Report on GLAST Pulsar Radio Timing Discussions at the Prague IAU GA

1. Report onGLAST Pulsar Radio Timing Discussions at the Prague IAU GA 16-17 August 2006 David Smith CENBG/In2p3/CNRS Bordeaux, France

2. Topics • 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 items • Most hyperlinks in this talk can be found at « radio confluence », i.e. • https://confluence.slac.stanford.edu/display/SCIGRPS/Radio+timing+for+GLAST

3. Intro: radio 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.

4. TOA’s for "bread & butter" pulsars • “Bread & butter” pulsars – hundreds of gamma candidates that are relatively easy to measure in radio.

5. The Big Three pulsar telescopesfor long term timing of hundreds of "bread & butter" gamma ray candidates Parkes (Australia) Jodrell (England) Nançay (France)

6. TOA’s for "important but tough" 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

7. The Big Guns Arecibo (Puerto Rico) Green Bank (West Virginia) Oversubscribed – not for bread & butter, only caviar & champagne. Save for e.g. deep searches of new geminga-likes.

8. 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 , andhttps://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 d=+2°, so have the Big Three share 0< d <-30°. • That is, for d <-30°, only Parkes, and for d > 0°, only Jodrell+Nançay.

9. Parkes strawman proposal (2 of N) • For d <-30°, only Parkes.

10. Nançay ephemeredes example in TEMPO format Date: Fri, 12 May 2006 20:56:24 +0200 (CEST) From: Ismael COGNARD icognard@cnrs-orleans.fr [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)

11. Tfghz • About

12. Sharing the load • 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. Effelsberg (Germany) ATA (Hat Creek, California) Nanshan (China)

13. Catalog of pulsar radiotelescopes List provided with the TEMPO software package: Nanshan (China)

14. Filling 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, ms, or mP? • Double precision. Integer + floating parts. Et cetera. • The devil is in the details…

15. 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 g pulsars, you’ll probably need to know what you’re doing.

16. more on 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?

17. TEMPO 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.

18. TOAs 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?

19. Random Comments & Question • No significant extra cost to include non-gamma candidates in D4.fits, if more or less valid ephemeredes exist. Should be done… • 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 • 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)

20. Radio Timing Action Items • 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? • 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. • Continue to excercise D4.fits and pulsar Science Tools with real ephemeredes, from other observatories. Develop QA tools. • Affiliated memberships to principal actors. • Face to face with radio folks in February or March?