NGS Search lists: adjusted coordinates now listed?

[Papa-Bear-NYC]

What happened to my post?

 

Here it is again:

 

When I recently searched for all the stations in Mass beginning with "NAHANT" (using the "Station Name" option from this link: http://www.ngs.noaa.gov/cgi-bin/datasheet....ype=DATASHEETS) I got this:

 

 

Notice under latitude and longitudes it now gives 5 decimal places after the seconds. I checked a few datasheets and this is the full adjusted coordinates.

 

was this always like this or is this a new feature? I could swear it always just gave the whole number for degrees, minutes and seconds?

 

Anyone?

[timz2]

Dunno how new, but it's new all right. Maybe the last month or two?

[+Klemmer]

Papa-Bear:

I agree. I've never seen scaled marks with that precision on NGS before. Something new and.... ummm.... possibly misleading? Seeing that level of precision on scaled marks is just weird.

[holograph]

I was doing some point radius searches last Sunday, and in the lists the vertical control (scaled marks) just had whole seconds. Only the horizontal control (adjusted marks) had 5 decimals.

[Papa-Bear-NYC]

Papa-Bear:

I agree. I've never seen scaled marks with that precision on NGS before. Something new and.... ummm.... possibly misleading? Seeing that level of precision on scaled marks is just weird.

The positions of the marks I was looking were not "scaled", they were all horizontal control stations. The 5 decimal places were exactly what the adjusted coordinates on the datasheet gave.

 

Holograph mentions that vertical control stations (what you might call "scaled marks") show only whole seconds, which makes sense. I haven't looked for these.

 

Note: in the column "Vert Source" it says things like "29/scaled". These are not what we call "scaled marks", this just means that the elevation given for these adjusted marks is scaled. The word "scaled" can apply to either type:

 

Horizontal marks: position adjusted, elevation scaled

Vertical marks: position scaled, elevation adjusted.

 

It's the second category (aka "true bench marks") that we sometimes call "scaled marks" but this usage misses the distinction "scaled what?" For my list it is the elevation that is scaled, something we seldom care much about, but a surveyor would.

 

So just be a little careful when you use the term "scaled marks".

Edited May 1, 2009 by Papa-Bear-NYC

[NGS Surveyor]

PapaBear, Yes, there was a change in the output. Those results were formerly displayed to only the nearest second but are now displayed to 5 places. This was done to improve the plotting of points on an interactive map.

 

GeorgeL

NGS

[Papa-Bear-NYC]

PapaBear, Yes, there was a change in the output. Those results were formerly displayed to only the nearest second but are now displayed to 5 places. This was done to improve the plotting of points on an interactive map.

 

GeorgeL

NGS

Thanks George.

 

It also helps me when I want to get an accurate position for a non-published station. One of those old Nahant Mass. stations mentioned in my other recent thread is one of these. With this accuracy I can place NAHANT BORDEN 1834 right across the street from No. 14 Tudor Rd, in Nahant, which is where I thought it must be. (And I won't have to ask you NGS guys for the non-published datasheets as a favor, when you have enough to do besides helping some guy looking for a 175 year old station! )

 

Good change. My first county wide maps were built on those lists and there were always position miss-matches. Until I started using datasheet parsers, GPX, etc. etc. it was the best way to go. Now I may revisit that idea.

Edited May 1, 2009 by Papa-Bear-NYC