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

TL;DR

This paper presents a method to extract broadband soft X-ray irradiance from the Solar Aspect Monitor data, validating it against other measurements and demonstrating spatial resolution capabilities during solar flares.

Contribution

The study introduces a technique to isolate 0.01--7 nm irradiance from SAM data, providing the first broadband irradiance results and spatial analysis of solar disk regions.

Findings

SAM results agree within 25% with EVE/ESP measurements.

SAM's broadband irradiance correlates well with SNOE SXP and TIMED SEE data.

Spatial resolution of active regions during flares demonstrated.

Abstract

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. Contamination from energetic particles and out-of-band irradiance is, however, significant in the SAM observations. We 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%. We compare our results with measurements from the Student Nitric Oxide Explorer (SNOE) Solar X-ray Photometer (SXP) and the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) Solar EUV Experiment (SEE) at similar levels of solar activity. We show that the full-disk SAM broadband results compare well to the other measurements of the 0.01--7 nm irradiance. We also 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.