Auxiliary Telescopes Research Articles

A Survey of the Yellow-Red Interstellar Diffuse Spectrum Lines

A survey of about 100 lines of sight was made using the coudé auxiliary telescope and the coudé spectrograph of the Shane 3m telescope of the Lick Observatory. the data acquisition required 7 observing seasons. the spectra were recorded photographically at 17Ao/mm using a Varo tube intensifier. Each plate was separately calibrated for intensity and wavelength. the plates were measured using the PDS microdensitometer of the Royal Greenwich Observatory, Herstmonceux, and that data reduced on STARLINK using procedures developed by D.W.T. Baines. Care was taken to treat all photographic material in a consistent manner throughout the duration of the survey. the reduced data may therefore be considered self-consistent. the emulsion types used were (principally) Kodak IIIaF and (more rarely) 103aD.

Anomalous [NII]-emission from Mz-3

We obtained high resolution spectra of the red [NII]-lines in the bipolar nebula Mz-3, This object probably is a protoplanetary nebula (see e.g. Lopez and Meaburn, 1983 and Meaburn and Walsh, 1985). The spectra were taken in July and September 1982 at La Silla using the Coudé Auxiliary Telescope (CAT) combined with the Coudé Echelle Spectrograph (CES). The resolution depending on the slit width was 30000 and 100000, respectively. Fig. 1 shows the [NII]-lines at 6583.6 and 6548.3 Å together with Hα. The structure of the 6583.6 Å line, which is quite complicated in detail, is dominated by two narrow peaks, similar to the profiles of circumstellar O H-masers. The profile varies strongly with the slit width and shows substantial differences between the observations in July and September. - The most striking result of our observations is that the intensity ratio 6584/6548 deviates strongly from the canonical value of 3 as shown in Fig. 2.

Coude Auxiliary Telescope: A Low Cost Telescope At European Southern Observatory

The 1.4 m Coude Auxiliary Telescope (CAT) was designed for spectroscopy and will be used in coude focus. The telescope was designed as an "alt-alt" mounting ( i.e., altitude-altitude, which means that when the telescope is vertical, both axes about which it rotates are horizontal), which gives, mechanically, an attractive and inexpensive structure without any need for big counterweight systems. The optical configuration is of the Nasmyth type, with a flat, movable third mirror mounted in the center of the telescope. The main mirror has an f-ratio of f/3. The exit f-ratio is f/120. The telescope, situated in a tower separate from the operating center, is completely remote controlled. Guiding is performed via a low-light-level TV camera on the slit of the Coude Echelle Spectrograph (CES). The identical drive systems for the two axes in the alt-alt mounting are of the direct-drive type, with a torque motor, tacho generator, and encoder connected directly to the shaft without any reduction gear. The positioning system is based to a great extent on microprocessors.

Outburst in U Cephei

A SYSTEMATIC survey of the profiles of the Hα line in binary stars, shell stars, Be stars and related peculiar objects is being conducted by us (and G. J. Peters) with the Varo image intensifier attached to the coude spectrograph of the 120-inch telescope and the 24-inch coude auxiliary telescope of the Lick Observatory. Emission at Hα is found to be a more common Phenomenon among the Algol-type eclipsing binaries than was thought before. Usually, but not always, the emission is best observed during the primary minimum when the light of the hotter and brighter component is either greatly reduced or completely occulted. This is in agreement with the models representing the Algol systems as evolved binaries in which mass is still being transferred from the late-type secondary component to the hotter primary star1,2. Although the general picture is fairly clear, the problem remains how the on-flowing material and its angular momentum are distributed among the primary star, the disk revolving around it and a possible envelope enclosing the whole system. The purpose of our survey is to furnish quantitative data on this process.

Prof. Frantisek Nusl

IN honour of Prof. F. Nusl, director of the National Observatory of Prague and professor in the Charles University, who has entered on his seventieth year, a composite work has been compiled with the title “Prage venovaneDr.FrantiskuNuglovi”. Prof. Null's interest in astronomy is well known; he was vice-president of the International Astronomical Union for the Leyden meeting held in 1928. His circum-zenithal instrument for the determination of time was described before the Czech Academy in Prague (see NATURE, 68, 376; 1903) and also in a number of other papers. Twelve authors have contributed to the volume and their papers embrace a wide range of subjects. Z. Kopal discusses the two-bodies problem where the central body is an oblate spheroid, not homogeneous, and shows that a steady advance of periastron will take place. V. Guth develops a graphical method for determining the heights and paths of meteors, and J. StSpanek has a most interesting paper showing the results of photographing Comet Finsler (1937f) from July 13 until August 15, 1937. It is easy to follow the developments of various parts of the head and tail of the comet by examining these photographs, and also the variations of the different luminous rays. J. Prochazka explains his method for investigating the stability of the Bouty meridional telescope at Paris by means of two auxiliary telescopes provided with micrometers, and has found that the stability of the instrument is excellent. J. Svoboda supplies a detailed account of his experimental method for finding the personal error in observations with the NuSl-Fri8 circum-zenithal instrument. Z. Horák deals with Svoboda's method for determining the radiant of a meteor stream with a minimum of error, and towards the end of his paper shows how very satisfactory results can be obtained by a graphical method. These as well as the other papers, with all of which it is impossible to deal in the limited space, form most interesting reading.