Jonathan Elias

SN 1994I in M51 and the nature of type Ibc supernovae

Early spectra of SN 1994I in M51 (NGC 5194) are presented along with arguments that is a member of the class of helium-poor Type Ic supernovae. The issue of H and He in the spectra of Type Ib and Ic events is reexamined with the conclusion that Type Ib eject substantially less H than even transition events like SN 1993J and that Type Ic eject substantially less He than Type Ib and their optical spectra are consistent with no H or He. Type Ic show and absorption of the Si II lambda 6355 blend that characterizes Type Ia. This feature requires only a solar abundance of Si. Some Type Ic show an absorption that is probably C II lambda 6580. IR spectra are presented of SN 1990W which show the line of He I lambda 10830. The strength of this feature and the rather slow decay of the late time light curve suggest that this event could be better classified as a Type Ib. Even if trace abundances of H are present in Type Ib and of He in Type Ic the spectral differences still imply a distinctly different evolution for the progenitors of Type Ib from Type Ic and events like SN 1993J.

The energy sources powering the late-time bolometric evolution of SN 1987A

New optical and infrared data show that a third radioactive nuclide, 57 Co, is now powering the supernova nebula. The best fit to the late-time bolometric light curve is with 0.01 M ⊙ 57 Co (∼5 times the amount expected based on the solar ratio of 57 Fe/ 56 Fe). However, if recent theoretical upper limits on the expected production of 57 Co ans 44 Ti are correct, then either an additional energy input is needed or one of the fundamental assumptions used in the modeling of the data is in error

Optical Light Curves of the Type I[CLC]a[/CLC] Supernovae SN 1990N and SN 1991T

We present UBVRI light curves for the bright Type Ia supernovae SN 1990N in NGC 4639 and SN 1991T in NGC 4527, based on photometry gathered in the course of the Calan/Tololo supernova program. Both objects have well-sampled light curves starting several days before maximum light and spanning well through the exponential tail. These data supersede the preliminary photometry published by Leibundgut et al. and Phillips et al. The host galaxies for these supernovae have (or will have) accurate distances based on the Cepheid period-luminosity relationship. The photometric data in this paper provide template curves for the study of the general population of Type Ia supernovae and accurate photometric indices, needed for the Cepheid-supernova distance scale.

The Cerro Tololo Inter-American Observatory infrared spectrometer

Inter-American Observatory. The instrument has a slit of modest length and a selection of gratings that allow resolutions (λ/{DELTA}λ) from ~150 to ~3000 over the wavelength range covered by its photovoltaic InSb array: 0.9 microns to 5 microns. The design and operating characteristics of the IRS are described, and observing procedures and data-reduction techniques are outlined for potential users.

Optical light curves of the type ia supernovae 1990n and 1991t

We present UBVRI light curves for the bright Type Ia supernovae SN 1990N in NGC 4639 and SN 1991T in NGC 4527, based on photometry gathered in the course of the Calan/Tololo supernova program. Both objects have well-sampled light curves starting several days before maximum light and spanning well through the exponential tail. These data supersede the preliminary photometry published by Leibundgut et al. and Phillips et al. The host galaxies for these supernovae have (or will have) accurate distances based on the Cepheid period-luminosity relationship. The photometric data in this paper provide template curves for the study of the general population of Type Ia supernovae and accurate photometric indices, needed for the Cepheid-supernova distance scale.

Preliminary optical design for the TMT mid-infrared adaptive optics system and echelle spectrograph

We present a preliminary optical design for a mid-infrared, high-resolution spectrograph (MIRES), together with an integrated adaptive optics system optimized for the mid-infrared, intended for use on a 30-meter telescope. The design includes laser guide star wavefront sensors, a near-infrared natural guide star wavefront sensor with a patrol field of 60 arcseconds, and near-infrared and mid-infrared imaging channels, in addition to the cross-dispersed spectrograph itself. The spectrograph provides resolution of up to 120,000 and continuous spectral coverage over multiple cross-dispersed orders, with high efficiency between 4.5 and 25 microns.

KOSMOS and COSMOS: new facility instruments for the NOAO 4-meter telescopes

We describe the design, construction and measured performance of the Kitt Peak Ohio State Multi-Object Spectrograph (KOSMOS) for the 4-m Mayall telescope and the Cerro Tololo Ohio State Multi-Object Spectrograph (COSMOS) for the 4-m Blanco telescope. These nearly identical imaging spectrographs are modified versions of the OSMOS instrument; they provide a pair of new, high-efficiency instruments to the NOAO user community. KOSMOS and COSMOS may be used for imaging, long-slit, and multi-slit spectroscopy over a 100 square arcminute field of view with a pixel scale of 0.29 arcseconds. Each contains two VPH grisms that provide R~2500 with a one arcsecond slit and their wavelengths of peak diffraction efficiency are approximately 510nm and 750nm. Both may also be used with either a thin, blue-optimized CCD from e2v or a thick, fully depleted, red-optimized CCD from LBNL. These instruments were developed in response to the ReSTAR process. KOSMOS was commissioned in 2013B and COSMOS was commissioned in 2014A.

Design tradeoffs for a high spectral resolution mid-infrared echelle spectrograph on the Thirty-Meter Telescope

A feasibility design study was undertaken to assess the requirements of a mid-infrared echelle spectrograph (MIRES) with a resolving power of 120,000 and its associated mid-infrared adaptive optics (MIRAO) system on the Thirty-Meter Telescope. Our baseline design incorporates a 2K×2K Si:As array or array mosaic for the spectrograph and a 1K×1K Si:As array for the slit viewer. Various tradeoffs were studied to minimize risk and to optimize the sensitivity of the instrument. Major challenges are to integrate the spectrograph to the MIRAO system and, later, to an adaptive secondary, the procurement of a suitable window and large KRS-5 lenses, and the acquisition of large format mid-IR detector arrays suitable for the range of background conditions. We conclude that the overall risk is relatively low and there is no technical reason that should prevent this instrument from being ready for use at first light on the Thirty- Meter Telescope.

Design of an efficient infrared spectrometer for large telescopes

We present the conceptual design for a medium-resolution (R equals 2000, 6000) spectrometer for the near IR (0.9 micrometers - 5 micrometers ) to be used on the Gemini 8 m Telescopes. The design goal is to make optimum use of the unique characteristics of the telescopes: superb image quality and low near-IR background. This leads us to propose a mostly reflective design, with cold, pupil-reimaging fore-optics. We achieve a modest slit length of 100 arcsec. In addition to the basic high-spatial-resolution configuration, the design permits a number of important upgrades: a camera for use with a wider slit, a prism cross-disperser, an integral field module to spatially sample a small 2-D region of the focal plane. The spectrometer is designed around the next generation of InSb detectors, the 1024 X 1024 Aladdin arrays currently under development.

The SOAR Telescope as a node in a time domain followup-network: concepts and plans

With the advent of large-scale time-domain surveys such as the LSST, there is a strong desire for the 4-m SOAR Telescope to be able to respond efficiently and effectively to transient alerts. Enabling the required capabilities at SOAR will also support a greater variety of science programs than conventional telescope scheduling. These capabilities are best deployed with SOAR acting as one of several telescopes responding to alerts and supporting time domain programs. We outline how this might be done if SOAR is included as a node in the Las Cumbres Observatory network, at least part-time. This allows SOAR to make use of extensive existing software infrastructure, while adding a larger aperture to the existing network. Participation of SOAR also serves as a pathfinder for participation of other large telescopes in an evolved LCO network. The overall workflow is outlined. Required interfaces are described. Finally, the initial development efforts with this goal in mind are outlined.