Sky Quality Measurements

[Starwiz]

Does anyone know if it's possible to use a camera/telescope combination to derive the sky quality in terms of a number like a Sky Quality Meter would do?

My reasoning is that they both collect photons, which are converted to electrical signals.  The SQM presumably applies an algorithm to the data to come up with a number.

Thanks

John

[Miguel1983]

Hi,

not exactly what you asked, but i use the Dark Sky Meter app on my Iphone, the results are quite accurate, comparing with SQM meter.

As i recall it was only a few €.

[vlaiv]

Of course you can, it is just a matter of calibration.

You can either do calibration with SQM meter, or you can do a bit more serious calibration on stars of known magnitude.

In principle you need to take subs of sky in direction you are interested in, calibrate them, measure mean background ADU values and then scale those by

1. Imaging resolution - arc sec/pixel

2. Photometric measurement of star of known magnitude

It is in principle the same process as relative photometry, except you won't measure brightness of some star compared to star of known magnitude, but rather background level compared to star of known magnitude.

[Starwiz]

Thanks for the info.

John

[geoflewis]

On 18/05/2019 at 11:34, Miguel1983 said:

not exactly what you asked, but i use the Dark Sky Meter app on my Iphone, the results are quite accurate, comparing with SQM meter.

I also use the DSM app.  In my opinion it's a pretty reliable, cheap alternative to a dedicated SQM meter working down to about SQM 21.5.

Edited May 19, 2019 by geoflewis