Scope and Contents Correspondence with Brian Marsden of the Yale University Observatory, and subsequently the Smithsonian Institute, regarding many topics in the field of cometary orbits, including Comets Harrington-Wirtanen, Tempel-Swift, Halley and many others; cometary calculations by the IBM-650 electronic computer, with the program according to Väisälä's method; the Newton-Raphson method for the solution of Kepler's Equation; computer calculations of nearly parabolic orbits; the designation of comets by a...

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Correspondence with Elizabeth Roemer of the U.S. Naval Observatory, and subsequently of the University of Arizona, Flagstaff, regarding, among other matters, Comet Pons-Winnecke, with reports on I.A.U. Commission 20, the working group on comets and the international composition of Commission 20.

Scope and Contents Correspondence with Reginald L. Waterfield regarding problems relating to the measurements of photographic plates featuring comets and concerning the calculations connected to this; refraction corrections for stellar positions and the reduction of their coordinates as measured from photographic plates; the International Astronomical Union meeting at Brighton in July 1970 and Waterfield's desire to meet Brian Marsden and Elizabeth Roemer there; the fact that in November 1970 plates of Comet...

Scope and Contents Two copies of Porter's script for 'The Night Sky in August' on meteors originating in outer space, rather than as an atmospheric phenomenon, and Thomas Jefferson's opinion on this idea; Venus being at inferior conjunction on 1 September, Mars being also at conjunction, Jupiter and Saturn being visible in the evenings, and Mercury being visible in the mornings at the end of the month; Pegasus, Andromeda, the Pleiades and Aldebaran; Perseus and the Perseids, and the shift in the date of the...

Scope and Contents An annotated copy of Porter's script for 'The Night Sky in December' on the year in retrospect; Venus, a morning star; Jupiter near Castor and Pollux; the constellations of Perseus, the mythology of the Milky Way, the aspect of the stars near Mirfak and star clusters in Perseus; Algol and the Pleiades, Arabic star names, and the variability of Algol discovered by Goodricke; Goodricke's achievements, the explanation of eclipsing binaries and the timing of Algol's maxima; the light-time across...

Scope and Contents An annotated, incomplete copy of Porter's script for 'The Night Sky in December' on the seventh comet of the year, Dr Roemer's second recovery of a comet this year, the Flagstaff Observatory, and a review of the 1957 comets (Encke, Mrkos, Reinmuth and Harrington), as well as Arend-Roland (a comet dated 1956); Venus very conspicuous in the south-west at sunset and visible at midday for an observer who knows where to look; the brilliance of this planet, its phases and its elongations; its...

Scope and Contents A copy of Porter's script for 'The Night Sky in October' on the winter constellations now becoming visible to the east before midnight - Orion, Taurus and Aldebaran with the Pleiades, Gemini with Castor, and Pollux; Mars being in Gemini, as bright as Capella; Sirius rising after midnight to rival Mars in brightness; the eleven comets discovered in 1960, three new and eight returned, six of the total found by Dr Elizabeth Roemer at the Flagstaff Observatory; this Observatory, the unpopularity...

Scope and Contents An annotated copy of Porter's script for 'The Night Sky in September' on the Harvest Moon rising at the same time each evening; Jupiter's moons and the discovery of the 12th moon at the Mount Wilson Observatory in the previous year; the orbits of the four larger moons; Jupiter in Taurus near the Pleiades; the apparent retrograde motion of the planets; the epicycle theory and its overthrow by observation of Jupiter's moons; Milton and Galileo, Roemer and the velocity of light and its finite...