MARX Frequently Asked Questions
No. There are several reasons for this including the lack of resources. Rather, we have tried to make the installation process as simple as possible so that even the most inexperienced user can do it. Step by step instructions for compiling marx are available on the installation page. The reward for compiling it yourself is that you can be sure that marx was built explicitly for your system, and as such, no incompatibilities should arise. One cannot make this guarantee for a precompiled binary version.
The answer to this question may be found here.
The simple answer is "no". Out of the box, marx allows users to select either the ACIS-S array (6 CCDs) or the ACIS-I array (4 CCDs). Arbitrary mixtures of chips from the two arrays are not currently supported although we plan to add that option in a future version of marx.
In the meantime, if you do need to simulate other combinations,
one can assemble such composites by creating the desired ACIS-S
and ACIS-I chips separately and them merging the resulting event
lists with the dmmerge tool in CIAO. For such mergers, both pieces
of the simulation must have the same aimpoint position.
This configuration can be accomplished by a SIM translation in marx
For example, to create a marx simulation where the default
ACIS-S aimpoint was used, but ACIS-I chips were also active
during the observation, one would do two separate simulations.
The ACIS-S portion of the simulation would utilize the marx defaults.
The simulation of the ACIS-I chips however would require moving
the SIM to position the ACIS-I detector correctly relative to the
default ACIS-S aimpoint. The appropriate values in the
Note that the DetOffsetY parameter is not modified since SIM motion along the Y axis is not permitted. For simulations using the default ACIS-I aimpoint, the ACIS-S simulation would need to be offset using the values:
The dmmerge tool will produce some warning messages during the combination of the two event lists, but should produce a valid FITS event file. Unwanted CCDs can be removed using dmcopy.
No. marx does not currently recognize the new format of the CTI-corrected FEF file available in the CALDB (versions 2.18 and higher). So simulations cannot be created directly which feature the improved spectral response of the front-illuminated CCDs after CTI correction. Users wishing to simulate CTI--corrected spectra can however use the marxrsp tool to fold a given marx simulation through an existing RMF created from the CTI--corrected FEF.
If by ``constant'' you mean an effective area that does not not depend upon energy, then the answer is yes. To do so, use the following configuration:
DetIdeal=yes HRMA_Ideal=yes HRMAVig=1.0 Use_Unit_Efficiencies=yes mode=hThe
Keep in mind that some photons will still be lost if they scatter from the mirror and not hit the detector, fall in detector gaps, etc.
|This page was last updated Jan 24, 2012 by John E. Davis. |
Technical questions should be addressed to marx-help at space mit edu.