LIGO backstory delights and displeases

Robert Garisto tells us (Physics Today, August 2016, page 10) of the secrecy he maintained at Physical Review Letters prior to the announcement that a “chirp” had been detected at the Laser Interferometer Gravitational-Wave Observatory (LIGO). On sabbatical at Caltech, I had the pleasure of joining local astronomers to watch the press conference from the astronomy and astrophysics auditorium (whose street number, 1216, is the Lyman-alpha wavelength in angstroms). But as we left after the dazzling announcement, with music in our ears, they gave out coffee cups and bumper stickers each with the data already emblazoned on it. I should have hung out in the print shop days before

High-resolution Satellite Imaging of the 2004 Transit of Venus and Asymmetries in the Cytherean Atmosphere

This paper presents the only space-borne optical-imaging observations of the 2004 June 8 transit of Venus, the first such transit visible from Earth since AD 1882. The high-resolution, high-cadence satellite images we arranged from NASA's Transition Region and Coronal Explorer (TRACE) reveal the onset of visibility of Venus's atmosphere and give further information about the black-drop effect, whose causes we previously demonstrated from TRACE observations of a transit of Mercury. The atmosphere is gradually revealed before second contact and after third contact, resulting from the changing depth of atmospheric layers refracting the photospheric surface into the observer's direction. We use Venus Express observations to relate the atmospheric arcs seen during the transit to the atmospheric structure of Venus. Finally, we relate the transit images to current and future exoplanet observations, providing a sort of ground truth showing an analog in our solar system to effects observable only with light curves in other solar systems with the Kepler and CoRoT missions and ground-based exoplanet-transit observations

Did Lomonosov see the Venusian atmosphere?

Vladimir Shiltsev (Physics Today, February 2012, page 40) properly credits Mikhail Lomonosov with a wide range of scientific achievements. But we have been corresponding with Shiltsev for some months about our realization1 that Lomonosov did not discover the atmosphere of Venus. One of us (Pasachoff) analyzed spacecraft observations of the Cytherean atmosphere at the 2004 transit of Venus,2 and we realized that what Lomonosov reported did not match actual atmospheric observations. NASA’s Transition Region and Coronal Explorer spacecraft detected Venus’s atmosphere for about 20 minutes as Venus’s silhouette entered the Sun’s limb, and again for the first 20 minutes of its exit from the solar disk. Lomonosov saw only a bulge of light—shown in figure 4a of Shiltsev’s article—and a brief flash of light. We think that what he saw was an artifact of his relatively primitive and small telescope rather than the aureole that is sunlight refracted toward Earth by Venus’s atmosphere. Our conclusions were reinforced by observations made during the 2012 transit of Venus

On K-line central reversals

The double reversal at the center of the spatially-averaged profiles of the H and K resonance lines in the solar atmosphere has been used as a probe to give the distribution of temperature and density with height. Details of the interpretations depend on the mechanism assumed for the formation of the central reversals. The non-LTE theory of stellar atmospheres has succeeded in explaining a symmetric double reversal; the history of this effort has recently been reviewed by Linsky and Avrett (1970)

On K-line central reversals

The double reversal at the center of the spatially-averaged profiles of the H and K resonance lines in the solar atmosphere has been used as a probe to give the distribution of temperature and density with height. Details of the interpretations depend on the mechanism assumed for the formation of the central reversals. The non-LTE theory of stellar atmospheres has succeeded in explaining a symmetric double reversal; the history of this effort has recently been reviewed by Linsky and Avrett (1970)

Solar Eclipses Observed from Antarctica

Aspects of the solar corona are still best observed during totality of solar eclipses, and other high-resolution observations of coronal active regions can be observed with radio telescopes by differentiation of occultation observations, as we did with the Jansky Very Large Array for the annular solar eclipse of 2012 May 20 in the US. Totality crossing Antarctica included the eclipse of 2003 November 23, and will next occur on 2021 December 4; annularity crossing Antarctica included the eclipse of 2008 February 7, and will next occur on 2014 April 29. Partial phases as high as 87% coverage were visible and were imaged in Antarctica on 2011 November 25, and in addition to partial phases of the total and annular eclipses listed above, partial phases were visible in Antarctica on 2001 July 2011, 2002 December 4, 2004 April 19, 2006 September 22, 2007 September 11, and 2009 January 26, and will be visible on 2015 September 13, 2016 September 1, 2017 February 26, 2018 February 15, and 2020 December 14. On behalf of the Working Group on Solar Eclipses of the IAU, the poster showed the solar eclipses visible from Antarctica and this article shows a subset (see www.eclipses.info for the full set). A variety of investigations of the Sun and of the response of the terrestrial atmosphere and ionosphere to the abrupt solar cutoff can be carried out at the future eclipses, making the Antarctic observations scientifically useful

Simultaneous Observations of the Chromosphere with TRACE and SUMER

Using mainly the 1600 angstrom continuum channel, and also the 1216 angstrom Lyman-alpha channel (which includes some UV continuum and C IV emission), aboard the TRACE satellite, we observed the complete lifetime of a transient, bright chromospheric loop. Simultaneous observations with the SUMER instrument aboard the SOHO spacecraft revealed interesting material velocities through the Doppler effect existing above the chromospheric loop imaged with TRACE, possibly corresponding to extended non-visible loops, or the base of an X-ray jet.Comment: 14 pages, 10 figures, accepted by Solar Physic