iLiSA - international LOFAR in Stand-Alone mode

iLiSA provides a package to make observations on international LOFAR stations in stand-alone mode called observations and a package to handle metadata about the configuration of the LOFAR station's antenna metadata called antennameta. LOFAR is a low-frequency radio telescope array located in Europe.

What is this repository for?

iLiSA is of interest to people that have access to a LOFAR station or if you wish to process data taken with a LOFAR station in stand-alone mode.

The operations subpackage allows you to make and record standard stand-alone observations such as:

• BST - Beamlet statics (Temporal power of beamlets)
• SST - Subband statics (Dynamic spectra of each receiving unit)
• XST - Cross-correlated statistic (Array visibilities for one frequency)
• ACC - Autocovariance cubes (XST stepped through all frequencies)
• TBB - Transient Buffer Board (Direct sampling of each receiving unit)
• BFS - Beam-formed streams (Streamed complex voltages of beamlets)

The package also features special observational modes:

• Multi-band BST: BST data recorded over multiple bands, i.e. LBA, HBA-lo and HBA-hi
• SEPTON: Gives HBA an allsky field-of-view. Data taken in this mode is either SST or XST
• Multi-subband XST: Records XST data in over a sequence of subbands

Observation using iLiSA are made with science-level python functions which issue the hardware-level commands to the station's Monitoring And Control interface.

The antennameta subpackage is of interest if you wish access a LOFAR station's metadata concerning antennas. This metadata includes:

• AntennaFields - Positions of a station's antenna elements
• Delays - Cable group delay per antenna element
• CalTables - Complex, per antenna, gain factors to apply on station array visibilities

This metadata is useful for postprocessing stand-alone data, e.g. imaging XST data, handling TBB data or calibration.

The monitor subpackage provides tools for collecting information on the state of a station so that operators can remotely monitor the state of the telescopes.

The pipelines subpackage enables the setting up of pipelines that process data recorded during station operations. It also contains CLI support for handling LOFAR BFS data files, allowing e.g. conversion to numpy etc.

scripts contain some high level scripts such as a scheduling tool that can start observing sessions at specific times on specific stations and start pipelines.

Finally, the calim subpackage provides functionality to do calibration, imaging and modeling of radio interferometric observations, with e.g. routines for handling visibilities and global sky models.

How do I get set up?

• Use setup.py script to install
• (If you want to actually access the station) Setup password-less ssh access to LCU via tunnel on the LCU gateway node.
• Requires: numpy (for calim package also python-casacore)
• Optional features might require additional software...

Status

Please note that iLiSA is still in development. It has been used heavily on the Swedish LOFAR station. Features such as TBB handling require DAL software.