Turbulence (or seeing) is a great concern when recording images of the sky, because this is jeopardizing astronomical telescope resolution. Record images during best seeing is really a big advantage, to do so, continuous seeing measurement is required to optimize image recording time. To get seeing measurements, the DIMM method is mostly used by professionnal observatories in order to measure atmospheric seeing (or turbulence) and allowing to optimize targets and observation programs.
Nevertheless, DIMM method requires a telescope with enough focal length (>3000mm) and enough aperture (>250mm), and to track bright stars the whole night. This is quite stringent and can be a quite costly approach. The telescope needs a shelter, and automatically jump from a star to another.
ALCOR-SYSTEM provides a method to overcome some of the drawbacks of the DIMM system.
In the northern hemisphere, a bright star called "polaris" that does not move so much in the sky and is bright enough.
The fixed seeing monitor uses the Polaris star, and ALCOR-SYSTEM is proud to present this new product : CYCLOPE seeing monitor
The goal of this product is to measure atmospheric seeing condition in a continuous fashion, so this setup stays outdoor all the time 24h a day, and is aimed at the polaris star in a fixed fashion.
This system can only work in the northern hemisphere, at latitudes above 15° North, for southern hemisphere please contact us for solutions.
The fixed seeing monitor is a totally sealed system that can overcome all extreme weather conditions, and is not sensitive to wind gust due to its strong design. The software starts measurements automatically when the Sun is below the horizon and only when the stars are visible.
The system has four temperature sensors and two humidity sensors so that warming up of the entrance window is automatic (to prevent dew from forming), and also controls the cooling of the seeing detector.
The added value of this product compared to competitors are :
- better measurement accuracy because of more and smaller pixels
- the front window is heated against dew
- ethernet link to the host
- ability to measure very low seeing figure, whereas other systems are not reliable under 1.5 arcsec.
- strong and robust construction, that avoid measurements to be jeopardized by wind gust
This system offers watertight connectors, for continuous outdoor operation.
The line of sight can be adjusted accurately to aim at polaris star. Once this is performed, there is no need to carry out any further adjustements. The system is made of high quality alloy colorless anodized aluminum.
The software is embedded to this system. We have Windows software, for Linux, please ask us.
The field of view of the system is 3.6° x 2.5° and perfectly accomodates the polaris star path throughout the whole night / whole year, so that continuous measurements can be performed.
Since the image recording is performed continuously, it can provide a figure of seeing expressed in arcsec (or Fried's Ro) in a continuous matter, if weather conditions allows.
The next plot shows seeing measurement over the course of a night. The data is coming from this product (vertical axis is seeing, horizontal axis is time) :
It is very interesting to note that, over a night, large variation of zenith seeing can occur (from 1.2 to 2.3 arcsec in this case)