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Scientific Performance Analysis of the SYZ Telescope Design versus the RC Telescope Design D. Ma & Z. Cai contributed equally to this paper
Recently, Su et al. propose an innovative design, referred as the \"SYZ\" design, for China's new project of a 12 m optical-infrared telescope. The SYZ telescope design consists of three aspheric mirrors with non-zero power, including a relay mirror below the primary mirror. SYZ design yields a good imaging quality and has a relatively flat field curvature at Nasmyth focus. To evaluate the science-compatibility of this three-mirror telescope, in this paper, we thoroughly compare the performance of SYZ design with that of Ritchey-Chrétien (RC) design, a conventional two-mirror telescope design. Further, we propose the Observing Information Throughput (OIT) as a metric for quantitatively evaluating the telescopes' science performance. We find that although a SYZ telescope yields a superb imaging quality over a large field of view, a two-mirror (RC) telescope design holds a higher overall throughput, a better diffraction-limited imaging quality in the central field of view (FOV < 5′) which is better for the performance of extreme Adaptive Optics (AO), and a generally better scientific performance with a higher OIT value.
Journal Article
Telescopes
Introduces telescopes, discussing the types of telescopes, the civilizations and people who engineered them, and the advances in their construction.
Book
Thermal emission from the Earth-sized exoplanet TRAPPIST-1 b using JWST
The TRAPPIST-1 system is remarkable for its seven planets that are similar in size, mass, density and stellar heating to the rocky planets Venus, Earth and Mars in the Solar System
1
. All the TRAPPIST-1 planets have been observed with transmission spectroscopy using the Hubble or Spitzer space telescopes, but no atmospheric features have been detected or strongly constrained
2
–
5
. TRAPPIST-1 b is the closest planet to the M-dwarf star of the system, and it receives four times as much radiation as Earth receives from the Sun. This relatively large amount of stellar heating suggests that its thermal emission may be measurable. Here we present photometric secondary eclipse observations of the Earth-sized exoplanet TRAPPIST-1 b using the F1500W filter of the mid-infrared instrument on the James Webb Space Telescope (JWST). We detect the secondary eclipses in five separate observations with 8.7
σ
confidence when all data are combined. These measurements are most consistent with re-radiation of the incident flux of the TRAPPIST-1 star from only the dayside hemisphere of the planet. The most straightforward interpretation is that there is little or no planetary atmosphere redistributing radiation from the host star and also no detectable atmospheric absorption of carbon dioxide (CO
2
) or other species.
Observations from the James Webb Space Telescope suggest that the exoplanet TRAPPIST-1 b has little or no planetary atmosphere and no detectable atmospheric absorption of carbon dioxide.
Journal Article
Classic telescopes : a guide to collecting, restoring, and using telescopes of yesteryear
This text describes the telescopes built by such renowned makers as Dollond, Alvan Clark, Thomas Cooke & Sons, Carl Zeiss and others. It includes interviews with collectors of classic telescopes, and tips for readers on prospecting for and acquiring their own.
Book
Status Report on the Chicago-Carnegie Hubble Program (CCHP): Measurement of the Hubble Constant Using the Hubble and James Webb Space Telescopes
We present the latest results from the Chicago-Carnegie Hubble Program to measure the Hubble constant, using data from the James Webb Space Telescope (JWST). The overall program aims to calibrate three independent methods: (1) tip of the red giant branch (TRGB) stars, (2) J-region asymptotic giant branch (JAGB) stars, and (3) Cepheids. To date, our program includes 10 nearby galaxies, hosting 11 Type Ia supernovae (SNe Ia) suitable for measuring the Hubble constant (H0). It also includes the galaxy NGC 4258, whose geometric distance provides the zero-point calibration. In this paper, we discuss our results from the TRGB and JAGB methods. Our current best (highest-precision) estimate is H0 = 70.39 ± 1.22 (stat) ± 1.33 (sys) ± 0.70 (σSN), based on the TRGB method alone, with a total of 24 SN Ia calibrators from both Hubble Space Telescope and JWST data. Based on our new JWST data only, and tying into SNe Ia, we find values of H0 = 68.81 ± 1.79 (stat) ± 1.32 (sys) for the TRGB, and H0 = 67.80 ± 2.17 (stat) ± 1.64 (sys) km s−1 Mpc−1 for the JAGB method. The distances measured using the TRGB and the JAGB methods agree, on average, at a level better than 1%, and with the SHoES Cepheid distances at just over the 1% level. Our results are consistent with the current standard Lambda cold dark matter (ΛCDM) model, without the need for the inclusion of additional new physics. Future JWST data will be required to increase the precision and accuracy of the local distance scale.
Journal Article