david smith cenbg report from prague meeting with radio pulsar people psr f2f @ stockholm, 28 august...

David Smith CENBG 1

Report from Prague meeting with Radio Pulsar People PSR F2F @ Stockholm, 28 August 2006

Report on GLAST Pulsar Radio Timing Discussions GLAST Pulsar Radio Timing Discussions

at the Prague IAU GA

David SmithCENBG/In2p3/CNRS Bordeaux, France

16-17 August 2006

David Smith CENBG 2


TopicsTopics

Introduction – about the Prague meeting.

MAIN POINT – getting the radio TOA’s that we need onto somebody’s disk somewhere.

• “Bread & butter” pulsars

• “Most important and most difficult” pulsars

• Long term DM tracking as well as P, Pdot.

• A strawman proposal for who does which.

Also important point – that those TOA’s become D4.fits ephemeredes “soon”.

• Data formats, timing conventions & definitions, conversion routines

• Tempo vs Tempo2

• On the merging of TOAs at some future date.

Summary of action itemsMost hyperlinks in this talk can be found at « radio confluence », i.e.

https://confluence.slac.stanford.edu/display/SCIGRPS/Radio+timing+for+GLAST

David Smith CENBG 3


Intro: Intro: radio pulsar people in Pragueradio pulsar people in Prague

• Roger & Dave T on the JD02 organizing Committee, volunteered me to give “Future Gamma & TeV Observatories for Pulsars” (thank you!) (see talk at radio confluence.)

• Many attendees are members of Glast Pulsar Advisory Group (see slide 18 of http://glast.gsfc.nasa.gov/ssc/resources/guc/050606/MultiwaveObs.pdf by Steve Thorsett)

• So organized a Splinter Session (see PragueDiscussion and PragueDiscussionBis at radio confluence.)

• Well attended, about 20 people, a veritable Who’s Who of radio pulsar people.

• AGENDA: a) alert them to our ~250 favorite candidates, in hope of defining who-does-which ; b) alert them to D4.fits, to start process of translating their formats and conventions into ours.

• They’ve been waiting for our call for a couple of years apparently. Eager and very well informed.

David Smith CENBG 4


TOA’s for TOA’s for ""bread & butterbread & butter"" pulsars pulsars

• “Bread & butter” pulsars – hundreds of gamma candidates that are relatively easy to measure in radio.

David Smith CENBG 5


The Big Three pulsar telescopesThe Big Three pulsar telescopesfor long term timing of hundreds of "bread & butter" gamma ray candidates

Parkes (Australia)

Nançay (France)

Jodrell (England)

David Smith CENBG 6


TOA’s for TOA’s for ""important but toughimportant but tough"" pulsars pulsars

• “key but tough” pulsars – a dozen or so pulsars with the biggest spin-down energies (best gamma ray candidates) but faint radio signals (low S1400, high duty cycle, high Treq

David Smith CENBG 7


Green Bank (West Virginia)

Oversubscribed – not for bread & butter, only caviar & champagne.

Save for e.g. deep searches of new geminga-likes.

Arecibo (Puerto Rico)

The Big GunsThe Big Guns

David Smith CENBG 8


Building a strawman proposal Building a strawman proposal (1 of N)

• We have a list of ~250 gamma pulsar candidates, see confluence radio

timing page.

• Roger calculated Treq and VperY for these, see his TimingTriage.pdf , and https://confluence.slac.stanford.edu/download/attachments/9650/tri.list.xls?version=1

• If/when Manchester/Parkes & Kramer/Jodrell send me the names of pulsars they’re already tracking, I will look at overlap. But Manchester insists that GLAST (=Roger) should a) ask radio telescopes to state what they can provide (sensitivity, hours, declination) and based on that b) make an initial proposition.

• Prepare (b) before hearing answer to (a):

1st iteration – only the Big Three. Offload to other telescopes in 2nd iteration.

Start from tri.list.xls

Jodrell (Nançay) works down to declination –35° (-39°), Parkes good as far north as =+2°, so have the Big Three share 0< -30°.

That is, for -30°, only Parkes, and for 0°, only Jodrell+Nançay.

David Smith CENBG 9


Parkes strawman proposal Parkes strawman proposal (2 of N)

For -30°, only Parkes.

David Smith CENBG 10


Nançay ephemeredes example in Nançay ephemeredes example in TEMPO formatTEMPO format

Date: Fri, 12 May 2006 20:56:24 +0200 (CEST)

From: Ismael COGNARD [email protected] [icognard@asus 1946+2611]$ cat J1946+2611.par

PSR J1946+2611

RAJ 19:46:45.81000002

DECJ 26:11:49.2000000

POSEPOCH 49079.5000

F0 2.2985609872240267 1 0.0000000000783993

F1 -1.163600000000E-13

PEPOCH 49079.500000

START 53812.311

FINISH 53862.214

DM 165.000000

EPHEM DE200

CLK UNCORR

NTOA 99

TRES 590.27

TZRMJD 53812.31161112975441

TZRFRQ 1368.000

TZRSITE f

NITS 1

[icognard@asus 1946+2611]$

Over the summer, Nançay completed their de-dispersor and now have the full number of frequency channels. Also, they can now adjust gain so that high backgrounds don’t saturate their electronics (e.g. SNR 3C58 and PSR J0205+6449)



TTfghzfghz1. About



Sharing the loadSharing the load

Effelsberg (Germany)

Nanshan (China)

Several other instruments can easily time our radio-brighter (small Treq) pulsars.

• Relieve pressure on the Big Three

• Provide redundant measurements, fill in coverage gaps

• Special projects, e.g. tracking DM at frequencies besides 1400 MHz, searches for giant pulse correlations, etc.

• Remember – we need timing for years, but resources at each instrument ebb & flow.

Roger’s plan: « lock down the Big Three, then offload to the smaller telescopes ».

• Many (most!) eager to work with GLAST.ATA (Hat Creek, California)



Catalog of pulsar radiotelescopesCatalog of pulsar radiotelescopes

Nanshan (China)

List provided with the TEMPO software package:



Filling D4.fitsFilling D4.fits

• Getting the radio TOAs properly measured is the Top Priority.

• But for gtpphase etc to work, also need

TOAs to become proper timing solutions (« ephemeredes »)

Need ephemeredes to get loaded into a D4.fits on the GSSC servers.

• No show stoppers here. Nevertheless, some work must be done.

TDB versus geocentric time

Reference phase in ms, s, or mP?

Double precision. Integer + floating parts. Et cetera.

• The devil is in the details…



Filling D4.fits, Filling D4.fits, cont’d

• Everything (we think…) has been foreseen, huge work already done: see e.g. http://glast.gsfc.nasa.gov/ssc/dev/psr_tools/definitionD4.html

http://glast-ground.slac.stanford.edu/workbook/pages/sciTools_gtpulsardbEphemerisDataFileTutorial/gtpulsardbTutorial.htm

http://glast.gsfc.nasa.gov/ssc/dev/psr_tools/fakedata.html#dataset003

• Very little had been excercised by users.

• Nançay provided us with some TEMPO ephemeredes outputs, which we have appended to Masa & James CGRO D4.fits example, after conversion to the gtpulsardb my_pubsardb_*.txt format, see http://www.cenbg.in2p3.fr/ftp/astropart/Smith/Pulsars/Nan%e7ayTempoToLATascii.htm

• Nançay also providing some TOAs, see http://lpce.cnrs-orleans.fr/~icognard/science/GLAST/ and also http://klun.obs-nancay.fr/pulsar.html

• We are learning TEMPO – ephemeredes out of a black box won’t allow you to see weak pulsars, you’ll probably need to know what you’re doing.



more on Filling D4.fits Filling D4.fits• We applied TEMPO to TOA’s on 8 Nançay pulsars, generated ephemeredes,

converted to my_pulsardb_*.txt, and loaded into D4.fits. It all worked (yippee!). Except for the my_pulsardb_names.txt part…

• NEXT – do same excercise for Jodrell & Parkes timing parameters.

• Kramer & Manchester said they’ll send some sample outputs.

=======================================

• After this rustic beta-testing, need to industrialize.

• Masa & James say: format conversion routines should wind up as daemons at GSSC servers, radio-astronomers will send their numbers directly, to get loaded into D4.fits that will (automatically?) wind up on the GSSC servers.

• Need tools to test validity of final numbers ; need human intelligence for quality control & monitoring. Crab & Vela good, but for all pulsars?



TEMPO vs TEMPO2TEMPO vs TEMPO2

• Dick Manchester seized the discussion on ephemeredes file formats to make a pitch for all radio telescopes to use

http://www.atnf.csiro.au/research/pulsar/tempo2

• The others listened attentively and asked many questions. A key feature is better timing precision by using TDB instead of geocentric time. Some had tried it and had installation problems.

• A priori not our problem but be aware that issues exist.



TOAs from Multiple TelescopesTOAs from Multiple Telescopes

• Imagine the day you want to stack 5 years of gammas to look for pulsation.

• Imagine 4 observatories took data on that pulsar over those years, and that D4.fits has 10 or 20 timing solutions with different validity intervals.

• Suppose further that multifrequency data for different epochs exists, so that you can model DM versus time.

• You’ll want to build timing solution(s) combining that data intelligently.

• So, you’ll want the TOAs as well as the parameter templates that were used by the coherent de-dispersors when the raw data, long gone, was reduced.

• Nançay put some TOAs onto the web for us ; Dick Manchester said « no way! ».

• I believe that when that day comes, you’ll need to work directly with 4 people from the 4 observatories to build the timing solution(s).

• Which means we don’t need to worry further about archiving the inputs used to build entries in D4.fits? So long as we have the creators phone numbers?



Random Comments & QuestionRandom Comments & Question

1. No significant extra cost to include non-gamma candidates in D4.fits, if more or less valid ephemeredes exist. Should be done…

2. You old-timers lived through a debate we newcomers are unaware of, namely, scan versus point. Pulsar timing experts say POINT! See the reasoning by Paul Ray to the SWG in Dec. 2001, https://confluence.slac.stanford.edu/download/attachments/9650/Direct+Pulsation+Searches.ppt?version=1

3. DJT told us about the European Timing Network but I never heard those words in Prague. Quid? Means they pool TOAs? (slide 2 of https://confluence.slac.stanford.edu/download/attachments/2162/Meeting_May30_06.pdf?version=1)



Radio Timing Action ItemsRadio Timing Action Items

1. Refine strawman lists of who does the easy pulsars for us, propose to the radiotelescopes, and iterate. Roger, helped by Dave S. and Steve T?

2. Prepare for the hard pulsars

Refine strawman list

Identify PI’s for time requests at GBT and Arecibo.

Provide PI’s with letter from NASA or LAT PI stating i) vital for GLAST science, ii) coherent program to be shared by all radio telescopes.

3. Continue to excercise D4.fits and pulsar Science Tools with real ephemeredes, from other observatories. Develop QA tools.

4. Affiliated memberships to principal actors.

5. Face to face with radio folks in February or March?

david smith cenbg report from prague meeting with radio pulsar people psr f2f @ stockholm, 28 august...

Documents