data sheets using epoch date

Joe Pacheco · Post by **Joe Pacheco** » Tue May 01, 2012 3:08 pm

I am trying to figure out how to get a NGS Data Sheet for PID JS0755. I can only get the update that uses the epoch date of 2007. I need the data sheet that uses this PID and has an Epoch Date of 1991.35. Can anyone tell me how I can achieve this?
Thanks

Jim Frame · Post by **Jim Frame** » Tue May 01, 2012 3:21 pm

Unless you can find someone who has an old copy of the datasheet (it's out there, but finding it is another matter), I think you're stuck with using HTDP to backdate the epoch.

I've used this mark (G 1200) in a number of height mod projects -- it's a first-order NAVD88 leveled mark set in bedrock -- but the earliest copy of the datasheet I have is dated 1998, and it has the same 1997.30 superseded values as those shown on the current version.

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pls7809 · Post by **pls7809** » Tue May 01, 2012 3:27 pm

My guess is it didn't have 1991.35 coordinates established for it, only elevations at that time, since it is not shown in the superceded info.

Jim Frame · Post by **Jim Frame** » Tue May 01, 2012 4:30 pm

I think Ryan's got it. Its looks like the first bluebooked GPS project incorporating G 1200 is GPS1308, the 1997 Delta project conducted by DWR, thus the 1997.30 initial superseded epoch.

Got HTDP?

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Peter Ehlert · Post by **Peter Ehlert** » Tue May 01, 2012 5:42 pm

I think Jim and Ryan are correct.

I understand that the listing in SUPERSEDED SURVEY CONTROL is a complete history and shown on all data sheets

http://www.ngs.noaa.gov/cgi-bin/ds2.prl ... PID=JS0755