To qualify for this challenge you must:
1. Sign the logbook at the listed coordinates for this cache
2. Determine your cache centroid.
3. Determine the cache that is closest to your centroid
4. Find that cache (If you have already found that cache, Great! you qualify)
Include in your log:
- Your cache centroid coordinates
- The closest cache to your centroid coordinates
- The date you found your centroid cache
To calculate your cache centroid there's a few different methods:
1. Average Northerns and Westerns separately (either using a calculator or excel)
2. Use a macro in GSAK
3. Or within your Project GC stats
Just a quick note that your cache centroid will constantly change with every cache you find, so keep your eyes on this as you may qualify just by finding more caches :)
Now, in 2022, we have added a checker which makes it even easier! (Credit to bmuzzin) 