The autumn equinox occurs halfway between the summer and winter solstices, when Earth's tilt is such that the length of the day and night are almost the same.
The Great Pyramid of Giza was constructed about 4,500 years ago, under the orders of Egyptian pharaoh Khufu.
It is the largest of the three pyramids - standing about 138 metres - on the Giza Plateau and was considered a "wonder of the world" by ancient writers.
The pyramid of Khafre (also located at Giza) and the Red Pyramid (located at the site of Dahshur) are also aligned with a high degree of accuracy, Dash noted.
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"All three pyramids exhibit the same manner of error; they are rotated slightly counterclockwise from the cardinal points," Dash wrote in a study published in the Journal of Ancient Egyptian Architecture.
Dash discovered a method that makes use of the fall equinox could have been used, the 'Live Science' reported.
In an experiment conducted on September 22, 2016 (the day of the autumn equinox), Dash placed a rod on a wooden platform and marked the location of the rod's shadow throughout the day.
"On the equinox, the surveyor will find that the tip of the shadow runs in a straight line and nearly perfectly east-west," Dash wrote.