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#### A.4.14.3 Time Axes Control

Note: the Time Plot has multiple plot Zones, and the axes are configured individually for each zone.

The Axes () control for the time plot window has the following tabs:

Coords Tab

Coords tab of time Axes control

The Coords tab controls the vertical axis coordinates (you can't flip or rescale the time axis). It has the following options:

Y Scale
  Selects scaling (linear, log, asinh, symlog) for the Y axis. See Appendix A.4.2.4.
Y Flip
  If selected, vertical axis coordinate axes increase down rather than up.

Navigation Tab

Navigation tab of time Axes control

The Navigation tab controls details of how the navigation works. It has the following options:

Pan/Zoom Axes
  By default, dragging with the mouse or using the mouse wheel on the body of the plot will pan or zoom in the horizontal (time) direction only, which is usually what you want for a time series. Using this control you can make it work in the vertical direction as well.
Zoom Factor
  Controls the factor by which each zoom action zooms the plot. Moving this slider to the left/right makes the mouse more/less sensitive (one wheel click or dragging a fixed distance has more/less zoom effect).

Range Tab

Range tab of time Axes control

The Range tab provides manual configuration of the visible range of the plot. Making changes to this tab will reset the visible plot range, but not vice versa - zooming and panning in the usual way will not change the settings of this panel.

Filling in the Minimum/Maximum fields for either or both axes will constrain the corresponding range of the visible data. The limits corresponding to any of those fields that are left blank will initially be worked out from the data. The Subrange double-sliders restrict the ranges within the (explicit or automatic) min/max ranges. Note you can move both sliders at once by grabbing a position between the two. For the time axis, the range may be entered as an ISO-8601 date/time value.

The Clear button resets all the fields.

Grid Tab

Grid tab of time Axes control

The Grid tab configures the appearance of the axis grid. It has the following options:

Time Format
  Selects the representation for time/date in which the horizontal axis is labelled. Options are ISO-8601, decimal year, Modified Julian Day, and Unix (seconds since midnight on 1 Jan 1970).
Draw Grid
  If true, grid lines will be drawn across the plot for every tick mark.
Minor Ticks
  If set, minor (unlabelled) tick marks will be drawn between the major (labelled) ones.
Shadow Ticks
  If set and no secondary axis is in use, then tick marks without numeric labels are painted along the axis opposite to the primary axis, so that tick marks are visible along all edges not just the ones with numeric labels. If a secondary axis is in use, this setting is ignored.
Time/Y Tick Crowding
  Use the slider to influence how many tick marks are drawn on each axis.
Tick Label Angles
  Controls orientation of numeric labels on the axes. By default they are drawn with horizontal alignment, but you can also choose angled. If adaptive is selected, they will be horizontal where possible, but may be angled to accommodate more labels if crowding is high; note this option is currently not perfect and can result in suboptimal border placement.
Grid Colour
  Selects the colour with which grid lines will be drawn.
Grid Transparency
  Controls the transparency of the grid lines, which are drawn over the plot content.

Labels Tab

Labels tab of time Axes control

The Labels tab controls the text labels on the horizontal and vertical axes. If the Auto checkboxes are set, the Time axis will be unlabelled, and the Y axis label will be taken from one of the data coordinates being plotted on the Y axis. To override those with your own axis labels, unset Auto and type text in to the field.

Secondary Axes Tab

Secondary tab of time Axes control

The Secondary tab controls optional secondary Time and Y axes at the top and right edges of the plot, to go with the standard (primary) Time and Y axes at the bottom and left edges, so for instance you can annotate the vertical dimension with both magnitudes and flux, or the horizontal dimension with both decimal year and MJD.

Secondary Time Axis Value
  Defines the secondary axis in relation to the time value displayed on the primary one. The value you enter is an algebraic expression using one of the following variables:
  - `mjd`: Modified Julian Date
  - `jd`: Julian Day
  - `decYear`: decimal year CE
  - `unixSec`: seconds since 1970-01-01T00:00:00
  In most cases, you will just use one of these strings, e.g. "mjd" to label using MJD, but you can apply operations to these values in the usual way if required, for instance to provide a differently offset date scale. The function supplied should be monotonic and reasonably well-behaved, otherwise the secondary axis annotation may not work well. Tick marks will always be applied on a linear scale. Currently there is no way to annotate the secondary axis with ISO-8601 dates or other non-numeric labels.
Secondary Time Axis Label
  Provides a textual annotation near the secondary Time axis (at the top). This can be supplied whether or not the Time axis mapping function is actually present.
Secondary Y Axis f(y)
  Defines the secondary Y axis in relation to the primary one by means of a supplied function of the variable y that maps primary to secondary axis values, written using TOPCAT's expression language. The function supplied should be monotonic and reasonably well-behaved, otherwise the secondary axis annotation may not work well. TOPCAT will attempt to make a sensible decision about whether to use linear or logarithmic tick marks.
Secondary Y Axis Label
  Provides a textual annotation near the secondary Y axis (on the right). This can be supplied whether or not the Y axis mapping function is actually present.

Font Tab

Font tab

The Font tab configures the font used for axis annotation. It also affects some other things like the legend.

Text Syntax
  How to turn the text into characters on the screen. Plain and Antialias both take the text at face value, but Antialias smooths the characters. Antialiased text usually looks nicer, but can be perceptibly slower to plot. At time of writing, on MacOS antialiased text seems to be required to stop the writing coming out upside-down for non-horizontal text. LaTeX interprets the text as LaTeX source code and typesets it accordingly.
Font Size
  Size of the font in points.
Font Style
  Style of the font.
Font Weight
  Whether the font is plain, bold or italic.

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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