-The observations show the relativistic spin precession of strongly self-gravitating bodies, likely caused by the misalignment of the pulsar’s spin vector with respect to the binary system’s total angular momentum due to an asymmetric supernova explosion (Desvignes et al. 2019, Science, Vol. 365, Issue 6457, pp. 1013-1017)
-As a key collaborator of the NASA Planetary Defense Office, Arecibo radar system had an observation record of 126 NEAs (77% rate of success), of which 78 were recently discovered objects. It also observed 1 comet, Mercury, and the Moon.
-FRBs are millisec- duration radio pulses that appear to be extragalactic. The repeater demonstrates that its source survives the bursts and rules out a class of models requiring catastrophic explosions. (Spitler, L. G et al. 2016, Nature, Volume 531, Issue 7593) Fundamental Physics -- constraints on the variation of the fine structure constant with the age of the Universe.
-This study was possible thanks to the study of an unprecedented 27‐year baseline of ISR and Fabry-Perot interferometer data acquired at Arecibo. The study finds evidence for local time, seasonal, and solar cycle variation in derived F estimates, with the best agreement between data, theory, and model predictions observed near midnight at solar maximum. Joshi, P. P., et al. 2018, Journal of Geophysical Research: Space Physics, Volume 123, 9743– 9761)
-Arecibo weighed in on the controversy surrounding the possible variability of the fine structure constant, alpha, which describes the electromagnetic interaction between elementary charged particles. 150 hours of observing time at Arecibo revealed that alpha has not changed by more than 1.0 parts in a million in these three billion years (Kanekar et al. 2018 Physical Review Letters, Volume 120, Issue 6, id.06130).
-This has upended the widely held view that all pulsars are the orderly ticking clocks of the universe.
-150 hours of observing time at Arecibo revealed that a has not changed by more than 1.3 parts in a million in these three billion years.
-This temperature is so high that it forces astronomers to question the traditional model - synchrotron radiation - for the emission emanating from the vicinity of the supermassive black hole.
- FRBs are millisec-duration, radio pulses that appear to be extragalactic. - The repeater demonstrates that its source survives the bursts and rules out a class of models requiring catastrophic explosions.
- Upper limits are already constraining models of space-time strain.
- This work represents the first simultaneous and (very nearly) common‐volume observations of Ne and two alkali metals (Na and K) in the thermospheric region over Arecibo (120 to 150 km high). The results imply that neutral layers cannot result only from direct neutralization of metal ions in the TILs. (Raizada, S., et al. 2015, Geophysics Research Letter, Volume 42, 10,106– 10,112)
- TDaylight plasma lines in the ionosphere, excited by photoelectrons, have long been known. However, the origin of the nighttime plasma lines, observed in the Arecibo sky from 1982, is not yet known. A long term study published in 2015 found that these lines are recurrent and variable. Although the source of the fast electrons that engender the lines remains unclear, one strong possibility is leakage from Earth's radiation belts. (Carlson, H. C. et al. 2015, Geophysics Research Letter, Volume 42, 7255–7263)
- These arc rates may be used as an instrument to measure the environment (like local tropospheric weather stations) and also to monitor the degradation of the solar array power on board of the satellites expected at end-of-life (EOL) (Ferguson and Hoffman, 2019)
- This distance was just confirmed by the Gaia Collaboration.
- We can now measure the foreground dust signal more precisely, improving our ability to uncover the B-mode signature of inflation.
- Arecibo was essential for VLBI result that resolved the Pleiades distance controversy with measurements of ultra-faint radio stars. This distance was just confirmed by the Gaia Collaboration. (Melis et al. 2014 Science, Volume 345, Issue 6200, pp. 1029-1032)
- On March 12, 2013 an observation was made with the K Doppler lidar at the Arecibo and an intriguing descending layer was detected in the end of that night with a speed phase matching that of the semidiurnal tide. The discovery of this thermospheric K layer, coupled with the McMurdo discovery of similar Fe layers, might lead to a new approach to study the thermosphere in the altitude range of 100 – 150km with resonance fluorescence lidars. (J. Friedman et al. 2013, Journal of Atmospheric and Solar-Terrestrial Physics, Volume 104, 2013, P. 253-259.)
- This will provide the best test for the strong equivalence principle, an order on magnitude better than the Sun-Earth-Moon system.
- First radar observations of the Moon at large bistatic angles using the Arecibo radar transmitter and the Miniature Radio Frequency (Mini-RF) instrument on NASA’s Lunar Reconnaissance Orbiter (LRO) suggest the presence of near-surface deposits of water ice deposits in permanently shadowed regions near the poles of the Moon (Patterson et al. 2017)
- Three independent studies show that the thermospheric neutral winds (TNW) show strong variations in time and seasonal over a window of 30 years. These variations result in a change in the altitude of the ionospheric peak density of about 600m/year. The origin of these variations, anthropogenic or not, is not yet known. (Tepley et al. 2011 J. Geophysics. Res., 116,A00H06; Santos et al., 2011, J. Geophys. Res., 116, A00H13 0; Brum et al., 2012, J. Geophysics. Res., 117, A00H14)
- Arecibo have detected the molecules methanimine and hydrogen cyanide -- two ingredients that build life-forming amino acids -- in a galaxy some 250 light years away (Salter et al. 2008 The Astronomical Journal, Volume 136, Issue 1, 389-399)
(Nolan, M. C. et al., Central Bureau Electronic Telegrams, #1254, 2008)
(Taylor, P. A. et al. Science, Volume 316, 5822, pp. 274, 2007)
- This is the first time that two ion temperatures and three ion composition (O+, H+ and He+) have been measured from the same IS spectrum, and, as far as we know, one of the first measurements of both ion temperatures in the ionosphere (Sulzer, M. P. & Gonzalez, S. A., Geophysical Research Letters, 1996, 23, 3235-3238)
In subsequent observations, an entire planetary system was found around the pulsar PSR 1257+12.
- The ice persists in shadowed craters despite the high temperatures, 800 F, at the surface. (Harmon, J. K., and M.A. Slade, Science Volume 258, 640-643, 1992)
(Campbell, D. B. et al. Science, Volume 246, 373, 1989)
- Arp 220 is a merger undergoing a burst of star formation; the population inversion is produced by IR radiation from dust.
- In subsequent observations, an entire planetary system was found around the pulsar PSR 1257+12. (Wolszczan, A. and Frail, D. A. 1992, Nature, Volume 355, p. 145-147)
- Optical images show only the top of the thick cloud layer.
- Up to this day, no other radar target has shown as high backscattering enhancement as the Galilean Moons. (Campbell, D. B. et al. Science, Volume 196, 650-653, 1977)
- The target was the near-Earth asteroid 1580 Betulia. (Pettengill, G. H. et al. Icarus, Volume 40, pp. 350-354, 1979)
- The 1993 Nobel Prize in Physics was awarded to Hulse and Taylor for this discovery. (Hulse R A 1994 Review of Modern Physics, Volumen, 66, 699.)
- The Arecibo message is an interstellar radio message carrying basic information about humanity and Earth that was sent to globular star cluster M13 in 1974. It was meant as a demonstration of human technological achievement. The content of the message was designed by Frank Drake in collaboration with Carl Sagan and others.
- (Thompson, T. W., Icarus, 13, 3, p. 363-370, 1970; Campbell, D. B., et al. Science, Volume, 170, Issue 3962, pp. 1090-1092, 1970)
- Only sporadic radio pulses from the Crab nebula supernova remnant were know before Arecibo.
- Radar ranging of Venus and Mercury precisely determines the value of the astronomical unit, setting the scale of the Universe. (Dyce, B. R. et al. Astronomical Journal, Volume 72, p. 351, 1967; Muhleman, D. O., et al., Astronomical Journal, Volume 67, 191, 1962)
- The rotation is not tidally locked, but rather, the rate is an orbital resonance with 2 orbits for every 3 rotations. (Pettengill, G. H. and Dyce, R. B. Nature, Volume 206, 4990, pp. 1240, 1965).