pn_back not available under esas

For the first time, the Extended Sources Analysis System (ESAS) package has been included in SAS 9.0.0 (xmmsas_20090615_1801-9.0.0).
However, the version included in SAS 9.0.0 (esas-0.9.4) only provides support for EPIC MOS detectors.

Despite the fact that the current esas-0.9.4 "on-line documentation" ( http://xmm.esac.esa.int/sas/current/doc/esas/index.html) provides information about some ESAS tools to handle EPIC PN detectors, as for example pn_back, these are not yet available.

We hope these tools will be available in the next public release of SAS.