Friday, February 15, 2013

Close Earth Flyby of Asteroid

At 2:25 p.m. EST (19:25 UTC) on Friday, Feb. 15th, asteroid 2012 DA14 will fly past Earth only 17,200 miles above our planet's surface. This will put it well inside the orbit of geosynchronous satellites, closer than any asteroid of the same size has come since regular sky surveys began in the 1990s. Researchers speculate that Earth's gravity might even cause seismic activity on the 50m-wide space rock. Click to view a computer simulation of the flyby, courtesy of NASA:



During the hours around closest approach, the asteroid will brighten until it resembles a star of 8th magnitude. Theoretically, that’s an easy target for backyard telescopes. The problem is speed. The asteroid will be racing across the sky, moving almost a full degree (or twice the width of a full Moon) every minute. That’s going to be hard to track. Only the most experienced amateur astronomers are likely to succeed. For the rest of us, NASA will broadcast the asteroid's flyby on NASA TV.
Asteroid 2012 DA14 is about the same size as previous asteroids responsible for the Meteor Crater in Arizona and the Tunguska Event in Siberia. Unlike those objects, however, 2012 DA14 will not hit Earth. Even if seismic activity breaks the asteroid apart, there is no danger; the fragments would continue along the same non-intersecting path as the original asteroid.

source;
SpaceWeather.com 
 http://spaceweather.com/

NASA
http://www.nasa.gov/mission_pages/asteroids/news/asteroid20130201315144.html

My Stamp Collecting Blog

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HOW TO READ PROPAGATION NUMBERS

The A index [ LOW is GOOD ]

  • 1 to 6 is BEST
  • 7 to 9 is OK
  • 11 or more is BAD

Represents the overall geomagnetic condition of the ionosphere ("Ap" if averaged from the Kp-Index) (an average of the eight 3-hour K-Indices) ('A' referring to amplitude) over a given 24 hour period, ranging (linearly) typically from 1-100 but theoretically up to 400.

A lower A-Index generally suggests better propagation on the 10, 12, 15, 17, & 20 Meter Bands; a low & steady Ap-Index generally suggest good propagation on the 30, 40, 60, 80, & 160 Meter Bands.

SFI index [ HIGH is GOOD ]

  • 70 NOT GOOD
  • 80 GOOD
  • 90 BETTER
  • 100+ BEST

The measure of total radio emissions from the sun at 10.7cm (2800 MHz), on a scale of 60 (no sunspots) to 300, generally corresponding to the sunspot level, but being too low in energy to cause ionization, not related to the ionization level of the Ionosphere.

Higher Solar Flux generally suggests better propagation on the 10, 12, 15, 17, & 20 Meter Bands; Solar Flux rarely affects the 30, 40, 60, 80, & 160 Meter Bands.

K index [ LOW is GOOD ]

  • 0 or 1 is BEST
  • 2 is OK
  • 3 or more is BAD
  • 5 is VERY VERY BAD

The overall geomagnetic condition of the ionosphere ("Kp" if averaged over the planet) over the past 3 hours, measured by 13 magnetometers between 46 & 63 degrees of latitude, and ranging quasi-logarithmically from 0-9. Designed to detect solar particle radiation by its magnetic effect. A higher K-index generally means worse HF conditions.

A lower K-Index generally suggests better propagation on the 10, 12, 15, 17, & 20 Meter Bands; a low & steady Kp-Index generally suggest good propagation on the 30, 40, 60, 80, & 160 Meter Bands.

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