Thursday, September 30, 2010

Fermi LAT weekly report N. 119


Covered period: 2010.September.20 - 2010.September.26

LAT Mission week: 120.57 - 121.57



  • After the gamma-ray flux increase from the direction of the Crab Nebula reported by the AGILE and LAT Collaborations ( ATel #2855, ATel #2861) a dedicated pointed observation of the Crab Nebula from 2010-09-23 15:50 UT to 2010-09-27 19:49 UT was performed by Fermi.

    • The Fermi LAT monitoring of this source showed a flux enhancement during the interval 18-22 September. Measurements taken starting on 23 September are consistent with the typical flux of the Crab. The average total flux from this location (which includes the nebula and pulsed emission) above 100 MeV measured between 2010-09-23 00:00:00 and 2010-09-26 18:43:01 UTC was (280 +/- 20) x 10^-8 ph/cm2/sec. The systematic error on the flux is generally estimated to be ~10% at 100 MeV.
    A preliminary phase-resolved analysis of the flaring source shows that the excess flux due to the flare is the same in the on and off pulse selections for the pulsar and thus it does not appear that the enhanced emission is pulsed. This suggests that origin of the flare is related to the nebula rather than the pulsar emission ( ATel #2879).




  • PKS 0727-11 detected in flare on Sept. 21, with daily flux of (1.4+/-0.4)E-6 (see ATel #2860) and continued to be active during the entire week, at daily flux between 0.5E-6 (Sept. 24) and 0.8E-6 (Sept. 25).

  • NGC 1275 (Perseus A) detected on Sept. 23 and 26, with daily flux of (0.5+/-0.2)E-6 and (0.3+/-0.1)E-6.

  • PKS 1329-49 detected in flaring state on four consecutive days this week (Sept. 20-23), with daily flux between 2.5E-6 and 4.5E-6.

  • B2 1846+32A detected on Sept. 20 and 22, at daily flux of about 0.6E-6 and 0.8E-6, respectively.

  • 3C 279 detected on three consecutive days this week (Sept. 20-22), with daily flux between 0.6E-6 and 1.0E-6.

  • PKS 1313+333 detected on two consecutive days this week (Sept. 22 and 23), with daily flux between 0.6E-6 and 0.9E-6.

  • B2 1520+31 detected in high activity state on Sept. 22, with daily flux of about 1.1E-6.

  • PKS 2326-502 detected in high activity state on Sept. 20, with daily flux of about 1.2E-6.

  • B2 0619+33 detected on Sept. 24 and 26, at daily flux of about 0.5E-6 and 0.9E-6, respectively.

  • 3C 454.3 bright for all the week with daily flux between 3.0E-6 (Sept. 26) and 6.5E-6 (Sept. 22).


  • Sporadic daily detections of blazars B2 0200+30 (Sept. 20), S5 0716+714(Sept. 21), Mrk 421 (Sept. 21), 4C +21.35 (Sept. 22), PKS 0736+01 (Sept. 24) and PKS 0524-485 (Sept. 25).



Fluxes are in the unit of photons/cm2/s above 100 MeV. All errors are statistical only.



Note. All the fluxes reported above are from the ASP analysis and should be considered preliminary and should not be used for publication, however they are indicative of the flux range and the current status of a source. Source association is done on the basis of source location, considering spatial coincidence only, and it is not indicative of an identification.
- Please acknowledge the LAT team if you use information from this report.


For questions and comments please contact:

- F. D'Ammando (dammando[at]ifc.inaf.it) for generic information related to this week

- Contact persons on this page for individual sources cited above.



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