In May/June/July 2026 the control system and the AO system were successfully tested at VTT. With very limited support, we offer observing time in October and November 2026. Deadline for proposals is September 15, 2026. It is of advantage to have have experience with the VTT control system. The observations are offered on a best-effort basis.

HELLRIDE: The HELioseismic Large Regions Interferometric DEvice (HELLRIDE) is a dual Fabry-Pérot etalon-based tunable filtergraph at the back-end of the Vacuum Tower Telescope (VTT). Its salient feature is to observe a relatively large field of view (100x100 acrsec2) in multiple spectral lines with high cadence.  The new HELLRIDE now observes a field of view in four spectral lines, two chromospheric spectral lines in spectroscopy mode and two photospheric spectral lines in spectropolarimetry mode, with a cadence of 40 seconds. A liquid crystal-based dual-beam polarimeter is integrated into HELLRIDE. HELLRIDE observations can be done remotely. The VTT, the AO (KAOS), and HELLRIDE can be controlled remotely. Please contact Dr. Hemanth Pruthvi (pruthvi@tls-tautenburg.de) for more information. 

FaMuLUS: The Fast Multi-Line Universal Spectrograph (FaMuLUS) camera system is integrated into the Echelle spectrograph of VTT and has four simultaneous spectral windows: H beta 486 nm, Cr I 578 nm, H alpha 656 nm, Fe I 709 nm ranging with increasing wavelength from 0.55 nm to 1nm. The slit covers 216 arcsec and can be scanned accross a FOV of interest of up to 120 arcsec. The spatial sampling is 0.36 arcsec per pixel. In this configuration, a full scan takes about 90 s. Other spectral windows are possible and need to be discussed. FaMuLUS observations need to be done on site. Please contact Prof. Dr. Carsten Denker (cdenker@aip.de) for more information.

Spanish time (Solar CAT)

See www.iac.es/OOCC/solar-cat/ for more information. According to international agreements, 20% of the observing time is reserved for assignment by the Spanish solar CAT. Presently, there are no restrictions on nationality to apply for VTT time through the solar CAT. Application at www.iac.es/OOCC/solar-cat/.

CCI International Time Programme (ITP)

5% of the GREGOR telescope time is reserved for international access. The observing time is assigned by the EAST TAC. For ITP time, multi-national and/or multi-telescope applications are prefered. Submit the proposal template (see above) to east_tac@astro.su.se. Contact Dan Kiselman (dan@astro.su.se) for more information.