I agree Bill, it cannot be the equinox. On that date with an altitude of the sun at about 25.5 degrees, the azimuth would not be 90 degrees. But it is determinant and solvable using the usual navigators equations for time vs altitude and azimuth for dates (declinations) for that location (Lat 44.77). I used an Excel graphical solution. See attached file "Dead Horse.xls". Assuming altitude 25.5 and azimuth 90, the date works out to be August 2 at 4:44 pm solar time.
Regards, Roger Bailey -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Bill CS.Com Sent: April 9, 2007 10:20 AM To: Sundial-List Subject: Mistake in "Shadows in a Photograph" There is an error in this report--either by the reporter, or the photo analyst. The report states "Since South Eighth Street (then Griffith Street) runs north-south, the shadows point almost exactly east-west. There are only two days in the year when this occurs the spring equinox (March 19-20) and the fall equinox (Sept. 22-23). " This is not true. In the northern hemisphere, a shadow will fall along an exact east/west line every day between the spring and fall equinox (positive sun declination), but at a different time day-to-day. On the equinox a shadow falls exactly east/west only at sunrise or sunset, so in fact this photo could not possibly have been taken on an equinox. What the reporter or analyst may have meant to say was that the tip of a shadow will trace an east/west line over the course of the day on the equinox, but this would not help his photo interpretation. -Bill Gottesman ----- Original Message ----- From: Fred Sawyer To: Sundial List Sent: Monday, April 09, 2007 12:27 PM Subject: shadows in a photograph Another fascinating example of detective work using shadows in a photograph: http://www.sheboygan-press.com:80/apps/pbcs.dll/article?AID=/20070401/SHE04/ 704010376/1097/SHElife Fred Sawyer ---------------------------------------------------------------------------- --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
Dead Horse.xls
Description: MS-Excel spreadsheet
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