Observations of Faint Meteors with a Wide-field CMOS Camera

A presentation material in PERC Int'l Symposium on Dust & Parent Bodies 2018.

Transcript

1. Observations of Faint Meteors with a Wide-field CMOS Camera CITech, 2018.02.26-28 IDP2018 Ryou Ohsawa (Univ. of Tokyo) Shigeyuki Sako, Yuki Sarugaku, Fumihiko Usui, Takafumi Ootsubo, Mikiya Sato, Yasunori Fujiwara, Ko Arimatsu, Junichi Watanabe, and the Tomo-e Gozen project
2. Table of Contents 1. Meteor Observations 2. Observations with Tomo-e PM/Kiso Schmidt the size distribution of interplanetary dust particles optical observations of faint meteors introduction of Kiso Observatory and Tomo-e PM detections of faint meteors down to ~10 mag. luminosity function of faint meteors
3. Observation of Meteors Credit: Miloslav Druckmüller & Shadia Habbal
4. Interplanetary Dust Particles Solar system filled with small dust particles (IDPs) Credit: Miloslav Druckmüller & Shadia Habbal Comets & Asteroids: major supplier of IDPs Lifetime of IDPs: less than million years Good tracer of present activities of small bodies Observations of IDPs Zodiacal light (optical, infrared): sub-μm−mm In-situ obsesrvations with satellites: ≪ μm Meteor observations: μm−mm
5. Meteor Observations part of their kinetic energy converted into emission meteor luminosity function ⇉ mass distribution of IDPs brightness ≒ mass of a particle single particle experiments derive characteristics of individual dust particles
6. Meteor Observation Networks CAMS, SonotaCo, Edmond, and CMN mostly supported by amateur astronomers about 1,000,000 meteor orbits have been identified observing down to +4 mag. (~1cm, ~1g)
7. Log Particle Mass (g) Log Cumulative Flux (m-2s-12πstr-1) -12 -10 -8 -6 -4 -2 -0 Satellite Radio Visual s m = 1.55±0.02 s m = 2.03±0.02 s m = 2.62−2.89 Cumulative Mass Distribution of IDPs Cumulative flux of particles to the Earth's surface, adapted from Hughes (1987)
8. 1000 100 10 -2..0 -3.0 -1.0 0.0 +1.0 +2..0 +3.0 +4..0 Photographic Magnitude Cumulative Number Counts: N(<Mpg ) no correction weighted velocity correctied Luminosity Function of Sporadic Meteors Luminosity function with SuperSchmidt camera, adapted from Hawkins & Upton (1958) r = 3.4 log10 N0 = -5.1 log10 N(<M) = Mlog10 r + log10 N0
9. 10 1000 Pulse Height: h (chart units) 10 100 1000 10000 Cumulative Frequency N(>h) N(>h) = kh -1.332 Luminosity Function of Faint Sporadic Meteors Luminosity function with a 10-m reflector and a Phototube, adapted from Cook, et al. (1980) ~12 mag. ~7 mag.
10. Observations of Faint Meteors Important parameters to detect faint meteors: 1. large aperture 2. large field of view 3. video observation to collect as many photons as possible to increase the efficiency in detecting meteors to decrease sky background noise
11. Tomo-e Gozen Project Credit: Miloslav Druckmüller & Shadia Habbal
12. ©d-maps.com Kiso Observatory Chiba Institute of Technology Chiba Institute of Technology Kiso Observatory Kiso Observatory
13. ©d-maps.com Kiso Observatory Chiba Institute of Technology Chiba Institute of Technology Kiso Observatory Kiso Observatory
14. Tomo-e PM the first wide-field mocaic CMOS camera 8 CMOS sensors aligned in the RA direction monitoring ~2deg2 at 2Hz no photometric filter limiting mag.: 18.5 (0.5s) 20.1 (10s)
15. Meteors Detected by Tomo-e PM
16. Meteors Detected by Tomo-e PM N~500px M* lim = 18.5mag. + 2.5log10 t-1θv-1 ~ 14.0 mag. meteor moving effect integration along with the meteor for θ = 1″ .19, v = 10°s-1 + 2.5log10 N0.5
17. Observation with Tomo-e PM
18. Observation Data ＊ Apparent Video rate magnitude (Iye+ 2007) Obs. Date Obs. Field Exposures Filter 2016.04.11 Inside the Earth's shadow 1 set = 0.5s × 360frame Blank # Frames Unique Meteors Mean Rates Magnitudes 290880frm. 1514events ~15events/180s 4.5−12.5mag. ＊ Obs. Time ~5.1hours 2016.04.14 Inside the Earth's shadow 1 set = 0.5s × 360frame Blank 316800frm. 706events ~6.4events/180s 4.5−11.5mag. ~5.5hours
19. 0 5 10 15 20 Number of Events Event Rates (8 chips,180s) on 2016-04-14 0 5 10 15 20 22 24 26 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 zero mag. Observing Time (UT) 22 24 26 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 0 5 10 15 20 25 30 Number of Events Event Rates (8 chips,180s) on 2016-04-11 0 5 10 15 20 25 30 22 24 26 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 zero mag. Observation Time (UT) 22 24 26 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 Unique Meteor Events Timeline Each bar indicates the number of meteor detections in 180s.
20. Video Rate Magnitude 1. Measure the averaged line intensity of a meteor 2. Assume the meteor angular velocity = 10°s-1 3. Convert the line intensity into the intensity for 0.5s 4. Derive the meteor magnitude from field stars Iye et al. (2004) 5. Distance to the meteor was estimated by the elevation angle
21. 0 50 100 150 200 250 Number of Meteros 2016-04-11 0 50 100 150 200 250 0 50 100 150 200 250 2 4 6 8 10 12 Number of Meteros Magnitude (at 100km, V-band) 2016-04-14 0 50 100 150 200 250 2 4 6 8 10 12 Meteor Magnitude Distributions Magnitudes are calibrated at the distance of 100km from the observer. ~0.3mg ~50mg
22. Derived Luminosity Function Parameters 0 2 4 6 8 10 12 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 (×10-2) Frequency Slope Parameter 2016-04-11 2016-04-14 0 2 4 6 8 10 12 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 3.24 3.08 0 2 4 6 8 10 12 -6.2 -6.0 -5.8 -5.6 -5.4 -5.2 -5.0 -4.8 -4.6 (×10-2) Frequency Log Meteor Rate 2016-04-11 2016-04-14 0 2 4 6 8 10 12 -6.2 -6.0 -5.8 -5.6 -5.4 -5.2 -5.0 -4.8 -4.6 -5.59 -5.34 log10 N0 =-5.1 Hawkins&Upton(1958) r = 3.4 Hawkins & Upton (1958)
23. Derived Luminosity Function Parameters 1000 100 10 -2..0 -3.0 -1.0 0.0 +1.0 +2..0 +3.0 +4..0 Photographic Magnitude Cumulative Number Counts: N(<Mpg ) no correction weighted angular velocity correction Hawkins & Upton (1958) Tomo-e PM +10.0 mag.
24. Tomo-e Gozen 21 CMOS sensors monitoring ~5deg2 at 2Hz no photometric filter limiting mag.: 18.5 (0.5s) 20.1 (10s)
25. Tomo-e Gozen FOV
27. Tomo-e Gozen FOV T omo-e Gozen in Feb. 2018 T omo-e Gozen in Feb. 2018
28. Tomo-e Gozen FOV T omo-e Gozen in 2019 photoshopped image T omo-e Gozen in 2019
30. Summary Meteor Observations with Tomo-e PM Tomo-e Gozen with 21 sensors gets ready 2,220 unique meteor events detected in two nights. Tomo-e PM can detected meteors between 4 and 10 mag. The luminosity function was fully consistent with literature. The first-light observation successfully completed in 2018.02. The world most powerful camera(?) to observe faint meteors. Coordinated observations with Kyoto U. MU radar scheduled. Useful as well as in timedomain astronomy of solar system small bodies.
31. An overview of the Tomo-e Gozen camera Tomo-e Gozen Specifications Observatory Kiso Observatory Telescope 1.0-m f/3.1 Schmidt telescope Sensor format 2160×1200pixchip-1 Field of view 39′.7×22′.4 × 84chips Pixel scale 19μm, 1″ .189pix-1 Wavelength 350−700nm (peak at 500nm) Filters optical broadband (transparent) Frame rate 2Hz (max, continuous, full frame) Read noise ~ 1.9e- at 2Hz Dark current ~ 0.1e-sec-1pix-1 at 277K Well depth ~ 6,400e - 5σ lim. mag. ~ 18.5mag. in 0.5sec exposure
32. An Image containing a faint meteor(stellar sources are masked)
33. An Image containing a faint meteor(stellar sources are masked)
34. An Image containing a faint meteor(stellar sources are masked)