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Dennis Rawlins (1937 Baltimore, Maryland, U.S. –) is an American astronomer, historian, and publisher. He has investigated several scientific causes célèbres, and made proposals and recommendations that seemed far-fetched originally, but have become scientific orthodoxy in the course of time.

In 1996, Ohio State University invited Rawlins to examine the newly recovered diary of Richard E. Byrd, which contained at critical points erased but still legible altitudes observed by sextant. Rawlins discovered the uncontested fact that these placed Byrd roughly 100 miles south of where his official report put him at the corresponding times. Rawlins thus concluded that despite navigating successfully for most of the necessary distance, Byrd's effort had also fallen short, and that therefore the Norwegian explorer Roald Amundsen, fourth claimant to the North Pole, was first to genuinely reach it, on May 12, 1926. Given that Amundsen is undisputed first attainer of the South Pole, Rawlins announced that Amundsen was thus first to each geographical pole of the earth. When in 1973 Rawlins had published this opinion in his Peary book's final chapter, it had appeared extreme; however, that Amundsen has the first verifiable claim to each pole is now the majority opinion among polar experts.

Rawlins's detailed report on Byrd's trip and on the competence of lingering defenses of it was co-published in 2000 by the University of Cambridge adding the new finding that Byrd's long-suppressed original June 1926 report to the Secretary of the Navy and the National Geographic Society contained alleged raw sextant readings entirely given to 1" precision; it is uncontended that such precision was not possible on Byrd's standard portable sextant and that it contradicts his 1926 diary, where all sextant observations are expressed to half or quarter arc-minute accuracy.

- Starting in 1967 Rawlins consistently contended that Pluto is far smaller than one earth-mass, the then generally accepted gravitationally based figure, and that its effects upon Uranus and Neptune must be effectively imperceptible in the observational data of that day.
- At this time, he also recovered a lost 1714 observation of Uranus the first addition to the list of pre-discovery planet observations in over a century and the last of Uranus to date.
- In 1970, he extended the E. Brown transformation to discover planetary perturbation's amplitude as a function of distance, graphically and asymptotically.
- Two papers by Rawlins and Max Hammerton (University of Cambridge) produced upper limits on the gravitationally permissible masses of planets beyond Neptune, showing that exterior planets at probable distances were far from giant, suggesting that the main bodies of the solar system may end at Neptune. which has since been found to be the case.
- Pointing to several resemblances of Pluto with Triton, Rawlins proposed in 1973 a mass of Pluto which though too high eventually proved to be closest to the truth among all estimates published by astronomers until the mass of Pluto was accurately ascertained in 1978 through newly discovered Charon's orbit.
- In 1979, Rawlins developed and distributed the first non-series formula for computing atmospheric refraction from zenith to horizon to one percent relative accuracy His altered argument method of simplifying computation of refraction is now widely adopted.
- Soon after, he produced a similar compact formula for Rayleigh extinction.
- Rawlins and Myles Standish (J. P. L., California Inst. of Techn.) showed in successive papers that the 1613 position of Neptune recorded by Galileo probably did not contradict modern theory.
- Rawlins originated and programmed the standard method of analytically determining the dimensions and axes of the solar tidal ellipsoid produced by the combined gravitation of all the planets, speculating that such analysis might also assist in explaining the behavior of some irregular variable multiple stars.
- Starting in the early 1980s, Rawlins argued that the long history of scholarly disagreements over which lunar eclipse reports from the classical era were valid for gauging secular earth spin behavior was unnecessary, since centuries of untroubled ancient use of the synodic lunar tables surviving in the Almagest showed that they could be employed as an empirical average. He also suggested that the accuracy of the Almagest tables of the synodic motion of Mars might offer a similar if less sensitive check of modern theory.
- While attempting (1982-1991) to reconstruct Hipparchus's solar and lunar theories, Rawlins showed that the length of the year preserved on the important Babylonian System B astronomical cuneiform text BM55555 was based upon well known Greek solstices and thereby revealed the previously long disputed time of day of Hipparchus's dawn June 26, 135 B. C. E. summer solstice. (Explicitly on the basis of this proposal, BM55555 has since been placed on permanent display at the British Museum.) This permits a rough check upon the modern theory of the sun's motion independent of eclipses. Likewise for Rawlins's reconstruction of Callippus's dawn June 28, 330 B. C. E. solstice.
- Rawlins has noted a peculiarity of the solar system which he contends may contribute to solving its origin; the only two twin pairs of planets are contiguous, relatively close to each other, and their inner members are the only planets that rotate in retrograde; the suggestion follows that Mercury and Pluto (smallest and most eccentric of the traditional solar system's planets) might be escaped satellites respectively of Venus and Neptune.
- His further developments of formulas for atmospheric refraction, and for Rayleigh, ozone, and aerosols extinction appeared in the 1990s; later refined by Keith Pickering
- While establishing (1987-94) the standard critical edition of Tycho Brahe's catalogue of stars, Rawlins noticed and incorporated the fact that Brahe's data were consistent with virtually zero aerosols on the nights when dim stars were observed, a finding which relates to current debates on environmental degradation trends. This point was tested and made conservatively quantitative by K. Pickering.

- The Great Pyramid was probably oriented ca. 2600 B. C. E. by using at winter solstice the star 10i Draconis (previously unnoticed in the ever accumulating pile of mostly dubious Great Pyramid literature, which Rawlins facetiously calls "the Greater Pyramid").
- Recognizing in two ancient lists of year lengths the oldest surviving data in continued fraction form, Rawlins proposed that these indicate that ca. 280 B. C. E., heliocentrist astronomer Aristarchus of Samos discovered precession over a century before Hipparchus, deriving the same faulty 1° per century estimate later adopted by the heretofore-accepted discoverer.
- The slim surviving calendar data associated with Aristarchus suggest that he possessed and maybe originated the very accurate so-called Babylonian month (29 days 12 hours 44 minutes 3⅓ seconds) decades before the earliest known cuneiform hint of it.
- The accuracy of this estimate of the mean month's duration is most convincingly explained by its having been (as stated in Ptolemy's much questioned testimony) computationally based on the uniquely stable eclipse cycle, 4267 synodic months = 4573 anomalistic months, which (dividing by 17) generates the supposedly Babylonian equation 251 synodic months = 269 anomalistic months.
- Until the moon is greater than about 3° distant from quarter phase, curvature in its terminator cannot be discerned by the unaided eye, so assuming Aristarchus knew the eye's limits (he is said to have been a student of human vision) his famous 87° elongation for half moon makes more sense as not a precise angle but a lower bound.
- Aristyllus was long chronologically grouped with fellow Alexandrian Timocharis (ca. 300 B. C. E.), the other earliest known observer of star declinations, and thus mis-dated about forty years early. His date was fixed by least squares to ca. 260 B. C. E. , showing that his previously denigrated accuracy was actually among the ancients' best. The same analysis also finds Aristyllus's probable latitude, and shows that his estimate of it was accurate to about 1'.
- The successive lunar distances of Hipparchus (ca. 140 B. C. E.), 3144 and 3122½, heretofore elaborately investigated without satisfactory fit, can both be exactly elicited in two lines of secondary school trigonometry, using Aristarchus's 87° half moon elongation, and are consistent with a hypothesis of ancient incorporation of heliocentrist astronomical measure .
- Recognition of a mean longitude of the sun computed by Hipparchus for May 2, 127 B. C. E., inadvertently preserved by Ptolemy's careless plagiarism .
- Recovery of two lost Hipparchus orbits of the sun's motion, a crude early one and a refined last one.
- Proposing that the central equation of Babylon's System A, 6247 synodic months = 6695 anomalistic months, was based on an eclipse relation about 1010 years long, from just dividing by 2 the 12,494 months elapsed between then contemporary lunar eclipses and corresponding very ancient, now lost Babylonian lunar eclipse reports. Pairs of eclipses thus separated are so infrequent that the only two available to the Seleukid empire which birthed System A were November 23, 1292 versus January 16, 281 and December 5, 1274 versus January 26, 263 B. C. E. The earliest certain System A cuneiform tablet is dated to 263 B. C. E.
- Among indications of Hipparchus's early use of spherical trigonometry are his climata, his tables for parallax, and a 1994 proposed solution of the long-vexing source of atypical randomness of fractional endings of the southern longitudes in Hipparchus's stellar catalogue.
- There is a hitherto submerged problem with Otto Neugebauer's and other panBabylonianists' long reigning conventional belief that Ptolemy mis-attributed the extremely accurate equation 5458 synodic months = 5923 draconitic months to Hipparchus instead of to declining Babylon's astrologers, since the only explicitly dated cuneiform tablet computationally based upon this ratio is from 103 B. C. E., which is after Hipparchus.
- The 5458 month equation in question could have been found by dividing 5/2 into the large apogee-perigee eclipse relation 13,645 synodic months = 14,807½ draconitic months, which is 14,623½ anomalistic months long or about 1103 years. Exceptionally, one of Hipparchus's few surviving eclipse records, January 27, 141 B. C. E., will work with this equation. The equation is cited to him by Ptolemy, and Hipparchus is the only astronomer known ever to have used an apogee-perigee eclipse relation (half integral in anomaly); but no record survives today of the required prior eclipse of November 13, 1245 B. C. E. or indeed of any other eclipse even nearly this ancient.
- The planetary data of Pliny are inconsistent with geocentric astronomy but compatible with heliocentric astronomy.
- Elementary and undisputed chronological evidence shows that Ptolemy's adoption of his orbital parameters was not based upon his purported empirical justification of them.
- Persistent doubts of the -7.5° remainder for the 4267 month eclipse relation (see above) underlying the canonical ancient tables of the moon's mean motion are found to be based upon previous investigators' failure to use the appropriate anomalistic year when computationally checking it.
- Ptolemy's remarkably accurate last lunisolar equation (ca. 160 C. E.), 8523 Metonic years = 105,416 synodic months, is consistent to its full high precision with having been intelligently based upon the 781 sidereal year cycle by which eclipses return to the same star.
- To explain Ptolemy's final equation, 3277 synodic months = 3512 anomalistic months, Rawlins resorted to proposing that it was based upon dividing by 5 an eclipse cycle that is longer than any ever considered as used by ancient Greek astronomers, 16,385 months or about 1,325 years. Parallel to the 13,645 month Rawlins proposal cited above, umbral eclipses recorded by Ptolemy in his era happen to have occurred 16,385 months after prior umbral eclipses, e. g., those of July 11, 1201 B. C. E. and June 12, 1190 B. C. E.; but there are no surviving records of the much earlier events.
- Though Rawlins's calculations are not disputed, most historians do not accept that eclipse data as early as 1292-1190 B. C. E. were known to the hypothesized classical era discoverers of eclipse cycles 1010, 1103, and 1325 years long. They are certain that there is no significance in the coincidence that all three of Rawlins's unambiguous cyclic reconstructions (directly from centuries-separated classical data) via ancients' standard methodology, point to their use of eclipse data from the same slice of time, the 13th century B. C. E.
- Generalizing beyond these still quite controversial cyclic hypothese, Rawlins proposed in 2002 the inclusive theory that all mean motions adopted by genuine ancient astronomers (moon and planets, as well as the sun's sidereal motion) were based upon the simple, reliable, and anciently well attested method of observing and counting integral cycles. When Rawlins in 1980 first questioned centuries of orthodoxy on this issue by imperfectly proposing that all five planets' Almagest mean motions were based on cycles, the idea continued for over 20 years to be not acceptable to historians. In 2003 its truth became undisputed, following A. Jones's unexpected discoveries.
- Rawlins was also long involved in the now concluded controversy over the origin of the star catalogue in the Almagest, discovering strong mechanical and statistical evidence that Hipparchus was the catalogue's primary observer, as had been obvious to most astronomers since Brahe's 1598 accusation that Ptolemy had usurped it.

- Verified, sharpened, and expanded the data base and fit of Aubrey Diller's important 1934 discovery that Strabo's list of Hipparchus's climata (longest day correlated to latitude) are based upon spherical trigonometry in the earliest period to which this branch of mathematics can be traced .
- Discovered and refined a potential common solution to both erroneous ancient earth circumferences, 29000 and 21000 statute miles (the two values used successively by Ptolemy and other ancient mathematicians), suggesting that the former was based upon observations of mountaintop dip or light-house distance visibility, the latter upon multiple sunsets, thus both were corrupted by horizontal light rays' curvature which is 1/6 of the earth's curvature.
- Calculated to 1' precision that Eratosthenes's serious errors for obliquity and for the latitudes of Alexandria and Rhodes could all three be explained as arising from one source, his use of an asymmetric gnomon for his famous altitude of the noon sun at the summer solstice.
- Showed that Strabo's chart of the Nile river is consistent with being the earliest surviving map in spherical coordinates .
- Restoring an ancient scribal error in which 105 ("cv") feet was misread as 100 vnciae ("c v"), Pliny's "circuli" are solvable as a Roman linear fit to an ancient climata table for a Mediterranean interval of latitudes (Greenwich centenary symposium, 1984)
- The list of cities' equinoctial ratios of a gnomon's height to its shadow's length given by Vitruvius is a fit within approximately 1' to a climata table .
- The Giza pyramids, Amarna's Great Aten Temple, Karnak, and Biga Island (legendary sacred tomb of Osiris) lie upon latitudes equal to unit fractions of a circle, respectively 1/12, 1/13, 1/14, and 1/15 which if not a coincidence might imply early Egyptian realization that the earth is round. Rawlins's only venture into the speculative area of archaeoastronomy.
- In 2006, DIO Editor Dennis Duke published online preeminent Indiana University classicist-philologist Aubrey Diller's edition of the final portion of Ptolemy's "Geographia", book eight, in which sites are purposefully positioned by hours, not degrees as in books 2 through 7. Appended is an afterward by Rawlins, to whom Diller had bequeathed the manuscript.
- Rawlins soon after posted (2006 and 2007) the results and theories that had arisen during his own researches into the "Geographia":
- Redating Marinus of Tyre, Ptolemy's cited source for the bulk of the work.
- Tyre is absent from book 8, so Marinus did not author that distinct portion of the "Geographia".
- The traditional equation of the Blessed Islands with the Canary Islands is suspect, since the earliest extant maps of the "Geographia" show islands at 0° longitude that are much more consistent with the location of the Cape Verde Islands.
- Primary cities' "Geographia" latitudes show errors many times larger than ancient astronomers' knowledge of their geographical latitudes because the former were computed by spherical trigonometry from astrological manuals' crudely rounded climata.
- Sign errors in latitude are proposed as the cause of ancient maps' elimination of the Pacific Ocean.

- http://www.dioi.org/cot.htm DIO online - A compact compendium of several hundred of Rawlins's contributions.
- Starbabyby Dennis Rawlins. originally published in Fate Magazine, October 1981

- James Evans (1987). "On the origin of the Ptolemaic star catalogue".
*Journal for the History of Astronomy*18 (3 and 4): 155-172 and 233-278. - Thomas Davies (1990). "New Evidence Places Peary at the Pole".
*National Geographic Magazine*177 (1): 44-61. - D.Rawlins "Evaluating…".
*DIO*1 (1): 7 and 22. - David Dicks (1994). "Pan-Babylonianism Redivivus?".
*DIO*4 (1): 3-13. - Curtis Wilson (1997). "Hipparchus and Spherical Trigonometry".
*DIO*7 (1): 14-15. - William Molett (1998). "Due North? Byrd's Disputed Flight to the Pole".
*Mercator's World*3 (2): 58-63. - Bradley Schaefer (2001). "The Latitude of the Observer of the Almagest Star Catalogue".
*Journal for the History of Astronomy*32 (1): 1-42. - K.Spence "Astronomical Orientation of the Pyramids".
*Nature*412 (6848): 699-700. - Bradley Schaefer (2002). "The Great Ptolemy-Hipparchus Dispute".
*Sky and Telescope*103 (2): 38-44. - D.Rawlins (2003). "DR's … Utterly Unhistorical Mars Fit".
*DIO*11 (2): 29-33 and 41-5. - John Wall (2007). "A Tomb With Latitude?".
*Ancient Egypt*7 (4): 24-26.

- William Warntz (1975). "Peary at the North Pole: Fact or Fiction? by Dennis Rawlins. Review".
*Annals of the Association of American Geographers*65 (1): 79-82. - John Noble Wilford "Did Byrd Reach Pole? His Diary Hints `No'".
*New York Times* - Elly Decker (1998). "Tycho's Star Catalogue: The First Critical Edition. DIO (Special Triple Issue) 3 (1993). Review".
*Annals of Science*53 (4): 423. - John Tierney "Author Says Photo Confirms Mt. McKinley Hoax in 1908".
*New York Times* - Beau Riffenburgh (2000). "Note".
*Polar Record (Scott Polar Research Institute, University of Cambridge)*26 (1): 50. - John Noble Wilford "Star-Crossed Ideas of How Pyramids Came to Point North".
*New York Times* - William Schomaker (2001). "Math Error Sparks Age Debate".
*Astronomy*29 (12): 34. - Hugh Thurston (2002). "Greek Mathematical Astronomy Reconsidered".
*Isis*93 (1): 58-69. - William Sheehan, Nicholas Kollerstrom, Craig B. Waff (2004). "The Case of the Pilfered Planet".
*Scientific American*291 (6): 92-99.

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Last updated on Thursday October 02, 2008 at 14:18:30 PDT (GMT -0700)

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