Permanent object 28 is the repository identity for Mintaka, Delta Orionis and HIP 25930. The International Astronomical Union assigns the proper name specifically to Delta Orionis Aa, the close central source within the wider system; an unaided observer receives blended light and cannot separate those component labels. “Mintaka” descends from an Arabic expression for Orion's belt. Source: [IAU, Naming Stars](https://www.iau.org/public/themes/naming_stars/).
Modern orbital work shows why a single star name needs care. Delta Orionis Aa1 and Aa2 form a detached eclipsing binary with a 5.732436-day period and a slightly eccentric orbit. A third star, Ab, follows a much wider orbit. A 2023 analysis combined spectroscopy, eclipse timing and speckle interferometry, and constrained that outer period to about 152 years. Using the Gaia parallax of a fainter component, the authors placed the system at 381 ± 8 parsecs, about 1,240 light-years, consistent with the Orion OB1b association. Their three-body model estimated masses of 17.8, 8.5 and 8.7 solar masses for Aa1, Aa2 and Ab, with uncertainties near one solar mass. Source: [Oplištilová et al., *Astronomy & Astrophysics* 672, A31](https://www.aanda.org/articles/aa/full_html/2023/04/aa45272-22/aa45272-22.html).
Those masses and orbits are model results, not features visible in a backyard telescope. The eclipse is shallow in the combined light because several luminous components contribute. The distance also illustrates a recurring problem with bright multiple stars: a parallax or spectrum assigned too casually to “Mintaka” can mix physically different components.
Mintaka's most important historical spectrum was obtained for another reason. In 1904 Johannes Hartmann tracked lines that shifted back and forth as the spectroscopic binary orbited. The narrow calcium K line did not share that motion. Hartmann inferred that the absorbing calcium lay in a cloud between the Sun and Delta Orionis rather than in either orbiting star. Later observations established stationary calcium and sodium absorption as probes of interstellar gas. Source: [Astrophysical Institute Potsdam, Hartmann discovery plate and account](https://www.aip.de/highlight_archive/hartmann/index2.html). The line was “stationary” relative to the moving stellar spectrum, not proof that the cloud had zero motion through the Galaxy.
The stored position is approximately right ascension 5h 32m and declination −0° 18′, almost on the celestial equator. It culminates about 45° high from latitude 45° N and 55° high from 35° S. These are original geometric calculations that omit refraction, terrain and the week's timing.
To find Mintaka, identify the straight three-star Belt. From the Northern Hemisphere while facing south, it is the western, right-hand endpoint; Alnilam is central and Alnitak is eastern. Check the Belt's spacing before selecting the endpoint, because the surrounding Orion field is rich. HIP 25930 is part of the repository's accepted Orion and Belt geometry, but the rendered finder and reader link still require visual review.
Mintaka is easy to see without optical aid. Binoculars reveal the surrounding field, and a telescope may show wider visual companions, but it does not split the five-day eclipsing pair. Detecting that orbit requires timed photometry or spectroscopy; detecting the interstellar calcium requires a spectrograph. Keep component resolution, brightness change and field identification as separate claims, and leave Moon and darkness conditions to the weekly calendar.
