XMM-Newton Status report - November 2004
Operations and archiving
The completion status of the observing programme is as follows:
- Guaranteed time: 99.7 %
- AO-1 programme: 99.6 %
- AO-2 programme: 99.7 %
- AO-3 programme: 61.8 %
Completion of the above programmes is expected by March 2005 and is in line with the planned start of AO-4 observations. Currently, over 3514 observation sequences have been executed and the data for 3398 of these have been shipped. The fourth announcement of opportunity (AO-4) was released on 30 August 2004, as planned, and closed on 8 October 2004.
Several Targets-of-Opportunity and discretionary time targets were observed, namely
- RX J0720.4-3125
- RX J0513.9-6951
- 1E 1048.1-5937
- SN 2004dk
The GRB observation was triggered by INTEGRAL and data taking began only 4.5 hours after the notification was received!
Version 6.0 of the XMM-Newton Science Analysis System (SAS) had been downloaded 780 times by end September. Based on replies to a questionnaire, about 1650 scientists have access to this version and 250 people were downloading the SAS for the first time.
The XMM-Newton Science Archive (XSA) has some 1700 registered users as of end September. The monthly usage can be characterized by the following numbers for August 2004: 130 scientists used the XSA and about 1400 separate data sets were downloaded.
Science (2004, 305, p.376) published a paper by P. A. Caraveo et al. about the isolated neutron star Geminga. The paper reports that the pulsar shows a thermal spectrum with a temperature of 43 eV from the whole surface, as well as a power-law component above 2.0 keV. In addition, the authors detected hot (170 eV) thermal emission from an ~60-meter-radius spot on the pulsar's surface, which is only visible at selected phase intervals, and may be coming from polar hot spot(s), long thought to exist as a result of heating from magnetospheric accelerated particles. This detection may provide the missing link between the X-ray and gamma-ray emission of the pulsar.
The Astrophysical Journal accepted a paper form J. P. Henry et al. about a mosaic of XMM-Newton observations of the nearby major merger cluster A754. The authors construct maps of X-ray surface brightness and temperature integrated along the line of sight and these show a basic pattern similar to numerical hydrodynamic simulations of cluster mergers. A new feature revealed by these observations is a plume-like structure that appears to emerge from the bar heading northwest. Another new feature is a rim of hot gas to the east, south and west. The authors interpret the bar as the core gas from the original main cluster flattened and displaced from the dark matter potential minimum by the merger. The hot rim is the outgoing forward shock from the merger. These observations lend support to the merger hypothesis in A754, but some of the parameters of existing models need modification.