The Argos Arbitrator is the software that orchestrate the different components of the system and acts as an interface between the Argos subsystems and the telescope and instruments.

Simplified Arbitrator Work Flow

In preparation for the observing night, the system will be powered up, calibrated and warmed up. At this point (STARTED UP) the laser heads are on, but in standby mode. Access to the chamber is allowed (Laser class 1). Laser state is ON. After clearance from the laser safety officer, the arbitrator will be put in READY TO OBSERVE. This means that the lasers are on, full powered, but the propagation shutter is closed. Access to the chamber is restricted (Laser class 4). Laser state is HOT. Finally, after receiving a PresetAO command followed by AcquireRefAO, the lasers are launched and acquired on the wavefront sensor. Laser state is ON_SKY.

Laser heads Propagation shutter Laser system state
  aos.side[X].argos.ArbitratorState? aos.side[X].argos.LaserState?
Lasers off Closed OFF
Lasers in standby Closed ON
Lasers full powered Closed HOT
Laser full powered Open ON_SKY


  1. Arbitrator aircraft avoidance interface
  2. Arbitrator AOS interace
  3. Arbitrator beam avoidance interface
  4. Arbitrator engineering interface
  5. Arbitrator observation interface
  6. Arbitrator operator interface
  7. Arbitrator satellite avoidance interface

Finite State Machine

As all other Argos subsystems, the Arbitrator's behaviour is described by a finite state machine (FSM). The latest version of this FSM can be found in the Argos repository as an Umlet UXF file. In this diagram, the different instrument states are modeled in green, error states in red, transition states in yellow. The transitions are triggered by events, modeled with arrows. TCS events are translated into Argos events and modeled with orange boxes.

Topic revision: r5 - 07 Aug 2018, AndrewColson
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