the Degree Confluence Project


2.2 km (1.4 miles) NW of Gresten, Niederösterreich, Austria
Approx. altitude: 412 m (1351 ft)
([?] maps: Google MapQuest Multimap world confnav)
Antipode: 48°S 165°W

Accuracy: 4 m (13 ft)
Click on any of the images for the full-sized picture.

#2: View to the South #3: View to the West #4: View to the North #5: View to the East #6: GPS Reading #7: Ground Zero #8: The Confluence Hunter #9: The Meridian Trail #10: The Confluence Monument #11: The Farm with Lots of Geese #12: No GPS Allowed

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  48°N 15°E (visit #10)  

#1: The Confluence from 25 m distance

(visited by Rainer Mautz)

28-Sep-2013 -- This confluence visit is the second out of 3 visits that I made during another cycling week-end in Austria’s Alpine mountains. The story starts from 48°N 14°E.

After the hazy morning visit of 48°N 14°E the sun came out and I a had wonderful cycling day through the mountain valleys in Lower and Upper Austria. Not too far from this confluence point (in the Raming Valley) I saw a NO GPS sign. Funny, I thought, finding here in peaceful Upper Austria my first sign that clearly forbids the use of GPS. I had travelled through whole countries where the use of GPS is forbidden (e.g. Cuba) or an issue (e.g. China), but never experienced such a sign. Should I have turned off my handheld GPS receiver, GPS of my mobile phone and my GPS-based camera?

In the village of Randegg, located 2 km from the confluence point, I saw another interesting sign. It showed that I was following a Meridianweg, which is basically a bicycle trail dedicated to the meridian of 15°E longitude with special reference to “MEZ 15/48°”. The signposting continued all the way to the confluence monument, where the last post located in 200 m distance calling for “Meridianstein”.

Indeed, this confluence can be found without the use of GPS. But at the confluence monument I secretly unpacked my GPS unit and measured an error of 92 m. Obviously, the surveying team was also not allowed to use GPS while surveying the confluence point! Well, another sign mentions that the monument had been surveyed on September 25th of 1987. At this time, they didn’t have GPS anyways. So there are three explanations for the “wrong” location of the monument: Either the commune of Gresten was putting the monument intentionally on a more convenient location or the surveying team was using the Austrian reference grid or the surveying was based on astronomical observations. If the last of these three possibilities was true, I had measured the vertical deflections (i.e. the difference between the ellipsoidal coordinates measured by GPS and the astronomical azimuth measured by observing stars with a telescope). My GPS measurement at the monument was 47° 59' 58.1" N, 14° 59' 56.6" E. That means that the vertical deflections for this confluence point are ξ=1.9" and η=3.4".

By the way, the monument is a nice place to rest with several benches and a picnic table. But I didn’t dare to sit on the benches as every minute a rotting pear would fall off from the pear tree above.

The WGS85 (GPS) referenced confluence is located 92 m further down from the monument directly next to the paved road. As far as I could tell from my GPS reading with an accuracy of 4 m, the confluence is located in a hedge squeezed in-between the road and a little private fish pond. To the north, there is a nice view into the valley with the stream “Kleine Erlauf”. This 70 km long river flows into the Danube at Pöchlarn.

After the visit I continued cycling eastwards and when dusk came when passing through the town Kirchberg, I retired to a cozy guesthouse.

CP Visit Details:

  • Distance to an asphalt road: 1 m
  • Distance to a track: 1 m
  • Distance of bicycle parking: 1 m
  • Time to reach CP from bicycle parking: 0 seconds
  • Time at CP: 4:00 PM
  • Measured height: 418 m
  • Minimal distance according to GPS: 0 m
  • Position accuracy: 4 m
  • Topography: hilly
  • Vegetation: hedge with vines and hazelnut trees. A meadow on the northern side.
  • Weather: overcast, 15° C (felt temperature)
  • Means of transport: bicycle
  • Given Name: The No GPS Confluence

The story continues is at 48°N 16°E.

 All pictures
#1: The Confluence from 25 m distance
#2: View to the South
#3: View to the West
#4: View to the North
#5: View to the East
#6: GPS Reading
#7: Ground Zero
#8: The Confluence Hunter
#9: The Meridian Trail
#10: The Confluence Monument
#11: The Farm with Lots of Geese
#12: No GPS Allowed
ALL: All pictures on one page (broadband access recommended)