Lunar Impact workshop ESTEC ESA Center Noordwijk, 2-3 June, 2015
Observation, analysis and results from 56 hours of video survey data observed by using one telescope
Ait Moulay Larbi mamoun PhD student
Atlas Golf Marrakech Observatory 1 Moroccan Observatories
Oukaimeden Observatory Discoveries from Oukaimeden MO““ Ne to teles ope “i e O to er, 2011 : - 4 comets ! : (C/2013 V5 - P/2013 CE31 - C/2012 CH17 - P/2011 W2) - 3 NEA ! : (420478)2012 EQ1,(421365)2013 TE129 and (421400)2013 VD14 2
Lunar Flashes Observation : Instrumental setup
Watec 902H2 Ultimate C14 or C8 Telescope 0.33x or 0.63x Focal reducer Data Acquisition : - high speed and Optics : - “C teles ope or . sensitivity sensor (ICX429 EXveiw HAD CCD - 0.33x or 0.63x Focal reducer. technology). Effe ti e fo al le gth ≈ -1150 mm. GPS antenna Hight speed Camera Watec 902H
USB Videos Time C14 or C8 Celestron Converter inserter Telesope
Computer SCT spacer ring AME TIM-10 Focal reducer 0.33x or 0.63x
3 Detections: • From February, 2013 to December, 2014 : (56±2) hours of high quality video data. - VirtualDub Software : PAL interlaced mode (20fps -> i ; ideo .avi at ×576 pixels. • LunarScan software is used on recorded videos to perform automated detections. -Search for adjacent pixels that have collected a sudden illumination with values that exceed the threshold value defined by the user. -The dark is subtracted before processing. • We process the analysis to the whole field of the view (without masks), because the coordinates stamped by the time inserter are configured to be displayed blackly, and.. we do not want to miss any impact we want some reference stars near the lunar disk.
• False detections: over a thousand detection (more than 90% of them are one frame events • os i ra a d ele tro i oise . Different false detections. Each one appeared in one half-frame (20 ms). Flash movement, The full frames are presented here Bright crater indicates a satellite detection
4 • Feb 6, 2013 • Apr 14, 2013 Mag (V): 9.4 Mag (V): 7.6
Dec 25, 2014 Nov 26, 2014 • • Mag (V):9.6 Mag (V) : 7.1
Four multi-frame sporadic flashes • unfavourable lunar phase + inadequate orbital crossing + weather : have prevented us to observe at the peak of meteor showers By using one telescope ,we estimate to have missed more than 4 short flashes (1 frame)5 Multi-frame flash confirmation : • The light source shines at the same pixels cluster (no motion across the successive frames ) • The surface brightness profile • Light curves profile (sudden signal increase followed by a sharp decrease)
+ +
• The magnitude VS flash duration shows a consistency on the trend revealed in Bouley et al,2012 First remarks: • Among the four flashes, three were detected very close to the terminator. - 2nd flash : 09.10°±0.15 W; 3rd flash : 2.5°±1 W; 4th flash : 17.50°±0.5 E • For the 1st and the 2nd flashes, the peak of intensity is reached at the 2nd half-frame. The expansion phase has lasted more than 20 ms
1st flash : 60 ms
2nd flash : 160 ms
YANAGISAWA AND KISAICHI 2002 • The 3rd flash was shorter but brighter than the 2nd ! • The 3rd flash has quickly peaked; while the plume of 2nd flash has required twice more time to finish its expansion phase. Dur : 160 ms 2nd flash Mag : 7.6
3rd flash Dur : 120 ms Mag : 7.1
This can be explained by the fact that fastest meteoroids have capacity to produce bright and short flashes as clarified in the work of Bouley et al.,2012 in the case of the Leonid impacts. th rd So, It is more likely that the projectile caused the 4 flash is fastest and which of the 3 is larger.7 Measured parameters : Date and Time
Longitude and Latitude Of the site observation
Date Time
first • The impact time : appearance
Raw interlaced frame separate frames Odd row field
Even row field
20h 00min 45s 422ms (± 0.01s)
8 Measured parameters : Flash duration ? 1 2 3 4 5 -> 5 × 40 ms = 200 ms positive Raw sub-images ? ? Deinterlaced Sub-images 1 2 3 4 5 6 7 -> 7 × 20 ms = 140 ms
Check negative -> 8 × 20 ms = 160 ms Raw sub-images
9 Measured parameters : the impact site (to be presented later)
10 Measured parameters : Magnitude 8-bit frame from Watec; Pretreatment of images (Dark, flat) • Pixel value : 0-255
• Aperture photometry flux= sum of pixels values
• flu = flu + a kgrou d − a kgrou d i stru e tal ag itude of a flash = − . × log10(flux)
• During every night of observation and from time to time we record videos of references stars (with known magnitudes), and we measure their instrumental magnitude .
11 Deduced parameters : Luminous energy of impact • The energy received at Earth [J/m2] is appro i ated usi g Pogso ’s for ula : -0.4mv E lum_rec = Exposure time × F0 × 10 - Exposure time = 0.02 s - Mv = V magnitude of the flash -8 2 - F0 = 1,5 10 J/m /s, is the flu fro a zero ag itude star i the a era’s pass- a d ≈ . µ 2 • The radiated energy at the moon is then: E lum_moon = f × π × d × E lum_rec
The emission may be considered hemispherical in early stages of the impact and the expansion phase, but ongoing the expansion it is more isotropic if we take in consideration the elevation of the plume above the ground : 2 < f < 3 ƞ the lu i ous effi ie The impact energy : E × E • impact = ƞ lum_moon the amount of the initial kinetic energy that is Converted into luminous energy
• Nu eri al si ulatio : . < ƞ < . , Artemieva et al. 2000,2001 • Leonids i pa t O ser atio : ƞ = . , the a i u alue k /s ;Bellot Rubio et al. 2000 • More s ar s o ser atio : ƞ= . -3 exp(-9.32/v2); Swift et al. (2011). 6/2/2015 12 Deduced parameters : Diameter of the produced crater
- The diameter of the crater is estimated from the Gault’s scaling law (Melosh, 1989) valid for craters up to 100 m in diameter:
• Inputs parameters : 3 - p Projectile density : to be assumed equal to 3.2 g/cm (sporadic asteroids) 3 - t Target density : to be assumed equal to 1.5 g/cm . - g : lunar gravity. - E : impact energy. - θ : impact angel.