Linear feature detection algorithm for astronomical surveys – II. Defocusing effects on meteor tracks

Abstract

Given the current limited knowledge of meteor plasma micro-physics and its interaction with the surrounding atmosphere and ionosphere, meteors are a highly interesting observational target for high-resolution wide-field astronomical surveys. Such surveys are capable of resolving the physical size of meteor plasma heads, but they produce large volumes of images that need to be automatically inspected for possible existence of long linear features produced by meteors. Here we show how big aperture sky survey telescopes detect meteors as defocused tracks with a central brightness depression. We derive an analytic expression for a defocused point source meteor track and use it to calculate brightness profiles of meteors modeled as uniform brightness disks. We apply our modeling to meteor images as seen by the SDSS and LSST telescopes. The expression is validated by Monte Carlo ray-tracing simulations of photons traveling through the atmosphere and the LSST telescope optics. We show that estimates of the meteor distance and size can be extracted from the measured FWHM and the strength of the central dip in the observed brightness profile. However, this extraction becomes difficult when the defocused meteor track is distorted by the atmospheric seeing or contaminated by a long lasting glowing meteor trail. The FWHM of satellites tracks is distinctly narrower than meteor values, which enables removal of a possible confusion between satellites and meteors.

Discovering Earth’s transient moons with the Large Synoptic Survey Telescope

“…Similarly to artificial satellites in LEO, meteor PSFs will be out of focus. Meteor PSFs will also be wider than those of artificial satellites in LEO due to the plasma cloud surrounding them during the atmospheric entry (Bektešević et al, 2018). There is thus a negligible possibility that TCOs and meteors are confused with each other.…”

Luminosity function of faint sporadic meteors measured with a wide-field CMOS mosaic camera Tomo-e PM

“…The projected profile of the meteor was obtained by averaging the signal along with the streak. The projected profile was broad and sometimes double-peaked since meteors were usually defocused [3]. The line-intensity of the meteor, Ĩ in units of ADU pix −1 , was measured by fitting the projected profile with a combination of Gaussian profiles.…”

The challenges in hypervelocity microphysics research on meteoroid impacts into the atmosphere

“…For example, meteors are integrated into the science case for EISCAT_3D (McCrea et al, 2015), a large radar system in Scandinavia (with separate stations in Norway, Sweden, and Finland) for the scientific study of the Earth's atmosphere and ionosphere. Similarly, Bektešević, Vinković, Rasmussen, and Ivezić (2018) showed how the LSST telescope (Legacy Survey of Space and Time, n.d.) will resolve meteors and be a great instrument for studying meteors. However, the incorporation of meteor science into large astronomical facilities requires a significant investment into Big Data tools to extract the meteor data-from algorithms to dedicated personnel (Vinković et al, 2016).…”