Engineering topics

Caldwell, John

Publications and source records attributed to Caldwell, John.

22 records · Page 2

NASA NTRS1988

Observations of Neptune and Uranus below 2000 A with the IUE

The present IUE observations of Neptune, together with improved observations of Uranus below 2000 A, indicate excellent agreement between the UV-derived C2H2 abundance and that obtained from independent IR data for Uranus, while for Neptune, the derived IUE C2H2 abundances differ from IR spectra by orders of magnitude. Attention is accordingly given to aspects of IR modeling requiring modification. The agreement for Uranus may be due to approximately global uniformity, while the disagreement for Neptune may have its basis in such spatial variations as a warm summer pole, as well as in inaccuracies in current model temperature profiles.

Caldwell, John↗

NASA NTRS1988

Strong north/south asymmetry in the Jovian stratosphere

Trailed spectra of standard B stars have been used as the 'flat' field light source for spatial calibration of IUE large-aperture observations of the north and south polar regions of Jupiter. Longward of 2000 A, the south polar spectrum is lower than the north polar one by a factor of 2.5; shortward of 2000 A, strong C2H2 absorption appears in both north polar and midlatitude spectra, while neither continuum nor band absorption features of C2H2 appear in the south polar spectrum. The very low reflectivity of the south polar region calls for the presence of a stratospheric absorber at pressures lower than 10 mbar.

Wagener, Richard↗

NASA NTRS1987

The spectra of Uranus and Neptune at 8-14 and 17-23 microns

The 3-m NASA Infrared Telescope Facility was used to observe the disks of Uranus and Neptune between May 30 and June 1, 1985 in the 7-14 and 17-23 micron spectral regions. Maximum stratospheric mixing ratios of 9 x 10 to the -9th for C2H2, and of 2 x 10 to the -8th for C2H6, are found for Uranus, and the spectrum is otherwise smooth, consistent with the opacity provided by H2 collision-induced absorption and spectrally continuous stratospheric emission. Strong emission features of CH4 and C2H6 are found in the short-wavelength spectrum of Neptune, and the spectrum near 13.5 microns is consistent with C2H2 emission in local saturation equilibrium with a maximum mixing ratio of 9 x 10 to the -7th.

Orton, Glenn S.↗

NASA NTRS1987

Infrared radiometry of Uranus and Neptune at 21 and 32 microns

Mauna Kea's NASA IRTF has been used to obtain 21- and 32-cm radiometric measurements of Uranus and Neptune; brightness temperatures of 54.1 + or - 0.3 K for Uranus and 58.1 + or 0.3 K for Neptune were obtained by calibrating the 21-cm data against Alpha Boo. A calibration of the 32-cm data against Callisto and Ganymede yielded respective temperatures of 51.8 + or - 1.5 K and 55.6 + or - 1.2 K. The general decrease of brightness temperatures with wavelength from 20 to 30 microns is confirmed. The two planets are noted to appear as bodies sufficiently different to depart from the hypothesis of smooth planetary bulk property variation as a function of heliocentric distance.

Orton, Glenn S.↗