\chapter{GCM Martian Calendar}

\label{sc:sol2ls}


For Mars, dates and seasons are expressed in Solar Longitude ($L_s$,
in degrees or in radians) counting from the northern hemisphere spring equinox.
In the GCM, time is counted in Martian solar days, or ``sols''
(1 sols = 88775 s) from the northern spring equinox. 
The following table gives the correspondence between sols and $L_s$,
calculated for the GCM using one Martian year = 669 sols exactly.

\vspace{0.5cm}

\footnotesize

\hspace*{-2.cm}\begin{tabular}{|c|c|c||c|c|c||c|c|c|}
\hline
 sol & $L_s$ & & sol & $L_s$ & & sol & $L_s$ &  \\
\hline
  0. & 360.000 & Spring equinox N &240. & 111.455& &480. & 247.408&  \\ 
  5. &   2.550 & &245. & 113.816& &485. & 250.666&  \\ 
 10. &   5.080 & &250. & 116.190& &490. & 253.925&  \\ 
 15. &   7.590 & &255. & 118.578& &495. & 257.182&  \\ 
 20. &  10.081 & &260. & 120.981& &500. & 260.435&  \\ 
 25. &  12.554 & &265. & 123.400& &505. & 263.683&  \\ 
 30. &  15.009 & &270. & 125.835& &510. & 266.924&  \\ 
  &  &  & & & &514.76 &   270.& Winter solstice N \\ 
 35. &  17.447 & &275. & 128.287& &515. & 270.156&  \\ 
 40. &  19.869 & &280. & 130.756& &520. & 273.377&  \\ 
 45. &  22.275 & &285. & 133.243& &525. & 276.587&  \\ 
 50. &  24.666 & &290. & 135.750& &530. & 279.783&  \\ 
 55. &  27.043 & &295. & 138.275& &535. & 282.965&  \\ 
 60. &  29.407 & &300. & 140.821& &540. & 286.130&  \\ 
 65. &  31.758 & &305. & 143.388& &545. & 289.277&  \\ 
 70. &  34.096 & &310. & 145.975& &550. & 292.406&  \\ 
 75. &  36.423 & &315. & 148.585& &555. & 295.515&  \\ 
 80. &  38.739 & &320. & 151.217& &560. & 298.604&  \\ 
 85. &  41.046 & &325. & 153.872& &565. & 301.671&  \\ 
 90. &  43.343 & &330. & 156.550& &570. & 304.715&  \\ 
 95. &  45.631 & &335. & 159.251& &575. & 307.737&  \\ 
100. &  47.912 & &340. & 161.977& &580. & 310.735&  \\ 
105. &  50.186 & &345. & 164.727& &585. & 313.709&  \\ 
110. &  52.453 & &350. & 167.502& &590. & 316.658&  \\ 
115. &  54.714 & &355. & 170.301& &595. & 319.583&  \\ 
120. &  56.970 & &360. & 173.126& &600. & 322.483&  \\ 
125. &  59.222 & &365. & 175.975& &605. & 325.358&  \\ 
130. &  61.471 & &370. & 178.850& &610. & 328.207&  \\ 
   . &         & &371.99 & 180.   & Autumn equinox N &   . &        &  \\ 
135. &  63.716 & &375. & 181.750& &615. & 331.032&  \\ 
140. &  65.959 & &380. & 184.675& &620. & 333.831&  \\ 
145. &  68.201 & &385. & 187.624& &625. & 336.606&  \\ 
150. &  70.442 & &390. & 190.598& &630. & 339.356&  \\ 
155. &  72.683 & &395. & 193.596& &635. & 342.082&  \\ 
160. &  74.925 & &400. & 196.618& &640. & 344.783&  \\ 
165. &  77.168 & &405. & 199.662& &645. & 347.461&  \\ 
170. &  79.413 & &410. & 202.729& &650. & 350.116&  \\ 
175. &  81.661 & &415. & 205.818& &655. & 352.748&  \\ 
180. &  83.912 & &420. & 208.927& &660. & 355.357&  \\ 
185. &  86.167 & &425. & 212.056& &665. & 357.945&  \\ 
  &  &  & & & &669. &   0.& Spring equinox N  \\ 
190. &  88.427 & &430. & 215.203& &670. &   0.512&  \\ 
193.47  & 90.  & Summer solstice N  & & & & &  &  \\ 
195. &  90.693 & &435. & 218.368& &675. &   3.057&  \\ 
200. &  92.965 & &440. & 221.549& &680. &   5.583&  \\ 
205. &  95.245 & &445. & 224.746& &685. &   8.089&  \\ 
210. &  97.532 & &450. & 227.955& &690. &  10.577&  \\ 
215. &  99.827 & &455. & 231.177& &695. &  13.046&  \\ 
220. & 102.131 & &460. & 234.409& &700. &  15.498&  \\ 
225. & 104.446 & &465. & 237.650& &705. &  17.933&  \\ 
230. & 106.770 & &470. & 240.898& &710. &  20.351&  \\ 
235. & 109.107 & &475. & 244.151& &715. &  22.755&  \\ 
240. & 111.455 & &480. & 247.408& &720. &  25.143&  \\ 
\hline

\end{tabular}