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Current Projects
- Origin and Location of the Wow! Signal.
Professor has his own webpage detailing his research.

Previous Research
Arecibo Wow! II: Revised Properties of the Wow! Signal from Archival Ohio SETI Data
Abstract
The Wow! Signal, detected in 1977 by the Ohio State University SETI project, remains one of the most intriguing unexplained radio transients. The most recent significant revision of its properties took place in the late 1990s; however, further advances were limited by readily available data from this event. Here we retrieved and analyzed decades of previously unpublished Ohio SETI observations, enabling the most comprehensive re-evaluation of the properties of the Wow! Signal to date with modern methods. Our results reveal significant revisions to its parameters that may help explain why its source has been so difficult to identify. We refine its potential origin to two adjacent fields centered on the right ascension α = 19h25m02s ± 3s or 19h27m55s ± 3s, and the declination δ = −26◦57′ ± 20′ (J2000), a location both narrower and slightly displaced from earlier estimates. We measure a higher peak flux density exceeding 250 Jy and a frequency of 1420.726 ± 0.005 MHz, implying a galactic source with a substantially higher radial velocity than previously assumed. Our analysis provides additional support for the hypothesis that the Wow! Signal most likely had an astrophysical origin rather than being attributed to radio interference. In particular, we confirm that small, cold Hi clouds can produce narrowband signals similar to its detection, which might suggest a common origin. These findings provide the most precise constraints to date on the location, intensity, and frequency of the Wow! Signal and offer a new path to identify its origin.
The Last Arecibo Message
Abstract
The Arecibo Message was a brief binary-encoded communication transmitted into space from the Arecibo Observatory on November 16, 1974, intended to demonstrate human technological prowess. In late 2018, to commemorate the 45th anniversary of this message, the Arecibo Observatory initiated the New Arecibo Message competition. Following a series of challenges, our Boriken Voyagers team was recognized as the winner of the competition in August 2020. Although the primary objective of the competition was to conceptualize rather than transmit a message, the collapse of the Arecibo Telescope in December 2020 precluded any subsequent transmission efforts. Therefore, to commemorate the 50th anniversary of the Arecibo Message, this paper presents the Last Arecibo Message, as originally developed for the Arecibo Telescope. If the original message says we are a form of life reaching out to connect, our message says we are ready to explore the universe together. The prospect of transmitting this or a similar message remains an open question.
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News Related to Prof. Mendez
- Prof. Mendez Research of the Wow! Signal Appears in the El Nuevo Dia Newspaper
- Prof. Mendez on the Future Arecibo Observatory at Universe in Frequency Podcast
- Students Present their Research in the 43rd PRISM and 58th ACS JTM at the UPR Río Piedras
- The Science History Institute’s Magazine Writes Article from the Work of Prof. Acosta and Mendez
- XIX Research Forum of UPRA (2024)