Special configuration of a very large Schmidt telescope for extensive astronomical spectroscopic observation

Wang, Shouguan; Su, Ding-qiang; Chu, Yaoquan; Cui, Xiangqun; Wang, Yanan

doi:10.1364/ao.35.005155

Cited by 255 publications

(160 citation statements)

References 10 publications

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“…WD J0308+5140 is the only target that we observed that does not fall within the SDSS footprint; it was instead originally identified from a LAMOST (Large Sky Area Multi-Object Spectroscopy Telescope; Wang et al 1996;Cui et al 2012) spectrum. For convenience, we follow the convention of Gianninas et al (2015) and include it in tables under the "SDSS" column header.…”

Section: Wd J0308+5140mentioning

confidence: 99%

Pruning The ELM Survey: Characterizing Candidate Low-mass White Dwarfs through Photometric Variability

Bell

Gianninas

Hermes

et al. 2017

ApJ

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We assess the photometric variability of nine stars with spectroscopic T eff and log g values from the ELM Survey that locate them near the empirical extremely low-mass (ELM) white dwarf instability strip. We discover three new pulsating stars: SDSS J135512.34+195645.4, SDSS J173521.69+213440.6 and SDSS J213907.42+222708.9. However, these are among the few ELM Survey objects that do not show radial velocity variations to confirm the binary nature expected of helium-core white dwarfs. The dominant 4.31-hr pulsation in SDSS J135512.34+195645.4 far exceeds the theoretical cutoff for surface reflection in a white dwarf, and this target is likely a high-amplitude δ Scuti pulsator with an overestimated surface gravity. We estimate the probability to be less than 0.0008 that the lack of measured radial velocity variations in four of eight other pulsating candidate ELM white dwarfs could be due to low orbital inclination. Two other targets exhibit variability as photometric binaries. Partial coverage of the 19.342-hr orbit of WD J030818.19+514011.5 reveals deep eclipses that imply a primary radius > 0.4 R -too large to be consistent with an ELM white dwarf. The only object for which our time series photometry adds support to the ELM white dwarf classification is SDSS J105435.78−212155.9, with consistent signatures of Doppler beaming and ellipsoidal variations. We interpret that the ELM Survey contains multiple false positives from another stellar population at T eff 9,000 K, possibly related to the sdA stars recently reported from SDSS spectra.

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Section: Wd J0308+5140mentioning

confidence: 99%

Pruning The ELM Survey: Characterizing Candidate Low-mass White Dwarfs through Photometric Variability

Bell

Gianninas

Hermes

et al. 2017

ApJ

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“…The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST, also called Guo Shou Jing Telescope) is a National Major Scientific project undertaken by the Chinese Academy of Science (Wang et al 1996;Cui et al 2012). LAMOST has a field of view as large as 20 square degrees, and at the same time a large effective aperture that varies from 3.6 to 4.9 m in diameter.…”

Section: Introductionmentioning

confidence: 99%

M Dwarf Catalog of the Lamost Pilot Survey

Luo

Song

et al. 2014

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We present a spectroscopic catalog of 58,360 M dwarfs from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope pilot survey. For each spectrum in the catalog, spectral subtype, radial velocity, Hα equivalent width, a number of prominent molecular band indices, and the metal-sensitive parameter ζ are provided. We use the Sloan Digital Sky Survey Data Release 7 Spectroscopic M dwarf catalog to verify the precision of our methods of classifying the spectral types and measuring the radial velocities. The magnetic activity properties of M dwarfs are also traced by Hα emission lines. The molecular band indices included in this catalog are sensitive to temperature or metallicity, and can be used for further study of the physical properties of M dwarfs. This M dwarf catalog is available on the Web site http://sciwiki.lamost.org/MCatalogPilot/.

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“…The principal axis lengths of the elliptical clear aperture entrance pupil M1 are 2R 0 and 2R 0 / cos i. Such reflective Schmidt design geometries have been adopted for broad-band faint object spectrographs with aspherised gratings [21] and also for the giant Chinese segmented telescope LAMOST [22,23]. However, in these cases, the focal surface in the middle of the beam creates a central obscuration and additional diffraction spikes are caused by the holding spider.c Therefore, in our proposed design, both the spiders and the corresponding diffractive deformation of the PSF are eliminated by adding a folding flat mirror.…”

Section: Bi-folded Schmidt Design a The Design Conceptmentioning

confidence: 99%

Fast, wide-field and distortion-free telescope with curved detectors for surveys at ultralow surface brightness

et al. 2017

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We present the design of an all-reflective, bi-folded Schmidt telescope aimed at surveys of extended astronomical objects with extremely-low surface brightness. The design leads to a high image quality without any diffracting spider, a large aperture and field of view, and a small central obstruction which barely alters the PSF. As an example, we design a high-quality, 36 cm diameter, fast ( f /2.5) telescope working in the visible with a large field of view (1.• 6 × 2.• 6). The telescope can operate with a curved detector (or with a flat detector with a field flattener) and a set of filters. The entrance mirror is anamorphic and replaces the classical Schmidt entrance corrector plate. We show that this anamorphic primary mirror can be manufactured through stress polishing, avoiding high spatial frequency errors, and tested with a simple interferometer scheme. This prototype is intended to serve as a fast-track scientific and technological pathfinder for the future space-based MESSIER mission.

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Special configuration of a very large Schmidt telescope for extensive astronomical spectroscopic observation

Cited by 255 publications

References 10 publications

Pruning The ELM Survey: Characterizing Candidate Low-mass White Dwarfs through Photometric Variability

Pruning The ELM Survey: Characterizing Candidate Low-mass White Dwarfs through Photometric Variability

M Dwarf Catalog of the Lamost Pilot Survey

Fast, wide-field and distortion-free telescope with curved detectors for surveys at ultralow surface brightness

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