Azimuth Mark - How To Find It Question

[+Klemmer]

This is a bit of an esoteric question for the more serious survey type folks out there. It also relates to a nice long hike friends and I just did, and not being able to find an azimuth mark.

Details:

Triangulation Station AA7647 (SIER RESET) was recovered by us with no problem, as were it Reference Markers RM 1 and RM 4. Note that RM 1 is also defined as separate mark DX2176 (SIER RM 1). The nearby DX5283 (SIER AUX 3R 75 71) was also recovered, but does not seem to be related to the AA7647 triangulation station, even though the name implies it is.

 

What we COULDN'T DO was find AA7647 SIER RM 3 (which is also the Azimuth mark for the triangulation station. The description relates it to a large boulder (no help - lots there!), and the "Track Road" (actually the Main Divide Road, if anyone familiar with the Santa Ana Mountains in SoCal). There is a very accurate azimuth (bearing) given on the datasheet from the triangulation station, but no distance that I could find. The "Geod. Az." bearing is 122°10'45.5'. I assume for our non-professional purposes that GPS WGS True North is close enough to a proper Geodetic Azimuth. With a poor description, and no distance, we gave it up.

 

By the way, the hike to Sierra Peak is a fairly steep, serious 8 miles, 2700 ft elevation gain hike. Fun day geocaching / benchmarking, actually. Planted 4 caches also.

 

On our way back, we kept a sharp eye out for witness posts, and sure enough, we found one guarding an Orange County disk numbered 3R-78-71 at N33°50.823, W117°38.880. Not in the NGS database, that I find. It was SE of the triangulation station, and east of the road. Hmmm. Here's the weird thing: back home, plotting it on my topo map program, it comes out 123.3° True from the triangulation station. Within our likely handheld GPS error, it is on (or very close to) the proper azimuth from the station. yes, visible form the staion, near as we could see.

 

Is 3R-78-71 the Azimuth Station for AA7647? Wrong disk stamping for sure. Is there anyway to figure out the distance the azimuth station RM 3 should be from AA7647? or the propoer Lat / Long of the Azimuth Mark?

 

Small map segment might help:

 

Red line is my hypothetical azimuth line. Blue is our GPS track data (mainly the "track road"). Red pins are the main marks in question.

Edited March 14, 2005 by Klemmer & TeddyBearMama

[+Black Dog Trackers]

The 1973 description says (past the azimuth mark,) "CONTINUE UPHILL FOR 0.55 MILE TO THE TOP OF THE MOUNTAIN AND THE STATION ON THE LEFT". So, 0.55 miles is your distance. I assume that is slope distance or even odometer distance, not horizontal distance.

 

It also says the azimuth station is at the top of a low ridge and and on a large boulder only 4 inches above the ground surface. These being the case, there must not be many large rocks at the top of the ridge, at least in the direction of the station, otherwise they'd have put it on top of one of them.

[+PFF]

Excellent question, and one I have struggled with. Often, the AZ mark is a half-mile away from the station. I'm not a surveyor, so this is just my layperson's experience speaking.

 

In the case of AA7647, the AZ Mark was 0.55 miles from the station. Here are two examples of how you sometimes can get the REST of the story (as Paul Harvey would say):

 

(1) Look through the entire description of each recovery. In this case, you will find the following:

 

AA7647'KEEP THE RIGHT FORK, PASSING THROUGH A GATE, FOR

AA7647'2.0 MILES TO THE TOP OF A LOW RIDGE AND REFERENCE MARK 3 ON

AA7647'THE RIGHT. CONTINUE UPHILL FOR 0.55 MILE TO THE TOP OF

AA7647'THE MOUNTAIN AND THE STATION ON THE LEFT.

 

Notice that when following the NGS directions, you come to the AZ Mark, first. Then you proceed .55 miles to the station. If you were travelling west and turned left, as per the directions, the new path would be southward--putting the AZ Mark to the north of the station. Except in this case, the road twists and turns. So we move to Step Two.

 

(2) Note the referenced station list--which is where you got the bearing. On the left side of the chart, you will see that RM-3 has an ID number of CC3821. If you go to the NGS data base, you'll find that CC3821 was "unlisted" at some point in the past because someone felt the mark was not there. However, it gives the position as:

N33 51 00, W117 39, 15. Comparing this with the coordinates of AA7647 confirms that it was to the west. (The Latitude is the same as the station, and the Longitude is 02 seconds higher.)

 

I hope this is helpful. It is not as precise as one would wish. But if CC3821 had not been "unlisted", you would have hit "paydirt" when you called up that data sheet......

 

Best wishes,

-Paul-

 

(Edited to correct the directions and coordinates.)

Edited March 14, 2005 by PFF

[+PFF]

Well, BlackDog......I see great minds think alike!

 

-Paul-

[+Klemmer]

Thanks, guys. That .55 miles makes sense. I missed that - after all, I sure knew where the peak was! I've been poking around the NGS Datasheet database, and found that if you retrieve an area (like a radial distance of 1.5 mi from AA7647), you get the "Unpublished Data" at the end, which has the Lat/ Long of RM 3.

 

To be continued, as I think there might still be more to this....

[+PFF]

I think there might still be more to this....

 

Agreed. I want one of the "pro's" to explain why the data sheet coordinates are WEST of the station, and the referenced direction is "bearing 122 degrees". In other words, why was RM3 not located at:

 

N33 50 46

W117 38 48

 

??

 

-Paul-

[+Klemmer]

The "unpublished data" for RM 3, as PFF says is: N33°51'00", W117°39'15". That can't be right. It is no way .55 miles. That is only about 150 ft from the station. It is also the wrong azimuth from the station (122°....). Right? The undocumented mark I found on the 123° bearing from the station is almost exactly .55 trail miles from the station (within 2 feet!), using my mapping digital topo tools. The text description also fits. The terrain also fits (low ridge). I'm 90% convinced something is totally fishy with the azimuth mark, and / or the undocumented 3R-78-71 has replaced the azimuth mark (RM 3).

 

Opinions?

[+Klemmer]

PFF: Where / how did you come up with the AZ coords you "proposed" above????

[+PFF]

PFF: Where / how did you come up with the AZ coords you "proposed" above????

 

First, let me say that this mountain top appears to be a very "busy" place in terms of benchmarks, communications equipment, and roads. If you go to the NGS site and do a RADIAL search to 0.9 miles, centered on N335100 W1173913, you will get numerous "hits". Notice that

 

*The original SEIR (DX2175) had about the same coordinates as the reset;

*Motorola, Yellow Cab transmitter sites are mentioned, as well as several additional benchmarks;

*That a station called SEIR AUX 3R 75 71 (DX5283) was placed about 400 feet from SEIR. (Interesting similarity to the numbering on the disk you found. Probably placed at the same time.)

*That RM2 is now classified as missing/destroyed.

 

As for the estimated coordinates for RM3, I'm afraid this was not very scientific. I simply plotted a line from the station, outward .55 miles along a bearing of 122 degrees. Using TopoZone, I clicked on the spot and read the cursor's position. I got the "122" from the same place as you, namely

 

AA7647

AA7647|---------------------------------------------------------------------|

AA7647| PID Reference Object Distance Geod. Az |

AA7647| dddmmss.s |

AA7647| DX4279 CALIF INSTITUTE FOR WOMEN TANK APPROX.10.9 KM 0083813.0 |

AA7647| DX4219 CORONA US NAVAL HOSPITAL STACK APPROX.11.9 KM 0414257.1 |

AA7647| DX4211 CORONA EXCH LEMON PROD CO TANK APPROX. 9.4 KM 0680152.1 |

AA7647| DX4231 CORONA FIRST BAPT CH SPIRE APPROX. 8.4 KM 0715944.2 |

AA7647| CC3821 SIER RM 3 AZIMUTH 1221045.5 |

AA7647| DX2176 SIER RM 1 13.901 METERS 15530 |

AA7647| DX2177 SIER RM 2 13.691 METERS 24413 |

AA7647| DX4271 SIER ECC 16.941 METERS 30513 |

AA7647| DX4245 SIERRA PK YELLOW CAB MICROWAVE 24.208 METERS 33944 |

AA7647| DX4269 SIERRA PK MOTOROLA MAST 15.167 METERS 34104 |

AA7647| CC3822 SIER RM 4 15.028 METERS 34815 |

AA7647| DX4277 CHINO CALIF INST FOR MEN STACK APPROX.15.5 KM 3502505.3 |

AA7647| DX4284 CHINO CALIF INST FOR MEN TANK APPROX.16.2 KM 3534306.1 |

AA7647|---------------------------------------------------------------------|

AA7647

 

I'm leaning toward your original theory--that RM3 is gone but that a RESET was placed nearby. Interesting case. If I were independently wealthy, I'd hop on a plane and join you for an exhaustive inventory of everything on that mountain! But such is not the case, so I'm leaving it in your hands. Enjoy playing detective when you have a chance to revisit the site.

 

Regards,

Paul

[evenfall]

Hey All,

 

That list of stations Paul pasted and placed in bold in his last post is called the "Box Score" and there is commonly a box score on many but not all higher order Triangulation, or horizontal control. It commonly lists stations near the mark with bearings to and distances in meters. A useful bit of info, but watch out, as not all the stations can be directly searched by PID if they don't have one, and some stations have been removed from the database if they have truly been confirmed destroyed.

 

It does look like RM 3 could have a couple conflicting locations, and that A Grid and Geod Az are not always the same thing... Good catch there! But it is worth knowing that Azimuth marks in the old days were commonly set south of the actual station and were commonly a quarter mile or so away, give or take.

 

It seems with every mark we are to solve a puzzling confusion made different by time...

... a lot like a box of chocolates, you never know what you are going to get!

 

Rob

Edited March 14, 2005 by evenfall

[+PFF]

Rob wrote:

But it is worth knowing that Azimuth marks in the old days were commonly set south of the actual station and were commonly a quarter mile or so away, give or take.

 

Rob:

 

Is it safe to assume the AZ will always be perpendicular to the line between two of the reference marks? (I did okay with high school Geometry but never got to Trig.)

 

... a lot like a box of chocolates, you never know what you are going to get!

 

LOL! Do I sense an idea for a new thread, the topic of which will be Great Movie Lines That Apply to Surveying? If so, I'll contribute one......

 

"Miss Scarlett, I don't know nothing 'bout

birthing babies or finding benchmarks!"

 

It's been years since I saw that movie, but I'm certain I got the quotation correct. (If not, then apply the famous line from Cool Hand Luke where the Chain Gang Boss looks up from a 1930's NGS recovery note and says, "What we have here, is a failure to communicate.")

 

-Paul-

[Bill93]

Start with the descriptions on the original triangulation station DX2175 SIER. To get the data sheet from NGS site you have to click the "include destroyed" box. It only has location to whole seconds, since it isn't being updated like current marks. To that accuracy, its location is the same as AA7647 SIER RESET.

 

DX2175 has various descriptions of where RM3 was located. It says it was stamped SIER NO.3 1928 1933. I think regardless of what you find in its neighborhood, if it doesn't have that stamping or you don't find a note saying it was re-stamped then you haven't found it.

 

Those descriptions include statements that it was at (1971 adjusted) elevation of 2989.33 ft. Does that check?

 

Those descriptions also say 3/8 mile from the triangulation station. It seems like 3/8 mile direct could match up pretty well with 0.55 on the trail. The direction was given as S 57 deg 47 m E, which is moderately close to Az 122 10 45.5

 

CC3821 SIER RM 3 AZIMUTH does not have a real data sheet, but does get a nominal coordinate listing, which is probably SCALED and thus not of much value in pinning down the exact location. Those numbers that look like PIDs but do not fit in the old grid numbering scheme for PIDs (now abandoned for new marks in favor of the AA type numbering) are almost always a designation for a reference mark that is not by itself geodetically controlled.

 

Using the NGS utility program FORWARD.exe as found on their web site to do the precise geodetic calculation, starting at the triangulation station at N33 51 00.54 W117 39 13.29 and going a little more than 3/8 mile (=603.5 meters but I picked a distance closer to your mystery disk) 628.7 meters at az 122 10 45.5 you end up at coordinates N33 50 49.7 W117 38 52.6 which is within handheld accuracy of the disk you found. The distance is a lot cruder than the angle, so if you set a goto on those calculated coordinates and search several feet either side of the line where your GPS says the goto bearing is 122 or 302 degrees you would be looking in the right place.

 

So I agree RM3 is/was very close to 3R-78-71, but I would say you can't assume somebody replaced it unless you find a record. There could be two marks in close proximity here. Re-read all the data sheets again for clues we've missed.

[+Klemmer]

Thanks all!! I guess we have squeezed out what we can from the NGS archives.

 

I particularly liked Bill93's technique of "dredging up" the original mark (DX2175) that the current mark (AA7647) replaced. Sherlock would have been impressed! My mapped straight line distance of 2061 feet from the station to the azimuth mark compares nicely with the 3/8ths mile from that old datasheet. Kudos!

 

Very interesting stuff. My next step will be to try to get some info from the Orange County Surveyor's Office, which set the "mystery" disk. I have the feeling that the mysterious 3R-78-71 replaced RM3, but the 1971 report of that action to NGS is lost in the gears of beauracracy somewhere.

 

Agreed, not enough proof at this point to say that 3R-78-71 is the Azimuth mark for AA7647. No plans to get back up there anytime soon. It is a HECK of a hike!

 

Any other opinions / contributions welcome!

Edited March 15, 2005 by Klemmer & TeddyBearMama

[evenfall]

Paul,

 

I wish it were safe to say that you could assume anything. I have found that I keep finding a series of usual practices punctuated by varying unusual oddities, so in the critical thinking process, there is no patent logic which we can ever apply other that the misnomer type which follows that in most cases the practice seems to follow this trend, or that, but sometimes doesn't. From there, we consult the bank of known weirdnesses to reconsider one off options... As silly as that sounds it seems true enough. We have a general idea what the common practices were for all the eras involved but there always seems to be something that just turns some of them into a puzzle... and so it goes...

 

Enter the thousand mile stare with me as I recall the time mloser telling us how this particular weirdness was observed on one of his finds.... Hmmmmm, And Zhanna had this one that was totally off but figured out... How was that again?!?!?

 

In the end it would be cool to see what a boolean go-no go chart for benchmark hunting would look like, you know like diagramming a sentence looked like in english classes back in the day... but there would be a lot of weird exception rules clogging the chart. We have a learnable system but only experience with it will teach us how to handle the quirks...

 

So as for the Rules? I guess my observations are that usually, and I mean just most usually Azimuth Marks were mainly used with first order optical stations. They usually had 2 and up to 4 RM's as well, since they were the baseline, the most important triangulations. Remember these stations usually has 12-16 separate observations to bring them to first order, and then they were used to help establish second and third order stations... I have never seen an Az mark on a third order mark, and rarely have I seen many with RM's either. Second orders have usually got 1-2 RM's in my findings but rarely Az Marks, but I think I have seen a few that did.

 

The Az Mark was placed near enough and meant to aid the survey crew in orienting the set up quickly and so that they could begin turning meaningful angles shortly there after, but not so close that you would be looking straight down from the top of a bilby tower. The geodetic Az was used until the 70's so most AZ marks were set in the south from the station mark.

 

The asset we have as a community here is that we share the weirdnesses amongst ourselves and learn from each other... Nevertheless, I have found my share of stations that took a bit of hard thinking... I think there is a hard rule, one for sure and it goes that each mark has the potential to introduce terms like Fubar and Snafu, maybe even Bohica to our vocabularies on each and every attempt. It is easy to see why and I am sure many others take each easy find as a gift! :-) Truly, I love the hard ones... Even thinking them through from afar. The Forum allows us the armchair benchmarking opportunities after dark... 'tis nice indeed.

 

Rob

[+BuckBrooke]

I have the feeling that the mysterious 3R-78-71 replaced RM3, but the 1971 report of that action to NGS is lost in the gears of beauracracy somewhere.

Am I reading the description wrong, in that RM3 it's on top of the white ridge that lies along the red azimuth line in the initial picture, and not on the far side of that ridge, in a gulley?

[+Klemmer]

BuckBrooke: Uhhh... not sure exactly what you mean in your question. BUT:

From the mystery mark 3R-78-71 (which is MAYBE a replacement for the missing azimuth mark / RM3), there is a clear line of sight to the triangulation station AA7647. The topo is not real easy to interpret, because you don't see enough of it. The straight red line is the line from the triangluation station to 3R-78-71. The zigzag / broken "arrowed" line is a label that shows the line straight red line's azimuth (bearing) and distance. More colors would have been a good idea......

Answer your question?

[+Klemmer]

Evenfall: You are truly a philospher amongst surveyors! I am pleased to have come up with an inquiry that has evidently evoked your interest in such a fine and noble cause. My gratitude for your insightful advisory opinions continues unabated, albeit tempered by my still somewhat confused state of azimuth marked mind.

 

[not bad for a chemical / electronics engineer, huh?!]

 

Seriously: this is one of the things that makes benchmark hunting so much fun, at least for me! Thanks!

[+BuckBrooke]

To clarify:

From your picture at the top of the forum, the marks you've found look like they're on a small hill to the upper left of a larger North/South ridge. The azimuth line from the found marks runs upper left to lower right, intersecting the top of the N/S ridge, and pointing through the mark you found on the far side, the lower right, which looks like a road/stream that runs around the N/S ridge. From the description to the mark, it seems to me like it would be on top of the N/S ridge, roughly where your jagged arrow is pointing, and not further to the lower right, where you've found the new mark.

[+Klemmer]

BuckBrooke: Thanks for your interest (I do mean that), but you are mis-interpreting the Topo. It is easy to do, even sometimes if you have been looking at them for years. Having a small section makes it more difficult to visualize correctly. There is a LARGE peak at the top left (triangle symbol), tallest in the area. The straight red line runs from the peak down to the SE (to the bottom right), and ends on a small hill / ridge, just east of the road. In between (where the jagged label line points) is a VALLLEY (notice the blue-green water symbol starting just south of the straight red line?). Sorry, it is not a north-south ridge. Anything down in the valley would likely not be visible from the peak (triangulation station). You are having a bit of an "optical illusion" problem with the topo. The mystery mark IS visible from the peak (or a minimum 3 foot tall pole would be, to get above the scrub brush). Trust me. Wish I had taken more pictures.

[mloser]

BuckBrooke,

That broken arrow is pointing to a valley. Going to the Topozone link from the page and selecting a larger scale (1:48,000 or 1:50,000) will help you see this.

 

I think the AZ (RM3) is where Klemmerer thinks it is, but like most azimuth marks the description is just vague enough to make the hunt a bit of a crap shoot. From what I have seen related to triangulation stations, I would expect the mark to be on the highest point of that small ridge.

 

Is the "new" mark in a boulder? If so, it would be hard to place it exactly where the old RM3 was because if RM3 was knocked out the stem would have remained. Also, the azimuth indicates 123 degrees as opposed to 122.

 

Another thing to look for if you go back is the eccentric mark, shown in the box score as DX4271 SIER ECC 16.941 METERS 30513. The eccentric has a PID but no datasheet, either on Geocaching or the NGS, but it still may exist. I will let the experts explain what an eccentric is but my understanding is that they are often set when the station is hard to occupy or the line of sight to another station is blocked. Then an eccentric is set for easier use.

 

RM4 is in the base of DX4269 (or DX4245, it is hard to tell), which is another station with a PID and no datasheet, but if you found it you should have found the mast or remains of it. That means you can either claim that station or submit it as destroyed. The same goes for the other tower. Is it there? Are there remains?

 

I hope you get a chance to go back and finish your hunt. If you can, get some area pics of the marks so we can see the big picture!

[+Klemmer]

mloser: Thanks for your topo confirming words.

 

I too would like some info from the experts on eccentric marks. Didn't know what the "ECC'" was until your post! Use, reason, etc. Since they were not mentioned on the triangulation station datasheet, I didn't look for them.

 

As far as 122° vs 123° to the "azimuth" mark, remember that the "mystery marker" my estimated 123° azimuth goes to n unknown mark, that there is no datasheet for it, so the Lat / Long is from my handheld GPS. I feel pretty confident that the 1° difference is easily attrributable to that likely error.

 

For some reason I didn't know about the intersection (tower) marks when I was up there. I need to figure out why that was.... RM4 was found where is was supposed to be, so I suppose the tower is also, but I'm not sure....

 

Guess I'll just have to go back! Quite a hike, but I can always use the exercise.

[mloser]

Was the mark you observed in a boulder? If so, it might be a replacement for RM3. If not, I suspect RM3, or some remnants of it, still exist on that hill.

 

As for the towers, were there any there? You found RM4 in the base of a tower support. Did you look up?

 

Finally, according to the Manual of Geodetic Triangulation, published by the US Coast and Geodetic Survey, eccentric stations are to be set up "in cases where it will not be practicable to occupy the true station in the future". This eccentric was most likely set when, or sometime after, the original 1928 station was set, but before the reset. This may explain why the reset was done, as well as why the eccentric was not identified in the reset description--it was no longer needed.

 

To get some more information, and interestingly enough, to see that there is a RM5, take a look at: SIER, the original station description, which was retired when it was marked destroyed in 1973 and SIER RESET was described. It does not mention the eccentric, which I find odd, but does mention RM4 and RM5 being iron pipes:

DX2175'R.M. 4 AND R.M. 5 ARE BOTH NEW REFERENCE MARKS. THEY ARE

DX2175'BOTH FD. 2 IN IRON PIPE WITH NAIL SET IN CONCRETE 0.4 FT.

DX2175'ABOVE GROUND SET IN CONCRETE BLOCK. NO REFERENCE FOR EITHER

DX2175'PIPE.

 

RM3 is described two different times in this sheet:

1933

DX2175'NO. 3 IS ALMOST IN LINE WITH TELEPHONE POST, 40 FEET

DX2175'NORTH OF ROAD, AND APPROXIMATELY THREE-EIGHTHS MILE

DX2175'FROM STATION S 57 DEG 47 MIN E.

 

and 1958

DX2175'THE AZIMUTH MARK IS A STANDARD REFERENCE MARK DISK STAMPED

DX2175'SIER NO 3 1928 1933, CEMENTED IN A DRILL HOLE IN A 10-INCH

DX2175'BOULDER THAT PROJECTS 4 INCHES ABOVE GROUND. IT IS 55 FEET

DX2175'NORTHEAST OF THE CENTER LINE OF A TRACK ROAD AND 3 FEET SOUTH

DX2175'OF A CAIRN.

 

In short, you could spend quite some time at this location finding the history of the stations here. Even looking for all the evidence of SIER could take an afternoon!

 

I hope you get a chance to go back.

[+Klemmer]

Thanks, mloser. No, the Mystery Mark was NOT in a boulder. Good question. It was in a small concrete pad:

Mystery Mark

That IS significant. Thanks.

 

Yep, there are a BUNCH of radio masts up there. Here's a pic from a nearby hill, where we placed Bowling for Copters, one of the four new caches we left up there. RM4 was in the foundation of one of the masts. I GUESS it is the mast in question, but it is a little hard to tell for sure. I don't think I will log it as found until I'm more sure. Another reason to go back!

Sierra Peak from a nearby hill

Interestingly, both the 1933 and 1958 descrciptions are for the same azimuth line from the station (within 1933 accuracy)! Sier Reset (AA7647) has the Geodetic Azimuth (I believe this esssentially a True bearing) at 122°10'45.5". The old 1933 Sier (DX2175) has it as S 57 DEG 47 MIN E. That is, 57 DEG 47 MIN EAST OF SOUTH, which is equal to Geodetic Azimuth 122 DEG 13 MIN!!!! [180 DEG MINUS 57 DEG 47 MIN]. They agree within about a minute and a half. Maybe as close as 1933 accuracy, but might also be due to a datum changes ("adjustments")?

 

The saga continues.....

[mloser]

That hill looks like a porcupine! Good luck telling which are the two towers in question. At least you know RM4 is in the base of one of them. Take a look at some of the discussions here about intersection stations. There may still be towers at the locations described in the datasheets, but they may not be the SAME towers. There is an FCC site to check tower build dates that has been mentioned here also and may help you determine if the tower is the one described or not.

 

SIER RESET seems to have been set exactly where SIER was, or at least close enough for our purposes. The recovery states that the underground mark was recovered and used to reset it. So your angle for the azimuth should be the same on both sheets. The error you mention would not be due to 1933 lack of accuracy, as they were just as accurate then as they are now, but more likely just a description. I wouldn't consider it to be an issue.

 

I thought you were in trees at this location but see you are just in scrub. Can you shoot the angle that the box score has? Either to the station from your suspected RM3 location or the other way around? Yes, the bearing is to true north, so don't forget to correct for the magnetic declination. Pull up the Topozone map from the benchmarking page and at the bottom you will see the declination. It is about 13 degrees east in this area if I remember right.

 

Also, I forgot to mention, the original SIER description mentions a cairn near RM3. It may be there or there may be remnants of it, which would help you a lot in determining if you are near RM3.

 

This is the sort of hunt a lot of us really enjoy--research and then some field work. It makes the find much sweeter. Even a definitive Not Found is ok if you know you have done your homework.

 

Good luck!

 

Matt

[+Klemmer]

Thanks mloser. Yep, it's a porcupine! A big one. Been seeing it from down in the valleys for years. Didn't see any cairn, but also wasn't looking for one. Yes, it is 95% probable you could shoot an angle to / from my mystery mark to the station. Certainly no terrain in between. My only concern is that there is a slight possibility that one of the radio "shacks" is in the way. Don't think so, but.... real hard to tell just by eye from what I have here / remember. The azimuth I measured on the map at the beginning of this thread is probably more acurate than an azimuth I could shoot with a handheld compass. It is laid exactly on top of the two Lat/Long coords (one very accurate from AA7647, one is from my handheld GPS at the mystery mark). My GPS (Magellan Meridian Plainum) has a built in electronic compass, and if set right, will read out True auto corrected for magnetic variation(s). It uses the right variation based on where you are. Neat.

 

I'll get up there again sometime.

[+jwahl]

Back to one original question. Azimuth marks seldom have distances to them.

 

If I go that azimuth forward geodetic about a half mile and then back up the line to the east side of the road, I get a coordinate of about

 

33-50-50.1 / 117-38-53.2.

 

Of course judgement about where it is in relation to the road, possible road widening, grading, etc. , may affect that. The 0.55 miles would be road distance. Also, so you should be able to clock down from the station with odometer and be within a few hundred feet. If no vehicles are involved you could build a route and check it.

 

I am looking at photos from terraserver using usaphotomaps.

 

doing that I come out very close to the same point, i.e.

 

33-50-50.4 / 117-38-53.2

 

Again guessing a distance beside the road maybe 30 feet from center or so.

 

Look there.

 

- jerry

[+Klemmer]

Jerry:

Thanks for the input. Makes sense. That is also very close to my "mystery mark". See my first post for it's position (by handheld GPS):

N33° 50.823'

W117° 38.880'

Which in Jerry's terms (I believe he is talking minute & seconds) is:

N33° 50' 49.38"

W117° 38' 52.8"

(where ' = minutes, " = seconds)

I think with the potential inaccuracies in my handheld position, and Jerry's estimates, they are within each other's error range.

All the more reason that undocumented mark mark 3R-78-71 is looking like (or very close to) the "so far missing" Azimuth mark.

[+BuckBrooke]

Mloser/PFF,

I just spent 30 minutes playing around with Topozone. It's great! I've been confused in a few places where I only found one or two in a series of older benchmarks. The whole line shows up in Topozone. Of course, many of the newer marks don't show, but...

[+PFF]

Mloser/PFF,

I just spent 30 minutes playing around with Topozone. It's great! I've been confused in a few places where I only found one or two in a series of older benchmarks. The whole line shows up in Topozone. Of course, many of the newer marks don't show, but...

 

Glad you are enjoying TopoZone. It's a very valuable tool. Those aerial photos that you see me posting are from the same server. I have a subscription (about $30/year) which gives me aerial photos and also street maps--all with the famous TopoZone "X" marking the spot. The nice thing about being a real estate agent is that things which normally would be "toys" become tax-deductible "tools"......

....GPS

....Metal Detector

....Map, aerial photo, and tax record subscriptions

....100-foot tape measure

 

The list goes on and one. I play it safe, however. I've not tried cornstarch as a tax deduction. Even *I* am not that great a salesman!

 

-Paul-