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Darkness Conditions

Deep-Sky Planner can display darkness conditions on the Equipment/Conditions Bar. This data can be entered manually or read automatically from Unihedron's Sky Quality Meter models LE, LU or LR. Darkness is a very important element in describing sky conditions. Deep-Sky Planner uses this darkness value in the visibility model for extended deep-sky objects.

Darkness Data Source allows you to choose how darkness data is acquired for display on the Equipment/Conditions Bar. There are 3 modes of darkness data acquisition:

▪No Darkness Data disables the display of darkness data on the Equipment/Conditions Bar.

▪Enter Manually allows you to enter darkness data for display on the Equipment/Conditions Bar. This selection is useful if you need to enter data from a push button model Sky Quality Meter, or if you want to enter your naked-eye estimate of the faintest star that you can see at the zenith. Enter the darkness value in Darkness (MPSAS). Data entry is in magnitudes per square arcsecond (MPSAS), but the naked-eye limiting magnitude equivalent is computed and displayed on screen. Darkness (MPSAS) is available only when Enter Manually is selected.

▪Read from SQM allows Deep-Sky Planner to read a darkness value from a connected model of Sky Quality Meter periodically as you observe, and display the result on the Equipment/Conditions Bar. This option is available only if there is a Sky Quality Meter configured and selected (Favorite) in Sky Quality Meters. SQM communication configuration settings, including the reading interval, are specified in Sky Quality Meters.

▪Zone is a color swatch corresponding to MPSAS that represents the darkness zone as used in The New World Atlas of Artificial Sky Brightness (Falchi et al, 2016).

Show Darkness allows you to open a mini-browser to your favorite darkness information web page such as a page created by SQM Reader Pro. A default (local) web page is displayed until you select another page in the mini-browser. The web icon indicates that a live Internet connection may be required for this function.

Press OK to accept the changes.

Press Cancel to discard the changes.

Important: Darkness conditions change throughout an observing session. If you choose to enter darkness data manually, it is recommended that you update the value periodically while you observe.

Important: If you select Read from SQM, a reading is attempted as soon as this dialog box is closed with OK. After the first successful reading is acquired, the system continues to read the device periodically as specified in Sky Quality Meters. If a reading is attempted and it fails, the system will try again at the next scheduled reading time. After a third failed attempt, the system reverts this setting to No Darkness Data.

What About?

If the Read from SQM selection is disabled, there is no SQM configured and selected as Favorite in the system. A meter must be configured and marked Favorite to be used by the SQM reading function. Use Sky Quality Meters to configure a meter and mark it as Favorite.