Light Curves and Colors of the Ejecta from Dimorphos after the DART Impact

On 26 September 2022 the Double Asteroid Redirection Test (DART) spacecraft impacted Dimorphos, a satellite of the asteroid 65803 Didymos. Because it is a binary system, it is possible to determine how much the orbit of the satellite changed, as part of a test of what is necessary to deflect an asteroid that might threaten Earth with an impact. In nominal cases, pre-impact predictions of the orbital period reduction ranged from ~8.8 - 17.2 minutes. Here we report optical observations of Dimorphos before, during and after the impact, from a network of citizen science telescopes across the world. We find a maximum brightening of 2.29 $\pm$ 0.14 mag upon impact. Didymos fades back to its pre-impact brightness over the course of 23.7 $\pm$ 0.7 days. We estimate lower limits on the mass contained in the ejecta, which was 0.3 - 0.5% Dimorphos' mass depending on the dust size. We also observe a reddening of the ejecta upon impact.Comment: Accepted by Natur

Strip meniscometry: a new and simple method of tear meniscus evaluation. Invest Ophthalmol Vis Sci

PURPOSE. To investigate the applicability and efficacy of a new and simple method of quantification of the volume of tear meniscus, termed "strip meniscometry," in the diagnosis of the dry eye syndromes in a prospective controlled study. METHODS. One hundred eyes of 50 patients with dry eye (19 males; 31 females) aged between 18 and 76 years (mean, 54.3 years), as well as 80 eyes of 40 normal subjects aged from 15 to 70 years (mean, 50.8 years; 12 males, 28 females) were recruited in this study. The patients and the control subjects underwent strip meniscometry for 5 seconds, tear film lipid layer interferometry, tear film break-up time measurement, and ocular surface vital staining with fluorescein and rose bengal dyes and the Schirmer-1 test. RESULTS. Strip meniscometry scores correlated with tear quantity and stability, ocular surface staining scores, and lipid layer interferometry grades and improved after 2 weeks of punctal plug occlusion. CONCLUSIONS. Strip meniscometry is a swift, noninvasive, promising new method that is expected to find application in the diagnosis and evaluation of the outcome of treatment of dry eye syndromes. (Invest Ophthalmol Vis Sci