CAMERON MITCHELL MCDONALD OBSERVATORY POSTDOCTORAL FELLOWSHIP IN INSTRUMENTATION

The University of Texas at Austin’s McDonald Observatory announces competition for the Cameron Mitchell McDonald Observatory Postdoctoral Fellowship in instrumentation. This Fellowship is open to anyone with a Ph.D. in Astronomy or a closely allied field. Candidates are expected to have completed all requirements for a Ph.D. upon arrival, to reside in Austin, and to primarily work on-site. The successful applicant will join the McDonald Observatory instrumentation group and play an important, career-enhancing role in a current instrument project for the McDonald 2.7m telescope or the 10-m Hobby-Eberly Telescope (see below).  Candidates are encouraged to contact instrument team leads to discuss specific opportunities. The instrumentation group consists of astronomers and engineers and has a track record of delivering significant instruments and training the next generation of instrumentalists.

In addition to the instrumentation project, the successful candidate is encouraged to undertake research of their choosing in any area of astronomy and astrophysics, including their own instrument development. The fellowship includes funding for research expenses, including travel. Additional funds are available for relocation expenses. The initial appointment will be for one year, beginning September 2024, with the expectation of renewal for a second and third year following satisfactory research performance. An earlier start date may be considered, depending on individual circumstances.

For information on employee benefits, please see the HRS-Benefits home page at http://www.utexas.edu/hr/current/insurance.

Cameron Mitchell Fellowship Application Instructions:

1. Applicants should complete the application form at: https://utexas.qualtrics.com/jfe/form/SV_50xYH7zeVUGTIea.

2. After submitting the form, you will see a confirmation message in your browser with instructions to watch your Inbox for an email containing further instruction.

3. The emailed instructions will include details for submitting your application materials, as well as instructions for providing to your letter writers so that they may submit their letters. Please carefully follow the instructions in this email.

The submission deadline for all application materials and letters of recommendation is Sunday, December 31, 2023 at 11:59 pm Central Time.

Inquiries only may be sent to: astro_mcdobs_postdoc@utlists.utexas.edu

The University of Texas at Austin, as an equal opportunity / affirmative action employer, complies with all applicable federal and state laws regarding nondiscrimination and affirmative action.

Current McDonald Observatory Instrumentation Projects and Initiatives

(September, 2023)

The following projects are ongoing for McDonald Observatory facilities on Mt Locke and Mt Fowlkes and approximate timeframes are indicated. Please contact the project leads indicated for further information.

VIRUS2 – Gary Hill, Hanshin Lee, Niv Drory

The Visible Integral-field Replicable Unit Spectrograph 2 (VIRUS2) is a new facility instrument at the McDonald Observatory 2.7 m Harlan J Smith Telescope (HJST) that combines novel technologies developed as part of the HET VIRUS and LRS2 instruments to achieve an integral field spectrograph with both large wavelength and large area coverage. The lenslet-coupled fiber integral field unit has a 2.33 square arcminute field of view and a separate sky field. Light is split into 24 spectrograph channels to provide simultaneous coverage of this area over 370-930 nm at R~2000. VIRUS2 utilizes novel beam splitting and scrambling techniques as part of the fiber feed and is being assembled in Austin. Delivery and commissioning will take place during 2024, and the Cameron Mitchell Postdoc will immediately be able to join this effort on specific aspects of characterizing the performance in relation to the goals for the instrument. The design requirement of very accurate sky subtraction is of particular interest for future ELT instrumentation, and the Postdoc could lead the evaluation of performance in this area. VIRUS2 has a unique niche and science applications include studies of nearby galaxies, including the circumgalactic medium, starburst driven outflows, galaxy clusters, and transients. In addition to technical projects, there will be interesting science to pursue.

Enhancements to VIRUS2 are funded and would be interesting projects, starting after commissioning, that the Cameron Mitchell Postdoc could lead. A spectral calibration and image stability evaluation system based on Fabry-Perot Etalons will be added to the VIRUS2 calibration unit. This system will provide enhanced calibration but will also be used to evaluate the effectiveness of the scrambling and instrument stability for photon-limited sky subtraction. The Postdoc could lead the deployment, commissioning, and evaluation of this unit and lead the project to characterize the instrument performance. The second area of enhancement is the provision of a new set of green channel grisms based on reactive ion etching techniques (see gratings section below). The Postdoc can contribute to the design and testing of these elements and can lead their evaluation on-sky, comparing to the original volume-phase holographic gratings. An extensive grating test facility is available for this work. Lastly, the existing higher spectral resolution VIRUS-W integral field spectrograph will be integrated into the same feed as VIRUS2 so that both instruments can be used in parallel. The Postdoc could lead the deployment and commissioning of this mode. See Hill et al. (2022) and Lee et al. (2022a) and references therein for details of VIRUS2 development and see Lee et al. (2022c&d) for details of the reactive ion-etched grating development.

HET CCAS instrument upgrade – Hanshin Lee, Herman Kriel

The Center of Curvature Alignment Sensor (CCAS) for the HET is being upgraded with a suite of advanced metrology instruments to provide improved alignment precision and metrology for the 91 primary mirror segments. These instruments will be integrated into a complex opto-electro-mechanical system that will be mounted near the center of curvature of the HET M1 within the 90-foot-tall CCAS tower. In particular, the upgrade features a new dispersed fringe sensing (DFS) technique capable of measuring the piston error of all 240 segment edges across the HET’s 11m primary mirror in a single-shot exposure based on wavelength multiplexing, arrayed diffractive components, and spatial filters. This Single-Shot DFS will be the first of its kind and could potentially become a blueprint of the DFS instruments for future telescopes, such as the European ELT and TMT, where piston errors in thousands of segment edges must be efficiently controlled to nanometer level for reaching the diffraction-limited Adaptive Optics performance of these telescopes. Opportunities are available to participate in the overall development of the upgrade project and to become a lead scientist of the DFS instrument.

AWACS – Hanshin Lee

The Arrayed Wide-Angle Camera System (AWACS) is a novel segmented-field corrector architecture that can be scaled to a much larger than meter-size field of view featured in Extremely Large Telescopes (ELTs). The desired field expansion is accomplished via a suite of small optic units over a telescope’s focal surface for field aberration and atmospheric dispersion compensation. A dual-unit science-grade AWACS, with fully-fledged opto-electro-mechanical system including miniature ADC mechanisms, precision freeform lenses, anti-reflective nanostructures, and CNC-machined mechanical structures, has been developed and successfully tested on the HJST. Part of the ongoing AWACS-related research includes developing a large automatic positioning system for deployable IFUs, a super-stiff and light-weight mechanical structure design based on Silicon Carbide material, and a low-profile ADC control circuit design that can be fully integrated into AWACS Unit mechanics. These are all topics that the Postdoc could collaborate on. See Lee et al. (2021 & 2022b) for details.

HRS - Phillip MacQueen

The High Resolution Spectrograph (HRS) of the HET is currently off line for a substantial upgrade in performance and capabilities.  HRS is a fiber fed instrument that is configurable into multiple modes of resolving power, spectral coverage, sky coverage, and precision radial velocity capabilities. The objectives of the upgrade include much improved throughput at high resolving powers (70k and 105k), a bluer UV limit for abundance work (365 nm), improved radial velocity performance for exoplanet work, improved sky subtraction for faint object work and bright moonlight observing, and exposure metering for efficient observing and radial velocity precision. Before the current upgrade, HRS was a single arm spectrograph, after the upgrade, part of the existing HRS will become the red arm of a future two-arm spectrograph.  A blue arm is designed with some development work done to date and is a future second phase of the upgrade that will significantly improve HRS capabilities. Much of the hardware, control system, and software is built for the first phase, so the completion time is about 3 years or less.  Work opportunities exist in the key remaining tasks, including the blue arm, hardware installation, alignment, and the science commissioning. There is also interest in feeding both the HRS, and the HET HPF (Mahadevan et al. 2018) spectrographs from the same optical fiber, with a wavelength split around 800-900 nm.

HJST coude spectrograph upgrades - Phillip MacQueen

The Tull Spectrograph 2 (TS2) of the HJST is a high resolution, prism cross-dispersed echelle spectrograph at the 5-mirror coude feed to the HJST. Currently, TS2 uses a majority of the HJS telescope time. The TS23 mode at R=60k is the primary configuration and covers spectral orders from 360 nm to 1050 nm, with complete spectral coverage to 580 nm. Over the last decade, TS2 has undergone many subsystem upgrades, and more are planned and desired.  TS2 can now be run by an observer from their home with support from an on-site Remote Observing Assistant operating aspects of the telescope and facility safety. A high performance calibration system is nearing completion. Concepts for future projects that the Postdoc might lead are being considered. An image rotator is planned for atmospheric dispersion compensation in the coude feed, and an image stabilization subsystem is also under consideration. A fiber feed from the HJST f8.8 Ritchey-Chretien foci is highly desired.  Such a feed would include image stabilization, atmospheric dispersion compensation, wavefront sensing for telescope focus, calibration light injection, sky subtraction, image slicing for high throughput, and a different collimator.

Grating Development – Dan Jaffe, Cyndi Brooks, Greg Mace, Hanshin Lee

An area of technology development at McDonald Observatory is in etched gratings for infrared and optical spectroscopy. Immersed silicon gratings have been developed based on a wet-etching technique for near-infrared high-resolution spectroscopy by the team developing IGRINS and the future GMTNIRS spectrograph for the Giant Magellan Telescope. See Jaffe et al. (2014) and Kidder et al. (2016). Gratings for the optical regime, created with dry Reactive Ion-PLasma Etching (RIPLE) techniques, are under development in collaboration with the University of North Carolina at Charlotte and supported by the National Science Foundation. See Lee et al. (2022c & d). There is the prospect of adding RIPLE gratings to the VIRUS2 instrument to enhance throughput, and opportunities are available to be involved in this initiative. In particular, the team is working beyond the current effort toward creating a new facility capable of building very large RIPLE gratings in support of future ELT-scale spectroscopic instruments. This new initiative presents opportunities for the Postdoc to contribute to a variety of research topics, including diffractive wave propagation modeling, nano-scale real-time metrology system/motion control design, and highly uniform large area UV exposure instrument design.

Bibliography

Gary J. Hill, Hanshin Lee, Brian L. Vattiat, John M. Good, Jason Ramsey, Niv Drory, Trent Peterson, Briana L. Indahl, "VIRUS2: a next generation replicated integral field spectrograph with wide field and broad wavelength coverage," Proc. SPIE 12184, Ground-based and Airborne Instrumentation for Astronomy IX, 1218413 (2022)

Daniel T. Jaffe, Stuart Barnes, Cynthia Brooks, Michael Gully-Santiago, Soojong Pak, Chan Park, Insoo Yuk, "GMTNIRS (Giant Magellan Telescope Near-Infrared Spectrograph): optimizing the design for maximum science productivity and minimum risk," Proc. SPIE 9147, Ground-based and Airborne Instrumentation for Astronomy V, 914722 (2014)

Benjamin T. Kidder, Cynthia B. Brooks, Michelle M. Grigas, Daniel T. Jaffe, "Approaching perfection in the manufacturing of silicon immersion gratings," Proc. SPIE 9912, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation II, 99123L (2016)

Hanshin Lee, Brian L. Vattiat, Gary J. Hill, Niv Drory, Jason Ramsey, John M. Good, "Mix and match as you go: integration/test of the first beam switch module production that splits wavelengths, scrambles beams, and switches fibers for the VIRUS2 instrument," Proc. SPIE 12184, Ground-based and Airborne Instrumentation for Astronomy IX, 121846L (2022a)

Hanshin Lee, Brian L. Vattiat, Uma Subash, Menelaos K. Poutous, "Integration/test of dual unit arrayed wide-angle camera system and its evaluation in the context of Extremely Large Telescopes," Proc. SPIE 12184, Ground-based and Airborne Instrumentation for Astronomy IX, 121848E (2022b)

Hanshin Lee, Menelaos K. Poutous, "Arrayed wide-field astronomical camera system for spectroscopic surveys on Extremely Large Telescopes: system architecture, proof-of-concept, and enabling technologies," J. Astron. Telesc. Instrum. Syst. 7(3) 035007 (19 August 2021) https://doi.org/10.1117/1.JATIS.7.3.035007 (2021)

Hanshin Lee, Menelaos K. Poutous, "Reactive ion plasma etched surface relief gratings for low/medium/high resolution spectroscopy in astronomy," J. Astron. Telesc. Instrum. Syst. 8(4) 045002 (28 October 2022) https://doi.org/10.1117/1.JATIS.8.4.045002 (2022c)

Hanshin Lee, Uma Subash, Menelaos K. Poutous, "Fabrication and evaluation of reactive ion-plasma etched astronomical diffraction grating with anti-reflective surface nanostructures," Proc. SPIE 12188, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation V, 1218826 (2022d)

Mahadevan, S., et al. 2018, “The habitable-zone planet finder: engineering and commissioning on the Hobby Eberly telescope”, Proc. SPIE, 10702, Ground-based and Airborne Instrumentation for Astronomy VII, 1070214 (2018)