Surveyors Week March 18-24, 2018 GPS on BM

Posted by: Bill93

Tell us more about the report they didn't post.?ÿ

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Briefly .. We did a shared solution in 2014 that reported it 0.5 ft. low and we did the extra work to verify that conclusion by comparing to other marks in the area.?ÿ We did a recovery note at the same time with that information along with the fact that none of the ties in the original description could be verified leaving open the possibility that the mark could have been moved. This never made it to the data sheet.?ÿ?ÿ

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We submitted 5 of the priority marks last week and they were shared Feb. 23. The priority map updated the 23rd. does not show this. I hope it does next time or the updated map isn't updating.?ÿ

btw repeated new shared solutions are shown and previous shared solutions are linked to the newer one.?ÿ We can't do all the work called for in one week so?ÿ we are getting a head start and maybe a rear finish.?ÿ ?ÿ?ÿ

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Is it updated today?

Yes, Indeed

I submitted a 4-hour observation this week on the only priority mark within 40 miles of me (JS2282, D 644, a Priority B mark).?ÿ It was a repeat of an observation I shared almost a year ago.?ÿ Getting old being what it is, I had forgotten that I'd done that, but redundancy is good, right?

I unintentionally used the same receiver as last year, but used a different antenna this time:?ÿ a Compact L1/L2 w/GP in 2017, a Zephyr Geodetic in 2018.?ÿ The horizontal results between the two solutions are 1 mm (!), and the vertical spread is 16 mm.

We're kind of debating what to do up here. Most places in this neck of the woods aren't conducive to 4 hr long GPS observations in the middle of March.......

I'm expecting some?ÿof our submittals to be in early April- early May for some "iffy"?ÿlocations due to the emerging vegetation- others will be all opportunity based.

I've been working on GPS_on_BM _2018 for a couple of weeks and have done 11; 1 not on the list, 6 of them are Priority B/1 , and 4?ÿ are Priority A/1. Occupation times from 4h15m to 5hr. I'm waiting for the Precise ephemeris to submit.

I see that some of the ones requested are along active railroad lines, apparently within the RR right-of-way. This requires coordination/permission from the RR to enter (RR are VERY jealous of their rights-of-way), and probably will give really bad results anyway because of the passing trains (my guess).

Some of the ones they want are along main roads and railroads through the Cascades and using Street View on Google Earth, look like there's very little sky available - trees and mountains everywhere. I haven't done any really bad ones yet, but a couple of the Priority A were kind of marginal.

Posted by: Jim Frame

The horizontal results between the two solutions are 1 mm (!), and the vertical spread is 16 mm.

I did one the other day that was a repeat.?ÿ Older precise solution vs new rapid solution:?ÿ Horizontal difference 3 mm vertical 5 mm.?ÿ Sometimes the dice roll looks amazingly good.?ÿ Just don't bet the farm on it.

Will wait for the precise solution before sharing.

A few of us students, from our university's surveying club, got out in support of GPS on BM. It was a crisp, beautiful day. We didn't even need snowshoes...

Awesome! Thank you for sharing. 🙂

To the top...

I just got an email with the stats for the month:

601 marks shared by OPUS users in March 2018

807 marks shared by OPUS users in April 2018

Itƒ??s good to remember those are just the number of ?ÿmarks observed not the number of observations.