Call for Proposals for the
NASA Infrared Telescope Facility

DEADLINE: Thursday 01 April 2021

NASA Infrared Telescope Facility Observing Proposals. The due date for the 2021B semester (August 1, 2021 to January 31, 2022) is Thursday, April 1, 2021. See our online submission form, which is available for proposal submission from 12:00AM on March 01, 2021 until 5:00PM on April 01, 2021 HST. The deadline on a world clock listing is available here.

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

COVID-19 Precautions and Impact on Observing

The IRTF remains operational but with strict COVID protocols in place. All observing will be done remotely for the remainder of semester 2021A and possibly 2021B. Visitor instrument runs require the presence of out-of-state support staff. Despite the apparent slow easing of the pandemic and the increasing numbers being vaccinated, we are still uncertain if visitor instrument runs can be supported in 2021B. Nevertheless, we are planning to accept 2021B observing proposals for TEXES, HIPWAC and BASS but with no guarantee that these can take place. If the runs cannot happen, accepted proposals will be offered replacement time with facility instruments. Please include a brief description of the contingency program in the proposal.

Due to social distancing needs, staff presence at the summit (the day crew and telescope operators) is more limited, resulting in reduced efficiency and inevitable delays in some upgrade work. Where possible all other IRTF staff are encouraged to work from home. For nationwide COVID updates visit the CDC website. Hawaii COVID updates are available here and here. For IRTF updates please contact John Rayner (

Maunakea Observatories Update

Following the protests over the construction of TMT, access to all Maunakea Observatories has returned to normal. The status quo is likely to be maintained until and if TMT decides to take further action. If that happens access might become limited again but we will keep observers appraised of the situation. For updates contact John Rayner (

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 now 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 now automatically generated. For more information, see the instrument page and instrument manual or contact Bobby Bus (

(3) iSHELL is a 1.06 – 5.3 micron cross-dispersed echelle spectrograph (up to 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 of ~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 now 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 (

Information on available instruments and performance can be found at: The instrument manuals were updated in February 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 instruments TEXES and HIPWAC will be offered in 2021A. BASS will be offered for the first two months of 2021B (August and September). These PI-led visitor instruments are available on a collaborative basis with the instrument team: TEXES (5-20 micron high-resolution spectrograph; contact Tommy Greathouse at for more information), HIPWAC (a mid-IR heterodyne spectrograph; contact Tim Livengood at for more information) and BASS (3-14 micron spectrometer; contact Jon Mauerhan at for more information).

If the runs cannot happen due to continued 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.

TAC Information

Following feedback from the IRTF TAC, investigators 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. Address any comments made previously by the TAC. 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. Do not include target visibility plots. We encourage proposals that will provide data for thesis work. The student should be listed as PI or at least as Co-I. The TAC gives extra credit for student PIs. You will be asked to provide details of the thesis on the proposal form, including the anticipated year of graduation. In addition to comments, TAC feedback 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.

IRTF has been tasked by NASA HQ to move towards a Dual-Anonymous Peer Review (DAPR) of observing proposals. This will be an incremental process but we expect that steps towards anonymizing proposals will begin with proposals for 2022A (due 01 October, 2021). As an example, a detailed description of the DAPR process is provided by ESO. We will provide more details in the 01 September, 2021 call for 2022A observing proposals, at which time observers will need to download a new application form.

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 Bobby Bus (, 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.

Remote Observing

Remote observing is available with SpeX, MORIS, and iSHELL. 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.

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.