NASA IRTF Spring 2020 News

Last updated 27 March 2020

IRTF Shut Down Until Further Notice

The IRTF is shut down until April 30 at the earliest. This is in response to Governor Ige's proclamation for the state to shelter in place except for essential services due to the coronavirus. All other Maunakea observatories are also closed.

Maunakea Observatories Update

Following a declaration from TMT in December that no attempt to start construction would be made for at least three months, access to all Maunakea Observatories has returned to normal. It seems that 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.

Coronavirus Precautions

Observers are reminded that remote observing on IRTF with facility instruments, including staff support, works very well and that travelling to Hawaii is not needed. We normally encourage first-time students to visit but in light of the current epidemic this should possibly be avoided for now. Observers and support teams using visiting instruments still need to come out unless the epidemic precautions recommend avoiding travel. For updates contact John Rayner.

2020A Call for Proposals

Proposal Deadline for Semester 2020B (August 1, 2020 to January 31, 2021) is Thursday, April 9, 2020, 5PM Hawaii Standard time.

Please review the information and use our ONLINE application form

Available instruments are listed here. Remote observing is offered from any location with broadband Internet access for any project that utilizes IRTF facility instruments. Click here for more information.

IRTF Future Directions Workshop Update

We held a very successful workshop on the future of IRTF at the Biosphere 2 facility near Tucson on Feb 12-14, 2018. Input from the workshop is being used to explore possible future directions, to prepare white papers for input into the upcoming planetary and astrophysics decadal reviews, and to inform plans through and beyond the lease that ends in 2033 for operations of all the Maunakea telescopes. Workshop presentations are viewable here. The white papers resulting from the workshop are posted here.

Telescope Allocation Committee

The current TAC members for non-solar system proposals are: Mike Cushing (University of Toledo), Harriet Dinerstein (University of Texas at Austin), Joe Hora (CfA Harvard), and Andy Mann (University of NC at Chapel Hill), and for solar system proposals are: Mark Bullock (Southwest Research Institute), Katherine de Kleer (Caltech), Mário De Prá (University of Central Florida), and Lori Feaga (University of Maryland). Katelyn Allers (Bucknell University), Melissa McClure (University of Amsterdam), and Alan Tokunaga (University of Hawaii) rotated off the TAC effective 2020B. If you are interested in serving on the IRTF TAC please contact John Rayner.

Help Keep Our Publications List Current

Please continue to acknowledge the IRTF in your publications following the instructions shown here. 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.

IRTF Spectral Library

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 for more details.

SpeX Prism Library

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

NEO Spectral Survey

The MIT-IRTF Near-Earth Object spectral survey is underway, and many spectra are publicly available. See the side bar for more information or go to smass.mit.edu/minus.html.

IRTF Data Reduction Update

A new version of Spextool for iSHELL (5.0.3) was made available on the IRTF data reduction pages. The Lp4 mode can now be reduced, a number of bugs were fixed, and the manual was improved.

We have implemented "quicklook" reduction of SpeX and iSHELL spectra. 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 are 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.

The dark current frames for iSHELL that are taken by the support astronomers after each night are now automatically averaged. The instructions for downloading the processed (or raw) darks are given on the iSHELL instrument page.

We are still improving a version of Xtellcor (named Xtellcor_model) that uses atmospheric models instead of standard stars to remove telluric absorption lines in iSHELL spectra. A beta version of the software, sample data, and a manual can be downloaded from the IRTF data reduction pages. 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. We are currently improving the automated fitting algorithm. Xtellcor_model also includes a method to correct the iSHELL echelle order curvature using flat fields. This typically leaves more instrumental artifacts than when using standards stars, and observers should keep planning to take standard star spectra until they have verified that Xtellcor_model satisfies the calibration needs for their science programs.

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 us (Adwin Boogert) for requests and questions about the reduction of IRTF data.


IRTF News

Staffing:

Congratulations to Darryl Watanabe on his promotion to Observatory Manager. Darryl has been acting Observatory Manager since Imai Namahoe retired at the end of 2019. We also welcome two new day crew members: Electrical Technician Lee Tieche and Junior Mechanical Technician Kyle Usui. Kyle is a temporary replacement for a day crew member currently on long term medical leave.

IRTF Data Archive:

The IRTF Data archive is now open for use, and is being hosted by the NASA/IPAC Infrared Science Archive (IRSA). 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.

Further information can be viewed on the IRTF Data Release Policy page or contact Bobby Bus.

Hour Angle Drive Problem Fixed

Following servicing of the telescope hour angle (HA) drive in March 2019 the telescope has occasionally experienced oscillations in RA while tracking and also banging during slews that required slowing the slew speed. Extensive testing found that the west motor had lost torque probably due to demagnetization of the motor’s permanent magnet when it was removed during servicing. The telescope was stood down for three weeks in December while the motor was sent to a vendor on the mainland to be remagnetized. Once the motor was reinstalled together with an increase in the gearbox backlash current oscillations are longer experienced and performance is back to normal. During the enforced telescope shutdown the opportunity was taken to modify and fit more modern motors as drop-in replacements.

New Moveable Counterweights

With the addition of iSHELL it is currently not possible to balance the telescope for all combinations of facility and visitor instruments stowed on the multiple instrument mount (MIM), reducing scheduling flexibility. To correct this, two new moveable counterweights, each weighing 1000 kg, are being fabricated. Installation of these counterweights will require several days of telescope downtime. Installation of the new counterweights has been delayed by troubleshooting and eventually fixing the HA drive problem. Since installing the new counterweights are not critical for telescope operations we want to experience a few months of problem-free tracking and slewing before adding the extra weight to the telescope.

Instrumentation Update

SpeX:

SpeX is a 0.7-5.3 micron medium-resolution 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. Electronic observing logs are now automatically generated. Real-time spectral extraction runs automatically in the background. For more information, see the SpeX instrument page or contact Mike Connelley.

MORIS:

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. Electronic observing logs are now automatically generated. For more information see the MORIS instrument page or contact Bobby Bus.

iSHELL:

iSHELL is a 1.06 – 5.3 micron cross-dispersed echelle spectrograph (up to R=80,000) and imager. Unfortunately, wedging the order sorting filters did not fix the fringing observed in the flat fields. Consequently, to reach S/N>100 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. Thus beginning 2019B, we are no longer limiting the number of proposals requiring higher precision radial velocities. The RV data reduction code is available on github or by request from Peter Plavchan (pplavcha@gmu.edu). 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. For more information, see the iSHELL instrument page or contact Adwin Boogert.

MIRSI/MOC:

MIRSI/MOC is a 5 – 20 micron camera and grism spectrograph and optical imager. Due to operational reasons MIRSI now uses a ZnSe window, limiting the long wavelength cutoff to 20 microns. MIRSI was recently upgraded by IR Labs with a closed-cycle cooler to replace its liquid nitrogen and liquid helium cryostat. It is currently undergoing further refurbishment by IRTF staff with a new array controller and addition of an optical channel similar to MORIS (MOC) with a 60"x60" field-of-view. Unfortunately fixing read out problems is taking much longer than anticipated. The original science grade array no longer works but we plan to use a science grade array being loaned to IRTF from Gemini and which was originally used in T-ReCS, once MIRSI is successfully tested on IRTF with the engineering grade array. Because MIRSI has yet to be recommissioned on the telescope, we will offer MIRSI in shared risk mode during the 2020B semester. A new chopping secondary mirror should also be available for use with MIRSI. Remote observing will be available with MIRSI and MOC. For more information see the MIRSI instrument page or contact Charles Lockhart or Mike Connelley.

Proposed New IRTF Facility Instrument:

SPECTRE (Spectrograph Express) is a R=150 0.4-4 micron 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 2.4-4.0 micron, and the integral field unit has a ~6x6 arcsec FOV to remove slit losses and to acquire absolute photometry on point sources. Object acquisition and guiding is done with a 3 arcmin FOV CCD. There are no cold mechanisms, facilitating easy and once-per-night calibration. The preliminary science case and instrument concept were presented at the IRTF’s Future Directions Workshop in February, 2018. SPECTRE received strong support from the workshop participants. High priority science cases include: the characterization of NEOs and small bodies, measuring fundamental stellar parameters (Lbol and Teff) and characterizing exoplanet hosts, optical-IR transient follow-up and variability, ISM dust and ice studies through stellar extinction measurements, spatially resolved spectroscopy (binaries), occultation spectroscopy, and spectral-spatial mapping of ice and dust in comet comae. IRTF submitted a funding proposal for SPECTRE to the NSF MSIP program in December 2019. For more details contact Mike Connelley or John Rayner.

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

FELIX will replace the current off-axis telescope guider. It consists of a CCD, optics and pick-off mirror on an XY stage. The pick-off mirror patrols a U-shaped 50 square arcminute surrounding the three arcminute diameter telescope on-axis FOV. In addition to imaging a one arcminute diameter FOV, the optics can switch to a 3x3 Shack-Hartman wavefront sensor. By controlling the hexapod secondary the system will initially provide real-time focus and alignment correction. Since only slow correction is needed, closed loop correction can be done on stars to V=18 in about one minute. Aside from atmospheric seeing, defocus is currently the largest error in the telescope’s image quality budget. FELIX will be available for use with all Cassegrian-mounted facility and visitor instruments. We expect FELIX to be operational by 2021. For more details contact Mike Connelley or John Rayner.

A future upgrade could include a deformable mirror on the hexapod mount. Using slow wavefront corrections measured with the Shack-Hartmann additional corrections could then include the astigmatism introduced by slight bending of the primary mirror as the telescope points around the sky. The UH 2.2-m telescope is currently developing a deformable secondary technology that would be suitable for IRTF. The PI for the UH 2.2-m project is Mark Chun.

`Opihi: wide angle finder

`Opihi is conceived as a wide angle finder for IRTF. The goals are to acquire asteroids with large position uncertainties for SpeX and MORIS, to monitor extinction and cloud cover (like CFHT’s Skyprobe), and to provide general context imaging. ‘Opihi consists of a 17-inch diameter Planewave corrected Dall-Kirkham telescope with Andor 2k x 2k CCD array to provide a 0.5 degree FOV. ‘Opihi will mount (‘cling’) to the side of the mirror cell. We are currently investigating possible issues with the clearance of the beam at the telescope shutter. We hope to install ‘Opihi by 2021. For more details contact Mike Connelley or Bobby Bus.