June 24, 2017

January 2014-Life in the Astro-Blogosphere: Bizarro Astronomy

Our (Familiar?) Moon…

Photo by author

Weirdness is where you look for it. This was drove home to me while observing the Transit of Venus back in June 2012. While we strugged to grab a few brief views of the event through the pervasive cloud cover, we noted that life around us was going on pretty much as usual.

What else would we expect? Cars honked, dogs barked, kids played, all while a dim celestial event transpired just overhead, if you only knew where to look for it. [Read more...]

Space Telescopes, Part I: Optical.

 
(Credit: NASA/ESA/S. Gallagher/J. English).
(Credit: NASA/ESA/S. Gallagher/J. English).
 

 Hickson Group 31 of galaxies as imaged by Hubble.

   This weeks’ expose will kick off our four part series on orbiting space telescopes. For starters, we’ll begin with the most familiar; the optical wavelength. True, we as humans are biased towards this narrow band of the spectrum; we love to see pretty pictures that we can relate to.  But beyond this, telescopes that operate in the visual wavelengths have no less than revolutionized astronomy, as well as laid promise for perhaps giving us images of exo-Earths in our lifetimes. What follows is a rapid fire list of what was, is, and what to look for up and coming in the realm of optical astronomy in space: [Read more...]

02.11.09:The Low-Down on LOFAR.

The LOFAR station at Effelsberg, with the low-band masts in the foreground and the high band antenna in the background. (Credit: The Netherlands Institute for Radio Astronomy).

The LOFAR station at Effelsberg, with the low-band masts in the foreground and the high band antenna in the background. (Credit: The Netherlands Institute for Radio Astronomy).

European radio astronomers at the Netherlands Institute for Radio Astronomy (ASTRON) have recently opened a potentially new window on the universe with an exotic new instrument. Dubbed LOFAR, or the Low Frequency Array, this unique instrument will examine the sky at extremely low radio frequencies, with a low band of 30 to 78 MHz and a complimenting high band of 120 to 168 MHz. In contrast, the radio dish at the Arecibo Observatory in Puerto Rico operates in a range of 400-5000 MHz. We’re talking very low frequencies, in a range not well understood. Three arrays currently centered on Exloo in the Netherlands saw first “radio light” earlier this year, examining the powerful radio source Cygnus A, a suspected black hole candidate. As computer power increases, scientists hope to add arrays across Europe from Britain to the Ukraine to increase the resolution of the array. The low gain antenna masts are simple and cheap to construct, and are basic omni-directional dipole antennas utilizing a synthetic aperture. LOFAR will map events at low radio frequencies, from ionization in the Earth’s atmosphere caused by gamma-ray bursts to corneal mass ejections on the Sun to re-ionization of neutral hydrogen in the primordial universe. And that’s not to mention any surreptitious discoveries that always seem to crop up when a new portion of the electromagnetic spectrum gets analyzed… perhaps some ultra-advanced race communicates via low frequency black hole resonances? I seem to remember a plot in Arthur C. Clarke’s Imperial Earth that involved intelligent aliens and low frequency waves… watch for LOFAR “antenna farms” cropping up along the European country-side soon!

11.10.09: Zooming in on Blazars.

the VLBA Radio Telescope (1 of 10) in Hancock, New Hampshire. (Credit:NRAO / AUI / NSF).

The VLBA Radio Telescope (1 of 10) in Hancock, New Hampshire. (Credit:NRAO / AUI / NSF).

Astronomers have recently utilized an enormous radio telescope to examine some of the most exotic objects in the universe; active galactic nuclei. Sometimes called “Blazars”, these distant galaxies are spewing huge jets of particles at amazing relativistic speeds. These emit immense energy across the electromagnetic spectrum. NASA’s Fermi Gamma Ray Space Telescope has identified and monitored these sources since its launch in 2008 and now scientists at the Max Planck Institute for Radio Astronomy have used the National Science Foundation’s Very Long Baseline Array (VLBA) to map these jets with unprecedented accuracy. The VLBA is a series of 10 interlinked radio telescopes spanning an area from the Virgin Islands to Hawaii that utilize interferometry to produce an effective baseline of 5,300 miles and can resolve details less than 100 light years across at a distance of 7 billion light years. Fermi, the predecessor to the Compton Gamma Ray Observatory that was de-orbited in 2000, scans the entire sky once every three hours looking for gamma-ray bursts. First spotted in the early 70′s during global monitoring of nuclear weapons tests, pinning down gamma-ray bursts has been the name of the game in astrophysics over the past decades. The backup study proves the link between the gamma-ray emissions seen by Fermi and the energetic radio jets pinpointed by the VLBA… expect more high resolution radio maps to come!