The Hera facility at HEASARC can run tasks from numerous environments, such as CIAO, xselect, and ftools, and includes the SAS environment, which is the software designed specifically for the reduction and analysis of XMM-Newton data. Hera lets users have access to this software remotely, without asking the users to download to the user's local machine such things as the calibration files or software. Data files stored on the user's local machine may be copied to a private space on the Hera server, or downloaded directly from the HEASARC data archive.
There are two flavors of Hera: anonymous and standard. These have identical graphical interfaces and produce identical outputs. Anonymous Hera is accessed though the HEASARC data archive by simply clicking on the ``H'' next to the dataset the user would like to examine. Files created through anonymous Hera will be deleted at the end of the session, but the user will be given the option to save the files to a new or existing Hera account. Standard Hera requires the user to install fv, available through the HEASARC, on his or her local machine (see § 4.2). Standard Hera requires the user to log in to an account, and only processes data that is located on the Hera server. Files may be transferred there via anonymous Hera, HEASARC archive links, or by right-clicking the filename on the local directory list in the Hera GUI and dragging it to the desired location. Please note that only file at a time may be copied, and that due to security restrictions, whole directories cannot be copied (see § 4.1).
There is no difference between the data analysis tasks in Hera's SAS and a locally-installed version of SAS - the only difference, as far as the user is concerned, is in the interface. Users who are familiar with SAS will need only to learn to navigate the Hera ``wrapper''; all tasks, procedures, and techniques of data reduction are the same as if SAS were locally installed.
For the sake of simplicity, it will be assumed throughout this Guide that the user will only use SAS tasks (unless where explicitly stated). Thus, anonymous and standard Hera are synonomous with the locally-installed SAS GUI and command line.