[Tex/LaTex] Subcaption package error: aastex61

aastexsubcaption

I am trying to include subcaption package in the document class aastex61.

Here are the relevant lines of my LaTeX source file

\documentclass[twocolumn]{aastex61}
\pdfoutput=1 %for arXiv submission
\usepackage{amsmath,amstext}
\usepackage[T1]{fontenc}
\usepackage{apjfonts} 
\usepackage[figure,figure*]{hypcap}
\usepackage{url}
\usepackage{graphicx}
\usepackage{subcaption}

\renewcommand*{\sectionautorefname}{Section} %for \autoref
\renewcommand*{\subsectionautorefname}{Section} %for \autoref

\shorttitle{AASTeX 6.1 Template}
\shortauthors{Author A et al.}

\begin{document}

\begin{figure}
    \centering 
    \begin{subfigure}[width = 0.3\linewidth] 
    \includegraphics{}[width=\textwidth]{4915_sval.pdf} 
       \caption{plot} 
       \label{plot:sval} 

    \end{subfigure} 

\end{figure} 

\end{document}

The error prompted is:

LaTeX Error: Command \longtable* already defined.
           Or name \end... illegal, see p.192 of the manual.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
...                                              

l.20 \begin{document}

Any suggestions are welcome!

Best Answer

When you try compiling your example, you get

Package caption Warning: Unsupported document class (or package) detected,
(caption)                usage of the caption package is not recommended.
See the caption package documentation for explanation.

The revtex4-1 class, which aastex61 is based on, is not compatible with caption and therefore also with subcaption.

You can use subfig, to be loaded with the caption=false option.

Here's some code to get you started:

\documentclass[twocolumn]{aastex61}
\pdfoutput=1 %for arXiv submission
\usepackage{amsmath}
\usepackage[T1]{fontenc}
%\usepackage{apjfonts} 
%\usepackage[figure,figure*]{hypcap}
\usepackage{url}
\usepackage{graphicx}
\usepackage[caption=false]{subfig}

\usepackage{lipsum} % just for the example

\renewcommand*{\sectionautorefname}{Section} %for \autoref
\renewcommand*{\subsectionautorefname}{Section} %for \autoref

\begin{document}

\title{An Example Article using AAS\TeX{} v6.1}
\author{Greg J. Schwarz}
\affil{American Astronomical Society \\
2000 Florida Ave., NW, Suite 300 \\
Washington, DC 20009-1231, USA}

\author{Butler Burton}
\affil{National Radio Astronomy Observatory}

\begin{abstract}
Whatever
\end{abstract}

\keywords{One, two}

\section{Test}

\lipsum[1-6]

\begin{figure}
\centering 
\subfloat[plot]{%
  \includegraphics[width=0.3\columnwidth]{example-image-a}%
  \label{plot:sval}%
}\qquad
\subfloat[plot]{%
  \includegraphics[width=0.3\columnwidth]{example-image-b}%
  \label{plot:whatever}%
}
\end{figure}

\lipsum

\end{document}

I commented apjfonts.sty because I don't have it and hypcap because it cannot work with subfig.

enter image description here

Related Question