# FRAM telescopes and their measurements of aerosol content at the Pierre Auger Observatory and at future sites of the Cherenkov Telescope Array

## TL;DR

This paper discusses the deployment and operation of FRAM telescopes for atmospheric monitoring, focusing on aerosol measurements at the Pierre Auger Observatory and future Cherenkov Telescope Array sites, highlighting their hardware, status, and preliminary results.

## Contribution

It presents the hardware setup, deployment status, and initial aerosol measurement results of FRAM telescopes at key observatory sites, supporting atmospheric characterization for cosmic observations.

## Key findings

- FRAM telescopes successfully measure aerosol content at observatory sites.
- Preliminary aerosol data show site-specific atmospheric transparency variations.
- FRAM deployment aids in site characterization for CTA planning.

## Abstract

A FRAM (F/(Ph)otometric Robotic Atmospheric Monitor) telescope is a system of a robotic mount, a large-format CCD camera and a fast telephoto lens that can be used for atmospheric monitoring at any site when information about the atmospheric transparency is required with high spatial or temporal resolution and where continuous use of laser-based methods for this purpose would interfere with other observations. The original FRAM has been operated at the Pierre Auger Observatory in Argentina for more than a decade, while three more FRAMs are foreseen to be used by the Cherenkov Telescope Array (CTA). The CTA FRAMs are being deployed ahead of time to characterize the properties of the sites prior to the operation of the CTA telescopes; one FRAM has been running on the planned future CTA site in Chile for a year while two others are expected to become operational before the end of 2018. We report on the hardware and current status of operation and/or deployment of all the FRAM instruments in question as well as on some of the preliminary results of integral aerosol measurements by the FRAMs in Argentina and Chile