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Datasheet deleted?


chiknlips45
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Anyone ever experience a datasheet listed on geocaching.com but not in the NGS DB? I recoved TT0860 on 13 May in good condition and filed a report using DSworld. When I went to check in the NGS DB,the datasheet was unlisted due to no Geodetic Control (Vertical and Horizontal). They called it good in 1964. Any ideas?

Edited by chiknlips45
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Anyone ever experience a datasheet listed on geocaching.com but not in the NGS DB? I recoved TT0860 on 13 May in good condition and filed a report using DSworld. When I went to check in the NGS DB,the datasheet was unlisted due to no Geodetic Control (Vertical and Horizontal). They called it good in 1964. Any ideas?

 

If you look near the top of the Geocaching.com page it says: Coordinates may not be exact. Altitude is UNKNOWN and location is SCALED.

 

Looking at the Geocaching.com cached datasheet page you can see the following:

 

TT0860* NAD 83(1986)-  61 22 36.     (N)    149 32 52.     (W)     SCALED
TT0860* NAVD 88     -
TT0860  ___________________________________________________________________
TT0860  GEOID HEIGHT-          10.38  (meters)                     GEOID99
TT0860
TT0860  VERT ORDER  -  FIRST     CLASS II (See Below)
TT0860
TT0860.The horizontal coordinates were scaled from a topographic map and have
TT0860.an estimated accuracy of +/- 6 seconds.
TT0860
TT0860.The vertical order pertains to the superseded datum.
TT0860
TT0860.The geoid height was determined by GEOID99.
TT0860
TT0860                          SUPERSEDED SURVEY CONTROL
TT0860
TT0860  NGVD 29     -        43.089  (m)          141.37   (f) ADJ UNCH    1 2
TT0860
TT0860.Superseded values are not recommended for survey control.
TT0860.NGS no longer adjusts projects to the NAD 27 or NGVD 29 datums.
TT0860.See file dsdata.txt to determine how the superseded data were derived.

 

My guess is that it's height never got updated to the current datum because they couldn't find the mark in order to verify the height.

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A couple of years ago, a datasheet for a mark that I had been eyeing for recovery disappeared from the NGS database. I had the mark in my GSAK database and had marked :) it as having something funny about the info in the datasheet. I hadn't updated my GSAK database in a while and for whatever reason wanted to look at the datasheet on the NGS site - and it didn't come up. This drove me crazy till I figured out that when my GSAK database gets updated it only adds and updates it doesn't subtract. Anyway, since my last update wasn't to far off, I was able to look in the NGS datasheet archives and find when it disappeared. The datasheet anomaly was something like stations with the same descriptions and locations. The funny thing was, it got corrected even though there wasn't a recovery submitted.

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Datasheets getting updates without recovery reports doesn't seem that uncommon. I know an area where a whole bunch of benchmarks got updated from scaled to handheld coordinates without any recovery reports.

 

Actually, there were recovery reports, just not on the NGS site. Dave D. (one of the top honchos at the NGS) has collected coordinates from recovery logs on GC.com and used them to update the NGS datasheets.

 

John

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Datasheets getting updates without recovery reports doesn't seem that uncommon. I know an area where a whole bunch of benchmarks got updated from scaled to handheld coordinates without any recovery reports.

 

Actually, there were recovery reports, just not on the NGS site. Dave D. (one of the top honchos at the NGS) has collected coordinates from recovery logs on GC.com and used them to update the NGS datasheets.

 

John

 

In my book, Geocaching.com logs are not the same as Recovery Reports. That said, at least two I know of do not have any coordinates posted in logs/recovery reports on either site and still have been updated to HD_HELD1. (Differentially corrected hand held GPS observations) While I'm not quite sure what the difference is between HH1 and HH2, (other then accuracy) I have noticed that a mark that did have coordinates posted in a Geocaching.com log was updated to HD_HELD2 coordinates. (I did know he has been collecting info about benchmarks from this site to update the NGS database with, and there was one mark I wanted to go find specifically to provide updated coordinates for since the NGS didn't find it but Geocachers have. But I couldn't get near that one.)

 

I just happened to read an older thread with a post by Dave D. that seems to provide an explanation for the HH1 coordinates I mentioned above, which fits case 2 as they are reference marks of a triangulation station:

http://forums.Groundspeak.com/GC/index.php?showtopic=254978&view=findpost&p=4404204

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Thanks TillaMurphs for the kind words and thanks to all for your input. I did a little more research but it just confuses me more. The coordinates on the non-published NGS printout for TT0860 has my updated coordinates at the bottom. At least the coordinates are updated even if the datasheet is unpublished. I guess my next question is, what exactly does "Geodetic control" mean on the non-published printout? I could understand the horizontal value having no geodetic control as it isn't tied to anything else of horizontal value. The vertical having no control seems wrong since this is listed as a first order vertical station and is also listed in special pub 169 (First-order leveling in Alaska). Some of the other stations along the same line are in the DB with a full datasheet such as TT0698 and some have the non-published report such as TT0858 but both have the same first order vertical control. I did notice that the published datasheets have "U.S. NATIONAL GRID SPATIAL ADDRESS xxxxxxxxxx(NAD 83)" and the non-published sheets don't have that line. Could that be the reason it's not published?

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Thanks TillaMurphs for the kind words and thanks to all for your input. I did a little more research but it just confuses me more. The coordinates on the non-published NGS printout for TT0860 has my updated coordinates at the bottom. At least the coordinates are updated even if the datasheet is unpublished. I guess my next question is, what exactly does "Geodetic control" mean on the non-published printout? I could understand the horizontal value having no geodetic control as it isn't tied to anything else of horizontal value. The vertical having no control seems wrong since this is listed as a first order vertical station and is also listed in special pub 169 (First-order leveling in Alaska). Some of the other stations along the same line are in the DB with a full datasheet such as TT0698 and some have the non-published report such as TT0858 but both have the same first order vertical control. I did notice that the published datasheets have "U.S. NATIONAL GRID SPATIAL ADDRESS xxxxxxxxxx(NAD 83)" and the non-published sheets don't have that line. Could that be the reason it's not published?

 

The vertical data for TT0860 is apparently too old and unchecked to be reliable. I assume, for it to be used again, someone would have to go out there and do a leveling run. (At least I think that's the right terminology.)

 

TT0698.The orthometric height was determined by differential leveling and

TT0698.adjusted in June 1991.

 

Data on both marks from DSWorld, note the parts I highlighted in red.

 

TT0698:

Vertical Data:

ORTHOMETRIC HEIGHT (m): 10.0824

SOURCE: A

QUALITY:

DATUM: 88

ERR_DIST:

OBSERVATION DATA:

REDUNDANCY:

TECHNIQUE: N

AVAILABLITY: U

ADJUSTMENT ID: 00000025

ORDER: 1

CLASS: 1

NAD83 MOD GRAVITY (mg) 981.9213

 

Level Lines:

82290/1, L19859, L20245, L23844

 

TT0860:

Vertical Data:

ORTHOMETRIC HEIGHT (m): 43.0890

SOURCE: B

QUALITY:

DATUM: 29

ERR_DIST:

OBSERVATION DATA:

REDUNDANCY:

TECHNIQUE: N

AVAILABLITY: U

ADJUSTMENT ID: UNCHECKD

ORDER: 1

CLASS: 2

NAD83 MOD GRAVITY (mg)

 

Level Lines:

82290/1, L19859

 

TT0698 was used in two level lines that TT0860 was not. (Probably because TT0860 wasn't found.) I'm thinking that data from those level lines were probably used to provide height data to more modern standards. The height data for TT0860 was never updated, and I'm thinking this is why:

 

TT0860 HISTORY - 1973 MARK NOT FOUND USGS

 

TT0860 STATION RECOVERY (1973)

TT0860

TT0860''RECOVERY NOTE BY US GEOLOGICAL SURVEY 1973

TT0860''MARK NOT FOUND.

 

You can't check the height of a mark if you can't find it. :)

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Thanks EdrickV for taking the time to respond. What you stated makes sense to me. It's always nice to understand why something is the way it is. I was not aware of being able to view PIDs by project in DSWorld but thanks to your response I am now.

Edited by chiknlips45
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Thanks EdrickV for taking the time to respond. What you stated makes sense to me. It's always nice to understand why something is the way it is. I was not aware of being able to view PIDs by project in DSWorld but thanks to your response I am now.

 

DSWorld has surprised me on more then one occasion. (Like when I discovered it can, sometimes, pull up useful information about nonpub benchmarks.) Some of the info I posted above came from "View Mark Data by PID." The Google Earth features are nice too.

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