UV OBSERVATIONS WITH THE TRANSITION REGION AND CORONAL EXPLORER

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Abstract

The Transition Region and Coronal Explorer is a space-borne solar telescope featuring high spatial and temporal resolution. TRACE images emission from solar plasmas in three extreme-ultraviolet (EUV) wavelengths and several ultraviolet (UV) wavelengths, covering selected ion temperatures from 6000K to 1MK. The TRACE UV channel employs special optics to collect high-resolution solar images of the Hi Lα line at 1216Å, the Civ resonance doublet at 1548 and 1550Å, the UV continuum near 1550Å, and also a white-light image covering the spectrum from 2000–8000Å.

We present an analytical technique for creating photometrically accurate images of the Civ resonance lines from the data products collected by the TRACE UV channel. We use solar spectra from several space-borne instruments to represent a variety of solar conditions ranging from quiet Sun to active regions to derive a method, using a linear combination of filtered UV images, to generate an image of solar Civ 1550Å emission. Systematic and statistical error estimates are also presented. This work indicates that Civ measurements will be reliable for intensities greater than 1014photonss−1cm−2sr−1. This suggests that Civ 1550Å images will be feasible with statistical error below 20% in the magnetic network, bright points, active regions, flares and other features bright in C IV. Below this intensity the derived image is dominated by systematic error and read noise from the CCD.

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