I see that GPS on BM has been extended. And a comment on shorter observation times.
I recall static observation requirements ?ÿon BM was 4 hrs.(like using a Z-12.) ?ÿHas that been reduced? I can??t manage 4 hrs, but 2 hrs would get me out there.?ÿ
GPS on BM observation instructions
4+ hours is still required.
I am glad to see this is getting extended.?ÿ I have 2 BMs near here that I have been trying to work into the workflow, but just haven't had the time.
Quick question, I set up on a bench mark that doesn't show up in the NGS file. Is there any reason to submit that? I've only done ones I feel are uncompromised and are in the data base.
I believe it??ll be incorporated regardless of the wish list.?ÿ
I pinged NGS specifically asking if 2 hrs Z-XII is acceptable?ÿ
In my experience, NGS will try to use data on any mark they have a good classically measured orthometric height for, even if it isn't on the wish list.
There are marks in their data base with less reliable categories of vertical data, and marks that only have GPS-derived heights, that won't be used.
Of course, they can't use data on marks not already in their data base (lots of the USGS marks, etc.) unless you go through the Bluebook process and give them both leveling and GPS data.
@bill93?ÿ
so, choose wisely. Old BM leveling lines. What needs to accompany the observation is reliable description of the HI, and condition of the mark ?ÿ
Even 2nd order??ÿ
Even 3rd order, if they are believed to be stable and don't look like outliers.
@bill93?ÿ
I don't know what class this mark is, for some reason it's not in the NGS data-base. I have a book of level runs that cover a large area and many marks not in the data-base are in my book, but this area is outside my list. I used to track down level-runs through the USGS office in Denver but haven't in a long time. I don't like sending in data if the bench mark is questionable.?ÿ
Only a small fraction of the US Geological Survey marks were included in the National Spatial Reference System as defined by the US Coast & Geodetic Survey, now National Geodetic Survey.?ÿ This is true over most of the country, and typically this was because looser procedures were used to densify the network for USGS mapping.
I don't see GPS on BM going away given what it's being used for. Don't tell anyone I said that.?ÿ
I see why 4 hours is required with 10 GPS tracked. But with 45 on a full constellation, 2 hours should be fine.?ÿ
NGS is still working on adding constellations other than GPS to OPUS so you will not have more than about 10 sats.
