Call for Proposals for the
NASA Infrared Telescope Facility

DEADLINE: Monday 01 April 2024

NASA Infrared Telescope Facility Observing Proposals. The due date for the 2024B semester (August 1, 2024 to January 31, 2025) is Monday, April 1, 2024. See our online submission form, which is available for proposal submission from 12:00AM on March 01, 2024 until 5:00PM on April 01, 2024 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. After fine tuning during the first few semesters of DAPR, the guidelines remain unchanged this semester. See the instructions for semester 2024B below.

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

Facility 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 (

(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 (

(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). Commissioning observations involving radial velocities have yielded good results, with precisions better than 10 m/s achieved for targets brighter than K=10. The RV data reduction code is available on github or by request from Peter Plavchan ( 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 spectral extraction now 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 Adwin Boogert (

(4) MIRSI/MOC is a 5-20 micron camera and grism spectrograph and optical imager. MIRSI was recently 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 current engineering grade array was replaced with a science grade array. Current MIRSI capabilities are given here. Initial estimates are that sensitivity has not significantly improved (possibly since performance is already background limited) although array systematics and cosmetics are better. In the longer term we are hoping to improve performance by replacing degraded filters and by adding a chopping capability to the hexapod secondary stage. Spectroscopy with the grism is not offered this semester. For more information, see the instrument page and instrument manual or contact Mike Connelley (

(5) ‘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 (

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.

Visitor Instruments

Observing time with the visitor instrument TEXES, 5-20 micron high-resolution spectrograph, will be offered in 2024B. TEXES is a PI-led visitor instrument and is made available on a collaborative basis with the instrument team: please contact Tommy Greathouse ( for more information.

If the runs cannot happen due to continued re-introduced COVID precautions, accepted proposals will be offered replacement observing time with facility instruments. Please include a brief description of the contingency program in the proposal.


The IRTF was instructed by NASA Headquarters to implement Dual-Anonymous Peer Review (DAPR) procedures in the review and ranking of observing proposals beginning with the 2022A semester. To meet this requirement, some changes were made to the Online Application Form, and instructions for preparing the proposal attachment file were updated to meet the NASA DAPR guidelines. After fine tuning during the first few semesters of DAPR, the guidelines were relaxed to better align with the needs of the IRTF user community for 2023A and remain unchanged this semester. PLEASE follow the directions for preparing your proposal for observing time CAREFULLY. Note that we allow only one page of figures including both the science and technical cases. Any proposal that does not make a good-faith effort to maintain anonymity WILL BE REJECTED.

Should you have any questions about the DAPR rules please contact Adwin Boogert (

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.

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

Target of Opportunity Programs

Observers may apply for Target of Opportunity (ToO) programs on IRTF, but the total time that can be allocated to ToO programs is 24 hours for Solar System and 24 hours for non-Solar System proposals (an increase from 12 hours previously each for Solar System and non-Solar System proposals). Each ToO interrupt is limited to 3 hours in length. The proposal team must include at least one member that is highly familiar with the IRTF instrument being used, who will be able to carry out the interrupt observations without support from the IRTF staff. 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.

Engineering Time and Director Discretionary Time (DDT)

The IRTF schedule includes about 18 nights per semester for engineering. This time is used to address technical problems with the facility, calibrate instrumentation, and for IRTF staff science. Usually not all of this time is needed for engineering purposes, and some can be offered to observers in the form of Director’s Discretionary Time (DDT). 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 ( and Adwin Boogert (, 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. 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.

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.).

Remote Observing

Remote observing is available 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 ( 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).

IRTF Bibliography

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:

Please send any missing references to Bobby Bus (, and please continue to include in your paper the acknowledgement to the IRTF and the name of the instrument used as described at:

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

Data Archive

The IRTF Data Archive is hosted by the NASA/IPAC Infrared Science Archive (IRSA) at: 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 18 months from the date of observation. 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.