Add date/timestamp to an image

[sizzzzlerz]

Is your feature request related to a problem? Please describe. Having the date and time printed onto an image would be greatly beneficial is tagging the date and time for which the image was created.

Describe the solution you'd like It doesn't appear as if there is room on the margins of a plot so perhaps the string could be placed into one of the corners or centered at the top or bottom maybe with a optional string. Ideally, the string would have a default style applied to it which could be overridden in the same manner many of the plot objects can be styled.

[steveberardi]

There is a title function that can do this -- it plots any text you want centered above the plot.

I'm also planning to make it easier to plot things in different coordinate systems, including matplotlib's axes coordinates which would, for example, let you easily plot text at a 20% margin from the top and right.

Zenith projections also have an info function that plots the date and location, but this will probably be deprecated when the coordinate system helpers are finished.