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### A.4.14 Time Plot Window

Time Plot Window

The Time Plot () is intended for plotting time series data.

The horizontal axis represents time, and can be labelled accordingly (for instance in minutes, hours, days, months and years), and the window can display appropriate types of plot including spectrograms.

To define the time coordinate, use the Time selector in position tabs as usual. Note however that this contains a time format selector on the right hand side that indicates how the selected quantity will be interpreted as a time value. The options are:

- DecYear: Years since 0AD
- MJD: Modified Julian Date (days since 17 Nov 1858)
- JD: Julian Day (days since 1 Jan 4713 BC)
- Unix: Seconds since midnight 1 Jan 1970
- Iso8601: ISO 8601 date-time string

If the input table contains suitable metadata, for instance in a CDF file or a TIMESYS-bearing VOTable 1.4, additional options may be available that are taken from information in the table. TOPCAT will make a guess at the correct format to use, but if it gets it wrong you can set the format selector manually. The format selector is updated to the best guess when you choose a new Time value; if you want to stop it doing that, use the Lock button ().

Unlike most of the other plot windows the Time plot can display different data plots in different plot Zones stacked vertically on top of each other, so that different plots share a time axis but have their own Y axis. The vertical spacing between the stacked plots can be configured using the Cell Gap configuration option in in the Spacing tab of the Frame Control.

It is possible to abuse this plot type to stack plots that do not actually have time on the horizontal axis. To do that, select mjd as the Time Format in the Grid tab of the Axes Control, and make sure that any time format selectors (described above) are similarly set to MJD. You may need to check that the right Zone is chosen (usually the bottom one) when you configure the axes.

The Time Plot offers the following plot controls:

- Position Layer Control, with these form options:
  - Line
  - Linear Fit
  - Mark
  - Error Bars (vertical bars only)
  - Label
  - Fill
  - Quantile
  - Grid
- Histogram Layer Control with these form options:
  - Histogram
  - KDE
  - KNN
  - Densogram
  - Gaussian
  Note that some of these histogram-like controls offer the Combine option that lets you define how values are combined together. If you choose the sum-per-unit or count-per-unit options, you can also use the Per Unit selector to determine whether values are represented as sums/counts per second, hour, day, year, etc.
- Spectrogram Layer Control
- Function Layer Control

As well as the standard actions, this window additionally provides the following toolbar button:

- Measure Distance

See the Window Overview for features common to all plotting windows. The following subsections describe zones, navigation and axis configuration.

- A.4.14.1 Plot Zones
- A.4.14.2 Time Navigation
- A.4.14.3 Time Axes Control

Next Previous Up Contents
Next: Plot Zones
Up: Plot Windows
Previous: Corner Axes Control

TOPCAT - Tool for OPerations on Catalogues And Tables
Starlink User Note253
TOPCAT web page: http://www.starlink.ac.uk/topcat/
Author email: m.b.taylor@bristol.ac.uk
Mailing list: topcat-user@jiscmail.ac.uk