Scanning the Internet for External Cloud Exposures via SSL Certs
Mace2010
1. Martino Nicolini
CARA Project (Cometary Archive for Amateur Astronomer)
Osservatorio Astronomico di Cavezzo (MPC 107) – Italy
Two algorithms to enhance
cometary comae
morphology
MACE 2010
Višnjan/Tićan, Croatia
May, 21-23, 2010
2. Digital Image Processing For Cometary Morphology
Log 10 Intensities
It is the simplest operation. To alter the intensity scale by some non
linear contrast stretch, such as the base 10 logarithm to suppress the
steep intensity peak near the photocenter.
I (x,y) = log I0(x,y)
C/2002 V1 (NEAT) - Red Filter - 26 Jan 2003 - Oss. di Cavezzo - Italy
3. Digital Image Processing For Cometary Morphology
Spatial derivatives
Spatial derivatives, or “shift difference” algorithms enhance intensity
discontinuities, but only in the direction of the shift.
I (x,y) = I0(x,y) - I0(x+n,y+m)
5000 km
I (x,y) = I0(x,y) - I0(x+1,y)
I (x,y) = I0(x,y) - I0(x,y+1)
Scale : 2.15 “/pixel
C/1996 B2 (Hyakutake)
Unfiltered - 28 Mar 1996
Observatory of Cavezzo
Italy
4. Digital Image Processing For Cometary Morphology
Radial and Rotational Shift-difference
Particles generally move radially away from the nucleus then it is better to use
a polar reference and to develop a radial and rotational shift-difference
algorithm (Larson & Sekanina, 1984).
I (r,θ) = I0(r,θ) - I0(r+Δr,θ+Δθ)
Where Δr = radial shift and Δθ = rotational shift.
Unprocessed image
C/1996 B2 (Hyakutake)
Unfiltered - 28 Mar 1996
Observatory of Cavezzo
Italy
5. Digital Image Processing For Cometary Morphology
Radial and Rotational Shift-difference
Particles generally move radially away from the nucleus then it is better to use
a polar reference and to develop a radial and rotational shift-difference
algorithm (Larson & Sekanina, 1984).
I (r,θ) = I0(r,θ) - I0(r+Δr,θ+Δθ)
Where Δr = radial shift and Δθ = rotational shift.
LS : Δr = 2.5
Δθ = 15°
C/1996 B2 (Hyakutake)
Unfiltered - 28 Mar 1996
Observatory of Cavezzo
Italy
6. A new approach…
Classical image processing techniques using derivatives and/or
convolution kernels are extremely invasive and often sources of
artifacts.
Which details are “really” real?. And how can measure
these details in a processed image?
We need a different approach to process cometary images:
We can build a “coma model” directly from the unprocessed
image ... in 2 ways:
7. Digital Coma Models
Radial Weighted Model (R.W.M.)
Based on the work “SPATIAL DISTRIBUTION OF THE DUST COLOR IN
COMET C/2000 WM1 (LINEAR)“ byTanyu Bonev and Klaus Jockers
The algorithm extract the pixel values from the comet coma, it will
subtracts the background value from each of them and multiply this
value with the cometocentric distance (the distance from the
optocenter of the comet). Then it builds pixel x pixel a new synthetic
image with these values.
Median Coma Model (M.C.M.)
From the coma center to a radius R (user defined), the algorithm will map
the pixels intensity of concentric circles starting from the optocenter of
the comet: then it will compute the median value for each set of pixel
of the same circle and built another image with a synthetic circular
coma.
8. Radial Weighted Model - Implementation
Developed as an Astroart
Plug-in:
http://www.msb-astroart.com/
Free source code
(Delphi Pascal)
at:
http://cara.uai.it/
9. Radial Weighted Model (R.W.M.) – The Algorithm
1 - Find the optocenter of the coma
2 – Determine the background value (BG)
(BG)
of the image.
R
3 – Start a scan of the image pixel x pixel.
For each pixel (value = I[x,y] ) subtract the
BG value and calculate the distance
R from the optocenter.
Multiply R(I[x,y] -BG) to obtain the
new value I’[x,y] .
optocenter
4 – Create a new comet image with the
new values I’[x,y] .
C/2004 Q2 (Machholz) Filter @650 nm 10 nm FWHM - 5 Jan 2005
0.4m. Newton Observatory of Cavezzo Italy
10. Radial Weighted Model (R.W.M.) – Example
C/2000 WM1 (LINEAR)
2001-12-06T20:04:12
Unfiltered
0.4m. Newton
Observatory of Cavezzo
Italy
R.W.M. Model
The image above is multiplied
here with the projected radial
distance to the nucleus. This
procedure removes the mean 1/r
gradient in the images and
enhances the radial structures.
11. MedComet Coma Model - Implementation
Free source code
(Delphi Pascal)
at:
http://cara.uai.it/
12. Median Coma Model (M.C.M.) – The Algorithm
1 - Find the optocenter of the coma
2 – From the optocenter to a desired
radius R, extract the pixel values on a
series of circles
3 – Each circle is a vector of pixel values:
calculate the MEDIAN value for each
vector of values.
4 – With each median value calculated,
build a circle of the same brightness
in the same place to obtain a
synthetic coma model of the desired
radius R.
R
optocenter
5 – Subtract the model from the original
or….
6 – Divide the model from the original.
C/2004 Q2 (Machholz) Filter @650 nm 10 nm FWHM - 3 Jan 2005
Observatory of Cavezzo Italy
14. Median Coma Model (M.C.M.) – Examples
7000 miles (11265 km)
5’
17P/Holmes 4 Nov 2007 HST WFPC2 NASA, ESA,
H. Weaver (Johns Hopkins University Applied Physics Lab)
and A. Dyer
STScI-PRC07-40
C/2004 Q2 (Machholz) Filter @650 nm 10 nm FWHM
3 Jan 2005 Observatory of Cavezzo Italy
Scale 2.24”/pixel – 1 pixel = 564 km
15. Median Coma Model (M.C.M.) – Examples
Click on the image to start the movie
C/2004 Q2 (Machholz) Filter @650 nm 10 nm FWHM (dust continuum)
3 Jan 2005 Observatory of Cavezzo Italy
Scale 2.24”/pixel – 1 pixel = 564 km
16. Median Coma Model (M.C.M.) – Examples
Click on the image to start the movie
C/2004 Q2 (Machholz) Filter @405 nm 10 nm FWHM (C3)
3 Jan 2005 Observatory of Cavezzo Italy
Scale 2.24”/pixel – 1 pixel = 564 km
17. Median Coma Model (M.C.M.) – Examples
20 March
17 March
C/2007 Q3 (SIDING SPRING) Filter: Bessel R
17 Mar 2010 Nick Howes (2 mt. Faulkes Telescope North)
Scale 0.27”/pixel – 1 pixel = 482 km
18. Median Coma Model (M.C.M.) – Examples
5.5 arcsec ( about 9600 km.)
C/2007 Q3 (SIDING SPRING) Filter: Bessel R
27 Mar 2010 Nick Howes (2 mt. Faulkes Telescope North)
19. Median Coma Model (M.C.M.) – Examples
Click on the image to start the movie
C/2007 Q3 (SIDING SPRING) Filter: Bessel R
17-20-27 Mar 2010 & 2-12 April 2010 Nick Howes (2 mt. Faulkes Telescope
20. Median Coma Model (M.C.M.) – Examples
C/2007 Q3 (SIDING SPRING)
Luca Buzzi
March, 27
2X
Danilo Pivato
March, 17
2X
200,000 km
200,000 km
21. Digital Coma Models – Examples
Comet P/2010 H2 (Vales)
30 April 2010
Faulkes Telescope North
Scale:
0.2785 [arcsec/pixel]
Credits:
Richard Miles
(B.A.A.)
22. Digital Coma Models – Examples
Comet P/2010 H2 (Vales)
480 sec R filter, May 1, resolution 0.93 arc sec/pixel, tracked on comet
M.C.M
Credit: J. Skvarc, Crni Vrh Observatory
R.W.M
il CBAT ha pubblicato sulla IAUC nr. 9135 una nota sullo splitting della C/2007 Q3, di cui si era parlato anche in questa lista. Si dice che F. Colas (Observatoire de Paris) ha inoltrato un rapporto di F. Manzini (Sozzago, Italy) in cui il 13 Marzo si notava la presena di un frammento di 18.ma magnitudine, e di uno ancora più debole. Il follow-up effettuato da Colas stesso il 14 Marzo, col telescopio da 1-m del Pic du Midi, confermava la presenza del frammento di 18.ma magn, circa 6 arcsec in PA 240 gradi. Altre conferme sono arrivate da N. J. Howes (Faulkes Telescope North) il 17 Marzo (che poi non lo trova più il 12 Aprile, suggerendo una sua disintegrazione) e dal nostro Erik Bryssinck, che il 19 Marzo ha trovato il frammento a 5,5 arcsec in PA 258 (complimenti Erik!).
