[1] Matteucci, F. 2008, in Massive Stars as Cosmic Engines, ed. F. Bresolin, P. A. Crowther, & J. Puls, Vol. 250, 391–400; [2] Hopkins, P. F., Kereš, D., Oñorbe, J., et al. 2014, MNRAS, 445, 581; [3] Garcia-Segura, G., Mac Low, M. M., & Langer, N. 1996, A&A, 305, 229; [4] Krause, M., Fierlinger, K., Diehl, R., et al. 2013, A&A, 550, A49; [5] Kudritzki, R.-P. & Puls, J. 2000, ARA&A, 38, 613; [6] Kudritzki, R. P., Bresolin, F., & Przybilla, N. 2003, ApJL, 582, L83; [7] Bromm, V., Kudritzki, R. P., & Loeb, A. 2001, ApJ, 552, 46; [8] Heckman, T. M., Borthakur, S., Overzier, R., et al. 2011, ApJ, 730, 5; [9] Belczynski, K., Holz, D. E., Bulik, T., & O’Shaughnessy, R. 2016, Nature, 534, 512; [10] Marchant, P., Langer, N., Podsiadlowski, P., Tauris, T. M., & Moriya, T. J. 2016, A&A, 588, A50; [11] Dalton, G., Trager, S., Abrams, D. C., et al. 2020, SPIE Conf. Ser., 11447, 1144714; [12] Jin, S., Trager, S. C., Dalton, G. B., et al. 2024a, MNRAS, 530, 2688; [13] Monguió M., et al., 2020, A&A, 638, A18; [14] Pantaleoni González, et al., in prep.; [15] Pantaleoni González, M., Maíz Apellániz, J., Barbá, R. H., & Reed, B. C. 2021, MNRAS, 504, 2968; [16] Bailer-Jones, C. A. L., Rybizki, J., Fouesneau, M., Demleitner, M., & Andrae, R. 2021, AJ, 161, 147; [17] Simón-Díaz, S., Pérez Prieto, J. A., Holgado, G., de Burgos, A., & Iacob Team. 2020, in XIV.0 Scientiﬁc Meeting (virtual) of the Spanish Astronomical Society, 187 An up-scaled endeavor for exploring OB stars in the Milky Way within the WEAVE-SCIP survey A. de Burgos(1,2), S. Simón-Díaz(1,2), J. Drew(3,4), M. Monguió(3,5), S. R. Berlanas(1,2), A. Herrero(1,2), the WEAVE-SCIP collaboration Context and motivation The study of massive OB stars signiﬁcantly contributes to our comprehension of galaxies [1,2]. Despite their importance, OB stars gather many open questions concerning both their evolution and physical properties that remain unanswered. In this context, the Milky Way is a perfectly suited laboratory to study them. Spectroscopic observations of statistically signiﬁcant samples of these stars are needed to address those questions. In this regard, the WEAVE-SCIP [11,12] Low-Resolution (LR; R=5000) survey aims at building the largest and most homogeneous spectroscopic sample of OB stars up to date, covering most of the Northern Galactic disk. (1) Instituto de Astrofísica de Canarias (Spain), (2) University of La Laguna (Spain), (3) University of Hertfordshire (U.K.), (4) University College London (U.K.), (5) Universitat de Barcelona (Spain), Ph.D. Student IAC Progenitors of gravitational wave emitters[9,10] Tracers of star-forming regions Feedback to the interstellar medium[3,4] Chemo- dynamical evolution of galaxies[1] Reionization of the Universe[7,8] Extragalactic tools[5,6] Building the catalog for the survey IPHAS (Hα, Sloan r, i) + UVEX (URGO, Sloan g, r) |b| < 5° and 29° < l < 215° Bad sources ❌ Saturated sources ❌ Missing photometry ❌ 10.0 < gUVEX < 17.5 ❌ Data retrieval from IGAPS[13] Initial ﬁlter U,g,r Selection ﬁlter Additional ﬁlters For each IGAPS ﬁeld, a U-g / g-r diagram with a U-band correction was initially used to select 54.000 sources earlier than B3V star. 2MASS J,H,K and Gaia DR3 were used to remove unwanted sources. Using ALS III and Gaia DR3 Additional ~4000 targets from the Alma Luminous Star III (ALS III)[14,15] of OBA-type stars were added. Gaia DR3 photometry and distances from Bailer-Jones et al. (2021)[16] were used to ﬁlter out ~25.000 sources located below the extinction line of a 7M⊙ star. Very different reddenings → The OB candidates of the WEAVE-SCIP LR survey ● Magnitudes: 10 < G [mag] < 16 ● Distances: 2000 < d [pc] < 8000 ● A total of 410 pointings distributed in the Galactic plane. ● A maximum of 150 ﬁbers per pointing. ● Different priorities are assigned based on the location of the targets in the different diagrams. ● About 5000 targets have the highest priority and they lie above the 15M⊙ extinction line. Conclusions The U-band correction The