Gargash Site | Iranian National Observatory

Site Selection

The site selection activities began in 2000 before even the formal approval of the project in 2004. The investigation looked into many parameters including atmospheric turbulence, wind speed and direction, sky darkness and clearness, temperature and relative humidity, etc. In 2009 and after an eight-year long site selection and monitoring, Mount Gargash was chosen as the preferred site to build and operate INO.

Location

Gargash site is located at latitude 33°.674 and longitude 51°.319 in central Iran and at an altitude of 3600m above the sea level. The peak is the highest among the Karkas chain of mountains within a 50 km radius. The site is about 300 km south of Tehran and about 100 km north of Isfahan.

Microthermal Variations

In order to quantify the ground layer atmospheric turbulence INO has carried out thermal variation measurements with a high frequency (~1 kHz) and with high thermal resolution (0.01 C). For this purpose 6 masts have been installed in Gargash. The sensors made of pure Platinum wires, are positioned in pairs at 8 levels from 3m to 15m height, separated 2m horizontally. Check out INO site monitoring for current weather conditions at Mount Gargash.

Seeing Measurements

One of the most important parameters in determining the suitable location for an observatory is the Seeing. Astronomical seeing measures the amount of apparent blurring and twinkling of astronomical objects due to turbulent mixing in the Earth’s atmosphere which causes variations of the optical refractive index. This parameter is constantly being measured on Mount Gargash and the data is stored via the Auto DIMM facility. The results of the seeing measurements carried out in Gargash mount during summers of 2010 and 2011 are shown in the figure. For a long term monitoring of the seeing throughout the year a robotic DIMM system is installed on a 6m tower. The system was installed in spring 2012.

In general the site is located in a relatively dry region on the earth. The number of nights with clear sky is estimated to be about 230 nights. Night time monitoring indicates that during summer and fall there is a 60% chance of photometric nights.