To better illustrate the functionality and effectiveness of the filter MCM, we analyze an image captured by Nick Howes the Faulkes Telescope North (full remote control of a telescope with a diameter of 2 m at the place in Hawaii ' Haleakala Observatory and run by LCOGT ). The comet is the subject of recovery time C/2007 Q3 (Siding Spring).
Again, as you can see from the trace of the fixed stars, it is actually a composite image of the sum of 11 frames taken with a standard red filter (Bessel) broadband. But the remarkable thing is the image of this sample: 0.2785 arcseconds / pixel with an average seeing of 1.3 arc seconds! (In fact, quite normal for the skies of Hawaii). Fantastic! It seems that the "Professor" of FTN have taken at my remarks on the principle of Nyquist . It is therefore a series of images taken in poor conditions that we hardly can find Italian amateurs (including 2-meter telescope ...).
Well, if we apply the filter to the MCM crown of this comet, that's what we discover:
In the short clip above we can see in black and white original image and its transformation in false colors after applying the filter. It appears evident in the lower right to the presence of the fragment abscission from the nucleus of the comet, together with an area of \u200b\u200bstrong activity.
In the film, Below is a longer sequence formed by the images taken on 17-20-27 in March and April 2 to 12: You can note the progressive attenuation of the event.
As for those who understand English very close to Nick Howes, here is an interview about it on YouTube:
Finally, there report some considerations Giannantonio Milani, head of the Research Section of Comets UAI e coordinatore del gruppo CARA , riguardo all'utilizzo e al funzionamento del filtro M.C.M.:
In linea teorica un nucleo sferico che emette polveri in tutte le direzioni a velocità e quantità costante dovrebbe creare una chioma perfettamente simmetrica e , in questi caso, se applicassimo il filtro MCM otterremmo una chioma "regolare" sostanzialmente identica all'originale.
Ma l'effetto di accelerazione dovuto alla pressione di radiazione solare sui grani di polvere e il fatto che i nuclei cometari non emettano gas e polveri in modo isotropo, rende spesso le chiome cometarie tutt'altro che simmetriche. A questo possiamo anche aggiungere gli effetti dovuti the perspective and the way in which our line of sight 'to and positioned relative to the Sun to the details of the coma.
The MCM, creating us a head "regular", which represents the average performance of real hair, there permatte to highlight even small inhomogeneities in the crown.
Often we have an excess of brightness' in the direction of the Sun, at the day side of the nucleus more excited by solar radiation.
But sometimes, as in the presence of phenomena of disintegration of the nucleus, we also find an excess of brightness in the tail.
The interpretation is never easy or obvious and is complicated by the fact that the observations are generally made with broad band filters (BVRI or RGB) that do not strictly discriminate between gaseous emissions and dust.
In the blue and green in the active comets we have often a strong gaseous contamination in red longer dominate the dust emission but may still be present in both the foliage in the queue.
interpretations of images without filters are even more problematic because not at all selective.
more effective results from a scientific point of view would require the use of narrow band filters which, however, is subject to several additional problems, including calibration and il fatto di dover avere una cometa luminosa per raggiungere un elevato rapporto segnale/rumore.
L' MCM non fornisce di norma un andamento 1/r ma ci si può aspettare che in generale non se ne discosti troppo, salvo in caso di eventi peculiari come frammentazioni del nucleo, outburst, ecc..
la formula più corretta potrebbe essere 1/r^n con n=1 se ovviamente fossimo uguali a 1/r.
In caso di evidenti disomogeneità però non rispetterà esattamente neppure questa formula, che sarà tuttavia indicativa.
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