Veloce

The Veloce project equips the Anglo-Australian Telescope with a compact, stabilised and hyper-calibrated spectrograph, able to obtain Doppler velocities for Sun-like and M-dwarf stars at sub-m/s precision. When complete it will provide essentially all the functionality delivered of the old UCLES spectrograph - but with a larger collecting aperture on the sky, higher spectral resolution, simultaneous wavelength coverage across the whole optical, and better throughput.

Key features of Veloce

A CYCLOPS-style IFU fibre-feed
Compact asymmetric, white-pupil design, including pressure and temperature stabilisation.
Wavelength coverage of ~390-930nm at R~80,000 in three cameras : Azzurro 391-431nm, Verde 431-590nm, and Rosso 590-930nm
Simultaneous calibration by a pulsed-laser-comb to deliver a bright, calibration source stable at the few cm/s level, with tens-of-thousands of lines across the green and red cameras.

Veloce Rosso has been available since 2019, and the Verde and Azzurro cameras are being commissioned in June-August 2023. Any Australian astronomer can apply for use it as a standard facility instrument on the AAT.

International astronomers can purchase time on the AAT to use Veloce - enquiries regarding the terms and conditions for AAT Paid Time should be made through Astronomy Australia Limited (AAL).

You don't have to collaborate with the Veloce team to get time - but we are happy to work with you if you'd like to work with us. In particular, many Veloce science programs benefit from sharing time across multiple programs, because while you might only need 2 nights for your favourite planet target, you want those nights spread over a much longer period.

We are happy to collaborate with teams who'd like to exchange time across the semester - please get in touch if you'd like to share time (modulo the requirement we then all have to share weather losses as well).

Veloce operated with a single red arm (Veloce Rosso) over the last 3 years (as in the design rendering above). Two additional arms (green and blue cameras - Veloce Verde and Azzurro - below) now being installed (as per the design below). The total budget for the project is now around $5.9m, raised by a consortium led by UNSW and including ANU, USQ, AAO, U.Sydney and Macquarie and Swinburne.

Our calibration system - VeloceCal - uses a pulsed-laser-comb calibration system covering 450-950nm from Menlo Systems GmbH. We inject this into Veloce as a single-mode, diffraction-limited calibration source, calibrating the spectrograph for every science exposure. (The image below is the optical spectral flattening unit with its covers removed and "lit up" by the laser comb output spectrum)

The completed Veloce Rosso system was delivered to the AAT in April 2018.

Once sealed-up in its enclosure (above), its internal components (below) are temperature stablised at 25.00C to ~10mK and pressure stablised at 905.0mbar to better than 0.1mbar.

Veloce's fibre-fed design makes it amenable to a range of possible upgrades

1.A "faint object" fibre feed (i.e. larger fibres delivering spectra at lower-resolution, with more sky-fibre collection, and less read-noise through binning of the detector).
2.A science-quality slit-viewing camera.
3.VelocePol - a spectro-polarimetry module with dedicated fibre bundle at the AAT's Cassegrain focus.
4.Veloce-RAPTOR : a fibre feed from a 0.7m auxiliary telescope sited next to the AAT - allowing use of Veloce on every night of the year, and potentially upgradable with many more telescopes.

News

26 July 2023 - Veloce achieved first light for the full 3-camera system tonight. The image below (thanks to Gayandhi de Silva!) shows data from a star being captured all the way from 390-930nm. The green camera throughput looks very good, with the red part of the green camera collecting a significantly higher photon flux than the blue part of the red camera. Fibre throughput is an issue in the blue camera short of 400nm (as expected) though some photons seem to make it through down to 390nm.

18 July 2023 - The first 5 night commissioning run for the full Veloce Rosso+Verde+Azzurro system took place on June 28 - July 2. Sadly, the dome never opened. However, we were able to complete optical re-alignment for Rosso, and alignment for Verde. Azzurro performance image quality was a bit poorer than expected, so a second trip Jul 11-12 involved more adjustment, and the Azzurro performance is not greatly improved.

The ESO NGC controllers, and integration with the DARAMA VCT and vq observing system, has so far performed flawlessly. Seeing all three detectors read with noise < 3.5e- and largely featureless bias frames has been impressive.

A second commissioning run is scheduled Jul 26-31, to be followed by Community Science Verification Aug 24-30 - see the link if you’d like to acquire some data of your favorite class of object with the new full-wavelength coverage Veloce.

The Veloce Observing Guide and Instrument Manual is being continuously updated as we work through commissioning.

14 June 2023 - Integration at the AAT.
Over the last 3 weeks the two new optical cameras (and their detectors, plus the Rosso detector (in its new dewar) have been installed at the AAT. The pretty picture below shows the new system illuminated by a bright light during alignment.

More informative is the following image of the two new cameras integrated into the existing spectrograph. The two black cylindrical barrels at the front (each with a silver cylinder attached) are the Verde and Azzurro cameras with their dewar attached. The rectangular box art the rear is the existing Rosso camera, with its new silvery dewar attached. (The ‘box-like’ unit to the right is the echelle grating and its collimators - they feed dispersed light to all three cameras).

Fine adjustment of the optics is taking place now to (a) ensure the Rosso echellogram has the same positioning as previously, followed by (b) focus and rotation of the Verde echellogram, and then (c) focus and location of the Azzurro echellogram.

We already have test images of the LC spots on the Verde camera, delivering calibration all the way from 600nm to 450nm in that camera!

12 Feb 2023 - Veloce Verde+Azzurro Cameras go into final assembly and integration. The image below shows the Azzurro camera in assembly at the AITC.

1 August 2022 - Verde, Azzurro and new Rosso cryostats complete. And testing of the new cryostat shows them to hold vacuum stably for months at a time.

17 Sep 2018 - Veloce First Light and First Science!

On the night of 17 Sep 2018, the Veloce project took a huge step forward, acquiring its first data on the traditional "first light" target for planetary programs - tau Ceti. The image above shows the data obtained, with the small dots next to every echelle order showing the simultaneous ThXe calibration lines.

Our second target that night was the mid-M-dwarf planet host LHS3844, alerted by NASA's TESS just 12 days before to host a planet in a 0.46d orbit. We went on to observe it almost twice a night for every one of the 10 nights that followed.

By one night later, we started standard operations using our VeloceCal laser frequency comb as a simultaneous calibration source, delivering 10,000 diffraction-limited lines with positions known to better than 1-part-in-1011 !