Hectospec, the MMT’s 300 Optical Fiber‐Fed Spectrograph

Fabricant, Daniel G.; Fata, Robert G.; Roll, John; Hertz, Edward; Caldwell, Nelson; Gauron, Thomas; Geary, John C.; McLeod, B. A.; Szentgyorgyi, Andrew; Zajac, Joseph; Kurtz, Michael J.; Barberis, Jack; Bergner, Henry; Brown, Warren R.; Conroy, Maureen A.; Eng, Roger; Geller, Margaret J.; Goddard, Richard E.; Honsa, M.; Mueller, Mark; Mink, Jessica; Ordway, Mark; Tokarz, S.; Woods, D.; Wyatt, William F.; Epps, Harland W.; Dell’Antonio, Ian

doi:10.1086/497385

Cited by 357 publications

(324 citation statements)

References 26 publications

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“…Flux calibration and telluric correction were performed using a set of custom idl scripts (see, e.g., Matheson et al 2008;Blondin et al 2012) and standard star observations obtained the same night as the science exposures. Spectra obtained with the Hectospec multifiber spectrograph (Fabricant et al 2005) were reduced using the IRAF package "hectospec" and the CfA pipeline designed for this instrument.…”

Section: Optical Spectroscopymentioning

confidence: 99%

Rapidly Evolving and Luminous Transients From Pan-Starrs1

Drout

Chornock

Söderberg

et al. 2014

ApJ

316

444

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In the past decade, several rapidly evolving transients have been discovered whose timescales and luminosities are not easily explained by traditional supernovae (SNe) models. The sample size of these objects has remained small due, at least in part, to the challenges of detecting short timescale transients with traditional survey cadences. Here we present the results from a search within the Pan-STARRS1 Medium Deep Survey (PS1-MDS) for rapidly evolving and luminous transients. We identify 10 new transients with a time above half-maximum (t 1/2 ) of less than 12 days and −16.5 > M > −20 mag. This increases the number of known events in this region of SN phase space by roughly a factor of three. The median redshift of the PS1-MDS sample is z = 0.275 and they all exploded in star-forming galaxies. In general, the transients possess faster rise than decline timescale and blue colors at maximum light (g P1 − r P1 −0.2). Best-fit blackbodies reveal photospheric temperatures/radii that expand/cool with time and explosion spectra taken near maximum light are dominated by a blue continuum, consistent with a hot, optically thick, ejecta. We find it difficult to reconcile the short timescale, high peak luminosity (L > 10 43 erg s −1 ), and lack of UV line blanketing observed in many of these transients with an explosion powered mainly by the radioactive decay of 56 Ni. Rather, we find that many are consistent with either (1) cooling envelope emission from the explosion of a star with a low-mass extended envelope that ejected very little (<0.03 M ) radioactive material, or (2) a shock breakout within a dense, optically thick, wind surrounding the progenitor star. After calculating the detection efficiency for objects with rapid timescales in the PS1-MDS we find a volumetric rate of 4800-8000 events yr −1 Gpc −3 (4%-7% of the core-collapse SN rate at z = 0.2).

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Section: Optical Spectroscopymentioning

confidence: 99%

Rapidly Evolving and Luminous Transients From Pan-Starrs1

Drout

Chornock

Söderberg

et al. 2014

ApJ

316

444

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“…Hectospec is a 300 fiber spectrometer with a 1 • diameter field of view (FOV) mounted on the MMT (Fabricant et al 2005;Mink et al 2007). The combination of a wide field with a large aperture makes Hectospec well suited to cover extended areas, such as the LHS.…”

Section: Mmt 2009 Spectroscopymentioning

confidence: 99%

Mid-Infrared-Selected Quasars. I. Virial Black Hole Mass and Eddington Ratios

Dai

Elvis

Bergeron

et al. 2014

ApJ

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We provide a catalog of 391 mid-infrared-selected (MIR; 24 μm) broad-emission-line (BEL; type 1) quasars in the 22 deg 2 SWIRE Lockman Hole field. This quasar sample is selected in the MIR from Spitzer MIPS with S 24 > 400 μJy, jointly with an optical magnitude limit of r (AB) < 22.5 for broad line identification. The catalog is based on MMT and Sloan Digital Sky Survey (SDSS) spectroscopy to select BEL quasars, extending the SDSS coverage to fainter magnitudes and lower redshifts, and recovers a more complete quasar population. The MIR-selected quasar sample peaks at z ∼ 1.4 and recovers a significant and constant (20%) fraction of extended objects with SDSS photometry across magnitudes, which were not included in the SDSS quasar survey dominated by point sources. This sample also recovers a significant population of z < 3 quasars at i > 19.1. We then investigate the continuum luminosity and line profiles of these MIR quasars, and estimate their virial black hole masses and the Eddington ratios. The supermassive black hole mass shows evidence of downsizing, although the Eddington ratios remain constant at 1 < z < 4. Compared to point sources in the same redshift range, extended sources at z < 1 show systematically lower Eddington ratios. The catalog and spectra are publicly available online.

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“…We obtained the spectra of PNe and H ii regions in M 81 with the MMT Hectospec fiber-fed spectrograph (Fabricant et al 2005 (Magrini et al 2009(Magrini et al , 2010. We also endeavored to have PN targets at several galactocentric distances, in order to characterize the PN metallicity gradient.…”

Section: Observationsmentioning

confidence: 99%

The population of planetary nebulae and H II regions in M 81

Stanghellini¹,

Magrini

Villaver³

et al. 2010

A&A

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Context. M 81 is an ideal laboratory to investigate the galactic chemical and dynamical evolution through the study of its young and old stellar populations.Aims. We analyze the chemical abundances of planetary nebulae and H ii regions in the M 81 disk for insight on galactic evolution, and compare it with that of other galaxies, including the Milky Way.Methods. We acquired Hectospec/MMT spectra of 39 PNe and 20 H ii regions, with 33 spectra viable for temperature and abundance analysis. Our PN observations represent the first PN spectra in M 81 ever published, while several H ii region spectra have been published before, although without a direct electron temperature determination. We determine elemental abundances of helium, nitrogen, oxygen, neon, sulfur, and argon in PNe and H ii regions, and determine their averages and radial gradients. Results. The average O/H ratio of PNe compared to that of the H ii regions indicates a general oxygen enrichment in M 81 in the last ∼10 Gyr. The PN metallicity gradient in the disk of M 81 is Δlog(O/H)/ΔR G = −0.055 ± 0.02 dex/kpc. Neon and sulfur in PNe have a radial distribution similar to that of oxygen, with similar gradient slopes. If we combine our H ii sample with the one in the literature we find a possible mild evolution of the gradient slope, with results consistent with gradient steepening with time. Additional spectroscopy is needed to confirm this trend. There are no type I PNe in our M 81 sample, consistently with the observation of only the brightest bins of the PNLF, the galaxy metallicity, and the evolution of post-AGB shells. Conclusions. Both the young and the old populations of M 81 disclose shallow but detectable negative radial metallicity gradient, which could be slightly steeper for the young population, thus not excluding a mild gradients steepening with the time since galaxy formation. During its evolution M 81 has been producing oxygen; its total oxygen enrichment exceeds that of other nearby galaxies.

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Hectospec, the MMT’s 300 Optical Fiber‐Fed Spectrograph

Cited by 357 publications

References 26 publications

Rapidly Evolving and Luminous Transients From Pan-Starrs1

Rapidly Evolving and Luminous Transients From Pan-Starrs1

Mid-Infrared-Selected Quasars. I. Virial Black Hole Mass and Eddington Ratios

The population of planetary nebulae and H II regions in M 81

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