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Hello to all,

Kermit has become a bit lazy but this one has become a good bait to him.

I decided to solve it just from the photo, and nothing else.

Difficulties here are:

- Three bodies almost full lined up, so forget everything about classical LOP's ...

- As Frank Notices, Lunars not good either since the Moon apparent speed is almost perpendicular to both Venus and Saturn.

- Moon HP is important here and must be taken in account one way or the other.

Hence ... I decided to tackle this example from the raw photo itself and through implicitly taking in account both refraction and parallax.

Two clock hands are showing on the picture (see enclosed handwritten solution)

- One clock hand expected to move rather slowly i.e. the SV Saturn-Venus direction related to the Local vertical showing at an angle of "pseudo-azimuth" of 327°, i.e. 33° left of the local vertical on the photo. And:

- The second clockhand is drawn by the SM Saturn Moon-Center direction expected to move significantly faster and showing at 321° on the photo, with a separation angle of 6° from SV.

So I simply used reverse engineering starting from an arbitrary given position - assumed to be in the USA - and each time computing both the local angle of the SV and SM lines.

From initial guess at N30°/W085°/UT=10h on April 25th, I am getting SV=252.4° SM=320.7°, which prompts us to correct for a much earlier time.

From the enclosed document, very quickly I hit N40°/E035°/UT=02h on that same day.

By trial and error, I ended up with N34°/E30°/UT=02:15 with SV=327.2° (vs. 327° +/-1° on the picture) and SM  321.2° (vs. 321° +/-1° on the photo).

This puts us in the close vicinity of Cairo.

Error and uncertainties budget (related to "error bars") : with " ∂ " standing for partial derivative, on bottom of the second page, we have the following data :

(1) - With respect to Latitude : ∂SV/∂Lat = +3.7°/5° Lat, ∂SM/∂Lat  5.7°/5°Lat

(2) - With respect to Longitude : ∂SV/∂Lon = 0.4°/5° Lon, ∂SM/∂Lon = +0.9° / 5° Lon

(3) - and Finally with respect to UT : ∂SV / ∂UT = 0.2° / 10 minutes of elapsed UT and as expected - i.e. 24 times greater than the previous ∂SV/∂UT partial derivative : ∂SM/∂UT = -4.8° / 10 minutes of elapsed UT

(4) - HINT ! Partial derivatives in (2) and (3) are not independent, so they need to be used with care. By pure luck, I did not run into this case - since I hit the SM and SV values within their assessed uncertainty. Otherwise this would have brought me back to my Last millenium engineers courses to use simultaneous partial derivatives to find an optimum point.

Discussion : For a +/- 1° error on the Photo"vertical", 

It can be seen that the Latitude is quite reliable , since the SM clock handle indicates that our Latitude should be close to +/- 1° .

Totally different case for the Longitude since the same fastest clock handle indicates that our longitude should be accurate to only +/-6° . Certainly the additional data with a Sun rising just 46 minutes after the picture was taken might probably narrow the uncertainty here. But on that one, I feel quite lazy again.

So .. where can we be ?

We are close from Cairo, with a Sun at 12.9° under the horiozn, which does not seem unreasonable.

I would trust that there are no other areas on Earth fulfilling the stated conditions, although I have not formally checked this point, and cannot rule it out accordingly.

My best guess : picture taken from a site with no urban lights in the East - hence the Pyramides are ruled out - and I would then pick up the worldwide renown Kottamia Observatory  (N29°55.9' / E031°49.5' / AMSL476m), in spite of its Latitude slightly outside the error bars here-above (again, these are computed for a vertical tilt/offset of 1°, while it might be more important actually).

I have not looked up any of the other contributions yet, and will do so when this one has been published.

And I will certainly look them up with a lot of interest.

Antoine M. "Kermit" Couëtte