The Magellan InfraRed Multi-Object Spectrograph (MIRMOS) is a planned next generation multi-object and integral field spectrograph for the 6.5m Magellan telescopes at Las Campanas Observatory in Chile. MIRMOS will perform R similar to 3700 spectroscopy over a simultaneous wavelength range of 0.886 - 2.404 mu m (Y,J,H,K bands) in addition to imaging over the range of 0.7 - 0.886 mu m. The integral field mode of operation for MIRMOS will be achieved via an image slicer style integral field unit (IFU) located on a linear stage to facilitate movement into the beam during use or storage while operating in multi-object mode. The IFU will provide a similar to 20 '' x26 '' field of view (FoV) made up of 0.84 '' x26 '' slices. This will be the largest FoV IFS operating at these wavelengths from either the ground or space, making MIRMOS an ideal instrument for a wide range of science cases including studying the high redshift circumgalactic medium and emission line tracers from ionized and molecular gas in nearby galaxies. In order to achieve the desired image quality and FoV while matching the focal ratio to the multi-object mode, our slicer design makes use of novel freeform surfaces for the pupil mirrors, which require the use of high precision multi-axis diamond milling to manufacture. We present here the optical design and predicted performance of the MIRMOS IFU along with a conceptual design for the opto-mechanical system.

We report on the status of Henrietta, a new near-infrared low-resolution (R similar to 200) spectrograph for the 1-meter Swope telescope at Las Campanas Observatory in Chile. Henrietta is uniquely designed to perform transmission spectroscopy of tens of exoplanet atmospheres per year across a wide bandpass and routinely reach the photon noise limit on a nightly basis. Henrietta is currently at Carnegie Observatories, where it is undergoing assembly and optical alignment, as well as spectrophotometric testing to identify Henrietta's spectrophotometric noise floor. Upon finishing assembly and testing in Summer 2024, Henrietta will be shipped to Las Campanas Observatory where it will begin commissioning. In this talk, I will describe Henrietta's science mission, its overall design, the results of current testing, its goals for commissioning and future opportunities for collaboration.

This paper presents the design and technical progress of a precision X-Y stage for detector dithering and flexure compensation. The stage is being developed for use in the Magellan InfraRed Multi-Object Spectrograph, MIRMOS. MIRMOS is a very large Nasmyth mounted spectrograph containing a combination of refractive, reflective and diffractive optics mounted on a long cryogenic optical bench. The instrument utilizes five science cameras, each having a custom x-y stage to control the in-plane detector position within each camera, providing both dithering capability for improved sampling, and flexure compensation to correct for image motion that results from the gravity variant operation of the instrument. Designed to operate at 120 K, the stage will accurately control detector position in two orthogonal degrees of freedom, and have manual fine adjustment features to set detector tip, tilt and piston. The piezo-driven flexure stage provides high-resolution backlash-free motion of the detector and is very compact along the optical path, keeping camera length to a minimum. A magnetoresistive bridge provides position feedback in each degree of freedom, greatly reducing hysteresis, which is common in piezoelectric actuators. The system is designed to operate in open loop using a lookup table keyed to the Nasmyth rotator angle for flexure control. Here, the optomechanical design of the stage, electrical control system, and current performance results from early prototype efforts are presented and discussed.

The Magellan Infrared Multi-object Spectrograph (MIRMOS) is a near-infrared (NIR) spectrograph with both multi-object (MOS) and integral field unit (IFU) capabilities designed for the Magellan 6.5-meter telescopes. MIRMOS’s design is optimized for both faint-object spectroscopy, and with the insertion of a diffuser, for ultra-high-signal-to-noise transmission spectroscopy of exoplanet atmospheres. To maximize MIRMOS’s scientific returns, it has an instantaneous wavelength range from 0.89-2.4 µm with a spectral resolution >3, 400 in the Y, J, H, and K bands. The front end switches between a mechanical slit mask robot capable of deploying 92 slits over a 13′ × 3 ′ field, and an image slicer IFU with a wide field of 26′′ × 20′′. In this proceeding, we will describe the current state of the instrument, with a focus on its optical design.

We present the design of Henrietta, is a wide-band (0.6 - 2.4 µm) low resolution spectrograph located at the 1-m Swope Telescope in Las Campanas Observatory. Henrietta is designed to routinely suppress instrumental variations in spectrophotometric flux in order to reach the photon noise limit. The primary way Henrietta achieves this is by employing a wide-slit at the telescope focal plane to mitigate time-dependent slit losses; employing a diffusing optical element to broaden the shape of the PSF and mitigate flux variations due to the intra-pixel quantum efficiency variations; a wide field-of-view for access to reference stars with similar brightness and spectral type; and minimizing the number of optical elements to keep throughput high across a wide spectral range. Henrietta is currently in the integration and testing phase and will begin science operations in early 2023.

The Magellan Infrared Multi-object Spectrograph (MIRMOS) is a near-infrared (NIR) multi-object spectrograph (MOS) and integral field unit (IFU) to be deployed at the Magellan 6.5-meter telescopes at Las Campafias Observatory. MIRMOS is designed to address frontier scientific questions in extragalactic, cosmological, and exoplanetary science. These scientific questions led us to spectrograph with an instantaneous wavelength range from 0.89-2.4 mu m with a spectral resolution > 3, 700. The spectrograph is fed by a front end that switches between a robotic mechanical slit mask capable of deploying nearly 90 slits over a 13' x 3' field, or by an image slicer IFU with a wide field of 26 '' x 20 ''. MIRMOS is currently under design at the Carnegie Observatories.