Analysis of Cloud Cover Variability for Determining Astronomic Observatory Building Location in Sula and Lombok Islands

Astronomy is the study of celestial objects and cosmic phenomena, supported by observatories as centers of observation. One of the main factors in selecting an observatory location is cloud cover, which affects visibility and observation quality. Analysis of cloud cover for determining suitable locations for astronomical observatories is still limited. Therefore, this study analyzes cloud cover variability in North Maluku Province and the islands of Bali and Lombok using cloud cover data to identify optimal locations for observatory construction. This study aims to determine the variability of cloud cover in North Maluku Province, Bali Island, and Lombok Island and provide recommendations for constructing astronomical observatories in locations with the lowest cloud cover levels. The data used in this study are from 1994 to 2023 in the form of cloud cover data obtained from ERA 5 Copernicus. Analysis was carried out using the composite analysis method and tabulation method to evaluate cloud cover variability across three ENSO phases (El Niño, Neutral, and La Niña). The analysis indicates different suitable locations based on cloud cover levels:

1. In North Maluku Province, the lowest cloud cover is found in The Sula Islands, making it an optimal choice for observatory construction during all ENSO phases.
2. In Bali and Lombok, Bali Island exhibits relatively high cloud cover, making it less suitable for observatory development. Conversely, the lowest cloud cover is observed in East Lombok Regency on Lombok Island, particularly during all ENSO phases, making it the preferred location for observatory construction.

This study highlights the importance of analyzing cloud cover variability as a key climate factor in selecting suitable locations for astronomical observatories. The results provide recommendations for constructing observatories in The Sula Islands for North Maluku Province and East Lombok Regency for Bali and Lombok, ensuring optimal visibility and observation quality.