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Update on Pulsar timing for GLAST with the Nançay Radio telescope. David Smith et al CENBG/In2p3/CNRS Bordeaux, France. Topics. Big Nançay time request submitted today, see form-NRT-Avril2006\_HE4.pdf at

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Update on Pulsar timing for GLAST with the Nançay Radio telescope

David Smith et al


Bordeaux, France

  • Big Nançay time request submitted today, see form-NRT-Avril2006_HE4.pdf at
    • Two glast lists – Roger’s 10 pilot pulsars, and 138 gamma candidates
    • Joint GLAST+HESS+XMM request “French High Energy Pulsars”
  • About Nançay sensitivity… (work in progress)
  • Does a “pre-flight” D4 database exist? And a few other little questions.
Nançay time request due today
  • Initially, planned to study Roger’s 10 pulsars, to quantify sensitivity, and gradually ramp up our program.
  • But count backwards, and realize you better pick up the pace:
    • Sept 2007-- D4 database full
    • Summer 2007-- building timing solutions
    • Fall 2006 -- making periodic radio measurements of many pulsars, to be used to build ephemeredes.
    • Spring 2006 – big time request
  • We have submitted a list of ~140 pulsars and request >500 hours for the 2nd half of 2006.
  • Requesting “key program” status.
The ~140 pulsars
  • Our cuts on ATNF:
  • Edot > 1E34 .OR. sqrt(Edot)/d² > 1% of Crab
  • This gives all the famous pulsars (all the obvious and less obvious candidates), including a healthy sample of ms pulsars.
  • Declination > -39.5°
  • (Smith was wrong when he said that Nançay poops out north of d ~ +60°.)
  • The GLAST request is part of a more general “High Energy Pulsars in the French Community” proposal which includes 8 pulsars associated with HESS galactic sources (Yves Gallant, Montpellier) and 2 binaries to be observed with XMM (Natalie Webb, Toulouse). All 10 of the HESS+XMM pulsars are in the GLAST list, as are all 10 of Roger’s test cases. As work continues the GLAST list will evolve – the TAC shouldn’t bother us about the exact list.
  • Dave T re-made the list using the NE2001 distances from the “expert” ATNF www pages for the full sky, see PulsarListBordeauxFormula.xls & .pdfat There are 250 pulsars. Includes Geminga and 2 other “radio quiets”, J1846-0258 (SNR Kes 75) & J1811-1925 (G11.2-0.3).
How we calculate telescope time
  • Roger’s Feb 21 “Timing Triage” talk is our meat & potatoes.
  • He used f_gamma = sqrt(Edot)/d² normalized to Vela’s value to sort targets by “expected” gamma brightness.
  • He said that the time required for a 10 mP T.O.A. scales as (W/P)1.5/S_1400, and he normalized to 3 hours on 0205+6449.
  • Roger, where did you get that “3 hour” number from?
  • Nançay saw (?) it with signal-to-noise ~9 in 92 minutes in January, not as clear as they’d like. Work in progress.
  • Nançay picked up a few other tricky ones, so we’re normalizing “treq” to those.
  • (Nançay has detected 80 pulsars since BON installed 2 years ago, most of them repeatedly.)
Roger’s test pulsars

From [email protected] Tue Jan 31 20:00:23 2006

To: D.A. Smith Subject: some glast pulsars

Hi David -- as requested, here are a few pulsars that you candiscuss in your upcoming meeting with Ismael. I will describesome of my thinking in ranking things on the 21st. But here are10 PSR worth discussing, all above DEC -35. Note -- many of theseare presently being timed, although it is not clear that the timingis adequate or will continue during GLAST. You might want to avoid competing in the Arecibo DEC range (0-38), as well:

Ridiclously difficult, but important:

Name ~S_1.4(mJy)


J1833-1034 0.08767 0.07

J1930+1852 0.004619 0.06

J2021+3651 0.0001662 0.1

J1946+2611 5.776e-05 0.06

Not so hard, but likely interesting

J1747-2958 0.008501 0.25

J2229+6114 0.00108 0.25

J1815-1738 0.0002536 0.25

J1913+0832 0.0001506 0.6

J1734-3333 0.000144 0.5

J1735-3258 4.161e-05 0.46

Anyway, something to discuss, although certainly notan exhaustive list. Let me know what Ismael thinks... -- Roger

  • Discovered last year. 62 ms, both Edot/d2 and BLC greater than for e.g. 1951+32
  • f_gamma.
  • Discovered in ‘95, no published timing since (no publications, period!).
  • Serious fun -- galactic center, 3EG and HESS TeV sources nearby, big Edot/d2 , called the “Mouse”. Bow shock visible in Xrays.
Roger classed this as “ridiculously hard” but it is easily detectable. ATNF doesn’t have S1400 for this one, so RWR extrapolates from 400 MHz assuming a 2.5 spectral index, apparently an underestimate in this case. Also, ATNF doesn’t have W50, so RWR takes W/P = 10% but here it’s even narrower.

28 slices,

2 minutes each

One neutron star rotation 

Ismael is (understandably!) proud that Nançay achieves 0.6/435 = 1 mP timing in about 2 minutes.

Nota bene: a few points over a few months to get P and Pdot.

(this slide re-cycled from my 21 February talk…)
  • Ismael had J1751-2857 with 60 +/- 20 uJy in his list. Pops out in less than an hour.
  • BUT Roger says the 60 mJy isn’t reliable. I read the references, they seem fine to me…
  • Roger, do you still disbelieve the 60 mJy ?

A 60 mJy ms pulsar

2 minute slices

This is also one of the

10 HESS targets.

One neutron star rotation 

This one has S1400 1.4 mJy but the timing parameters in the literature are a bit off.

Ismael & Gilles load the ephemeredes into the BON de-dispersor front-end, which does heavy processing of terabytes of data. The raw data is lost. From this detection, refine the parameters, and iterate. This is part of why it’s good to get a head-start.


Ismael made this slide for the January workshop. Denis and I have fiddled with his list, to demonstrate RWR’s (W/P)1.5/S_1400 law. Again, more of a guideline than a hard & fast rule.



Telescope time, cont’d
  • You’ve seen that RWR’s “treq” is a useful guideline but not a rigorous prediction.
  • In “TimingTriage” Roger also estimated “visits per year”, based on D8, from this reference:

We’d like to write the same article, next year…

… but they took >3 years!

“Visits per Year” not an exact science

In consequence, at Nançay measurements of large numbers of “our” pulsars will allow us to nail down just how often we’ll need to come back to any given pulsar, in addition to knowing how long to dwell on any single pulsar.

Step 1: make sure you’re detecting ‘em.

Step 2: detect ‘em a few times over many months

Step 3: build timing solutions and load them into the D4 database.

(brief parentheses – What’s TEMPO for?)
  • At our last meeting, Marcus Ziegler showed results of his DC2 blind searches. MRF0054 brighter than Vela! We plugged his f, fdot into gtpphase – after one day the light curves get washed out.
  • Fiddled with f,fdot by hand, looking at this “radio-like” plot.
  • Say… isn’t this what TEMPO is for?
  • How do you “build timing solutions” anyway?
  • Our radio pals know, but I think we need too, before launch.

55 days

Of DC2

Towards a post-launch D4 database
  • I presume that someone has already built a D4 ephemeredes database and exercised the Science Tools with it… Like: take all the ephemeredes in ATNF and just load ‘em in.
  • That would be our starting point. Then, as GBT Jodrell Nançay Parkes Arecibo send fresh ephemeredes to various of us, we’ll have some standard procedure for making it propagate to the Official versions at the data servers, right? Like, we give them to Peachy and Masa or?…
  • The D4 .fits file has an “observer” column. That’s for traceability, right?
  • Presumably, a given pulsar at time t may have ephemeredes from later from one radio telescope and from earlier from another; and we’ll want to connect the two (with TEMPO?) ; and we want to avoid a large N_trials… ; is there a plan for all this?
  • Is barycentering and phase calculation foreseen to be part of gamma ray reconstruction?
DC2 Version 2 All Sky

Damien Parent ran his scripts over the new, improved V2 DC2 sky.

Flip through his 98 pages – it’s fun, they look great. Here’s page 96.

PSF cut done (“dist < 500/E”). Not big effect, investigating. Here, 3°cut.

Will study sensitivity & localisation.

  • A French 100-meter class radio telescope with modern pulsar electronics is working with GLAST to time faint, young, and noisy pulsars over our mission lifetime. We have submitted a request for >500 hours to time ~140 pulsars beginning in the 2nd half of 2006, and aim to become one of three “key programs” at Nançay.
  • Goal is to stock the D4 database with fresh products.
  • Timing measurements have begun. We’re ramping up faster than previously planned.
  • Various questions are raised, none of which are critical path items.

Extra slides

About the 140 pulsars
  • As stated: at Nançay we’re planning to attack the whole dang list. At some point in the next months it makes sense to start finding out which of the 140 are already being monitored elsewhere. (Thanksgiving’s probably soon enough…)

(from Steve Thorsett transparencies)

Introduction to Nançay
  • It is a meridian telescope : sources visible ~1 hour per day, at transit.
  • South mirror fixed (300 m x 35 m), north mirror tilts (200m x 40m), little trolley car (shown below) moves to focus. (94 m diameter equivalent)
  • Covers -40o < d < 60o ( best for -30o < d < 40o)
  • Lobe is 21’ north-south x 4’ east-west (at 21 cm ~ 1400 MHz)
  • 2.5 M$ refurbishing 5 years ago, big pulsar improvements 2 years ago
  • Some performance details in a galaxy survey paper,
    • G. Theureau et al, A&A 430 373-383 (2005)