Boltwood Cloud Sensor III


The newly-designed Boltwood Cloud Sensor III is the must-have weather monitoring device for astronomical observatories. Designed to protect your most valuable equipment from weather damage, the Boltwood Cloud Sensor III can sense wind, rain, and more while enabling automatic observation scheduling through your favourite observatory control applications.

Price is for serial version with custom cable of 100′ length

Available on backorder

SKU: ASC12302 Category:
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Powerful Sensor Technology
The primary sensors used for determining safe/unsafe observing conditions are cloud detection, rain detection, wind speed limits, and daylight. The user can also set limits on other parameters, including humidity, temperature, etc.

The Boltwood Cloud Sensor III will trigger a contact closure (relay) output when it detects adverse conditions. When connected to an observatory roof controller such as the MaxDome II system, this will cause the observatory to close. Note that this will not park your telescope or other equipment.

The Perfect Software
Many users use software to operate the observatory in response to the weather conditions. Diffraction Limited makes Cyanogen Imaging® MaxIm DLTM software, that includes a flexible observatory shutdown capability.

Connect Anywhere
Boltwood Cloud Sensor III communicates via a WiFi connection. It can operate as a WiFi hotspot or connect directly to your wireless network. It provides browser-based status and configuration screens. It also provides ASCOM Alpaca ObservingConditions and SafetyMonitor interfaces, enabling direct access to sensor readings by ASCOM-compatible astronomical software packages.

Powered. Always.
The sensor operates from a 10.5V to 24V DC power source, making it compatible with 12V solar-charged battery systems. A universal AC adapter and extension cable comes standard to connect with available central power locations.

The sensor detects:

  • Clouds
  • Rain Drops
  • Wet snow
  • Wind Speed
  • Temperature
  • Humidity
  • Dew Point
  • Barometric Pressure
  • Daylight
  • Input Voltage
Weight3 kg
Dimensions18 × 14 × 4 cm


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Approximate Dimensions:
Body 7.5” tall x 4” diameter (190 mm x 100 mm)
Optional Anti-Bird Wires add 1” (25 mm) Mounting Bracket 2.5” from center axis (65 mm)
DC Input Power: 10.5VDC to 24VDC, 1A Maximum
AC Adapter: 100VAC to 250VAC, 50/60 Hz
Power Connector: Barrel style, 2.5 mm ID, 5.5 mm OD, unpolarized Example: DigiKey CP3-1001-ND
Roof Close Connector: Barrel style, 1.3 mm ID, 3.5 mm OD, unpolarized Example: DigiKey EP505B-ND
Roof Close Circuit Rating: 12V, 1A
WiFi Communications: IEEE802.11b/g/n
Center Frequency Range: 2412 ~ 2484 MHz
Country Policy: Automatic configuration based on network station

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