STF 1338 AB (HD 80441) is a binary star system located 139 light-years from Earth. The primary component is a yellow-white main-sequence star of spectral type F2V, and the companion is a very similar main-sequence star of spectral type F4V. The components orbit their common center of mass with a period of about 303 years.

103mm: Attempting to resolve this binary system is quite a challenge for a 4" refractor. According to Dawes' criterion, the resolution limit for a binary star in a 4" refractor should be 1.14", assuming both components have roughly the same brightness around 6 mag. Moreover, this should not be a complete separation of the components but merely their elongation and confirmation that it is a binary star. The Rayleigh and Markowitz criteria are even more demanding. Given that the separation of the components is listed as 1" and according to the book "An Anthology of Visual Double Stars", it should be only 0.988" in 2025, my chances of completely resolving the components seemed slim. However, I was in for a pleasant surprise when I looked into the telescope. At 132x magnification, I started to suspect that the conditions were favorable, and the star began to elongate nicely. At 159x, the components were resolved but still connected, and at 198x, a very thin gap appeared between them. Despite all the negative assumptions, I consider my attempt to fully resolve this binary star with a 4" refractor a success. Both components appeared white with a subtle yellowish tint.