# [Tex/LaTex] How to format/include subfigures in AASTex document class

aastexsubfloats

I've been writing a document using the basic "article" class, but now I need to change it to "aastex." When I do this, my subfigures do not work. Is there any way aastex allows subfigures?

I tried to keep my original document as bare-bones as possible, so I'm pretty sure caption and subcaption were the only packages I included for this.

\usepackage{graphicx}
\usepackage{caption}
\usepackage{subcaption}

\begin{figure}
\centering
\begin{subfigure}[b]{0.45\textwidth}
\centering
\includegraphics[width=\textwidth]{fig1.pdf}
\caption{Caption 1}
\label{fig:fig1}
\end{subfigure}%
\begin{subfigure}[b]{0.45\textwidth}
\centering
\includegraphics[width=\textwidth]{fig2.pdf}
\caption{Caption 2}
\label{fig:fig2}
\end{subfigure}
\caption{Side-by-side figures.}
\label{fig:figures}
\end{figure}


First of all, let's see what a regular figure looks like under aastex:

\documentclass{aastex}
\usepackage{graphicx,showframe}

\begin{document}

\begin{figure}
\centering
\includegraphics[width=.3\linewidth]{example-image}
\figcaption{Side-by-side figures.}
\label{fig:figures}
\end{figure}

\end{document}


Note the use of \figcaption for the caption of a figure. The document class sets the caption flush left (fully justified). Now, let's look at using caption and/or subcaption:

\documentclass{aastex}
\let\captionbox\relax
\usepackage{graphicx,caption,subcaption,showframe}
\captionsetup[figure]{labelsep=space,singlelinecheck=false}
\captionsetup[subfigure]{justification=centering}

\begin{document}

\begin{figure}
\centering
\begin{subfigure}[b]{0.45\textwidth}
\centering
\includegraphics[width=.6\linewidth]{example-image-a}
\caption{Caption 1}
\label{fig:fig1}
\end{subfigure}%
\begin{subfigure}[b]{0.45\textwidth}
\centering
\includegraphics[width=.4\linewidth]{example-image-b}
\caption{Caption 2}
\label{fig:fig2}
\end{subfigure}
\caption{Side-by-side figures.}
\label{fig:figures}
\end{figure}

\end{document}


Letting \captionbox to \relax makes caption work with aastex (so it's a requirement). Then, we set the [figure] options to ignore a singlelinecheck - this sets the figure to be as wide as \linewidth regardless of the caption width. Also, a space is added as labelsep. We also reset the justification to \centering for [subfigures], as they inherit whatever is specified for [figure].

Of course, one can also fake it using tabulars (losing some of the cross-referencing functionality):

\documentclass{aastex}
\usepackage{graphicx,showframe}

\begin{document}

\begin{figure}
\centering
\begin{tabular}[b]{@{}p{0.45\textwidth}@{}}
\centering\includegraphics[width=.6\linewidth]{example-image-a} \\
\centering\small (a) Caption 1
\end{tabular}%