New Results from the Solar Maximum Mission Bent Crystal Spectrometer

TL;DR

This paper presents new calibration details and improved analysis methods for the Solar Maximum Mission's Bent Crystal Spectrometer, enabling finer spectral detail and better understanding of solar flare plasmas from historical data.

Contribution

It provides updated calibration factors, evaluates in-orbit performance, and offers recommendations for future X-ray spectrometer instrumentation.

Findings

Enhanced spectral resolution from re-calibrated data

Improved interpretation of plasma physics during solar flares

Validation of archived data for new scientific insights

Abstract

The Bent Crystal Spectrometer (BCS) onboard the NASA Solar Maximum Mission was part of the X-ray Polychromator, which observed numerous flares and bright active regions from February to November 1980, when operation was suspended as a result of the failure of the spacecraft fine pointing system. Observations resumed following the Space Shuttle SMM Repair Mission in April 1984 and continued until November 1989. BCS spectra have been widely used in the past to obtain temperatures, emission measures, and turbulent and bulk flows during flares, as well as element abundances. Instrumental details including calibration factors not previously published are given here, and the in-orbit performance of the BCS is evaluated. Some significant changes during the mission are described, and recommendations for future instrumentation are made. Using improved estimates for the instrument parameters and operational limits, it is now possible to obtain de-convolved, calibrated spectra that show finer detail than before, providing the means to improved interpretation of the physics of the emitting plasmas. The results indicate how historical, archived data can be re-used to obtain enhanced and new, scientifically valuable results.