LAT Science tools VRVS, 19 Oct. 2005
News and status of PulsarSpectrum
by M.Razzano
What is the status?
In the last weeks I released some new tags that include some
important modifications:
1) - The first one is the fix of some bugs related to the use of an external FT2 file
instead of using the usual orbit definition of gtobssim. This has some important
consequences on the barycentric de-corrections, that are extremely sensible to the
position of spacecraft.
2) - Change in Datalist management: in the past version the pulsar
data had to be added by hand to a PulsarDataList.txt file. Now the approach is
different and in some senses more similar to the one used by gtobssim to manage
the different XML source files. The PulsarDataList.txt is now (from v1r1p0) used as
container for other files that contains the pulsar data. For example one can load
different catalogs simple by adding entry like Cat1DataList.txt, Cat2DataList.txt
to the PulsarDataList.txt file. The "default" pulsars provided by the basic
version of simulator are now included in a file named BasicDataList.txt
3) - Multiple ephemerides:Finally these are implemented, and the
simulator can manage change in pulsar ephemerides. I've performed some
basic tests with the Muro pulsar, and it seems to be ok. This "Muro" is going to
become a good candidate for one of the new pulsars discovered by GLAST, even is not
so exotic as JXYZ.... :-)
I want to understand still a little bit more an issue related to the phase shift in order to implement
in a intelligent way the possibility to include abrupt phase shifts.This is now
already possible, but I need to investigate what number to put in to obtain a specific
phase. Another interesting issue. I'm working in relation to the multiple ephemerides
are the glitches and how to model them. I have the idea and I have already begun to
wrote down some code...
Troubles, MJDREF, timing and other stuffs...
During these recent development and the CheckOut 3, We've noticed some interesting
points regarding time reference. Now PulsarSpectrum uses MJDREF=51910.0.
Regarding the start_time I've encountered a problem related to the call to interval
function of the source when using a specific FT2 file and a start_time. I'm discussing with Jim
about that..
I've tried the sources with LATEST1.1164 and I'm able to recover the pulsar
curve without big troubles.
Road to DC-2
Now, the future...
This part of the developent should be about the definition of pulsar properties
for DC2, like a small tool to generate ephemerides and possibly glitches.
Apart from this "ancillary" tools, the remaining things to be implemented in order
to fit completely the DC2 objectives for pulsar simulations are binary pulsars
and specral variation with phase, and it will not require a big amount
of time, hopefully few weeks.
Massimiliano Razzano