To find and download HEASARC data in the cloud, you can use astroquery.heasarc or download our new tool, hark.
The HEASARC and NuSTAR teams are greatly saddened by the sudden passing of Katja Pottschmidt. Most recently Katja was the lead scientist for the NuSTAR Guest Observer Facility (GOF), a role she had supported for many years. During her science career she worked on many other high energy astrophysics missions and played an integral role in advancing our knowledge of the universe. She was a wonderful colleague and friend and will be keenly missed by all who knew her.
help
Get help on Xselect commands
Obtain help on the XSELECT commands, their syntax, and examples. Help uses the IHF interactive help facility. The optional topic list can be used to go directly to a particular topic and sub-topic. Once in help, typing ?? will summarise extra features and special characters that can be used within the IHF system.
To exit back to XSELECT, use an EOF, a /*, or type 
CR
until you leave the help facility.
Syntax:
xsel > help <topic list>
Examples:
xsel > help help
gives the text you are reading.
xsel > help "commands extract"
gives the text for the extract command.