[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
New XRT response software. [xrt_co:]
Dear XRT enthusiasts,
We are announcing the release of a calibration update and some new
XRT software. While some testing has been done, it is realistic to
expect that some of you may uncover new bugs. Please think of this as
a "beta" release, and contact us with any problems you encounter. The
new calibrations updates are available to you by using the new
software, which is distributed in the normal manner through the XRT
SolarSoft tree. (The update should percolate through SolarSoft
sometime around Oct.7-9.)
Bug reports should be sent to xrt_manager@head.cfa.harvard.edu, but I
encourage you to also have discussions on the majordomo community
list at xrt_users@head.cfa.harvard.edu .
Before I give an overview of the changes, let me say that the XRT
Analysis Guide will be updated to describe this new software, but is
not yet ready. However, the program headers already include extensive
documentation, and should be good enough for you to try the software.
The XAG should be updated some time before the end of the month
(October).
Why the changes? First, Narukage-san has completed a re-evaluation of
the calibration ground-tests and has modified the instrument SXR
response model. (He is finishing a paper on this.) Second, since the
last major release, we have discovered a contaminant layer on the CCD
that accumulates with time, and we bake it off every 3 to 4 weeks.
The effect of this layer needs to be accounted for in the effective
area, and is necessarily dependent on the specification of a data set
or mission time. This required some re-arrangement of the program
flow. Third, users are anxious to apply their own CHIANTI or APEC
models to create temperature response curves. Although this
functionality was present in the previous release, we have tried to
make it a little easier for users.
Regarding the responses, what has not been accounted for in this
release? (1) The XRT Team has begun to investigate a possible
contamination layer on one or more of the filters. There are some
inconsistencies in the current responses that we do not yet
understand, which we are considering as an "on-orbit" calibration
problem. Nevertheless, this current calibration update represents the
Team's best current understanding of the instrument responses
according to all of our ground tests (specifically, the filter
thicknesses and aperture area). (2) The XRT Team will now be working
on software for estimations of the measurement errors.
WHAT'S NEW?
- To get the effective areas and spectral responses, it is now
necessary to specify a thickness for the CCD contamination layer.
This may be specified by a data set INDEX, by a mission time, or by a
simple thickness. You use a single program called
<make_xrt_wave_resp.pro>, which you may learn to use by reading the
program header documentation. Here is a sample....
; Basic usage #1 (for a datacube INDEX, DATA):
; IDL> help, data, index
; IDL> w_resp = make_xrt_wave_resp(index=index)
; IDL> help, w_resp
; IDL> help, w_resp, w_resp.effar, w_resp.sprsp, /st
;
; Basic usage #2 (for all channels with single contamination
; thickness):
; IDL> w_resp = make_xrt_wave_resp(contam_thick=500.) ;;
Angstroms
; IDL> help, w_resp
; IDL> help, w_resp, w_resp.effar, w_resp.sprsp, /st
;
; Basic usage #3 (for all channels at single mission time):
; IDL> ctime = '2007-May-25 10:00:00'
; IDL> w_resp = make_xrt_wave_resp(contam_time=ctime)
; IDL> help, w_resp
; IDL> help, w_resp, w_resp.effar, w_resp.sprsp, /st
;
; Plotting the effective area for the 3rd image:
; IDL> ichn = 2
; IDL> print, w_resp[ichn].effar.name
; IDL> wlen = w_resp[ichn].effar.length
; IDL> plot, w_resp[ichn].effar.wave[0:wlen-1], $
; IDL> w_resp[ichn].effar.eff_area[0:wlen-1]
;
; Check the x-ray channel ID and contamination thickness:
; (This info should be in w_resp[ichn].name, too.)
; IDL> print, w_resp[ichn].confg.name
; IDL> print, w_resp[ichn].contam.thick, $
; IDL> w_resp[ichn].contam.thick_units
- To get the temperature responses, it is necessary to specify (a)
the spectral response, which comes from <make_xrt_wave_resp.pro>; and
(b) a spectral emission model, such as comes from APEC or CHIANTI.
You use a single program called <make_xrt_temp_resp.pro>, which you
may learn to use by reading the program header documentation. Here is
a sample....
; Basic usage:
; IDL> t_resp = make_xrt_temp_resp(w_resp, emiss_model)
; IDL> help, t_resp
; IDL> help, t_resp, /st
There is a default APEC model available for your convenience:
Basic usage:
IDL> t_resp = make_xrt_temp_resp(w_resp, /apec)
We are preparing a more up-to-date APEC default model, and we are
preparing an up-to-date CHIANTI option.
- What if you want to apply your own spectral emission model? You
must use CHIANTI or APEC yourself to get the model. However, this
information must be put into a particular format so that you may use
it as an input to <make_xrt_temp_resp.pro>. You may use the program
<make_xrt_emiss_model.pro> to assist you in transferring your model
information into the correct format. (Hint: Use /VERBOSE so that it
can tell you what your mistakes are, if it catches any.) You are
strongly encouraged to read the program header in order to understand
what information is expected. There are some "mandatory" details
(such as the name of the ionization model) that do not directly
affect the calculation of the temperature response curve, but which
represent information that is crucial for describing the temperature
responses. We STRONGLY encourage users to provide these details.
- Using the DEM solver. The previous solver <xrt_dem_iterative.pro>
has been updated and named <xrt_dem_iterative2.pro>. The new program
is compatible with the new format of the temperature response
structures. It works almost identically, but now the temperature
responses are mandatory, are provided explicitly by the user, and are
a parameter input instead of a keyword.
WHAT HAS BEEN DEPRECATED?
apec_09_c.genx
calc_xrt_effarea.pro
calc_xrt_spec_resp.pro
calc_xrt_temp_resp.pro
get_xrt_aperture.pro
get_xrt_chn_trans.pro
get_xrt_spec_genx.pro
mk_xrt_spec_genx.pro
xrt_apec_09_c.geny
xrt_channel_transmissions.geny
xrt_dem_iterative.pro