holograph

I updated the percentage map to change a few things, in case anyone is wondering: The percentage calculation now is based on the number of PIDs that have been reported by GEOCAC, rather than the number of reports. The colors were changed so that the state and county lines are more visible. The map includes Alaska and Hawaii, which were omitted from the quick-and-dirty map that I first generated. The full size image is larger.

All the maps give false emphasis to some group of counties. The original map using pure counts tends to favor large counties, hence the number of large counties in the West that are maxed out. The density map emphasizes populated urban areas, not only because that's where most geocachers hunt, but because the small urban counties tend to be more target rich. The percentage map favors undeveloped counties, because more of the marks are undisturbed and potentially recoverable. The merit of the original map is that it is easy to understand and simple for anyone to see how many recoveries are needed to change a color. That would be virtually impossible for the density map, and somewhat difficult for the percentage map without knowing how many total marks are in the database.

The download and analysis of the datasheets is done with a series of Perl programs that I wrote a number of years ago. The map images are created with an off-the-shelf GIS called Manifold, and I have a couple of Javascript scripts for Manifold that run to update the map data and generate the images. The datasheet archive resides in PostgreSQL and PostGIS, and I have some more Perl scripts which update the archive and extract the county ZIP files which get uploaded to the "data" page of the web site.

I'm still not sure if I understand what you were trying to see. I think you are saying, just look at counties that have 100 or fewer stations, and compute the percentage of those stations that were recovered. Only about a third of all counties have fewer than 100 stations. Here is a map showing all the counties in the lower 48 states, colored according to the percentage of marks that have been reported by GEOCAC in each county. edit: P.S. since the counts are are counts of *reports*, not counts of stations, there is some possibility that if people have made multiple reports for the same stations, the numbers will be skewed. For most counties, that isn't much of a problem.

I'm not sure what you mean by that. Way back when, I tried some kind of color scheme based on percentage of total, but the problem is determining what "total" means, especially what "total recoverable" or "possible" might mean. There are many, many destroyed and "not found" marks in every county, so the percentage of stations recovered is always pretty low except for a few small counties or cities.

Here's another map that is "fair" to all counties, in some sense of the word "fair". It shows the density of reports rather than simple counts. However, it would be hard for someone to calculate how many more reports are needed in order to bump a county to the next color. For those of you who are technically inclined, the map actually shows inverse density, because the counties are colored based on average square miles per report. Click on the thumbnail below for a larger map.

Yeah, I may have to add another color, just to keep them motivated. edit: How about these new colors? Click the image for a full-size view.

The October statistics are available on the statistics page. The maps and counts by county have been updated also. There were 512 datasheets updated with new GEOCAC recovery logs. The most recent recovery added to the datasheets was dated October 18.

Here are a few: Alaska UV8119 - Monumented UW6273 - Recovery TT7106 - Recovery Maine QG0562 - Monumented New Jersey JU0522 - Monumented JU0526 - Recovery JU0529 - Recovery JU0530 - Monumented JU0531 - Monumented Nevada LR0525 - Monumented LR0199 - Monumented Ohio KZ1883 - Recovery (destroyed) Texas CE0116 - Monumented CE0117 - Monumented Utah LP0494 - Recovery West Virginia KY3202 - Recovery Wyoming MQ0131 - Monumented

The entire set of datasheets has now been refreshed. The problem with missing characters seems to be resolved. There may be a few datasheets that were not updated. Those would be for marks that have been destroyed. When a mark is destroyed, the NGS removes the datasheet from the archive, and may remove it from the online retrieval, also. Since I don't remove the marks from my database, the archives you can download from my site will sometimes contain the last published and accessible version of the datasheet.

The September statistics are available on the statistics page. The maps and counts by county have been updated also. There were 1,527 datasheets updated with new GEOCAC recovery logs. The most recent recovery added to the datasheets was dated September 12.

I'm on my third GPS now, but unfortunately don't do much benchmarking in the field any more, although I still use it to create trail logs for my vacation hikes. My first was a Garmin E-Trex, which got stolen when my home was broken into in 2003. Then I got a Garmin GPS-60CS to replace it. Unfortunately, the USB port connector on that one was too tight and it eventually tore loose from the case a few years ago. Then I got a Garmin-60CSx to replace that one, and it had better sensitivity and has worked well since. The Garmin maps leave a lot to be desired, though. I guess I also have a GPS in my Motorola DroidX phone, but I haven't used that one for anything other than street navigation during vacations. I am amazed, however, at how quickly the GPS in the DroidX orients itself and acquires satellites and its location. Perhaps it retrieves the satellite ephemeris and its approximate location from the cellular network, but after turning on the GPS feature, it only takes a few seconds for it to figure out where it is.

The datasheets in question were retrieved from the NGS archive on November 5, 2009, and haven't been updated by the NGS since. When I looked at what I had retrieved from the NGS on that date, the datasheets at that time were missing characters, probably due to some problem at their end that has since been corrected. I'll start the process of updating all the datasheets from a more recent copy of the full NGS archive. That should clear up most of the problems. It may take a few days.

Was that disk set in 1961, or am I reading it upside down?

You may have wide set eyes, or a relatively small screen, because if you see inverted relief, it means that you are focusing behind the image so that your left eye is seeing the left image and the right eye is seeing the right image. It only works if you can focus in front of the image so that the left eye sees the right image, and the right eye sees the left image. The finger trick is supposed to help you focus in front of the image. Sitting further from the screen may help, if you normally sit close to the screen.

In another thread, there was some discussion about aircraft navigation beacons. Although this is not a beacon, I thought some of you might be interested to see one of the early (1939) aircraft navigational aids. The image below is a "cross-eyed" stereogram of the center of Scranton, Pennsylvania, on June 4, 1939. The images were aerial photos taken for the Agricultural Adjustment Administration and which were digitized and put online at the PennPilot web site. The top of the large tank has been painted with an arrow pointing to the nearest airfield. A pilot, flying visually, would see these signs and be able to find the airfield. I've seen such signs painted on top of barns, too. If you are not familiar with "cross-eyed stereograms", you need to cross your eyes slightly when viewing the image to see the stereo effect. No special glasses required, but it may take a little practice to see it. If you have trouble, try holding a finger near your face, focus on your finger, and move it toward the image until you see the stereo image converge.

The record has been uneven over the past year or so. Here is a breakdown of the datasheet updates over the last 12 months showing the approximate counts and date ranges of recovery reports: September 2010 - 521 (Jan 9 - Jun 24) October 2010 - 2329 (Mar 15 - Oct 3) November 2010 - 1188 (May 23 - Nov 14) December 2010 - 0 January 2011 - 1210 (Apr 21 - Jan 25) February 2011 - 0 March 2011 - 602 (Jul 22 - Mar 16) April 2011 - 0 May 2011 - 2 (Apr 17) June 2011 - 1085 (Feb 2 - Jun 6) July 2011 - 5 (Jun 3 - Jun 30) August 2011 - 0 These numbers are approximate. Keep in mind that often people wait and submit back-dated recovery reports, so the backlog often isn't as bad as it appears, and there is overlap from month to month. For instance, the September 2010 updates included some reports from March through September of 2009, because a couple of geocachers waited over a year before submitting backdated recoveries. In the table above, I just guessed at the date ranges of the reports that were actually waiting for publication, based on the recovery dates in the sheets that were updated.

The September statistics are available on the statistics page. There were no new recovery reports published on datasheets during September, so that only statistic that changed was the Geocaching counts.

Sometimes the local surveyors who do use the benchmarks don't really want people to find them. I remember discussing that with the property owner at KV1244. The local surveyor had taken great pains to hide the benchmark under some logs so that no one could find or damage "his" benchmark. In all fairness, most of the marks in that level line had been vandalized, and the few remaining ones were apparently precious to the surveyors.

The July statistics are available on the statistics page. There were only 5 updates to datasheets: one (AJ2823) for initials MTT, and four (BW1569,CP3384,CP3386,DK0988) for LSUFan. The reports were dated between June 3 and June 30. Even those reports appear to be duplicates, because the datasheets show two identical reports for each of those PIDs.

We were at the North Rim last September, but we flew in to Las Vegas and drove to Jacob's Lake. If you start in Arizona, it would be quite a detour to get to the North Rim. Having said that, we enjoyed it, and had the same experience we've had at many other heavily-visited national parks -- once you get out of the parking lots and onto the trails, you can be virtually alone. We spent two days dayhiking the north rim and probably encountered no more than a dozen people all day, once we got 100 feet away from the parking lots.

Thanks! So a magnetic station was really a station that had reference marks giving true azimuths/bearings. That makes sense. I thought perhaps they were places where the declination had been measured.

The June statistics are available on the statistics page. The maps and counts by county have been updated also. There were 1086 datasheets updated with new GEOCAC recovery logs. The most recent recovery added to the datasheets was dated June 6 and the updates seem to be from February to June.

There is a web site devoted to the issue: http://www.saveourgps.org/ This was a classic case of big-money expecting to dominate the regulatory agency, as has so often succeeded in the past. LightSquared was funded by one of the multi-billion-dollar hedge funds, and got the OK from the FCC to construct the infrastructure pending the outcome of the tests. I suspect that they expected to get approval as a result of their fait-accomplie: "hey we've already spent a billion or so and constructed the network on your preliminary OK, so you have to approve it now, don't you?" Their claim has consistently been: hey, the older GPS receivers were crappy, and should not have been sensitive to signals outside their allocated band. So it's not our fault if our signal disrupts them. They should all be replaced by receivers that have narrower filters. I'm surprised that the GPS manufacturers weren't also enthusiastically supporting LightSquared , since it would have meant that all those old GPS receivers would have to be replaced. You may want to curb your enthusiasm for the latest ruling, because Congress only said that LightSquared must not interfere with DoD and Homeland Security application of GPS. If LightSquared can do that, but still ends up disrupting civilian GPS I'm not sure anyone would object, since it means forced replacement of all those "cheap" consumer GPS units.

I wonder if the governor paid the fine.