Posted by Renzo Ramelli | May 31, 2024 | General news

High-precision spectropolarimetric observations with the ZIMPOL polarimeter at the 45 cm Gregory-Coudé Telescope (GCT) at Istituto ricerche solari Aldo e Cele Daccò (IRSOL) in Locarno (Switzerland) are offered in service mode for projects requiring a short observing time (up to a few hours). Remote participation and co-observations with other facilities are possible. Observations are carried out in combination with the Czerny-Turner spectrograph. A slit-jaw camera and a secondary full-disc telescope equipped with a Ha filter can provide context images. In combination with the Telescope Calibration Unit (TCU), the ZIMPOL setup at the GCT is particularly well suited for measuring polarimetric signals with the precision and accuracy down to 0.001 %, such as produced in the quiet photosphere near the solar limb by scattering and modified by the Hanle effect.

Applications by interested researchers should briefly describe scientific goals, specify the target, spectral region, minimal required polarimetric precision. They should be submitted in PDF format by email at the address [email protected] with the subject “ZIMPOL@IRSOL observing proposal”.
* Submission deadline: 15 July 2024
* Communication of the accepted proposals: 20 August 2024
* Observing period: 20 September – 31 October 2024 (indicative)

Data policy: the observing team members will carry out observations and provide reduced science-ready ZIMPOL data as well as data visualization tools. They are expected to appear as co-authors on papers with ZIMPOL data.

Contact: Renzo Ramelli, [email protected], Andrea Francesco Battaglia, [email protected]

Some technical data:
* Available spectral range: 4070 Å – 7000 Å
* Spectral window: few Angstroms (depending on order and wavelength)
* Polarimetric precision: down to ~10-5 depending on exposure time
* Pixel scale: 1.30 (±0.02) arcsec/pixel
* Total area covered by ZIMPOL camera: 182 (±3) arcsec.
* Slit width: variable, min. 0.40  arcsec (50 µm)

References:  Ramelli, R., Balemi, S., Bianda, M., Defilippis, I., Gamma, L., Hagenbuch, S., Rogantini, M., Steiner, P., Stenflo, J. O. 2010, “ZIMPOL-3: a powerful solar polarimeter,” Proc. SPIE 7735, Ground-based and Airborne Instrumentation for Astronomy III, 77351Y (15 July 2010); https://doi.org/10.1117/12.857120

Zeuner, F., Gisler, D., Bianda, M., Ramelli, R., Berdyugina, S. V. 2022, “Enhancing the accuracy of solar polarimetry by coalescing slow and fast modulation: method description and first performance tests”, Proc. SPIE 12184, Ground-based and Airborne Instrumentation for Astronomy IX, id. 121840T, https://doi.org/10.1117/12.2629250