The parameter-search method (PSM) established by Rengaswamy, Ravindra, and Prabhu (Solar Phys. 294, 5, 2019) for measuring the terrestrial atmospheric seeing from long-exposure solar H\(\upalpha\) images is further validated – through simulations – to include the effects of i) intermediate exposure-time, exposures that are neither as small as 1 to 20 ms used in solar speckle imaging in the visible nor as long as 1 second; ii) under-sampling of the data (with respect to the telescope’s diffraction-limit), and iii) non-ideal telescope point spread function. It is then applied to a large dataset to obtain the statistics of Fried’s parameter \(r_{0}\) at Merak: a cold desert in the Himalayas. The bias due to intermediate exposure is well within the error budget. Under-sampling results in an underestimation of \(r_{0}\) only when the seeing-limited point spread function is sampled at a rate worse than two pixels per seeing-limit, implying that \(r_{0}\) estimated in the low-resolution mode is unreliable beyond \(r_{0} = 10\) cm. The non-ideal telescope point spread function tends to reduce the estimated \(r_{0}\)-values significantly only when the RMS wave-front error of the aberrated pupil is worse than \(\lambda/14\). The median seeing at Merak estimated from data spanning over five months is 2.7 arcseconds.

通过Rengaswamy，拉温德拉，和帕布建立的参数搜索方法（PSM）（太阳能的PHY。 294用于从长曝光太阳能ħ测量地面大气视，5，2019）\（\ upalpha \）图像来进一步验证-通过模拟–包括以下方面的影响：i）中间曝光时间，即可见光中太阳斑点成像所用的曝光时间不短于1到20 ms，也不长于1秒；ii）数据的欠采样（相对于望远镜的衍射极限），以及iii）非理想的望远镜点扩展函数。然后将其应用于大型数据集，以获得弗里德参数\（r_ {0} \）的统计信息在Merak：喜马拉雅山的一片寒冷沙漠。由于中间暴露而造成的偏差完全在误差预算之内。仅当以低于每个视极限两个像素的速率对视限点扩展函数进行采样时，欠采样才会导致\（r_ {0} \）的低估，这意味着估计了（（r_ {0} \）在低分辨率模式下，\（r_ {0} = 10 \）  cm以上是不可靠的。仅当像差瞳孔的RMS波前误差小于\（\ lambda / 14 \）时，非理想的望远镜点扩展函数才趋于显着降低估计的\（r_ {0} \）-值。根据过去五个月的数据估算，在Merak看到的中位数为2.7弧秒。