Am I missing something?
I haven??t seen a single follow up from SapperPLS.
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We have provided SapperPLS with answers that require in depth research to begin a response. Moving from flat earth surveying to geodetic surveying is a steep learning curve. The numerous datums used and imperfect models of the earth they are based on only add to the confusion.
He traversed 1200 feet. And 800 ft. 4 setups. Total Station. Starting SPC XY, published NGS(reset), and he must have determined an azimuth, somehow. Even SF is on the data sheet. Not geodetic, SPC. It was on the exam.?ÿ
??I did stay up till 4 AM last night trying to find an answer and didn't find one.??
imo: he doesn??t have proper azimuth. He might??ve forgotten to subscribe to his own topic.
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I didn't take into account the convergence.?ÿ That was the issue.?ÿ I do appreciate everybody's in depth response.?ÿ I did reply, but I guess because I'm new my posts require moderator approval.?ÿ Hopefully it isn't long before you all see I did get your responses and tried to reply.
The 1:42k resection only means the two start point values related well with each other. If you have network adjustment software you should be able to push things around until you find the problem.
FWIW,
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I agree with other posters who encouraged you to provide more information.
I copy below extracts for a CT classically positioned monument for illustration as I do not know what monument you actually used. The source for the azimuth you used is also of interest. Unfortunately, azimuth marks for a monument do not in general include accurate distances making positioning impossible.
When dealing with classically positioned monuments, the data sheet will include a section known as the ??Box Score? that shows the geodetic azimuths and distances to the reference and azimuth marks for the main station. Use these values to position the reference monuments. The azimuths and distances are from the main station.
in addition, these monuments participated in the NAD83(1986) adjustment and fitted t0 the subsequent state-by-state HARN surveys.?ÿ
Sadly, I haven't looked at a data sheet in quite a while but don't they also list state plane coordinates for the monument and/or accessories?
I assume, perhaps unrealistically, that a licensed surveyor would know how to transform a geodetic to a plane azimuth especially since the convergence angle is on the data sheet. The data sheet even shows both!
Convergence angle and SF is given on the data sheet. If he has geo azimuth, I know I always have to double check if I added or subtracted correctly ?ÿ
And I hope he isn??t using the azimuths to the RMs for azimuth. I haven??t seen a Box Score lately on current data sheets.?ÿ
And the Q is: how did he get azimuth? If he is using the ??27 and ??83 discs, then he??s off in the woods.
imo it??s an azimuth problem.?ÿ
All... thanks for all of the responses. ?ÿI did use the geodetic azimuth??s in the box score for the NGS point. ?ÿI totally blanked on the convergence. ?ÿOnce Larry Scott mentioned it, I adjusted for convergence and everything matched up perfectly. ?ÿFor the record, the point I used was titled Asylum in New London County. ?ÿIt sits atop Jail Hill in Norwich, CT about 500?? more or less NW of City Hall. ?ÿThanks again to everybody.
And yes, I do know how to convert geodetic to state plane etc, but it was a classic case of staring at my problem too long and if it had been a snake it would have bitten me. ?ÿKind of feel a little bit silly, but hey, that??s why I asked. ?ÿSometimes a second set of eyes is all it takes.
I figured it was azimuth right off because I mostly use geodetic, and in Starnet that goes poorly right away. (There??s a geo-grid azimuth option setting.)
It??s either forgetting convergence or misinterpreting the (+) (-). Been there done that, got the tote bag.?ÿ
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I got into a recent discussion about a First order NGS point in the middle of a boundary I was doing.
It is one of those points in a convenient location in a County Road ROW so all you need to do is pull up and park next to it to occupy it. For that reason I've used it for a number of jobs. A young engineer working with us, doing some environmental and permitting work sent me an email that he sees that the coordinates I have for the point are about .5' off.
He was using the datasheet numbers and I was using 83/93 from DOT and the local HARN position which are about .1' from the recent NAD83 Epoch.
Trying to explain to him why my number was correct and the datasheet was not was a frustrating experience, not as bad when I tried to explain to them why the landowner calling the sheriff on their environmental guys digging holes in his field was correct and the county GIS lines were not and the guys with their little handhelds and their GIS lines could end up in jail.
The NGS Data Sheet
See file?ÿdsdata.pdf?ÿfor more information about the datasheet.
PROGRAM = datasheet95, VERSION = 8.12.5.5 Starting Datasheet Retrieval... 1 National Geodetic Survey, Retrieval Date = FEBRUARY 3, 2020 LX4762 *********************************************************************** LX4762 DESIGNATION - ASYLUM LX4762 PID - LX4762 LX4762 STATE/COUNTY- CT/NEW LONDON LX4762 COUNTRY - US LX4762 USGS QUAD - NORWICH (2018) LX4762 LX4762 *CURRENT SURVEY CONTROL LX4762 ______________________________________________________________________ LX4762* NAD 83(1996) POSITION- 41 31 37.05638(N) 072 04 40.32414(W) ADJUSTED LX4762* NAVD 88 ORTHO HEIGHT - 56. (meters) 184. (feet) SCALED LX4762 ______________________________________________________________________ LX4762 GEOID HEIGHT - -30.301 (meters) GEOID18 LX4762 LAPLACE CORR - -0.19 (seconds) DEFLEC18 LX4762 HORZ ORDER - THIRD LX4762 LX4762.The horizontal coordinates were established by classical geodetic methods LX4762.and adjusted by the National Geodetic Survey in August 1998. LX4762. LX4762.The orthometric height was scaled from a topographic map. LX4762 LX4762.Significant digits in the geoid height do not necessarily reflect accuracy. LX4762.GEOID18 height accuracy estimate available here. LX4762 LX4762.Click photographs - Photos may exist for this station. LX4762 LX4762.The Laplace correction was computed from DEFLEC18 derived deflections. LX4762 LX4762. The following values were computed from the NAD 83(1996) position. LX4762 LX4762; North East Units Scale Factor Converg. LX4762;SPC CT - 229,651.477 360,896.279 MT 0.99998315 +0 26 44.4 LX4762;SPC CT - 753,448.22 1,184,040.54 sFT 0.99998315 +0 26 44.4 LX4762;UTM 18 - 4,601,380.944 743,801.038 MT 1.00033153 +1 56 17.7 LX4762;UTM 19 - 4,601,832.454 243,204.045 MT 1.00041161 -2 02 30.0 LX4762 LX4762! - Elev Factor x Scale Factor = Combined Factor LX4762!SPC CT - 0.99999601 x 0.99998315 = 0.99997916 LX4762!UTM 18 - 0.99999601 x 1.00033153 = 1.00032754 LX4762!UTM 19 - 0.99999601 x 1.00041161 = 1.00040762 LX4762 LX4762: Primary Azimuth Mark Grid Az LX4762:SPC CT - NORWICH ST MARYS CH TOWER 077 53 42.6 LX4762:UTM 18 - NORWICH ST MARYS CH TOWER 076 24 09.3 LX4762:UTM 19 - NORWICH ST MARYS CH TOWER 080 22 57.0 LX4762 LX4762_U.S. NATIONAL GRID SPATIAL ADDRESS: 18TYM4380101380(NAD 83) LX4762 LX4762|---------------------------------------------------------------------| LX4762| PID Reference Object Distance Geod. Az | LX4762| dddmmss.s | LX4762| LX4752 NORWICH ST MARYS CH TOWER APPROX. 1.5 KM 0782027.0 | LX4762| LX4746 NORWICH ST JOSEPH CH SPIRE APPROX. 0.7 KM 0872520.3 | LX4762| CZ6958 ASYLUM RM 1 9.210 METERS 08939 | LX4762| LX4753 NORWICH GAS CO STACK APPROX. 1.1 KM 0902129.4 | LX4762| CZ6959 ASYLUM RM 2 18.370 METERS 17551 | LX4762| LX4748 LOWER COAL DOCK LIGHT 20 APPROX. 1.7 KM 1795340.1 | LX4762|---------------------------------------------------------------------| LX4762 LX4762 SUPERSEDED SURVEY CONTROL LX4762 LX4762 NAD 83(1992)- 41 31 37.05543(N) 072 04 40.32349(W) AD( ) 3 LX4762 NAD 83(1986)- 41 31 37.05615(N) 072 04 40.32567(W) AD( ) 3 LX4762 NAD 27 - 41 31 36.69700(N) 072 04 42.04300(W) AD( ) 3 LX4762.No superseded survey control is available for this station. LX4762 LX4762_SATELLITE: THE SITE LOCATION WAS REPORTED AS SUITABLE FOR LX4762+SATELLITE: SATELLITE OBSERVATIONS - April 24, 2006 LX4762 LX4762 HISTORY - Date Condition Report By LX4762 HISTORY - 1934 MONUMENTED CGS LX4762 HISTORY - 1961 SEE DESCRIPTION CGS LX4762 HISTORY - 20060424 GOOD USPSQD LX4762 LX4762 STATION DESCRIPTION LX4762 LX4762'DESCRIBED BY COAST AND GEODETIC SURVEY 1934 (GCM) LX4762'THE STATION IS LOCATED ON JAIL HILL ABOUT 90 METERS N OF SCHOOL LX4762'STREET AND ABOUT 60 METERS E OF CEDAR STREET ON THE PROPERTY OF LX4762'TYLER ALCOTT. THE STATION IS A STANDARD DISK SET IN OUTCROPPING LX4762'LEDGE AT THE TOP OF THE HILL. LX4762'REFERENCE MARK NO.1 IS A STANDARD DISK SET IN LEDGE 9.21 METERS E LX4762'OF STATION. REFERENCE MARK NO. 2 IS A STANDARD DISK SET IN LEDGE LX4762'18.37 METERS S OF STATION. LX4762 LX4762 STATION RECOVERY (1961) LX4762 LX4762'RECOVERY NOTE BY COAST AND GEODETIC SURVEY 1961 (GFW) LX4762'STATION AND R.M.S WERE RECOVERED IN GOOD CONDITION. THE STATION LX4762'IS STAMPED ASYLUM 1934 AND THE R.M.S ARE STAMPED ASYLUM NO 1 1934 LX4762'AND ASYLUM NO 2 1934. THE DISTANCES WERE CHECKED AND FOUND TO BE LX4762'CORRECT. LX4762'THE ORIGINAL DESCRIPTION BY G.C.M. IN 1934 IS COMPLETE AND ADEQUATE LX4762'WITH THE FOLLOWING ADDITION. THE STATION IS 67.4 FT. EAST OF THE LX4762'SOUTHEAST CORNER OF A SMALL GREEN SHINGLED HOUSE. LX4762 LX4762 STATION RECOVERY (2006) LX4762 LX4762'RECOVERY NOTE BY US POWER SQUADRON 2006 (AES) LX4762'STATION AND RMS ALL RECOVERED. *** retrieval complete. Elapsed Time = 00:00:01
(The RMs for the NGS (reset) are not an accurate source of azimuth.)
Interesting.?ÿ I just assumed the azimuth's given are geodetic.?ÿ Certainly worth checking
No matter how good the reference mark azimuths are, they are usually under 100 ft from the station, so not good to project 2000 ft.