  Authors often add text annotations to charts to provide additional context
for visually prominent features such as peaks, valleys, and trends. However,
writing annotations that provide contextual information, such as descriptions
of temporal events, often requires considerable manual effort. To address this
problem, we introduce Almanac, a JavaScript API that recommends annotations
sourced from the New York Times Archive of news headlines. Almanac consists of
two independent parts: (1) a prominence feature detector and (2) a contextual
annotation recommender. We demonstrate the utility of the API using D3.js and
Vega-Lite to annotate a variety of time-series charts covering many different
data domains. Preliminary user feedback shows that Almanac is useful to support
the authoring of charts with more descriptive annotations.
