1. T. Burnett: Anagroup 5/24/04 1 Latest PSF and Point-source sensitivity prediction status Anagroup meeting Toby Burnett 24 May 04

2. T. Burnett: Anagroup 5/24/04 2 Slide presented to Beyond Einstein: Based on proposal: is it consistent with current evaluations?

3. T. Burnett: Anagroup 5/24/04 3 Post DC1 IRF  Use GlastRelase v4r2 Major difference: “Tracker Iterative Recon”  Second iteration of track fit fixed many bad energy estimates Heather’s all_gamma production  ag-v4r2-merituple-180GeV-prune-20040427-fulltup.root Apply standard DC1 cuts.  All analysis code in package users/burnett/IRF v9  Results on glast.phys.washington.edu

4. T. Burnett: Anagroup 5/24/04 4 Slight modification to fit function So, two parameters: : scale factor, corresponds to rms for gaussian : exponent

5. T. Burnett: Anagroup 5/24/04 5 Example fits

6. T. Burnett: Anagroup 5/24/04 6 Comments  Form suggested by Jean Ballet  Same as previous function to 2 nd order in r 2  Slightly better fits  Simple integral gaussia n

7. T. Burnett: Anagroup 5/24/04 7 Application to point-source sensitivity  How does one measure the strength of a point source? No background: just count, rms error is Poison sqrt(N) for N  5 sigma corresponds to 25 events Background (assume constant): Use maximum likelihood to fit assumed PSF:  For N signal events, the expected variance is now less than N by a factor depending on the PSF shape and the background: the factor is the integral b is the ratio of background in 2 2 to the total signal

8. T. Burnett: Anagroup 5/24/04 8 Application to point-source sensitivity, cont The variance derating factor gaussian =2.5 = 2.0 =1.5

9. T. Burnett: Anagroup 5/24/04 9 Next step: combine with Aeff (front)

10. T. Burnett: Anagroup 5/24/04 10 Final step: predict the time required for high- lattitude 5-sigma detection  Assume: EGRET measurement of extragalactic diffuse (for now) E -2 spectrum Scanning mode gives uniform acceptance  Apply: All_gamma measurement of Aeff, PSF. Front section only for now

11. T. Burnett: Anagroup 5/24/04 11 A look at the energy dependence 1 year 1 day

12. T. Burnett: Anagroup 5/24/04 12 Preliminary result

13. T. Burnett: Anagroup 5/24/04 13 To Do  Verify with likelihood applied to actual simulation  Add contribution from back planes  Document as an analysis memo on LAT-docs  Create pictures as shown by Peter