Placing figures at top of margin with tufte-style book

Question

I am using the Tufte-style book document class and I would like to place a margin figure at the very top of the margin (there are no other figures in the page). I do this with the \begin{marginfigure} command. As is, it places the figure around the place I insert it. There is an argument which can be negative but it requires me to indicate the specific amount in centimeters, inches, etc. I don't want to be guessing how far the top is from where the image begins. Is there a way I can easily indicate for the figure to be at the top? maybe a variable that "knows" what my current y coordinate is and i can set the offset to -\ycoor? The usual parameter "t" for figures does not work in marginfigures of the tufte book. Please help! Here is a simple working example. I have used \sidenote so as not to insert a figure but they work the same. The second argument (which i made -1cm) is the offset:

\documentclass{tufte-book}
\usepackage{lipsum}

\begin{document}

\lipsum[1]
\lipsum[3]

\sidenote[][-1cm]{this is the sidenote, i want it to be at the top of the margin}

\end{document}

Answer 1

Have you tried baselineskip? this has worked for me:

\begin{marginfigure} [-3\baselineskip]\includegraphics[width=2in]{xxx.jpg} \end{marginfigure}