Titan

It is important, that the right filters are chosen for the observation. Specially, we have to consider, to use the same spectral filtering for all cameras which are contributing.

Here are some points for the discussion:

Folding the spectral responsivity of the TC245 chip (from Texas Instruments Data book) with the spectral curves of the filters (from Schott Filter Handbook) the following resulting relative spectral responsitivities can be calculated:

Spectral Response of TC245 and Filters

The same has been done for the ICX098 BL, a chip which can replace the ICX098 BQ, which is in many Webcams, such as the Toucam Pro 740K from Phillips and the Logitech Quickcam Pro 4000. At the moment the ICX098BL can not be delivered, but it is expected, that the chip is available again at the end of October.

ICX098 Relative Spectral response

The star HD 188105 = TYC 1058-120-1 = HIP 97859 has approximatively the same color as the first star to be occulted. The spectral class of HD 188105 is K0, with magnitudes of 8m8 (B) and 7m63 (V). This is about one magnitude brighter as the first star of the occultation.

Using different filters BG12 (1mm), BG39 (1mm), RG630 (3mm), RG715 (3mm), RG780 (3mm) and RG9 (3mm) this star has been imaged using the standard Iota Occultation Camera (IOC) with an exposure time of 0.22 seconds.

For the differents filters the following numbers of electrons have been measured for the IOC using an 11 inch Schmidt-Cassegrain telescope. An airmass correction has not been applied, all measurements have been carried out at zenit distance not larger than 60 degrees.

Filter used	electrons	calc. e- for occ. star
Unfiltered	80000	32000
BG12	3400	1400
BG39	19000	7600
RG630	45000	18000
RG715	25000	10000
RG780	12000	4800
RG9	24000	9600

Data for the ICX098 BL chip and the Toucam will be published soon.

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Last changed on 16th of September 2003