author = "Balmaceda, Laura A. and Vourlidas, Angelos and Stenborg, Guillermo 
                         and Dal Lago, Alisson",
          affiliation = "{George Mason University} and {The Johns Hopkins University 
                         Applied Physics Laboratory} and {US Naval Research Laboratory} and 
                         {Instituto Nacional de Pesquisas Espaciais (INPE)}",
                title = "How Reliable Are the Properties of Coronal Mass Ejections Measured 
                         from a Single Viewpoint?",
              journal = "Astrophysical Journal",
                 year = "2018",
               volume = "863",
               number = "1",
                pages = "e57",
                month = "Aug.",
             keywords = "catalogs, miscellaneous, Sun: coronal mass ejections (CMEs), 
             abstract = "We present an analysis of widths and kinematic properties of 
                         coronal mass ejections (CMEs) obtained via a supervised image 
                         segmentation algorithm, the CORonal SEgmentation Technique 
                         (CORSET), on simultaneous observations from the two COR2 
                         telescopes on the Solar Terrestrial Relations Observatory (STEREO) 
                         mission, from 2007 May to 2014 September. The sample of 460 events 
                         with measurements from two vantage points offers the opportunity 
                         to test the accuracy and constraints of single-viewpoint 
                         properties that underlie the bulk of CME research to date. In 
                         addition, we examine the dependence of the properties on the 
                         morphology of the events. The main findings are as follows. (1) 
                         The radial speeds derived from different perspectives are in good 
                         agreement with a relatively low intrinsic uncertainty of 39%. (2) 
                         Projection effects are more important for determination of CME 
                         width rather than for speed. (3) The expansion speeds depend on 
                         CME morphology, with loop-type CMEs expanding twice as fast as 
                         flux-rope CMEs, possibly underpinning the more explosive nature. 
                         (4) Triangulations of CME speed and propagation direction are 
                         optimal from viewpoints separated by 6090; e.g., between the 
                         Lagrangian points L1 and L5 (or L4). (5) The projected speeds are 
                         underestimated, on average, by at least 20% when compared to their 
                         deprojected (triangulated) values. We also discuss in detail the 
                         lessons learned from the application of the CORSET algorithm to 
                         event tracking. Our findings should hopefully be a useful guide in 
                         the use of (semi)automated algorithms for extraction of CME 
                         physical parameters and in the interpretation of singleviewpoint 
                         observations (likely to be the norm after the end of the STEREO 
                  doi = "10.3847/1538-4357/aacff8",
                  url = "http://dx.doi.org/10.3847/1538-4357/aacff8",
                 issn = "0004-637X and 1538-4357",
             language = "en",
           targetfile = "balmaceda-how.pdf",
        urlaccessdate = "25 jul. 2021"