Asgard Instrument Suite

Community Access

The Asgard consortium is committed to enabling community access after commissioning. In this page you will find guidance for each ESO period call for proposals and other ways to get involved.

Asgard CfP (ESO P118)

The Asgard consortium would like to involve members of the broad astronomical community in the exploitation of the BIFROST (JH-band), Heimdallr (K-band), and NOTT (L-band nulling) visitor instruments at VLTI. The goal is to maximise the science return of Asgard by exploiting its unique capabilities in science areas that are complementary to its core science areas. These core areas include:

• GAIA binary follow-up (Heimdallr and BIFROST)
• Spin-orbit alignments of binaries and planet-host stars (BIFROST)
• Accretion and ejection/mass loss around young stars, evolved stars and AGNs (BIFROST)
• Exoplanets with dual-field interferometry (BIFROST)
• Young planets (NOTT and BIFROST)
• Exozodiacal dust (NOTT)

We solicit ideas for science observations (outside of these themes), following a 2-stage proposal process:

1. Submission of an 'Expression of Interest' form to an Asgard-internal sifting panel that will select the proposal ideas that (a) seem technically feasible, (b) make the best use of Asgard's unique capabilities, and (c) show the best complementarity with the Asgard core science themes. Submissions have to use the Asgard template form (available for download from http://asgard-vlti.org/Asgard-eoi-form-P118.docx), and need to be submitted to eoi@asgard-vlti.org 2 weeks before the ESO P118 proposal deadline (i.e. by 2026 September 8, noon CEST). Later submissions will not be accepted.
2. The sift panel will inform applicants within 4 days whether their submission is selected, and whether they can prepare a full ESO proposal that needs to be submitted through the standard ESO submission system by the regular ESO proposal deadline.

Asgard commissioning is still ongoing, so we share below tentative estimates on limiting magnitudes and performance indicators. These will be revised in the future. All observations will be conducted on a shared-risk / best-effort basis. The available instruments/modes and expected limited correlated magnitudes for clear weather/median seeing are:

• Heimdallr (K-band, fringe tracking + visibility/closure phases, K_corr=9.5 with ATs, K_corr=12.5 with UTs). As we use the Baldr adaptive optics system, AT proposals with guide stars up to G=14 within the full Coudé field are acceptable (it is only important that the correction is enough so our DMs aren't saturated). For G>13, allow an additional 10 minutes for Naomi acquisition. Heimdallr/Baldr needed both for BIFROST and NOTT observing; fringe tracking on strongly resolved sources might be challenging.
• BIFROST (YJ-band or H-band, R=50 or R=950, visibilities/closure phases). Assuming all conditions are met for stable phase-tracking with Heimdallr, the tentative limiting magnitudes for P118 are: on-axis: ATs J_corr,H_corr=7.5, UTs J_corr,H_corr=11; off-axis (only wavelength-differential observables) ATs J_corr=12, UTs J_corr=15.5. The R50 mode (YJ-band and H-band) can be combined with a Wollaston prism to attempt polarised intensity measurements or to improve visibility calibration. For the total execution time of a CAL-SCI sequence, assume between 60 minutes (for R50, R50WOLL, or R950 mode on bright objects) and 150 minutes (for R950 mode on objects within 3 mags of the correlated magnitude limit). Y-band data can be recorded, but performance is not guaranteed and throughput is lower than in J-band.
• NOTT (L-band, nulling, single Bracewell, R=40, same limiting magnitude as Heimdallr, contrast=10^-4 at L=5)

Under excellent seeing conditions, we anticipate to reach 1 mag fainter sensitivity than listed above. Tools to help prepare NOTT observations (observation preparation tool, SCIFYsim, GRIP, and NIFITS) are listed on the Asgard/NOTT project page.

The data recording will be carried out by consortium members in visitor mode. Given the current absence of funding for community support activities, the consortium will only be able to support a small number of exploratory community projects (maximum of order 20% of proposed time), so that the data recording can be combined with other commissioning and consortium observing activities. We particularly welcome submissions where the proposing team can contribute staff time and expertise on relevant methodology and data analysis efforts that might also benefit other users of the instrument suite, and expand offerings in the future.

Growing our Community

The Asgard community is growing. If you have expertise that you think we need and time to commit, please contact us!