Wednesday, August 29, 2012

Fermi LAT weekly report N. 220

Covered period: 2012.Aug.20 - 2012.Aug.26
LAT Mission week: 220.57 - 221.57

  • First gamma-ray flare of the high redshift BL Lac object PKS2131-021 (z=1.284). The source reached a level of 0.6E-6 (about 30 times greater than the average flux reported in the second Fermi LAT catalog) on August 21. See ATel#4333 for more details. 
  • Bright gamma-ray flare from the gravitationally lensed blazar S3 0218+35 (also known as B2 0218+35, OD 330, lens B0218+357,z=0.944+/-0.002). S3 0218+35 was active in gamma-rays all week, peaking at a daily flux level of about 1.6 and 1.7E-6 respectively on August 26 and 27. The source is lensed by aspiral galaxy at z=0.6846, it possesses one of the smallest Einstein rings in the radio band (0''.33 diameter) and is an important object for studies of gravitational lensing, Hubble constant value and individual molecular clouds at high redshifts. The time delay between the variations in the two compact radio source images is 10.5+/-0.4 days. See ATel#4343 for more details.
  • Several blazars detected in flaring state during this week.
  • BL Lacertae peaked with daily flux about 1.9E-6 on August 25and was above the 1E-6 level most days of the week. 
  • PKS 1830-211 peaked with daily flux about 1.4E-6 on August 21.
  • The high redshift blazar B3 1343+451 (z=2.534) was detected with daily flux of about 1E-6 on August 26.
  • PKS 1510-089 and NRAO 676 were both detected at a daily flux level of 1E-6 on August 23.
  • Enduring activity from Mkn 421 was detected the entire week. The source peaked at a daily flux level of 0.6E-6 on August 21,22 and 26.
  • S5 0716+71 and 4C 38.41 (B2 1633+38) are active and detected all week above the 0.6E-6 level.
  • PKS 2326-502, PKS 1424-41, PKS 2233-148, PKS 0454-234, are other blazars observed above the 0.5E-6 level in some days of the week. 
  • Sporadic daily detections of blazars, with a daily flux level below about 0.5E-6: NGC 1275, PKS 0537-441, Mkn 501

Fluxes are in the unit of photons/cm^2/s above 100 MeV. All uncertainties are statistical only.

Note. All the flux reported above are by 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:
- S. Ciprini (stefano.ciprini[at] for generic information related to this week 
- Contact persons on this page for individual sources cited above.

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