Please enjoy these photos from last month's event and if you're interested in reading more about what it's all about, checkout the attached notice [Survey Party Ahead - Aroostook Meridian - Agenda Addenda 20211021.pdf]
Meridian Monuments - Aroostook County, Maine (230300)
- Thread starter Kelly Bellis
- Start date
avoidthelloyd
Active Member
That's COOL. Thanks for sharing.
Glen Yasharian
Member
Kelly: does anyone know how these monuments were originally aligned? star shots? 'staff' method at apparent noon? In any case how do they compare with geodetic north?
Typically, and in the mid to latter 19th century (and later) when US Coast Survey were conducting magnetic observations across the country, Polaris was the basis for their establishment.
As for your second question, this is in part the subject of my current research into Maine's Meridians. And while there's a lot to unpack in answering this question, below is a snapshot from yesterday's this morning's calculations which is a bit off topic, but hopefully close enough to generally answer your question Glen.
This week has flown by, but here's a brief progress report. Sunday through Tuesday were field days, Wednesday was swallowed nearly whole by preparations for a deposition, and yesterday and today have been focused on data processing.
My obsessive compulsion has always been to process static observations using two different computer programs and the above examples help to explain why it never hurts to look. I have absolutely no idea what happened with the first dataset for Hancock County. I have never seen anything like this! Nearly a meter off in the easting!!! I think Sunday's weather should be pleasant and will be when I re-occupy these two stones and I'm hopeful that DPOS and OPUS will be much closer to agreement
Of course the major fundamental difference between DPOS and OPUS is that NGS still does not process any other satellite constellations besides GPS, whereas DPOS uses all available satellites. The typical 1-2 cm differences between OPUS and DPOS were never alarming, but a meter between results has me scratching my head.
Again, I can't say thank you enough to Sage Collins for allowing my use of his Javad equipment, it's been great!
As for your second question, this is in part the subject of my current research into Maine's Meridians. And while there's a lot to unpack in answering this question, below is a snapshot from yesterday's this morning's calculations which is a bit off topic, but hopefully close enough to generally answer your question Glen.
This week has flown by, but here's a brief progress report. Sunday through Tuesday were field days, Wednesday was swallowed nearly whole by preparations for a deposition, and yesterday and today have been focused on data processing.
My obsessive compulsion has always been to process static observations using two different computer programs and the above examples help to explain why it never hurts to look. I have absolutely no idea what happened with the first dataset for Hancock County. I have never seen anything like this! Nearly a meter off in the easting!!! I think Sunday's weather should be pleasant and will be when I re-occupy these two stones and I'm hopeful that DPOS and OPUS will be much closer to agreement
Of course the major fundamental difference between DPOS and OPUS is that NGS still does not process any other satellite constellations besides GPS, whereas DPOS uses all available satellites. The typical 1-2 cm differences between OPUS and DPOS were never alarming, but a meter between results has me scratching my head.Again, I can't say thank you enough to Sage Collins for allowing my use of his Javad equipment, it's been great!
Hi Kelly, i'll gladly process the file to find a reason of discrepancy
Thanks Alexey! Are you able to see the files I've uploaded to DPOS?
No, i can't
I will email to you. Thanks for looking