Orbital elements of C2011 L4 (PanStarrs) Oort cloud comet, computed by MPC (Minor Planet Center, Minor Planet Electronic Circular 2012-T08), show that the closest approach to the Sun occurred on 2013 March 10th, at about 0.3 A.U., then about 4,51x10^7 km. Discovered by Richard Wainscoat (Institute for Astronomy, University of Hawaii) on four CCD images taken with the 1.8-m "Pan-STARRS 1" telescope at Haleakala taken on 2011 June 6th. My first observation of the comet was on 2013 March 10th whit the comet visible in the twilight. I did the following visual estimation; Mar. 10.73,-1.0*,5'(T. Scarmato, Calabria, Italy, 7x50 binoculars; altitude 7 deg, tail 1 deg in pa 140 deg), reported to the ICQ (International Comet Quarterly). Easy comet in 7x50 binoculars I started to see C/2011 L4 at 18:35 L.T. when the comet was at about 7° above the horizon. I saw a tail long about 1,5° in pa 140° with a coma well condensed and large about 5'. I followed the comet until to the set at 18:55 L.T., still clearly visible at so low altitude about 1° or less! I don't saw Mars (1.39 mag) at the same altitude, so I esteemed the comet using Aldebaran (1.1 mag) at 62,44° of altitude also using the ICQ Table of Atmospheric Extinction; but remembering C/2006 P1 in the same conditions of observation I could to assume that the comet was at negative apparent total magnitude m1= -1.0. The image of the comet was impressive (see Fig. 2). Here, I present my observations and results on the size of the nucleus, period of rotation, dust production and peculiar structures in the inner coma.
Key words: General: general; comets: C/2011 L4 (PanStarrs), PanStarrs, comets, afrho, photometry of aperture, flux, apparent magnitude, absolute magnitude; comet nucleus: size, rotation.
Emerging Diversity Among the Main-Belt Comets: Insights from JWST and Ground-Based Observations of 457P/Lemmon-PANSTARRS
Auburn University（奥本大学）；Planetary Science Institute（行星科学研究所）；University of Maryland（马里兰大学）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；Lowell Observatory（洛厄尔天文台）；ESA PDO NEO Coordination Centre（欧洲空间局近地天体协调中心）；Carnegie Institution for Science（卡内基科学学会）；University of Washington（华盛顿大学）
Hubble Space Telescope Observations of Active Asteroid P/2020 O1 (Lemmon-PANSTARRS)
我们提出了哈勃太空望远镜的活动小行星P/2020 O 1的观测，以检查其发展为近日点后一年。我们发现，质量损失在2020年8月达到峰值<~1 kg/s，然后在四个月内下降到接近零。长时间的质量损失（约180天）与升华起源一致，表明该物体可能是一颗含冰的主带彗星。小至1580平方米的水冰的平衡升华可以提供观测到的质量损失。时间序列测光显示了小核（有效半径~420 m）极快速旋转（双峰周期< 2小时）的初步证据。0.1 mm粒子的喷射速度与0.3 m/s的重力逃逸速度相当，而较大的粒子以低于逃逸速度的速度喷射。这些性质与近表面冰在向心加速度的帮助下升华是一致的。如果水冰升华得到证实，P/2020 O 1将是具有最小半长轴（最高温度）的冰冷小行星，为小行星带的冰分布设定了新的界限。
Single-dish observations and non-LTE analysis of CH3OH, HCN, and CO line emission in the Oort cloud comet C/2017 K2 (PANSTARRS)
Institute of Astronomy of the Russian Academy of Sciences（俄罗斯科学院天文研究所）；Department of Physics and Astronomy, Chalmers University of Technology（查尔姆斯理工大学物理与天文系）
