Contents - Index

Cloud Sensor

CCDAutoPilot incorporates support for the Diffraction Limited (Boltwood) Cloud Sensor, version I and version II.  The cloud sensor reports sky conditions as indicated below.  CCDAutoPilot monitors this report via a high performance separate thread to provide immediate response to changing sky conditions.


Sky Conditions

Unknown: The cloud sensor is not reporting sky conditions.  CCDAutoPilot assumes the sky is clear and the run proceeds.  An error condition is logged indicating the unknown sky condition.

Clear: The cloud sensor is reporting a clear sky.  The run proceeds.

Cloudy: Different actions are taken in the event of a cloudy report from the cloud sensor, depending on the selected option.  If CCDAutoPilot is waiting for the clouds to clear and dawn is approaching, then the shutdown tasks will be initiated.

Very Cloudy: the appropriate user-specified shutdown tasks are executed immediately upon the cloud sensor reporting this condition.  A session can not be started if this condition exists.

Wet/Rain: the appropriate user-specified shutdown tasks are executed immediately upon the cloud sensor reporting this condition.  A session can not be started if this condition exists.

Cloud Sensor option on the Options Page



If Pause is checked, the run will pause for the specified number of minutes to wait for the clouds to clear.  If they clear in that period of time, the run resumes.  If they do not, the run aborts and the appropriate user-specified shutdown tasks are executed.  If pause is not checked, then the appropriate user-specified shutdown tasks are executed immediately upon the cloud sensor reporting a cloudy condition.


Shutdown tasks

Upon initiating the shutdown event, the tasks specified on the Options page under "3. Shutdown", if checked, will be executed.  If these options are not checked, they will not be executed.

1. Any light exposures in process will be aborted.
2. If a dome is connected to CCDAutoPilot, a command will be sent to the dome via the automation interface to close the dome.
3. Commands will be sent to the telescope control program to park the telescope and/or turn tracking off, if selected by the user on the options page.
4. Any scheduled dark/bias frames will continue
5. Any scheduled dawn flats will not be taken.
6. Any scheduled shutdown activities such as turning the camera cooler off or running a shutdown application task will be executed.


CAUTION

Both the Cloud Sensor documentation and common sense advise against relying on this device to protect valuable equipment.  It is mainly intended as a monitor of sky conditions.  See the Cloud Sensor documentation for details.  CCDAutoPilot responds to changing sky conditions as a convenience to the user and in no way should be considered a fail safe approach.  The most reliable usage, again without guarantees, is to have a direct connection between the Cloud Sensor and the dome control hardware emergency close switch with no intervening software.  The dome controller should be on an uninterruptible power supply (UPS) to be able to close the dome in the event of a power failure.  

None of this is any substitute for an attendant.