Moon Trigger

The Moon (and Sun) trigger is aiming to register tracks coming from the Moon (and Sun) direction. Physical meaning of this search is to analyze our possibility to see the shadow of the Moon (Sun) in a flux of cosmic rays. This opens the door to the Far Detector angular resolution estimate as well as Moon (Sun) specific studies such as finding changes of the Moon (Sun) shadow shape to see changes of magnetic environment etc.


The trigger was initially created by Martin Frank using the analysis code by Chris Backhouse. Later it was developed and supported by Serdar Kurbanov.

The trigger code is located in the DDT repo:

The basis of the Moon (Sun) location algorithm is NOVAS (Naval Observatory Vector Astronomy Software). Despite similarity to NOvA, it has nothing to do with it. This is an API to find coordinates of celestial objects using the ephemeris file (DE405 ephemeris, in the trigger the file is named JPLEPH).

The trigger defines few parameters to make track finding more efficient:
  • AngleCut: 5 # degrees
    [defines cone around the Moon (Sun) around which we're registering tracks]
  • AvgRate: 16 # Hz
    [defines rate the trigger is set to. It's demanded by possibilities of the DAQ system]
  • AngularSuppression: 5 # degrees
    [the farther from the center of the cone, the less tracks we register, since the center of the cone contains data of bigger interest for us]
  • LengthCut: 150 # cm
    [minimal length of a track]
  • BinCut: 10 # number of bins
    [minimal number of bins in a track]
You can find more details of this algorithm and how it was developed in these materials:

Moon Shadow Analysis modules

In order to analyze Moon shadow trigger data, two modules in offline system were created. The key difference is that one uses pclist data (so, the window tracker is typically used to create tracks) and another one uses artdaq files with following processing using same modules that are used in the trigger (so, Hough tracker is used to create tracks).

Both modules use CelestialLocator module to find position of the Moon (Sun) - find it at

Moon Shadow Analysis module for pclist files

This module was created by Leo Aliaga. It uses pclist files to get all necessary parameters of tracks. This module was used to find Moon shadow using cosmic pulser data.

Moon Shadow Analysis module for artdaq files

This module was created by Serdar Kurbanov. It uses artdaq files and same processing chain as the trigger (..., Hough tracker, merge2D, ...) to get all necessary parameters of tracks. This module was used to find Moon shadow using Moon trigger files and to check if what we see corresponds to that of window tracker (not fully).