Projection: Find based on known location and Coordinates?

[AlexandreHughes1]

Hello ESRI community,

I have a pickle of a problem to solve. I have two sets of X/Y data that I am trying to import into Arcmap 10.5

x: 548806.3586555115

y: 4182528.116922065

I know one thing about these numbers--they relate to San Francisco, CA.

My professor suggested I try and troubleshoot the problem by setting up various projection styles in Arcmap and examining the change to the coordinate display in the bottom right. From this I can conclude that these numbers are likely in feet or meters rather than in decimal degrees. However, when I take the .csv into Arcmap and translate x/y to points with the projected NAD1987 US Feet these points are no where near SF. I brought in a known SF data set from their open portal and both feet and meters are no where near the numbers listed above.

How on earth (pun intended) can I get the right projection for this data set given the numbers I have so that I can turn my data into something useful?

I have looked at the following: How To: Identify an unknown projected coordinate system using ArcMap 10.1 and later versions but it doesn't address the problem that I have.

Thank you so much for any help.

[DanPatterson_Retired]

It is projected for sure.  Did you follow all the suggestions in the document you linked to?

Have your ruled out a UTM variant (if SF is about 4.2 million meters from the equator, then UTM and units in meters would be a good stab?, then you would have the easting issue, since standard zones numbers can be figured out from SF's longitude

What about the State Plane system? (I suspect it isn't as standardized as utm)

Someone will pipe in and just tell you what it is based on the numbers... sadly, the purpose of that document that was link to and your professor's suggestion will be for naught

[MelitaKennedy]

My first thought was UTM too, because State Plane zones in California are bigger east-west than north-south and use Lambert conformal conic. The x/easting values are in the millions, while the y/northing values are 6 digits.

Try a UTM zone, probably zone 10 N (North). It's harder to figure out the geographic coordinate system because they usually only change the positions of the data by a meter or less (unless it's NAD27 vs NAD83). Try NAD 1983. 

Melita

[AlexandreHughes1]

Ah, shucks. That was a lot easier than I was making it out to be! Thank you both, Dan and Melita. I did try the UTM to troubleshoot but I think I just picked the wrong zone. I'm so used to using FIPS III for California I just blanked that the UTM zone was drastically different.

Many many thanks!