DavidLeodis wrote:I will be grateful if someone could please inform me of the date when the image was taken (it is copyright 2001) as I do not seem to be able to find out (at least not fairly readily). The information brought up through the "Pictured above" link does not give the date. In the explanation to the APOD it states "Were Manhattan's road grid perfectly aligned to east and west, today's effect would occur on the Vernal and Autumnal Equinox, March 21 and September 21" but I'm unsure if the "today's" means July 6 2014 (the APOD date) or the "This coming Saturday" in the explanation.
The timing for this shot is a bit squishy. Without a timestamp, and without accurate coordinates for the sun's center (it's too bright!), there is a few-day time window within which the streets are flooded with sunlight. However, with some knowledge of local and horizon terrain (Google), an estimate for the APOD field of view (approximately 38°x50°), and a rough estimate for the sun's center(radial flare rays), I think that time window can be reduced.
It turns out there are two timings that differ by ~5 days: 1) When the technical sunset
is aligned with 34th St, and 2) When the full-sun is just above the local horizon and
aligned with the street. For case 1), I believe the sunset occurs on Thursday 7/17/14 ± 1day. For case 2), the lowest full-sun, street-center illumination occurs on Saturday, 7/12/14. According to Google, the heading for 34th St is 299.2 ± 0.1°. The time difference between these cases is due to a local horizon having a ½
° altitude (formed by a hill between Hoboken and Union City NJ), and that the sun moves at ~40° wrt the horizon.
For Neil's APOD photo, the sun appears slightly to the left of street center, but nominally positioned for full-sun street illumination (case 2 above). The ideal timing for this image would also have been 7/12/01 8:20pm EDT. Judging by the slight leftward decentered sun position, the picture could have easily been taken a couple minutes earlier. This is probably within my position errors. It is also possible the picture was taken the next day just before horizon contact. The sun's azimuth would be ~0.2° to the left. However, I'd bet the shot was planned and that Neil was not a day late.
Without a timestamp, you can see how squishy this timing can be.