Observing with iLocater
Following its delivery to the LBT in 2026, iLocater will be made available to the LBT community for science. For initial instrument operation we expect that:
- All observations will be considered shared risk during ongoing instrument commissioning (expected through at least the end of 2026B).
- iLocater will only be available on the SX (left) hand side of the LBT. Simultaneous observations with other instruments on the DX (right) side of the telescope are possible (e.g. PEPSI, LUCI, SHARK-VIS), and observations in this mode should be noted in any iLocater observing requests.
- Note: downstream instruments within LBTI (i.e. LMIRCam/NOMIC) cannot be used simultaneously with iLocater.
- The iLocater team will complete on-sky observations on behalf of the proposing team.
- To support this mode of operation, it is expected that observations will be completed as part of the OSURC queue on the telescope schedule, with time being tracked and accounted to each LBT member.
- Reduced data products will be provided to the proposing team.
- Reasonable efforts will be made to provide reduced data in a timely manner, however, given the new delivery of the instrument there may be delays to allow the iLocater team to validate the quality of the data.
Receive iLocater Updates/News
To keep up-to-date with iLocater news and status updates, you can subscribe to our users mailing list. To start the subscription process, send an email to: ilocater-users-list+subscribe@nd.edu
Current Instrument Status (July 2026)
iLocater was delivered to the LBT and achieved first light in June 2026. Characterization and optimization of the instrument is on-going in preparation for operations in 2026B.
Current Instrument Status (March 2026)
Status: The instrument is undergoing final laboratory testing prior to instrument shipping. Delivery to the LBT is expected in June 2026.
Current instrument performance:
-
Wavelength Coverage: 966-1312nm with continuous coverage blueward of 1100nm.
- Due to the instrument design being optimized for the Y-band, at wavelengths longer than 1100nm, spectrograph orders spill off the edge of the detector.
-
Median resolving power: 205,000
- Resolving power varies along each order from ~150,000 (blue) to ~250,000 (red).
- RV calibration stability: <1 m/s
- Spatial resolution on-sky: ~40 milli-arcseconds
Expected magnitude limits and target parameters (for 2026B semester)
With iLocater being an adaptive-optics (AO) fed instrument, its throughput (i.e. fiber injection efficiency) depends primarily on the LBT AO-system performance which is driven by target magnitude (in R or I band) and seeing conditions. The expected fiber-coupling performance is combined with the target spectral type to both determine the expected flux in the spectrograph bandpass, and performance of an internal instrument beam stabilization system which operates in the J-band (to compenstate for telescope vibrations). Detailed characterization of these limits is planned as part of the instrument commissioning activities.
For 2026B observations, we recommend observers plan on the following source limits, which are based on the demonstrated LBTI/SOUL AO performance, combined with previous observations using iLocater's fiber injection system:
| Target mag (Visible) |
Target mag (J band) |
Expected performance | Comments |
|---|---|---|---|
| R or I: < 8 | J < 7 |
|
Acceptable fiber coupling/instrument throughput expected. |
| J > 7 |
|
||
| R or I: 8 - 12 | J < 7 |
|
Limited risk of achieving acceptable fiber coupling/instrument throughput. |
| J > 7 |
|
||
| R or I: 12 - 15 | J < 7 |
|
Increased risk of achieving acceptable fiber coupling/instrument throughput. |
| J > 7 |
|
For more information about expected LBT AO performance, please refer to the following references:
SOUL: https://ui.adsabs.harvard.edu/abs/2023aoel.confE..80P/abstract
LBTI AO Performance: https://scienceops.lbto.org/lbti/lbti-users-manual/
Requesting time with iLocater
Scientists at LBT Member Institutions
Time requests for the use of iLocater should be handled through the time allocation process of the proposing members institution. Given the PI status of iLocater, of the time allocated for observations:
- 90% will be allocated to on-sky time for the science program;
- 10% will be allocated to a pool of time managed by the iLocater team to support engineering, key science programs, and to account for the time required by the team to support iLocater operations.
This breakdown of time should be accounted for in any time requests being made.
Prior to submitting a time request, proposers should email ilocater-obs-list@nd.edu with:
- A brief overview of the type of program being proposed
- Any specific precision requirements necessary for the observation/s
- Any specific time constraints on the observation/s
- Any simultaneous observations to be completed with another instrument on the DX side of the telescope
This will allow the iLocater team to ensure the instrument can support the proposed observation, prior to a time request being made.
Scientists outside the LBT Collaboration
At the present time, there is no direct path for iLocater time to be made available to scientists outside of LBT member institutions. We encourage scientists outside of the LBT Collaboration to build collaborative programs with scientists at LBT members institutions. For programs with compelling science cases requiring limited time, LBT Director's Discretionary Time may be requested however such requests are not guaranteed.
Use of iLocater Data/iLocater Collaboration Membership
Any person who supports and operates iLocater, or requests proprietary observations using iLocater is required to be a member of the iLocater Collaboration. This membership ensures that data products are used fairly, and their use is properly attributed. Proprietary data products may not be shared outside of the collaboration membership without explicit permission from the instrument Co-PIs.
If observing time with iLocater is awarded through a time allocation process, the proposing team will be invited to join the iLocater Collaboration prior to the observations being completed.
Last updated: 27 March 2026