<p> This dissertation is a series of textual case studies on nontraditional sources for <i>li</i>[special characters omitted]"calendro-astronomy" circa 250 BCE - 250 CE: (1) the silk manuscript guide to military planetary astronomy/astrology <i>Wuxing zhan</i>[special chracters omitted] (168 BCE), (2) excavated calendars and state <i>li</i> manuals, and (3) the <i>Jin shu</i>'s [special characters omitted] record of the debate surrounding a failed attempt at li reform in 226 CE. This selection affords us a number of unique cross sections through the astral sciences. Balancing transmitted with excavated sources, I emphasize realia and their perspective on era technical knowledge, the formats in which it was produced and consumed, and its transmission and practice beyond an elite court-centered context. In addition to the three elements of <i>li</i>--calendrics, eclipses, and planetary astronomy--my selection draws together the broad array of astral sciences, exploring distinctions in genre, sociology, and epistemology between, for example, mathematical astronomy, hemerology, and omenology, and the (tortuous) processes by which knowledge moved between them. Each chapter also juxtaposes the normative descriptions of manual literature with products of practice&mdash;tables, calendars, and test results&mdash;to reflect upon the distance between them and, thus, the limitations of the former as historical testimony. Across these cross sections, my study focuses on the question of empiricism and progress. I foreground these topics <i>not</i> because they define twentieth-century notions of science but because, as I argue, they define early imperial notions of <i>li</i>&mdash;a point that our twenty-first-century aversion to positivism and Whig history tends to obscure. To this end, I catalog the conceptual vocabulary of observation and testing, submit empirical practices to mathematical and sociological analysis, and, most importantly, explore the formation and function of legend&mdash;the histories of science that early imperial actors wrote and recounted in their own day. </p><p> As it stands, the dissertation has four body chapters. Chapter 1 provides a history and sociology of the astral sciences in the Han, covering the sources, legend, and conceptual vocabulary of <i>li</i>, the history of Han li from the perspective of both ideas and institutional reforms, and a survey of participants' backgrounds, motivations, education, and epistemological contentions. Chapter 2 examines how the Wuxing zhan manuscript segregates and conflates distinct genres of planetary models, then sketches the subsequent history of these genres, showing how, despite seemingly opposite orientations to reality, actors gradually rewrote and reassessed (crude) hemerology-based omenological (<i>tianwen</i>[special characters omitted]) models through the lens of progress made in mathematical (<i>li</i>) ones. Chapter 3 explores a similar gulf that opened between astronomy and calendrics in this period, as well as the gulf between imperial ideology&mdash;within which the calendar was the premier symbol of cosmo-ritual dominion&mdash;and the actualities of the production, distribution, and use of calendars in a manuscript culture. Lastly, chapter 4 analyzes the two epistemic strategies at the center of (the <i>Jin shu</i>'s take on) the circa 226 CE court debate on <i>li</i>: the quantitative determination of "tightness" (accuracy) of lunisolar and planetary models through competitive testing, and the contestation of claims through the deployment of precedence from the history of the field.</p>