Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI)

Abstract

The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) is a five telescope package, which has been developed for the Solar Terrestrial Relation Observatory (STEREO) mission by the Naval Research Laboratory (USA), the Lockheed Solar and Astrophysics Laboratory (USA), the Goddard Space Flight Center (USA), the University of Birmingham (UK), the Rutherford Appleton Laboratory (UK), the Max Planck Institute for Solar System Research (Germany), the Centre Spatiale de Leige (Belgium), the Institut d'Optique (France) and the Institut d'Astrophysique Spatiale (France). SECCHI comprises five telescopes, which together image the solar corona from the solar disk to beyond 1 AU. These telescopes are: an extreme ultraviolet imager (EUVI: 1-1.7 R ), two traditional Lyot coronagraphs (COR1: 1.5-4 R and COR2: 2.5-15 R ) and two new designs of heliospheric imagers (HI-1: 15-84 R and HI-2: 66-318 R ). All the instruments use 2048 × 2048 pixel CCD arrays in a backside-in mode. The EUVI backside surface has been specially processed for EUV sensitivity, while the others have an anti-reflection coating applied. A multi-tasking operating system, running on a PowerPC CPU, receives commands from the spacecraft, controls the instrument operations, acquires the images and compresses them for downlink through the main science channel (at compression factors typically up to 20×) and also through a low bandwidth channel to be used for space weather forecasting (at compression factors up to 200×). An image compression factor of about 10× enable the collection of images at the rate of about one every 2-3 minutes. Identical instruments, except for different sizes of occulters, are included on the STEREO-A and STEREO-B spacecraft.

Solar Weather Event Modelling and Prediction

“…Due to the projection effects inherent in the Thomsonscattered white-light data, it is difficult to obtain reliable speed estimates for the CMEs and extremely difficult to track them from the Sun to Earth. To date the first direct observations of CMEs all along the Sun-Earth line from the low corona to the Earth's magnetosphere are currently being analysed as provided by the unprecedented observations from the SECCHI (Sun Earth Connection Coronal and Heliospheric Investigation) on board the two NASA STEREO spacecraft launched in 2006 which image the Sun-Earth system from two vantage points leading and trailing Earth's orbit around the Sun (Howard et al 2008;Davies et al 2009). The STEREO observations will provide new insights into the 3D structure of CMEs and their evolution in the heliosphere which can directly be compared with existing models and simulations.…”

On the Nature and Genesis of EUV Waves: A Synthesis of Observations from SOHO, STEREO, SDO, and Hinode (Invited Review)

“…This is in our opinion an objective criterion because it does not depend on the derived speed of the propagating disturbance which seems to be sometimes a function of image cadence. For example, EIT captured only the slower of EUV waves, due to its low-cadence, as was revealed by the higher cadence STEREO/SECCHI (Howard et al, 2008) observations (Long et al, 2008;Veronig, Temmer, and Vršnak, 2008).…”

Interplanetary and Geomagnetic Consequences of Interacting CMEs of 13 – 14 June 2012

“…After the launch of twin Solar TErrestrial Relations Observatory spacecraft (STEREO: Kaiser et al 2008), the data from the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI: Howard et al 2008) have enabled us to continuously image CMEs from their lift-off in the corona up to the Earth and beyond Harrison et al, 2012;Liu et al, 2013;Möstl et al, 2015;Vemareddy and Mishra, 2015). These observations have also revealed direct evidence of CME-CME interaction when they are launched in close succession in the same direction Lugaz et al, 2012;Shen et al, 2012;Mishra, Srivastava, and Chakrabarty, 2015).…”