Call for Proposals for the
NASA Infrared Telescope Facility

DEADLINE: Wednesday 01 April 2026

NASA Infrared Telescope Facility Observing Proposals. The due date for the 2026B semester (August 1, 2026 to January 31, 2027) is Wednesday, April 1, 2026. See our online submission form, which is available for proposal submission from 12:00AM on March 01, 2026 until 5:00PM on April 01, 2026 HST. The deadline on a world clock listing is available here.

Note that the IRTF now implements the Dual-Anonymous Peer Review (DAPR) of observing proposals. See the instructions for semester 2026B below.

The proprietary period for observing data is 12 months starting from the date of the observation.

For up-to-date news about IRTF please read the Newsletter.

New Rules for Observers

1. We now request contact phone numbers and email addresses of TWO different observers be entered into the Observing Requirements Form (ORF). This is because of the increasing incidence of missed remote observing runs and occasional failure of observers to respond to phone and email reminders. Any missed runs may result in sanctions affecting the award of future observing time.

2. Due to vehicle shortages because of maintenance issues, we can no longer guarantee the use of an IRTF vehicle for the sole use of observing teams. Consequently, any visiting observing groups should make plans to travel from sea level to HP independently, and from HP to the telescope with IRTF Telescope Operators (unless you have your own 4x4 rental vehicle) and confirm the plans with IRTF staff before the run. These plans should be detailed in the ORF.

Facility and Visitor Instruments

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 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).

The precision of radial velocity measurements using the ¹³CH₄ gas cell is limited to 3-5 m/s for bright, K~4 mag stars on a time scale of a year (Cale, Plavchan, et al., 2019, AJ 158, p. 170). For fainter stars, 10 m/s is a more realistic precision. Observers should also take into account that 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 finder mounted to and aligned with IRTF. ‘Opihi consists 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 monitor extinction and cloud cover (similar to CFHT’s Skyprobe), and to flux calibrate SpeX prism or SXD spectra by simultaneously imaging in z'-band. ‘Opihi can locate asteroids down to V~20 in about one minute, propagate its motion across the sky, and send that ephemeris to the TCS. ‘Opihi is independent of other facility instruments and can thus be used in parallel with SpeX. For more details contact Mike Connelley (mconnell@hawaii.edu).

Observing time with the visitor instrument TEXES, 5-20 micron high-resolution spectrograph, will be offered in 2026B. TEXES is a PI-led visitor instrument and is made available on a collaborative basis with the instrument team: please contact Tommy Greathouse (tgreathouse@swri.edu) for more information.

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).

IMPORTANT NOTICE REGARDING IRTF TIME APPLICATIONS

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.

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.

General Proposal Requirements

You are asked to make a clear statement about the connection between the proposed observations and the overall science goal. It is important to concisely articulate the big science picture. Be specific about the number of targets needed, and for continuing proposals, what is needed for the program to be considered complete (follow-up proposals). Include observing overhead estimates. Figures need to be legible - no small print. Feedback to investigators now includes the proposal quartile ranking of successful proposals.

You are permitted one page for the science case, one page for the technical case and one page for figures and tables (including figures that are part of the technical justification. See the online submission form for details).

Investigators are reminded that any significant changes to the TAC approved observing program must be pre-approved by the IRTF Director.

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.

DDT observations have no proprietary period and are made publicly available via the IRSA archive very soon after the observations are obtained.

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.

Remote Observing

Remote observing is the standard observing mode with SpeX, MORIS, iSHELL, MIRSI, MOC, and ‘Opihi. You must comply with the requirements for video conferencing and instrument operation provided on the Remote Observers Information page. (A working three-button mouse is required.) Observers are strongly encouraged to contact Miranda Hawarden-Ogata (hawarden@hawaii.edu) or their support astronomer to set up a test of the video link and the user interface at least one month prior to their observing run. We cannot guarantee a successful remote observing connection on short notice since we have no control of hardware and software compatibility on the user’s side. It is the responsibility of the PI to provide up to date observing contact information through submission of the online Observing Requirements Form (ORF).

How to Acknowledge IRTF and the IRTF Bibliography

Acknowledgement is a formal requirement for any publications using IRTF observations. Observers must add the following footnote to any publications which incorporate data obtained at the IRTF:

"Astronomer observing with the Infrared Telescope Facility, which is operated by the University of Hawaii under contract 80HQTR24DA010 with the National Aeronautics and Space Administration."

If IRTF facility instruments have been used (iSHELL, SpeX, MORIS, MIRSI, MOC, `Opihi), the instrument paper must be cited. The citation can be found on the relevant instrument webpage. 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.

More details on how to acknowledge the IRTF in your publications is available here.

To keep our bibliography up to date, and to ensure future funding of the IRTF, we ask that you send us citations to your latest IRTF publications. You can check your publications using our website bibliography page for refereed papers:

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://irtfweb.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).

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.

Felix Off-axis Wavefront Sensor

Felix (IRTF’s new target acquisition camera) has a 2x2 Shack-Hartmann wavefront sensor mode to measure and maintain the focus of the telescope.

Felix is used by the telescope operator (TO) on an off-axis guide star. The TO initially focuses with the on-instrument guide camera (Guidedog, Kyle), then measures the focus with Felix on an off-axis guide star. Afterwards, Felix maintains focus by monitoring the off-axis guide star.

Felix focus control is setup by the TO while or shortly after the observer sets up on the science target. Observers should inform the TO if their observation will be short (under about 15 minutes), in which case the automated open loop focus control is sufficient. For longer observations, Felix should be used to minimize slit losses.