Astro station?

[WhistlingWind]

What is an 'astro station'? I have seen that name used in several 19th century benchmarks.

(There is one nearby I want to visit)

 

My guess is that some sort of astromomical observation was done to determine the precise

location rather than (or maybe in addition to)

the usual geodetic techniques.

 

W. Wind

[+gbod]

Would you be so kind to provide a PID as an example?

[Z15]

quote:

---

My guess is that some sort of astronomical observation was done to determine the precise

location rather than (or maybe in addition to)

the usual geodetic techniques.

---

 

Right on.

 

They used the North Star (Polaris) for tru North determination. A elaborate observation done at only at night. Certain station(s) in the triangulation scheme were used for this. They were usually ones that had clear sky for unobstructed view.

 

 

Mike

Survey Tech (Retired)

[DaveD]

Astro was an extremely important aspect of geodetic surveying until the development of space-based technologies such as GPS. It still survives in the form of some surveyors who may actually perform solar or Polaris (North star) observations to determined direction (azimuth). Astronomic observations were often used to determine all three primary components of a horizontal systems, latitude, longitude and azimuth. The horizontal coordinate systems of many islands (e.g. Puerto Rico, Virgin Islands, Guam, American Samoa, Hawaii etc.) were established as Astro Datums. Since it is too far to measure line-of-sight observations from North America, these islands, and many others around the world had their local coordinate system defined by someone performing astronomic observations of the primary components at some specific station. For example, in Hawaii this station was Oahu West Base (now destroyed). In the development of large regional systems, such as the North American Datum of 1927 (NAD 27) for the U.S. and Canada, when incorporated into the larger triangulation networks, these stations were important for the determination of what’s called the geoid separation, or the geoid height. There is an excellent description of this process in the novel “The Measure of All Things” by Ken Adler. I highly recommend this book if you have any interest in the history of the development of geodetic survey networks – It’s a very good read. You can also find images of astro observations on the NGS web site at:

http://www.photolib.noaa.gov/historic/c&gs/geodesy.html , then select “Astronomic Latitude and Longitude”

[+GEO*Trailblazer 1]

Thanks DaveD.

 

Were you in Washington D.C.on September 18,03 around noon at the Capitol???

 

Search PROPER MOTION

 

See the DIVA satellite that is due for launch 2004

 

WHEN ALL ELSE FAILS

*GEOTRYAGAIN*

TAKE PRIDE IN AMERICA

http://www.doi.gov/news/front_current.html

1803-2003

"LOUSIANA PURCHASE"

http://www.lapurchase.org

"LEWIS AND CLARK EXPADITION"

http://lewisclark.geog.missouri.edu/index

 

Arkansas Missouri Geocachers Association

www.ARK-MOGeocachers@yahoogroups.com

 

[This message was edited by GEO*Trailblazer 1 on October 16, 2003 at 09:36 AM.]

[AE5D]

An example would be BM0627, on the grounds of the State Capitol in Austin, which is called an ''astronomical station'' in the 1911 description but not in its designation.