Spectroscopy of Perseid Meteors with an Image Orthicon

Abstract

An image orthicon technique for recording meteors, developed some years ago by Hemenway at the Dudley Observatory, has recently been used at the Springhill Meteor Observatory, Ontario, for the recording of meteor spectra and combined with three other observational techniques—meteor radars, spectrographs, and a team of visual observers. Fifteen meteors, observed with the image orthicon during the August campaign in 1969, are here discussed out of a total of more than forty. Apparent visual magnitudes range from −1 to +3 and all 14 Perseid spectra in this group exhibit the oxygen green line at 5577 Å as well as other atomic lines normally found in the spectra of members of this shower. At the beginning of their trails all meteors show either a strong continuum, or evidence of band structure where the 1st and 2nd positive systems of N2 have been identified with reasonable certainty, while the first negative systems of N2+ and O2+, and the visible system of OH, are possible contributors.Measures of the 5577 Å line indicate a height spread from 120 to 95 km with a maximum near 106 km. After initial formation the intensity of this line increases for 0.2 to 0.5 s, after which it decays over periods up to 2 s. The decay constant for the 1S metastable state of neutral atomic oxygen is 0.76 s−1.The two chief advantages of the image orthicon technique are: its ability to record meteor spectra down to fainter thresholds of luminosity than in the case of conventional spectrography, and the time-resolution given by a recording of 15 complete frames per second.

Detection of the [FORMULA][F][RM]N[/RM][SUP]+[/SUP][INF]2[/INF][/F][/FORMULA] First Negative System in a Bright Leonid Fireball

“…Here we report the discovery of N + 2 B 2 Σ + u → X 2 Σ + g [N + 2 (1-)] in the wavelength range of 320-450 nm meteor emission from a Leonid meteoroid through the investigation of the OH A-X (0,0) band. The N + 2 (1-) plasma emission in meteors has been argued by Millman et al (1971) and Mukhamednazarov & Smirnov (1977). Meanwhile, Jenniskens, & Laux (2004a) found a N + 2 A 2 Π u → X 2 Σ + g Meinel band in the range of 780-840 nm.…”

Metallic abundances of the 2002 Leonid meteor deduced from high-definition TV spectra

“…In this paper, we focus on one spectrum obtained at 03 h 47 m 54 s UT Nov. 19, which is one of the highest quality data sets from the first peak activity of the 2002 Leonids. Altitude at the beginning of the meteor illuminations was estimated to be about 110 km, owing to onset of the [OI] (557 nm) emission (Millman et al 1971). The NASA DC-8 aircraft's position was latitude +48.062…”

One Hundred and Fifteen Years of Meteor Spectroscopy

“…Harvey (1973Harvey ( ,1974) employed a battery of fast Maksutov cameras, aperture ratios f/1.0 and f/1.3, in a systematic program of meteor spectrography carried out in New Mexico, USA; and Hemenway pioneered in the use of electronic image intensification (Hemenway et al 1971) by recording meteor spectra on video tape with image-orthicon equipment at the Dudley Observatory, Albany, NY, USA. o The forbidden line of 0 I at 5577 A was first identified in meteor spectra by Halliday (1958), a line which exhibits a duration of several seconds in the case of bright, fast meteors.…”

“…A detailed study of the spectra of meteor wakes and meteor trains was made possible by the development of the jumping-film camera o (Halliday and Griffin 1963). The decay characteristics of the 5577 A oxygen line were studied, using the jumping-film camera (Gault 1970) and the video-tape records obtained with the image orthicon (Millman et al 1971). An image-intensification system still more sensitive than the image orthicon was first used for meteor spectrography by Clifton in 1972.…”