# Soft X-ray irradiance measured by the Solar Aspect Monitor on the Solar Dynamic Observatory Extreme ultraviolet Variability Experiment

**Authors:** C. Y. Lin, S. M. Bailey, A. Jones, D. Woodraska, A. Caspi, T. N. Woods, F. G. Eparvier, S. R. Wieman, L. V. Didkovsky  
**arXiv:** [1605.01444](https://arxiv.org/abs/1605.01444)  
**Date:** 2016-05-04  
**Summary page:** https://www.summarizepaper.com/en/paper/1605.01444v1/

## Key points

- The Solar Aspect Monitor (SAM) is a pinhole camera on the Extreme-ultraviolet Variability Experiment (EVE) aboard the Solar Dynamics Observatory (SDO).
- SAM projects the solar disk onto the CCD through a metallic filter designed to allow only solar photons shortward of 7 nm to pass.
- Researchers present a technique for isolating the 0.01-7 nm integrated irradiance from the SAM signal to produce the first results of broadband irradiance for the time period from May 2010 to May 2014.
- The study compares these results with measurements from other instruments such as Student Nitric Oxide Explorer (SNOE) Solar X-ray Photometer (SXP) and Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) Solar EUV Experiment (SEE) at similar levels of solar activity.
- SAM's capability toward resolving spatial contribution from regions of solar disk in irradiance is explored, demonstrated with a case study of several strong flares that erupted from active regions on March 11, 2011.
- This study provides valuable insights into understanding how different parts of the sun contribute to overall solar radiation output and can aid in predicting space weather events that can impact Earth's technological infrastructure.

## Summary

The Solar Aspect Monitor (SAM) is a pinhole camera on the Extreme-ultraviolet Variability Experiment (EVE) aboard the Solar Dynamics Observatory (SDO). SAM projects the solar disk onto the CCD through a metallic filter designed to allow only solar photons shortward of 7 nm to pass. In this study, researchers present a technique for isolating the 0.01-7 nm integrated irradiance from the SAM signal to produce the first results of broadband irradiance for the time period from May 2010 to May 2014. The results of this analysis agree with a similar data product from EVE's EUV SpectroPhotometer (ESP) to within 25%. The study compares these results with measurements from other instruments such as Student Nitric Oxide Explorer (SNOE) Solar X-ray Photometer (SXP) and Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) Solar EUV Experiment (SEE) at similar levels of solar activity. The full-disk SAM broadband results compare well to other measurements of the 0.01-7 nm irradiance. Furthermore, researchers explore SAM's capability toward resolving spatial contribution from regions of solar disk in irradiance and demonstrate this feature with a case study of several strong flares that erupted from active regions on March 11, 2011. This study provides valuable insights into understanding how different parts of the sun contribute to overall solar radiation output and can aid in predicting space weather events that can impact Earth's technological infrastructure. The findings are published in Journal of Geophysical Research: Space Physics.