Marx 5 Highlights
Marx 5 is a major new release. This page is devoted to the new features.
New Dither Model
Marx Parameter File Updates
The EDSER subpixel algorithm was incorporated into CIAO 4.3. When computing Sky coordinates,
The marx 5 version of marx2fits introduces a
marx2fits v5.0.0: Usage: marx2fits [options] marxdir outfile Options: --pileup Process a marxpileup simulation --pixadj=EDSER Use a subpixel algorithm (default) --pixadj=RANDOMIZE Randomize within a detector pixel --pixadj=NONE Do not randomize within a detector pixel --pixadj=EXACT Use exact chip coordinates
The effect of these randomization methods may be seen in the following plot, which shows that the EDSER distribution approaches the exact limit.
The EDSER subpixel algorithm necessitated numerous changes to the marx aspect code. In particular, aspect reconstruction blur had to be cleanly separated into its independently contributing pieces, namely the telescope pointing uncertainty, the blur introduced by pixel quantization/truncation, and the blur associated with pixel randomization. Previous versions of marx incorporated these blurs under the guise of a single parameter,
It was also necessary to remove the blur parameters from marxasp, which computes an aspect solution file for use in reprocessing a marx2fits generated event file. Hence any scripts that pass blur parameter values to marxasp will need to be modified.
As mentioned above, the
There was a long standing issue of a relative rotation between the
LETG and the ACIS detector. The root of this problem was tracked down
(with the help of marx) to a rotation offset between the aspect
coordinate system and the focal plane detector system. This offset
was masked by compensating rotations of the detectors from astrometric
analysis, and manifested itself as a small rotation of the LEG
dispersion arm on the ACIS detector. Changes were added to CIAO 4.3
that effectively adds an additional rotation to the LETG when used
with ACIS. The corresponding change in marx 5.0 is implemented via a
new parameter called
The marx calibration data have been brought up to date with the Chandra CALDB 4.4.7.
The parameter files for earlier versions of marx (e.g., the marx.par
file for version 4.5) cannot be used with marx 5.0. The recalibrations
that were necessary for subpixel support resulted in changes to all of
the HRMA blur parameters, as well as the introduction of the new
The following marx.par parameter values have changed since marx 4.5:
P1Blur: 0.18129215 --> 0.303427 H1Blur: 0.13995037 --> 0.0051428 P3Blur: 0.11527828 --> 0.0951899 H3Blur: 0.16360829 --> 0.0713614 P4Blur: 0.1289134 --> 0.178899 H4Blur: 0.098093014 --> 0.0101367 P6Blur: 0.076202759 --> 0.151085 H6Blur: 0.079767401 --> 0.0239287 MEGRowlandDiameter: 8632.65 --> 8632.48 HEGRowlandDiameter: 8632.65 --> 8632.48 HETG_Shell1_Period: 0.400141 --> 0.400195 HETG_Shell3_Period: 0.400141 --> 0.400195 LETG_Shell1_Theta: -0.07 --> 0.07 LETG_Shell3_Theta: -0.07 --> 0.07 LETG_Shell4_Theta: -0.07 --> 0.07 LETG_Shell6_Theta: -0.07 --> 0.07 legCoarseNumOrders: 11 --> 121The following parameters have been removed:
DitherBlurThe following parameters have been added:
AspectBlur: 0.07 LETG_ACIS_dTheta: -0.0867 Use_This_Order: 0 DetExtendFlag: noThe latter two parameters were added for the purposes of calibration.
|This page was last updated Jan 25, 2012 by John E. Davis. |
Technical questions should be addressed to marx-help at space mit edu.