What does IBEX data look like?
These are the first and second sets of solar system boundary maps released by the IBEX team in September 2010. Each shows a range of energetic neutral atom (ENA) energies, using data collected over the course of six months. The IBEX map shows energetic neutral atom distributions for the first six months of the IBEX mission compared side by side to the map for the second six months at the 0.71 kiloelectron volt energy level. The energetic neutral atom "ribbon" was detected in the second set of maps as in the first set, but changes in the ribbon can be seen.
At the boundary of our Solar System, the interactions between solar wind particles and interstellar medium particles create Energetic Neutral Atoms (ENAs). ENAs are particles with no charge that move very quickly. The ENAs created in these interactions travel in all directions, as they are no longer affected by nearby magnetic fields. Some of the ENAs happen to be traveling in just the right direction so that they move inward through the Solar System toward Earth where IBEX can collect them. In this way, IBEX is a special kind of "telescope." This boundary region emits no light, so there is no light that can be collected by conventional telescopes. Instead, IBEX measures these inward–traveling ENA particles. IBEX provides the only way we currently have of studying the entire edge of our Solar System all at once.
Using two sensors, called IBEX–Hi and IBEX–Lo, the spacecraft measures and counts the ENAs in 14 specific energy levels, or "energy steps" (8 for IBEX–Lo and 6 for IBEX–Hi). The scientists can create maps of the boundary using this information. For each small area of the sky, IBEX has measured the number of ENAs coming from that direction. The IBEX data set consists of all–sky ENA images as a function of energy. Each of the images shows ENAs at a particular energy level, using data collected over the course of six months.
In each image released so far, red indicates the highest number of ENAs measured by the spacecraft. Yellow and green indicate lower numbers of ENAs, and blue and purple show the lowest number of ENAs detected by IBEX. There is a bright, narrow arc–shaped region in the sky that is creating a large amount of ENAs; this region has been dubbed the "IBEX Ribbon."
In addition to the global heliospheric ENA images, IBEX is designed to detect neutral atoms flowing into our Solar System from the interstellar medium outside the boundary. These observations are made at specific times of year by IBEX–Lo. Information about IBEX’s interstellar neutral atom detections can be found in the Archived Updates section of the IBEX website as the Mission Update released on October 15, 2009. (##TBR)
It is important that the heliospheric ENA images be free of ENAs attributable to processes in our Earth’s magnetosphere. Therefore, the IBEX science team removes the data that come from the direction of the Earth’s magnetosphere (a function of the orbital position of IBEX and the time of year). These are the black pixels appearing in the first few sets of ENA images. While not a part of the primary IBEX mission, magnetospheric ENA observations do provide a valuable additional data set for magnetosphere studies.
Information about IBEX’s magnetospheric observations can be found in the Archived Updates section of the IBEX website:
All raw data, calibration/conversion software, final heliospheric images, interstellar neutral atom observations, magnetospheric ENA observations, calculations, and scientific model results are made available to the public as soon as possible. Completed images and image sets, science results and conclusions, and model results are generally released upon publication in peer–reviewed scientific journals. Any delays in releasing this information are often because of the need to remove "noise" from the data and make corrections due, in large part, to the spacecraft’s motion (the "Compton-Getting Effect"), as well as due to the review and publishing schedules of various science journals.