Solar Activity May Impact GPS Users

A solar flare that occurred on February 12, 2010 may signal a return to high solar activity after several months of sustained low activity.  Intense solar flares can cause temporary disruptions in GPS signals due to the high levels of radiation they release into the Earth’s atmosphere. 

Solar activity generally occurs in eleven-year cycles, with the next peak expected by 2012.  Increased solar activity is particularly troublesome for the navigation devices many drivers reference in their vehicles.  GPS blackouts may last for a number of minutes during periods of peak solar activity and may occur several times each year.  In addition to GPS blackouts, the atmospheric charge can impact the amount of time it takes for a GPS signal to make it to a GPS receiver, which causes inaccurate readings.  Positioning may be off by as much as thirty feet during these periods, which will have the greatest impact on GPS survey equipment

For iPhone users that want to keep track of solar activity, NASA has helped implement a new app called “3D Sun” that allows users to access a live global view of the sun.  Data is provided in near real-time fashion by NASA’s STEREO mission, a pair of satellites that provide coverage of both sides of the sun simultaneously.  More information on the app is available at http://3dsun.org/.

A high resolution 2D image of the sun taken by NASA's STEREO mission.  STEREO is monitoring solar activity that may interfere with GPS and other signals.  (Public domain image courtesy of NASA.)

A high resolution 2D image of the sun taken by NASA's STEREO mission. STEREO is monitoring solar activity that may interfere with GPS and other signals. (Public domain image courtesy of NASA.)

Current Exhibitions of Historic Maps

We’re obviously pretty fond of digital maps and technology in general. However, sometimes you just have to marvel at the beautiful maps and images created by cartographers hundreds of years ago. With brushes, compasses, sextants, and not a computer in sight, they surveyed and recreated the physical world as they knew it.

Many of these historic maps have been photographed or digitized and are available online. In terms of maps of Philadelphia where Azavea is based, both the Hexamer and Locher maps on PhillyHistory.org and the maps available at the Greater Philadelphia GeoHistory Network give great insight into how the city has changed and developed.

There are some maps though that just have to be seen in person. This Spring, a number of museums and libraries are displaying beautiful historic maps as part of various exhibitions. If you have a chance, it just might be worth tearing yourself away from the computer for awhile to marvel at the talents of cartographers throughout the centuries.

The Matteo Ricci World Map (1602) at the Library of Congress: On exhibit for the first time in North America, this 5.5 feet tall by 12.5 feet wide map displays China at the center of the world and was also the first Chinese map to show the Americas. More information is available in the New York Times review of the exhibition.

Mapping New York’s Shoreline, 1609-2009 at the New York Public Library: An exhibition of maps, atlases, prints, and other items tells the story of New York’s waterways and harbors over the course of four centuries.

Mapping Discoveries in the Heavens and Controversies on Earth from the Harvard Map Collection: Maps are not always of land. This exhibition explores Galileo’s celestial observations and their impact on the world. 

Envisioning the World currently on view at the Princeton University Library: A traveling exhibition of rare world maps from the collection of Henry Wendt, a Princeton alumnus.

Tombigbee, USA

It’s tempting to take seriously Neil Freeman’s reimagining of the United States.

Philadelphia, Allegheny, Great Smoky, Lincoln, High Plains, Great Basin, Los Angeles…

Click to enlarge. Credit: Neil Freeman

Click to enlarge. Credit: Neil Freeman

Freeman, an artist and urban planner, reorganized the states into 50 bodies of equal population and presented this new political landscape on his website, FakeIsTheNewReal.org. He preserved major metropolitan areas and used dominant physical features — rivers, mostly — to name the new geographic units.

The resulting map is logical, thoughtful, and pretty damned faithful to the physical and cultural geography of our nation.

“It’s not serious,” says Freeman, “but people took it seriously.” (As in, you’ll split up Texas over my dead body.) Geographer Stentor Danielson, who blogs about environmental and social issues (with a spatial bent) at Debitage.net, suggests that the lumping together of South Jersey and Philadelphia rings true culturally but would be an environmental disaster. If it weren’t for the state border along the Delaware River, Philadelphia might have sucked the Pine Barrens dry.

“Really, this map is meant to be an ironic look at Electoral College reform,” says Freeman.

Freeman’s map caught a wave of attention when he first posted it to his website after the 2004 presidential election. Earlier this year it was picked up again by several political bloggers, including James Fallows and Matthew Yglesias. (Fallows invites his readers to imagine a decennial redistricting of the states to reflect changes in population: “In a reapportioned Senate each of of these units would have two votes.”)

Freeman followed a few simple rules:
1. Keep populations equal (Freeman’s states range from 5.4 to 5.6 million people, according to 2000 U.S. Census data. Actual state populations range from ~500 thousand to ~33 million)
2. Place major cities and close-in suburbs in a single state
3. When possible, follow existing state and county boundaries
4. Keep river valleys intact

“I used rivers as a guide for picking names,” he says. Turns out, this strategy makes a lot of sense. Freeman recently read ‘Names on the Land,’ an historical account of place-naming by George Stewart. “I think I was unconsciously following the names he gives in the book.”

Check out some of the Freeman’s other projects over at FakeIsTheNewReal, including my favorites:
Brooklyn Typology — linking photographs and data “to form a portrait of the urban fabric of Brooklyn”
Subways at Scale — aspatial maps of urban subways
Chicago Mile by Mile — photographing Chicago’s street grid

EFF Tool Analyzes your Browser Fingerprint

Online privacy issues are something we’re always conscious about in working on our projects. We gain useful insights into our products by tracking web visitors using Google Analytics, but these same techniques can also be used to maliciously track visitors online.

Electronic Frontier Foundation released a tool that analyzes how unique your browser fingerprint is.  I found it quite interesting that all three browsers on my work computer had unique fingerprints among the 104,584 tests that the site had conducted thus far.

In particular it’s interesting to see how little information needs to be looked at to be unique.   For instance, in Internet Explorer my User Agent string by itself is unique among all of the tests.  The same applies to my combination of browser plugin versions.   In Firefox my User Agent string appears in 1 out of 23.62 browsers, but my browser plugin combination is unique across all of the tests conducted thus far.

How do your browsers compare?  Panopticlick

Common Cause/PA Launches Our Philadelphia web site

Pennsylvania_logoCommon Cause of Pennsylvania has launched a new web site and blog, Our Philadelphia, to educate the public about elected officials.  Unlike many states, Pennsylvania has no limits on campaign contributions, and the online contribution databases maintained by the state and by the City of Philadelphia are barely usable with much of the data not available at all.  A search for contributions that would take minutes in a more transparent state, like Maryland, would take hundreds of hours in Pennsylvania.  So Common Cause is building its own web site and database to make this data available.  But wait, there’s more.  The site will include several features: 

  • Elected Officials lookups – enter an address and find your representatives as well as a list of their top contributors [we’re excited that this lookup service is powered by our Cicero API
  • Campaign Contribution database
  • Election Reform advocacy – including redistricting, campaign finance and ethics
  • Open Government and Transparency advocacy
  • City and State Government watchdog – with a diminished print media, there is an increasing need for other organizations to supplement the normal role of newspapers

our_phila_clip
Over the next year, Common Cause/PA hopes to add additional information for Pittsburgh as well as extend the contribution databases as well as its ability to report on government activities.

Mashing up Google Calendar and a Javascript Timeline

Usually, this blog is about geography and Azavea’s work, but I thought an internal project might be of interest to others.  Our marketing team recently faced an interesting problem.  Our marketing approach is not based on advertising. Rather, we focus on spreading the word about our work by performing presentations at conferences, writing articles, writing book chapters, our newsletter, etc.  We also respond to a fair number of RFP’s and grant solicitations.  As our marketing and business development team has grown, the number of activities to track has also increased.  Lots of activities also creates opportunities, but if we can’t effectively visualize how they all fit together, we run the risk of missing those opportunities.  In addition, the task of tracking all of the grant and proposal deadlines, conference attendance and other activities becomes pretty tough.

So we resolved to set up a shared calendar as a mechanism for collectively tracking all of these deadlines and activities.  We had  switched our e-mail system to GoogleApps Premium in early 2008.  When we did this, we gained a number of capabilities in addition to e-mail including: shared calendars, document authoring/storage and customizable home pages for each staff person.  So our starting point was to create a Google Calendar for the marketing folks to share.  However, many of the marketing and business development activities span several days, and while Google Calendar is a great way to enter and store events, the usual daily/weekly/monthly calendar layout does not make it easy to see several weeks or months together.  We were really looking for a ‘timeline’ display of the calendar so we would be able to see the juxtaposition of several events and their relationship to each other.  So we looked around for a low-cost system that would enable us to both enter our marketing activities and visualize them in a timeline layout.  We looked at online project management tools, some of which support Gantt charts, but while a Gantt chart is great for decomposing tasks into subtasks, it arranges each task into it’s own line.  So if you have 20 tasks, that’s ok, but if you have 100 or 200 spread out over a year, it’s not very readable – the chart just keeps growing vertically.

marketing timeline calendar

So we decided to build something in-house.  When we had first set up our wiki, David Zwarg had showed off a tool called Simile Timeline, created by some folks at MIT.  So we went back to that project and learned that not only had it continued to develop but it was available as an open source toolkit that could be used in a broad range of applications.  David picked up Simile and within a couple of days, he had mashed up 6 calendars within the account we’d set up for the marketing crew into a timeline-based calendar.  He also experimented with incorporating a map, but we decided it consumed too much screen real estate and nixed it.  After all, we’re still small enough that we generally know what part of the country every is in. :-)

While geography proved to not be very compelling for this application, the juxtaposition of space and time can be a very useful visualization.  Below are a couple of screenshots from one of the recent builds of of our HunchLab product (it’s used for forecasting and geographic change detection), where there’s a critical need to view both spatial and temporal patterns in the same view.

Figure 1: The points on the map represent the span of time selected on the graph with a heat map of the points.

Figure 1: The points on the map represent the span of time selected on the graph with a heat map of the points.

Figure 1: The graph below the map is a Time-of-Day/Day-of-Week graph, showing a "temporal heat map" of when the events in the map occured.

Figure 2: The graph below the map is a Time-of-Day/Day-of-Week graph, showing a "temporal heat map" of when the events in the map occurred.

The Third Point in China’s Compass

China launched the third satellite in its Compass Navigation Satellite System on January 17, 2010.  This satellite is one of five planned geostationary satellites that will ultimately provide navigation coverage within the Asia-Pacific region.  An additional 30 non-geostationary satellites are expected to be in place by 2020 in order to bring the Compass constellation to full global coverage.  

Also known as the Beidou system, the geostationary satellites will provide free open service within the local service area.  A second level of service will provide greater accuracy to authorized users only.