='temp_mos1_bkgt.evt'
attitudelabel='fixed' refpointlabel='user' withatthkset=no
atthkset='atthk.dat' withmedianpnt=no imagesize='0.36'
nominalra=1.98850000500000E+02 nominaldec=-1.63850000000000E+01 -w 5
-V
5 fixedra=1.98844293987737E+02 fixeddec=-1.63573613020474E+01
fixedposangle=1.14153542897433E+02
Here "temp_mos1_bkgt.evt" is just the mos1 background
template with standard screening. The settings for some of the other
keywords
are:
fixedra=RA_PNT
fixeddec=DEC_PNT
fixedposangle=PA_PNT
nominalra=RA_NOM
nominaldec=DEC_NOM
where the RA_PNT etc. are taken from the source events
file.
The problem is that these keywords are not propagated
exactly the background events file. As Pedro explained
to me, attacacl adds new keywords (ATTSRC, ATTRA,
ATTDEC, and ATTPA) from which the following keywords are
then computed:
TCRPX, TCRVL, TCDLT, TLMAX, TLMIN, TDMAX, TDMIN
It is these keywords that must be the same for the background and
image file in
order for the "image"
coordinates to be exact. However, this is not what I find:
I do find the following exact correspondences between the source
events file and
the background events file after performing attcalc.
RA_PNT ==> ATTRA
DEC_PNT ==> ATTDEC
PA_PNT ==> ATTPA
But the other keywords are not in general identical:
TCRPX, TCDLT are identical in both events files.
But the following are not:
TCRVL:
Source:
TCRVL6	= 1.98844293987737E+02 / [deg] coord. at X axis ref. pixel
TCRVL7	= -1.63573613020474E+01 / [deg] coord. at Y axis ref. pixel
background:
TCRVL6	= 1.98850000500000E+02 / [deg] coord. at X axis ref. pixel
TCRVL7	= -1.63850000000000E+01 / [deg] coord. at Y axis ref. pixel
TLMAX:
source:
TLMAX4	=		 19910 / Legal maximum for DETX
TLMAX5	=		 19820 / Legal maximum for DETY
background:
TLMAX4	=		 19905 / Legal maximum for DETX
TLMAX5	=		 19814 / Legal maximum for DETY
TLMIN:
source:
TLMIN4	=		-19768 / Legal minimum for DETX
TLMIN5	=		-20305 / Legal minimum for DETY
background:
TLMIN4	=		-19762 / Legal minimum for DETX
TLMIN5	=		-20299 / Legal minimum for DETY
TDMAX
source:
TDMAX4	=		 19905 / Actual maximum for DETX
TDMAX5	=		 19704 / Actual maximum for DETY
TDMAX6	=		 43623 / maximum projected image X axis data
value
TDMAX7	=		 43120 / maximum projected image Y axis data
value
background:
TDMAX4	=		 19910 / Actual maximum for DETX
TDMAX5	=		 19710 / Actual maximum for DETY
TDMAX6	=		 49042 / maximum projected image X axis data
value
TDMAX7	=		 44820 / maximum projected image Y axis data
value
TDMIN:
source:
TDMIN4	=		-19768 / Actual minimum for DETX
TDMIN5	=		-20195 / Actual minimum for DETY
TDMIN6	=		  1906 / minimum projected image X axis data
value
TDMIN7	=		  3366 / minimum projected image Y axis data
value
background:
TDMIN4	=		-19762 / Actual minimum for DETX
TDMIN5	=		-20189 / Actual minimum for DETY
TDMIN6	=		  8742 / minimum projected image X axis data
value
TDMIN7	=		  8936 / minimum projected image Y axis data
value
OK. I assume these keywords differences account for the problems I
have had
trying to associate extraction regions for both the source and
background
images. Let me summarize my problem:
My goal is to define a region on an image and then extract a spectrum
from that
region. The important thing is that I DO NOT WANT TO USE XMMSELECT --
I want to
use my own programs to define the region of interest.
I want to define an extraction region on the
source image and have that region apply also to the background image
(whose
(X,Y) coordinates have been filled using attcalc as we have
discussed).
I have created a circular region on the source image and have saved
it
to an ascii region file, src.reg, using ds9. I have saved this file
in
"image" coordinates and "SAOIMAGE" format.
Here's my problem: If I display the background image in ds9 and then
load
src.reg, it does NOT correspond to exactly the same region in
physical
coordinates that it did on the source image. It is close (maybe about
5"-10"
displaced), but it is not exactly the same.
I assume these differences arise because of the keyword
differences noted above.

Message of length 5685 truncated
Up to top level
AO11   AO12   AO13   AO14   Backgrounds   Calibration   Conference   Data   Docs   EPICMOS   EPICpn   Feedback   Gallery   Misc   OM   Pending   PhD_Theses   Publications   RGS   RadMonitor   SAS_Hardware   SAS_WS   SASv12.0   SASv12.0_Installation   SASv13.0   SASv13.0_Installation   SASv13.5   SASv13.5_Installation   SciSim   Simulators_other   Suggestions   Trash   Visibility   XMM-bouncing   XMM-news   XRPS   XSA   XSA_old   esas   incoming  

Logged in as guest


Please make your (short) question the subject of your request!


Web interface using JitterBug ... back to the XMM home page