Re: Sky Quality Meter

[Doug Welch <welch@physics.mcmaster.ca>]

Hi Richard,

The acceptance angle is mentioned in the FAQ. The "effective solid 
angle" is 1.53 steradians or
roughly a cone half-angle of 40 degrees. The reasons for this are listed 
in the FAQ. There is
some responsivity at higher angles.

Cheers,
Doug

Richard Miles wrote:

> Doug,
>
> The features listed on the website do not quote the acceptance angle 
> of the lightmeter.  Can you say what the size of the acceptance cone 
> is?  I imagine it subtends about 30 degrees or thereabouts.
>
> Thank you,
> Richard Miles
>
> ----- Original Message ----- From: "Doug Welch" 
> <welch@physics.mcmaster.ca>
> To: "TASS List" <tass@listserv.wwa.com>
> Sent: Monday, June 13, 2005 5:07 PM
> Subject: Sky Quality Meter
>
>
>>
>> Folks,
>>
>> Anthony Tekatch and I have developed a sensitive, handhelp meter for 
>> measuring the
>> brightness of the night sky. Please visit the webpage below and read 
>> the FAQ if you would
>> like to know specifics. (Of course, I would be happy to answer 
>> questions off-list, too!)
>> This seems like the sort of thing TASS folk might be interested in, 
>> so I hope you'll forgive me for
>> posting it here. Feel free to pass it along to anyone else that you 
>> thing might be interested!
>>
>> Cheers,
>> Doug
>>
>> ========================================================================= 
>>
>>
>> We wish to announce the availability of a reasonably-priced,
>> handheld meter for measuring the brightness of the zenith
>> sky at night. This meter displays the surface brightness
>> of the sky in visual magnitudes per square arcsec and can
>> be used at even the darkest sites to obtain precise
>> measurements. It is ideal for light pollution studies and
>> site selection.
>>
>> Use of the "Sky Quality Meter" is simple - point it at the
>> zenith, push the single button once, and the sky surface
>> brightness appears on the LED display.
>>
>> The "Sky Quality Meter" contains a very sensitive, solid-state
>> light sensor which is interfaced with a microcontroller
>> and temperature sensor to correct for temperature-induced
>> changes to the microcontroller oscillator and the sensor
>> dark current. An infrared blocking filter restricts the
>> sensitivity of the device to the visual bandpass. The meter
>> is designed for long battery life and automatically shuts
>> itself off after making a measurement.
>>
>> For additional features and ordering information please
>> visit the webpage:
>>     http://www.unihedron.com/projects/darksky/
>> A mailing list has been formed for SQM users.
>>
>> Individual units sell for US$79.99 plus shipping.
>> (A 9V battery *is* included!)
>>
>> We look forward to your potential orders!
>>
>> Anthony Tekatch, Unihedron
>> Lawrence Ave.
>> Grimsby, ON   L3M 2L9
>> CANADA
>>
>> Tel: (905) 741-9458
>> E-mail: sales@unihedron.com
>>