Chandra observations of the Crab Nebula following the new gamma-ray flare observed by the Fermi-LAT
ATel #3283; A. Tennant (NASA/MSFC), R. Blandford (Stanford), R. Buehler (Stanford), P. Caraveo (INAF-IASF Milano), E. Costa (INAF-IASF Roma), A. De Luca (INAF-IASF Milano), C. Ferrigno (ISDC Data Centre for Astrophysics, University of Geneva), S. Funk (Stanford), D. Horns (Institut fur Experimentalphysik, Univ. Hamburg), A. Lobanov (Max-Planck Inst. Radioastronomie, Bonn), R. Mignani (MSSL), M. Tavani (INAF-IASF Roma), Y. Uchiyama (Stanford), M. C. Weisskopf (NASA/MSFC)
on 14 Apr 2011; 18:32 UT
Credential Certification: Stefan Funk (firstname.lastname@example.org)
Subjects: X-ray, Gamma Ray, >GeV, Supernova Remnant, Pulsar
Chandra was observing the Crab as part of our monitoring program when Fermi-LAT team announced the detection of enhanced gamma-ray activity from the Crab Nebula (ATel #3276). The observation was for 5 ks with the ACIS instrument using a custom window on a 0.2s frame time. With this configuration the whole nebula, except the 2 arc-second region surrounding the pulsar, is observed with Chandra resolution. This program began following the previous flare in 2010-Sep (ATel #2855, ATel #2861). These observations revealed a bright knot 5.7 arcsec east of the pulsar that propagated outwards and faded in brightness. This knot is not aligned with the jet.
The new Chandra observation at 2011-Apr-12 14:24 (UT) and at 2011-Apr-13 23:33 (UT) shows a new knot, coinciding with the initial position of the faded knot from the 2010-Sep event. The error on the positions quoted are 0.5''. We will perform additional observations of 10 ks each to monitor the behavior of this knot and the overall behavior of the Crab Nebula at the following times:
We thank the CXC and its director, Harvey Tananbaum, for making these observations possible and on on such short notice. The data are available in the Chandra public archive.