Field Testing of the Durham/AGI Transmissometer

测量能见度，或众所周知的大气透过率，对天文学家来说很重要。为了在纳米比亚的望远镜现场进行这种类型的测量，达勒姆大学甚高能伽马射线天文学小组建造了一种名为透射计的仪器。它使用基于LED和CCD的技术进行测量，这比目前此类仪器中使用的白炽灯和光探测器具有优势。特别是，与旧设备相比，我们的设备更容易对准，需要的维护更少，耗电量更少，因此它可以使用太阳能，这对偏远的简易机场特别有用。因此，我们已经为这一设计申请了专利。我们升级了仪器，以便它可以在白天工作(天文学家只需要夜间测量！)，找到了一种更便宜的CCD相机来安装仪器，并更换了软件，以便可以使用Windows来控制它，我们需要进一步改进它，以便它可以用于机场和军用机场，而不是更传统的仪器。这包括使仪器更加坚固，并与我们的合作伙伴航空和通用仪器有限公司(AGI)目前制造的透射计之一并排进行广泛的现场试验。我们需要做的工作是由PIPSS两年的拨款资助的。在PIPSS授权期的早期，不幸的是，我们对新机场仪器的要求发生了变化；新的传输器不能使用任何移动部件。这给我们带来了问题，因为最初的设计使用了快门来掩蔽LED。因此，我们不得不改变系统，包括所有的软件，这比我们最初预期的花费了更多的时间，尽管已经产生了更好的仪器。然而，额外的工作意味着我们错过了从2008年10月开始进行实地试验的窗口(实地试验必须在冬季进行)。因此，我们要求再提供6个月的资金，使我们能够从2009年10月开始完成现场试验，并给AGI一些时间来了解新仪器，以便他们能够接管制造。

Measuring visibility, or atmospheric transmission as it is known, is important for astronomers. In order to perform this type of measurement at their telescope site in Namibia, the Durham University Very High Energy Gamma Ray Astronomy group built an instrument known as a transmissometer. This uses LED and CCD-based technology to perform the measurements, which has advantages over the incandescent light bulbs and light detectors currently employed in instruments like this. In particular, our equipment is easier to align, requires less maintenance and uses less power than older instruments, so that it can be solar-powered, which is particularly useful for remote airstrips. So, we have patented the design. Having upgraded the instrument so that it will work during the day (astronomers need only night-time measurements!), found a cheaper CCD camera to incorporate in the instrument and changed to software so that it can be controlled using Windows, we needed to improve it further so that it can be used in airports and military airfields instead of more traditional instruments. This involves making the instrument more robust and performing extensive field trials side-by-side with one of the transmissometers currently built by our partner company, Aeronautical & General Instruments Ltd. (AGI) in. The work we needed to do was funded by a 2 year PIPSS grant. Early on in the PIPSS grant period, unfortunately for us the requirements for new airport instrumentation changed; no moving parts can be used in new transmissometers. This caused us problems, as the original design used a shutter to mask the LED. We have therefore had to change the system, including all the software, which has taken more time than we originally anticipated, though has resulted in a better instrument all round. However, the extra work meant that we missed the window for field trails starting in October 2008 (field trials have to be conducted in winter). We are therefore asking for a further 6 months funding to enable us to complete the field trials starting in October 2009 and to give AGI some time to learn about the new instrument so they can take over manufacture.