# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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From: Frank Reed
Date: 2022 Nov 20, 13:46 -0800

Back to the basic question. Can you determine your latitude using standard celestial navigation from the photo?

Look for stars that are at nearly identical altitudes on the left and right sides of the image [UPDATE: REGULUS and POLLUX are nearly at the same altitudes]. To avoid image distortion issues, the stars should be roughly symmetrically-placed left and right. Estimate their altitudes [UPDATE: You could estimate angles from the photo, but I'll do that for you. Suppose your corrected altitude (Ho) for Regulus is exactly 26°00' and the corrected altitude for Pollux is exactly 28°30']. Determine your latitude.

You should be able to do that! Pick a date in March of any recent year. Then find a combination of LHA Aries and Latitude that puts those stars at about the right altitudes. See it?? [UPDATE: The second attached image should give you some help picking an AP if you decide to do this with standard cel nav tools. Get a fix. Read off the latitude.]. Note that you can also do this by sky simulation in an app like Stellarium. What is your latitude?

Want to go further? Figure out the exact date. How can you do that? Look for a planet (use Stellarium or other sky simulation software) [UPDATE: The planet is left and above Regulus. Which planet is that?]. In the past twenty years, which we can safely assume for a photo of this quality, there is only one date when a planet was at that location in Leo. Which planet? What day? There's no easy way to do this that I'm aware of. Just visit every month in the past twenty years. That's easy enough in Stellarium, but a bit disorienting. One trick I find useful. Focus on a star near the desired location (Regulus would work). Then move to the north pole. This will keep the view from spinning around. Advance the date a month at a time and wait for planets to show up. Several months out of the year can be excluded because the Sun is too close, but you should be able to find a planet that works.

Frank Reed

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