Engineering topics

Young, P.

Publications and source records attributed to Young, P..

5 records

NASA NTRS1981

The triple quasar Q1115+080A, B, C - A quintuple gravitational lens image

Spectroscopy and direct imaging of Q1115+080A, B, C with a CCD camera support the hypothesis that they are gravitational images of a single object. Spectroscopy of the semiforbidden C III 1909-A emission line shows all the images to have identical spectra and redshifts (to within 100 km/s), except that B is slightly redder. Gravitational lens imaging by a massive spiral galaxy is investigated, and a quintuple image model resembling Q1115+080A, B, C is found. In this model, Q1115+080A is a highly magnified close pair of images oriented in the position angle 23 deg. An elongation Q1115+080A at this angle is seen in the CCD pictures.

Young, P.↗

NASA NTRS1981

Q0957+561 - Detailed models of the gravitational lens effect

The galaxy responsible for causing multiple gravitational lens images of QSO Q0957+561 has been reobserved spectroscopically and a more accurate redshift of 0.36 was obtained. In addition, detailed models of the gravitational lens effect were computed. These models, which can explain all optical and radio data for the system, predict delays of up to five years between variations in the A and B images (with A preceding B). It is suggested that the third image is rather faint and located close to the center of the lens galaxy; it is possible that this third image contributes to the observed galaxy core. The possibility that this system can be used to measure the Hubble constant is discussed.

Young, P.↗

NASA NTRS1980

The double quasar Q0957 + 561 A, B - A gravitational lens image formed by a galaxy at z = 0.39

Deep CCD pictures show a rich cluster of galaxies around the double quasar Q0957 + 561 as well as faint extended wings on the image of the southern quasar. Calculations of gravitational imaging by King model mass distributions show that the cluster and the brightest galaxy together, acting as a gravitational lens on the light from a single, more distant QSO, can easily reproduce all of the present observations. It is concluded that the double quasar is almost certainly the multiple image of a single object produced by a gravitational lens.

Young, P.↗

NASA NTRS1980

Design of infrared astronomical satellite /IRAS/ primary mirror mounts

The design of an operational mount to rigidly secure the primary mirror to its baseplate without the introduction of figure error always proves to be a major task on diffraction limited optical systems. A summary of the design of the Infrared Astronomical Satellite (IRAS) primary mirror mount is given. The mirror was designed to be alligned and tested at room temperature and operated in a zero 'g' field at temperatures of 2K. To minimize overstressing, a stiffness requirement of greater than 150 Hz was required for cold launch and room temperature vibration acceptance testing. Additional isolation was required to minimize strains, introduced via the mounting base, due to thermal and mechanical distortions.

Schreibman, M.↗

NASA NTRS1980

Alignment design for a cryogenic telescope

This paper describes the alignment approach for the infrared astronomical satellite (IRAS) optical subsystem from initial design to acceptance testing. The constraints imposed by the requirement of maintaining alignment at 300K and 2K, in a 1-g and 0-g gravitational field, during warm and cold vibration, and during various stages of assembly, are discussed. The paper concludes with the methodology of applying NASTRAN finite element analyses to the alignment design, followed by the verification of the accuracy of the design with the test results.

Young, P.↗