NASA IRTF Spring 2026 Newsletter

Last updated 1 March 2026

Proposal Deadline for Semester 2026B (August 1, 2026 to January 31, 2027) is Wednesday, April 1, 2026, 5PM Hawaii Standard time.

Available instruments are listed here. Remote observing is offered for all projects, limited logistical supports for in-person observing and training on IRTF facility instruments is available for new observers. Each observing program has an assigned support astronomer. Click here for more information on remote observing.

Staff Update

Seizen Tshua started as day crew Observatory Technician in November 2026. Seizen comes from CFHT. We are also currently recruiting a day crew Electronics Technician to start within the next few months. Importantly, these recruitments bring the day crew back up to full complement.

Strategic Planning

A major recommendation from the NASA Independent Review and the NASA IRTF/Keck User Group is for IRTF to develop a strong strategic plan in order to ensure "its supremacy as a planetary facility" and its ability to serve the astronomical and solar system science community for the next decades.

Beginning in September 2025, we began developing a strategic plan that will consider both near and long term plans for instrumentation development, improvements in operations, and enhancements to the IRTF data archive. The plan will consider future funding, synergies with existing and future ground and spaced based observing facilities, the shape and evolution of the scientific landscape, in particular relating to solar system science and planetary defence but also including astrophysics more broadly, NASA and US federal benefits from IRTF, etc.

The development of the strategic plan requires significant community input. An online community survey was initiated in December 2025 and closed on March 6. Over 200 members of the community provided input, many volunteering to provide further details on science cases and ideas for future capabilities and operations. We will host a town hall and community workshop at the summer AAS meeting in Pasadena as well as some webinars and virtual workshops later in 2026.

If you have any questions, any inputs and opinions, or are interested in participating in the strategic planning process, please let Warren Skidmore (warren.skidmore@hawaii.edu) know.

Target of Opportunity (ToO) Programs and Director Discretionary Time (DDT)

Proposals for Target of Opportunity (ToO) programs are fully supported and are encouraged for programs when times of an event cannot be predicted. ToO interrupt proposals should include at least one team member capable of carrying out the observation without support from the IRTF staff.

The total time that can be allocated to all ToO programs in a semester is 24 hours for Solar System and 24 hours for non-Solar System proposals. Each ToO interrupt is limited to 3 hours in length. The proposal must also clearly define the criteria by which a ToO interrupt would be initiated. Time for ToO interrupts will be taken from scheduled, non-time critical observing programs. Programs affected by ToO interrupts will be offered make-up time from Director Discretionary Time (engineering time) when possible.

The IRTF schedule includes about 18 nights per semester for engineering. This time is used to address technical problems with the facility, calibrate instrumentation, IRTF staff science, and for Director’s Discretionary Time.

The fraction of engineering time offered to observers in the form of Director’s Discretionary Time (DDT) is for events that could not be foreseen and supported through a ToO program. DDT is reserved for follow-up of newly-discovered objects and of unexpected transient phenomena, or when developments since the last proposal cycle make time-critical observations necessary. A request for DDT should be submitted by email to both John Rayner John Rayner (jrayner@hawaii.edu) and Adwin Boogert (aboogert@hawaii.edu), and must include a strong programmatic or scientific justification, a technical description of the proposed observations (including target information, instrument settings, required S/N, and justification for the amount of time requested), and a discussion for why this work was not proposed in the last proposal cycle and why it can’t wait for the next proposal cycle.

Evaluation of DDT requests will be based on the same criteria used for regular observing proposals, and on the urgency or time-critical nature of the observation. Observers should avoid DDT requests if the request could have been proposed as a ToO proposal with specific interrupt criteria (e.g., comets, novae, NEO flybys etc.). As with ToO interrupt proposals, DDT requests should include at least one team member capable of carrying out the observation without support from the IRTF staff. In addition, observers may request DDT outside of the scheduled engineering time for events requiring fast response.

Observers should not negotiate with scheduled observers. All program changes, including those by the PI and/or observer for already scheduled time must be approved by the Director.

Applying for Observing Time

The IRTF was instructed by NASA Headquarters to implement Dual-Anonymous Peer Review (DAPR) procedures in the review and ranking of observing proposals, as is now common practice for all major astronomical facilities. Applications are required to submit proposals that meet NASA DAPR requirements criteria for anonymity. The goal of DAPR is to remove cognitive bias during the review process, not make identification of the applicants impossible. Violations of the DAPR requirements may mean a proposal is penalized or even rejected. PLEASE follow the DAPR Proposal Instructions when preparing your observing proposal.

Should you have any questions about the DAPR rules please contact Warren Skidmore (warren.skidmore@hawaii.edu).

Telescope time is divided 50/50 between Solar System and non-Solar System allocations, not including the 18 nights for engineering. There is a solar system TAC and a non-solar system TAC, each with four or more members. The TAC is independent of the IRTF although IRTF staff give input to the TAC on the feasibility of the submitted technical case. The TAC panels read and discuss proposals and then score them on a metric that weights the science and technical case, and subtracts points depending on any DAPR violations.Beginning in semester 2026A, we have added a bonus point system for the support of NASA’s strategic goals. This includes NASA science, mission support, and planetary defense.

We occasionally receive proposals with poor technical cases, usually from groups that are not familiar with the telescope and suite of observing instruments. If in doubt, IRTF staff (irtf-support@lists.hawaii.edu) can be contacted for help with the technical case provided you contact them well in advance of the proposal deadline. Since not all of the TAC are likely to be familiar with your particular area of science, please make sure to describe the big picture motivation for your science program.

FELIX: new off-axis guider and low-order wavefront sensor

FELIX is the new off-axis telescope CCD-guider and low-order (2x2) Shack-Hartman wavefront sensor for IRTF. It patrols a U-shaped 50 square arcminute field in the telescope image plane surrounding the 80 arcsec diameter on-axis FOV available to Cassegrain-mounted instruments. The guider images an 80 arcsec diameter FOV and can support non-sidereal tracking using moving guide boxes). Under the control of the telescope operator, standard operating mode for FELIX during most science operations is to measure the wavefront and provide inputs for automatic real-time closed loop focus control using stars as faint as V=18 in about one minute. Because of the improved focus control, we see measurable sensitivity improvements for the slit spectrographs. Full evaluation of the level of improvement will take place in the last part of Semester 2026A and part of 2026B. Felix has been in service since March 2025. For more details contact Mike Connelley (mconnell@hawaii.edu). FELIX is routinely used with all Cassegrain-mounted facility and visitor instruments.

Adaptive Secondary Mirror (ASM) Project

In Oct 2025, the ASM was successfully tested with FELIX for the correction of static aberrations (active optics) and seeing enhancement. Using SpeX’s SXD mode and the 0.3"} slit, we have measured an improvement in throughput by a factor of 1.6 in enhanced seeing mode. Although we do not expect to offer enhanced seeing for general use at this time, this is an important demonstration of the system’s ability to improve the performance of facility instruments. The measurement does not include gains from active optics, which is expected to be a similar amount. The ASM is also capable of a 5"} chop at 4 Hz with closed-loop correction from FELIX at both ends of the chop.

The ASM team is working on methods to automatically calibrate the reference spot positions in FELIX, which change depending on the off-axis position due to flexure and telescope field curvature. A week of engineering is scheduled at the end of May 2026 to test these calibrations methods, along with initial tests of an improved software interface that can be operated by facility staff as well as a demonstration of different science observing modes.

‘Facilitizing’ the ASM is the thesis project of Ellen Lee (ellenlee@hawaii.edu). Routine use of the ASM for active corrections with off-axis wavefront measurements from Felix is tentatively planned for early 2028. For more information contact John Rayner (jrayner@hawaii.edu).

Facility Instrumentation Update

The reduced telescope throughput reported last semester has been fixed by recoating the secondary mirror and by more regular cleaning of the instrument windows that can accumulate dust during observing (they are blanked off at other times). Given the apparent more limited life we’ve experienced with the slightly more efficient formerly applied over-coated silver coatings, the secondary mirror was coated with a more robust Aluminum coating this time.

Available facility instruments include:

(1) SpeX is a 0.7-5.3 micron medium-resolution (R=50-2500) spectrograph and imager. The 0.8 micron cut-on dichroic was replaced with a 0.7 micron dichroic during semester 2017A. This modification increases the spectral wavelength grasp for optically guided solar system targets. Sub-arrays and movie mode are working again in the IR guider. When observing point sources, we strongly recommend that at least three nodded pairs of integrations are acquired, even if the source is bright. This allows for more accurate measurement of the spectral slope in the presence of seeing and guiding variations. Longer integration times also help even out variations, even if they are not required to achieve the desired S/N. Electronic observing logs are automatically generated. Real-time quicklook spectral extraction runs automatically in the background and can be visualized in the data viewer (DV). For more information, see the instrument page and instrument manual or contact Mike Connelley (mconnell@hawaii.edu).

(2) MORIS is a 512x512 pixel Andor CCD camera mounted at the side-facing, dichroic-fed window of the SpeX cryostat (60"x60" field-of-view). MORIS can be used as an optical imager and as an optical guider for SpeX. For visible targets guiding with MORIS can significantly improve spectral sensitivity (better than one magnitude compared to IR guiding due to reduced slit losses). Electronic observing logs are automatically generated. For more information, see the instrument page and instrument manual or contact Mike Connelley (mconnell@hawaii.edu).

(3) iSHELL is a 1.06 – 5.3 micron cross-dispersed echelle spectrograph (up to about R=80,000) and imager. Slight fringing (5% contrast, spatial frequencies 20 pixels at J to 70 pixels at M) is observed in the flat fields. To reach S/N>100 on features at these pixel frequencies, more frequent flat fielding is required (for details contact your support astronomer). The general purpose data reduction tool for iSHELL is available as part of the Spextool package. We have developed a version of Xtellcor (called Xtellcor_model) that uses atmospheric models instead of standard stars to remove telluric absorption lines in iSHELL spectra. For now we recommend that observers still take standard stars until they have compared both methods. For details see the IRTF data reduction pages. Electronic observing logs are automatically generated. Observers are reminded that darks are automatically taken following observing and can be downloaded. Real-time quicklook spectral extraction now runs automatically in the background and can be visualized in the data viewer (DV).

On a timescale of a year, the radial velocity stability is limited by systematics. Commissioning observations involving radial velocities demonstrated precisions around 10 m/s achieved for targets brighter than K=10. 3-5 m/s has been achieved for bright, K~4 mag stars (Cale, Plavchan, et al., 2019, AJ 158, p. 170), however the number of iSHELL radial velocity epochs that can be scheduled is typically at most ~25 per semester, and less for low declination targets. This is at the cost of high overheads due to the need for frequent instrument changes. The RV data reduction code is available on github or by request from Peter Plavchan (pplavcha@gmu.edu).

For more information, see the instrument page and instrument manual or contact Adwin Boogert (aboogert@hawaii.edu).

(4) ‘Opihi is a wide-angle telescope mounted to and aligned with IRTF, consisting of a 17" Planewave CDK telescope, a CCD having a 32' FOV, and a filter wheel with g'r'i'z' and open filters. Its goals are to recover asteroids with large position uncertainties for SpeX and MORIS, to flux calibrate SpeX prism or SXD spectra by simultaneously imaging in z'-band, and to monitor extinction and cloud cover (similar to CFHT’s Skyprobe). ‘Opihi can locate asteroids down to V~20 in about one minute, propagate its motion across the sky, and send that ephemeris to the Telescope Control System. ‘Opihi is independent of other facility instruments and can thus be used in parallel with SpeX. Opihi has been used to gather multicolor photometry of various science targets. For more details contact Mike Connelley (mconnell@hawaii.edu).

Information on available instruments and performance can be found here. The instrument manuals were updated in August 2021. Exposure time calculators for SpeX and iSHELL are available on the respective instrument webpages. The ETC for iSHELL has been adjusted to allow for the lower throughput at J0.

MIRSI will not be offered during semester 2026B to allow for performance enhancing upgrades:
MIRSI/MOC is a 5-20 micron camera and grism spectrograph, and optical imager. MIRSI was upgraded with a closed-cycle cooler to replace its liquid nitrogen and liquid helium cryostat, and a dichroic-fed optical channel added (MOC, similar to MORIS). First light with the upgraded instrument occurred in April 2020. During semester 2023B, the engineering grade array was replaced with a science grade array. Current MIRSI capabilities are given here. Unfortunately the sensitivity has not been improved despite work to optimize the read out. We are currently working with a pre-thesis student to acquire fast imaging data as a proxy to estimate improvement of sensitivity through chopping. As part of this process we’ve found what is possibly a large internal light leak. This could also explain the loss of sensitivity and why optimization of the array clocking has not resulted in any improvement (signal dominated by the leak). Consequently, MIRSI will not be offered during semester 2026B as we attempt to find and fix the leak, and then optimize the read out. For more information contact John Rayner (jrayner@hawaii.edu).

New IRTF Facility Instrumentation Under Development

SPECTRE (Spectrograph Express - Planned first light late 2028) is a 0.4-4.2 micron, R=250, integral field spectrograph (IFS). For optimum efficiency, the wavelength range is covered simultaneously in three channels - 0.4-0.9 micron, 0.9-2.4 micron, and 2.4-4.2 micron, and the IFS has a 7.2x7.2 arcsec FOV to remove slit losses and to acquire absolute photometry on point sources. Object acquisition and guiding is done with an external cryostat-mounted 3 arcmin FOV CCD. On-target guiding can also be done at 1 Hz by taking advantage of H2RG non-destructive reads and collapsing the 3D data cubes. Apart from a pupil viewer there are no cold mechanisms, facilitating easy and once-per-night calibration. High priority science cases include: the characterization of NEOs and small bodies, in particular, followup of targets identified with NASA's NEO Surveyor, and optical-IR transient follow-up and variability. The cryostat vacuum jacket has been delivered, and fabrication is underway for the cold optical bench and other parts needed for cold testing scheduled for late summer 2026 (delayed by six months due to slow procurement through UH). This testing will include everything except for the long-lead optics (IFU and dispersing prisms). Most hardware with the exception of the cold optics is now in hand. We have just signed a contract with MIT-LL for the cold optical channel CCD (one science grade plus a spare). These devices are spares from the NASA TESS project.

A SPECTRE observations simulator and data reduction package are being written in Python. The simulator will be the basis for an online observing time estimator. This project is part of the IfA student Kenji Emerson’s PhD thesis work.

Please see SPECTRE 2026B update for more details. SPECTRE is funded by NASA. For more information contact John Rayner (jrayner@hawaii.edu).

Help Keep Our Publications List Current

Please continue to acknowledge the IRTF in your publications following the instructions shown here. This is a formal requirement for any publications using IRTF observations and failure to do so will be considered during the TAC process. It is important that you include in your papers the name of the instrument used and the citation for the instrument, as this helps to ensure future funding of IRTF instruments.

To keep our online bibliography up to date, we ask that you send us citations to your latest IRTF publications. You can verify that your refereed publications are listed in our bibliography at:

https://ui.adsabs.harvard.edu/search/q=bibgroup%3A%22irtf%22&sort=date%20desc%2C%20bibcode%20desc&p_=0

Please send any missing references to Warren Skidmore (warren.skidmore@hawaii.edu).

We are in the process of compiling a list of PhD Dissertations that have utilized observations obtained with the IRTF.

https://irtfweb2.ifa.hawaii.edu/research/biblio/dissertations.html

If you (or your student) has written a dissertation based on IRTF data that is not yet included in this list, please send the appropriate information (including a web link to the dissertation, if possible) to Warren Skidmore (warren.skidmore@hawaii.edu).

IRTF Spectral Libraries

Users are encouraged to make use of the spectral library of FGKM stars, which is available here. An extended spectral library including late-type non-solar stars observed by Alexa Villaume and collaborators is available here. Contact John Rayner (jrayner@hawaii.edu) for more details.

A library of more than 1000 prism spectra of low-mass stars and brown dwarfs is maintained by Adam Burgasser, and is available here.

The MIT-IRTF Near-Earth Object spectral survey is underway, and many spectra are publicly available. For more information go to http://smass.mit.edu/minus.html.

IRTF Data Reduction Update

Spextool for the SpeX instrument is being converted from IDL to Python by Mike Cushing (University of Toledo) and Adam Burgasser (UC San Diego). This eliminates the need for an IDL license, and enables data reduction with scripts, on the Python command line, and with Jupyter notebooks. A beta version of pySpextool for the Prism, SXD, and LXD modes is available on GitHub. It does not have GUIs yet, and while currently some Jupyter notebooks are available, there is no full manual yet. Users are invited to submit issues on GitHub and feedback is welcome.

All IRTF observers have the option to reduce their SpeX and iSHELL data remotely, on a dedicated IRTF computer instead of installing the software on their own machine. This computer, which is accessed via VNC, has IDL and the latest versions of Spextool for SpeX and iSHELL installed. Observers can request a temporary guest account by emailing their support astronomers. For more information, see here.

A beta version of Xtellcor_model is available, which uses atmospheric models instead of standard stars to remove telluric absorption lines in iSHELL spectra. The software, sample data, and a manual can be downloaded from the IRTF data reduction pages. Alternatively, the program can be run remotely on an IRTF computer in a VNC session. Optimization of the atmospheric column densities to the observed spectra is typically required, and thus the method works best if at least a few telluric lines are separated from stellar features. The telluric model can be further optimized interactively. Xtellcor_model also corrects for the iSHELL echelle order curvature using template spectra. We still recommend that observers plan to take standard star spectra until they have verified that Xtellcor_model satisfies the calibration needs for their science programs.

Fully automated "quicklook" reduction of SpeX and iSHELL spectra is operational during every observing session. This enables observers to assess the quality of their data in (near-) real-time and make better informed decisions. During an observing session, the software determines from the FITS headers if sufficient data is available to run a scripted version of Spextool. It then automatically extracts spectra and displays the signal and signal-to-noise values as a function of wavelength in DV (before division over a standard star). For more information, visit the Quicklook web page.

Please visit the IRTF data reduction pages for downloading the Spextool software for both SpeX and iSHELL, as well as sample data and other useful resources, and do not hesitate to contact Adwin Boogert (aboogert@hawaii.edu) for requests and questions about the reduction of IRTF data.

Data Archive

The IRTF Data Archive is hosted by the NASA/IPAC Infrared Science Archive (IRSA) at: https://irsa.ipac.caltech.edu/Missions/irtf.html. Raw data files taken with SpeX beginning Aug. 1, 2016, and with iSHELL beginning Feb. 1, 2017, are now publicly available via this site after a proprietary period of 12 months. As part of the archive process, the abstract field on the observing proposal form is being preserved and provided as metadata when data files are searched for or downloaded from the archive. For iSHELL and SpeX spectroscopy observations performed in the standard observing modes in semester 2019B and onward, best-effort automatically generated figures are available showing the extracted spectra and signal-to-noise values.

In June 2019, the IRTF Legacy Archive website was opened to the public. This site provides search and download capabilities for raw IRTF data files taken between 2001 and mid-2016. Possible search parameters include semester, start and end dates of the observations, program ID, target name and coordinates, and observer. Download of the data files is performed using a retrieval script that is generated from the search results. The Legacy Data are provided "as is" with no guarantee of quality or associated metadata other than the information contained in the fits file headers.

Adam Burgasser (UC San Diego) is leading a team that is using pyspextool to batch process archival SpeX data from the 2000-2020 period. Reduced data for those periods that have been processed will be provided to the community via the IRTF IRSA Archive; raw data for observations up to 2016 are currently served in the IRTF Legacy Archive and in the NASA/IPAC Infrared Science Archive for 2017 and later. As of August 2025, processing of the 2009-2010 SpeX observations is about 50% complete, and is expected to be part of a preliminary release later this year. Batch processing is typically carried out as part of undergraduate research projects where all observations of a particular type of object are systematically reduced and studied. The resulting catalogs of spectral data for asteroids, stars, galaxies, and other astronomical objects will be available for the community to use in any study, with the acknowledgement message posted on the IRTF website.