Enhancing Northern Sky Monitoring. Upgrades to Tartu Observatory's 1.5-m Telescope for High-Resolution Spectroscopy and Multi-Band Photometry

Enhancing Northern Sky Monitoring Upgrades to Tartu Observatory’s 1.5-m Telescope for HighResolution Spectroscopy and Multi-Band Photometry Exploring Star-Planet-Disk Connections conference Tõnis EenmäeTartu Observatory14. October 2025, Tartu Tartu Observatory Despite being in a challenging location, our telescopes at Tartu Observatory have following benefits: -Whole northern celestial hemisphere (declination > 0⁰) can be observed above airmass 2 -Objects with DEC > +31⁰ do not set* -Very long nights during the winter -Telescopes can be used every clear night -Photometric and spectroscopic measurements can be done in parallel Author: V. Allik, 2025 Astroclimate at Tõravere Astroclimate at the sea level is … not great, as expected However: We have used in average 62 nights per year (max ca 100) The most frequent seeing image FWHM in V-band is 2.7 arcseconds Extremes of night lengths: 0 to ~16 h The telescope AZT-12 ●A 1.5-metre Cassegrain reflector on an equatorial mount ●In operation since 1975, control system upgraded in 2011 ●Currently the only instrument is a Cassegrain long-slit spectrograph ●Project for acquiring new instruments is hopefully finishing any day soon ●Enabling remote operations in progress Author: V. Allik, 2020 Current capabilities of AZT-12 ●Computer-controllable telescope with the potential for remote control ●A long-slit spectrograph ASP-32 with a set of diffraction gratings ●Working range from 320 nm to 1000 nm ●Spectral resolutions from R~300 to ~10,000 ●Limiting magnitudes in 1 hour for SNR=100 ○R~300: V ≈ 17 mag (whole spectrum from 320-1000 nm) ○R~10000: V≈10.5 mag (short pieces of spectrum, ca 250 Å long) ●NO PHOTOMETRY New instruments at AZT-12 ●A CCD-photometer with 12 filters ●Attached to the Cassegrain focus of the telescope ●Using Andor iXon Ultra 888 as detector ●Field of view ca 3.6 x 3.6 arcminutes, ca 0.22 “/pix without binning ●2” filters from Baader Planetarium: ○Johnson-Cousins B, V, Rc,Ic ○Sloan u’g’r’I’z’ ○Luminance, ExoBB, Hα(3.5 nm) ●Estimated signal-to-noise ratio SNR≈900 in 100 sec for V=15 mag star ●A fibre-fed white pupil design echelle spectrograph Whoppsel from Shelyak Instruments, code name TOES ●Installed at the former Coude room for better environmental stability ●Using Andor Ikon-L BEX2-DD as detector ●Custom camera optics from Shelyak ●Provides spectral resolutions ca 32000 and ca 16000, depending on used fibre ●Spectral orders from 38-90, spectral range 380-910 nm ●Thorium-Argon hollow cathode lamp for wavelength calibration: RMS≈150 m/s The design of echelle spectrograph Author: F. Cochard First spectrum in June 2024… Testing under real sky in June 2024