IBIS-A: The IBIS data Archive

Abstract

Context. The IBIS data Archive (IBIS-A) stores data acquired with the Interferometric BIdimensional Spectropolarimeter (IBIS), which was operated at the Dunn Solar Telescope of the US National Solar Observatory from June 2003 to June 2019. The instrument provided series of high-resolution narrowband spectropolarimetric imaging observations of the photosphere and chromosphere in the range 5800–8600 Å and co-temporal broadband observations in the same spectral range and with the same field of view as for the polarimetric data. Aims. We present the data currently stored in IBIS-A, as well as the interface utilized to explore such data and facilitate its scientific exploitation. To this end, we also describe the use of IBIS-A data in recent and undergoing studies relevant to solar physics and space weather research. Methods. IBIS-A includes raw and calibrated observations, as well as science-ready data. The latter comprise maps of the circular, linear, and net circular polarization, and of the magnetic and velocity fields derived for a significant fraction of the series available in the archive. IBIS-A furthermore contains links to observations complementary to the IBIS data, such as co-temporal high-resolution observations of the solar atmosphere available from the instruments onboard the Hinode and IRIS satellites, and full-disk multi-band images from INAF solar telescopes. Results. IBIS-A currently consists of 30 TB of data taken with IBIS during 28 observing campaigns performed in 2008 and from 2012 to 2019 on 159 days. Of the observations, 29% are released as Level 1 data calibrated for instrumental response and compensated for residual seeing degradation, while 10% of the calibrated data are also available as Level 1.5 format as multi-dimensional arrays of circular, linear, and net circular polarization maps, and line-of-sight velocity patterns; 81% of the photospheric calibrated series present Level 2 data with the view of the magnetic and velocity fields of the targets, as derived from data inversion with the Very Fast Inversion of the Stokes Vector code. Metadata and movies of each calibrated and science-ready series are also available to help users evaluate observing conditions. Conclusions. IBIS-A represents a unique resource for investigating the plasma processes in the solar atmosphere and the solar origin of space weather events. The archive currently contains 454 different series of observations. A recently undertaken effort to preserve IBIS observations is expected to lead in the future to an increase in the raw measurements and the fraction of processed data available in IBIS-A.