# Time Series Table Format

Description of FITS tables intended for store of time series
(light curves) or another time series data.

The table is created as output of `munipack timeseries` command.

The specification slightly follows SimpleTimeseries format (IMPORTANT: This link is intentionally dead due authors themselves.
There is no widely accepted definition
of a format for light curves and related affairs yet.) Generally, Munipack's format is a bit more simplified and
restrictive.

# File Structure

FITS file structure
HDU | EXTNAME | Description |

0 | | Dummy^{[†]} |

1 | TIMESERIES | Time Series Table |

2 | CATALOGUE | Objects identification (coordinates) |

^{[†]}
The first dummy extension contains keywords of identification HDUNAME,
which is set mandatory to 'TIMESERIES', CREATURE is set to
'Munipack X.Y.Z' version and a link to this page as a comment.

# Time Series Table

The main table which stores the time series.

Time Series Keywords
Keyword | Value | Default | Description |

EXTNAME | TIMESERIES | TIMESERIES | extension identifier |

TIMETYPE | JD | JD | Type of TIME: JD (Julian Day),
MJD (modified JD), HJD (heliocentric JD), phase *φ*^{[1]} |

TIMESYS | UTC | UTC | Time system |

TIMEREF | GEOCENTRIC | | Reference time point |

TIMESTMP | MIDPOINT | MIDPOINT | time stamp = MIDPOINT,BEGIN,END^{[2]} |

^{[1]}
Definition of Julian (also other derived) days provides Julian day wiki page. The phase *φ = {(t - t*_{0})/P} is
defined as fractional
part (*{x} = x - ⌊x⌋*) of time difference HJD since the epoch *t*_{0}
per period *P*.

^{[2]}
The time is labeled by timestamps (the elapsed time is *T*):
at the begin *t*_{0} (BEGIN) up to finish *t*_{1} =
t_{0} + T (END) time. The midpoint
is computed as *t*_{0} + T/2.

Time Series Table
Column | Type | Description |

TIME | 1D | Time-like quantity^{[a]} |

EXPTIME | 1D | Integration time like quantity^{[b]} |

Q_{i} | 1D | Quantity for *i*-th object^{[c]} |

QE_{i} | 1D | Standard deviation of Q-*i*^{[c]} |

^{[a]}
Units of the time-like quantity in days (for H,M,JD). The phase has no units.

^{[b]}
The exposure time is directly copied from frames and units are (perhaps)
seconds.

^{[c]}
Table can contain many physical quantities. For their meaning, see
Photometry data table. The table
can contains multiple columns of the quantities for all required objects.

# Object Catalogue Table

This extension contains equatorial coordinates of objects of TIMESERIES extension.

Object Catalogue Keywords
Keyword | Value | Default | Description |

EXTNAME | CATALOGUE | CATALOGUE | extension identifier |

REFRAME | | ICRS | Reference celestial coordinate system |

EPOCH | | 2000 | Reference epoch for proper motion |

Object catalogue Table
Column | Type | Description | Units |

RAJ2000 | 1D | Right Ascension^{[§]} | degrees |

DEJ2000 | 1D | Declination^{[§]} | degrees |

^{[§]}
Coordinates are referenced for epoch of the observation.
Fast-moving objects can evince visible coordinate differences.

## See Also

Time Series