C/2020 F3 (NEOWISE) was discovered in images from the Near Earth Object program of the Wide-Field Infrared Survey Explorer (NEOWISE) taken on 2020 March 27 and has become the Great Comet of 2020. The Solar Wind ANisotropies (SWAN) camera on the Solar and Heliospheric Observatory (SOHO) spacecraft, located in a halo orbit around the Earth–Sun L1 Lagrange point, makes daily full-sky images of hydrogen Lyα. Water production rates were determined from the SWAN hydrogen Lyα brightness and spatial distribution of the comet measured over a 4 month period of time on either side of the comet’s perihelion on 2020 July 3. The water production rate in s⁻¹ was moderately asymmetric around perihelion and varied with the heliocentric distance, r, in au as (6.9 0.5) 10²⁸ r ^−2.50.2 and (10.1 0.5) 10²⁸ r ^−3.50.1 before and after perihelion, respectively. This is consistent with the comet having been through the planetary region of the solar system on one or more previous apparitions. Water production rates as large as 5.27 10³⁰ s⁻¹ were determined shortly after perihelion, once the comet was outside the solar avoidance area of SWAN, when the comet was 0.324 au from the Sun.

C / 2020 F3（NEOWISE）是在2020年3月27日从广域红外测量浏览器（NEOWISE）的近地物体程序的图像中发现的，现已成为2020年的大彗星。太阳风各向异性（SWAN）相机在太阳和日光层天文台（SOHO）的航天器，位于在围绕地球-太阳L1拉格朗日点卤代轨道，每日使得氢Ly的全天空图像α。水的生产速率从SWAN氢Ly的确定被α的亮度和随时间上的彗星的近日点的任一侧上有4个月期间7月3日产水率在s中测量了2020彗星的空间分布^-1是中等围绕不对称近日点并随日心距而变化，r，在^auHelion前后分别为（6.9 0.5）10 ²⁸ r ^-2.50.2和（10.1 0.5）10 ²⁸ r ^-3.50.1。这与彗星在一个或多个先前的幻影中穿过太阳系的行星区域是一致的。一旦彗星位于SWAN的避太阳区域之外，这颗彗星离太阳0.324 au，那么在近日点之后不久就确定了高达5.27 10 ³⁰ s ^-1的水生产率。