Meeting, 18
April 2006
“some short
items from Bordeaux”
INTRODUCTION: Dave S will be at the Beamtest meeting
today, same time as this meeting. Here are 3 small items.
1. Pulsar section of LAT paper
a. A realistic estimation of GLAST’s pulsar sensitivity
using DC2-like tools?
We were
thinking that it’d be relatively straightforward to take some “typical” gamma
light curve, say, Vela’s, and simulate for successively decreasing fluxes,
superposed on the simulated backgrounds as in the DC2 data. Then, search for
it, and plot “significance” versus flux, where we can settle on what we mean by
“significance” later. Repeat for a high background zone (like for 1951+32) and
for a medium background zone. Perhaps repeat for broad versus narrow pulse
peaks? Hard versus soft spectra? Whoa… one thing at a time…
Our group
has the know-how and the motivation to do this. It’s not clear today whether we
have the manpower – we’re spread a little thin…
b. A measurement of the LAT’s timing precision?
As we
speak, I&T is furiously demonstrating that the LAT meets the Science Req’ts
before shipping to NRL. Req’t 5.2.11 of LAT-SS-00010 says we’re supposed to
have 10uS event dating precision, but that we’re aiming for 2 uS. I was
wondering whether a plot or a number demonstrating that pulsar timing really
truly works would be appropriate for our section of the paper. So I got in
touch with Eric Grove who sent me to Pat Hascall who sent me to section 6.7.2.10
of LAT-MD-02730 which spells out how runs LAT 13x will achieve this.
I haven’t
had a chance yet to read the tests in detail… I have the names of the folks
doing the actual work, we know each other… they’re pretty busy… supporting them
in this critical task is probably a wise thing, and I’ll try to do it in any
case. Do we think this would be useful for the paper? You can answer if/when I
actually get some quantity to show you.
2. csh scripts to automate pulsar searches
Damien
Parent made a series of scripts and Root macros that go through all 98 pulsars
that are in the DC2 ephemeredes data base and make the light curves. We plan to
post his scripts soon (tomorrow?). In the meantime you may enjoy flipping
through his 98 pages.
http://www.cenbg.in2p3.fr/ftp/astropart/Smith/Pulsars/Damiens98Pulsars.pdf
Amongst my
favorites are pages 21 and 22, 1016m5857 and 1015m5719, because they’re so
close to each other and relatively clean.
3. Gamma ray candidates for Nançay
This is off-topic for today’s meeting – this is for general
info and for anyone who wants to chip in.
We’re in
the last two weeks before submitting a big request to the Nançay
radiotelescope.
A 1.5 page
outline of our reasoning is in
http://www.cenbg.in2p3.fr/ftp/astropart/Smith/Pulsars/NorthernGammaPulsarCandidates.pdf
and it
leads to the 108 pulsars in
http://www.cenbg.in2p3.fr/ftp/astropart/Smith/Pulsars/BordeauxPsrCandidates.pdf
To improve it, we want to favor the pulsars with large spin-down energy that are within EGRET error circles – Alice and Isabelle have provided tables and slides that blaze that trail. We cut on –35<decl<55 for Nançay but we want to reach a consensus for the whole sky.