Charon's radius and atmospheric constraints from observations of a stellar occultation

Gulbis, A. A. S.; Elliot, J. L.; Adams, Elisabeth R.; Babcock, B. A.; Emílio, M.; Gangestad, Joseph W.; Kern, S.; Kramer, Emily; Osip, D. J.; Pasachoff, Jay M.; Souza, S. P.; Tuvikene, T.

doi:10.1038/nature04276

Cited by 45 publications

(26 citation statements)

References 21 publications

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“…The Charon radius ranges from 603.6 ± 1.4 km to 606.0 ± 1.5 km, as estimated by various authors from the 2005 July 11 stellar occultation (Sicardy et al 2006;Gulbis et al 2006;Person et al 2006). Pluto, Charon, Nix, and Hydra have estimated GM values of 870.3 ± 3.7, 101.4 ± 2.8, 0.039 ± 0.034 and 0.021 ± 0.042 km 3 s −2 respectively (Tholen et al 2008).…”

Section: Introductionmentioning

confidence: 94%

“…Furthermore, a stellar occultation observed in 1985 revealed Pluto s atmosphere (Brosch 1995), which was observed more extensively during another occultation in 1988 (Millis et al 1993). Also, besides the first stellar occultation recorded for Charon (Walker 1980), only two others were so far observed, one on 11 July 2005 (Sicardy et al 2006;Gulbis et al 2006) and another on 22 June 2008 (Sicardy et al 2010, in prep. ).…”

Section: Introductionmentioning

confidence: 99%

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Precise predictions of stellar occultations by Pluto, Charon, Nix, and Hydra for 2008–2015

Assafin¹,

Camargo

Martins

et al. 2010

A&A

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Context. We investigate transneptunian objects, including Pluto and its satellites, by stellar occultations. Aims. Our aim is to derive precise, astrometric predictions for stellar occultations by Pluto and its satellites Charon, Hydra and Nix for 2008−2015. We construct an astrometric star catalog in the UCAC2 system covering Pluto s sky path. Conclusions. Recurrent issues in stellar occultation predictions were addressed and properly overcome: body ephemeris offsets, catalog zero-point position errors and field-of-view size, long-term predictions and stellar proper motions, faint-visual versus brightinfrared stars and star/body astrometric follow-up. In particular, we highlight the usefulness of the obtained astrometric catalog as a reference frame for star/body astrometric follow-up before and after future events involving the Pluto system. Besides, it also furnishes useful photometric information for field stars in the flux calibration of observed light curves. Updates on the ephemeris offsets and candidate star positions (geometric conditions of predictions and finding charts) are made available by the group at www.lesia. obspm.fr/perso/bruno-sicardy/. Also based on observations made at

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Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Precise predictions of stellar occultations by Pluto, Charon, Nix, and Hydra for 2008–2015

Assafin¹,

Camargo

Martins

et al. 2010

A&A

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“…Mean hemispheric albedo ranges are 0.49 to 0.66 for Pluto and 0.36 to 0.39 for Charon ). Charon's diameter is well determined to be 1208 km (Gulbis et al 2006;Sicardy et al 2006). Pluto's diameter estimates suffer from uncertainties related to the presence of the atmosphere and range from about 2290-2400 km .…”

Section: Kd77mentioning

confidence: 99%

TNOs are cool: A survey of the trans-Neptunian region

Mommert

Harris

Kiss

et al. 2012

A&A

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Context.The Herschel open time key programme TNOs are Cool: A survey of the trans-Neptunian region aims to derive physical and thermal properties for a set of ∼140 Centaurs and trans-Neptunian objects (TNOs), including resonant, classical, detached and scattered disk objects. One goal of the project is to determine albedo and size distributions for specific classes and the overall population of TNOs. Aims. We present Herschel-PACS photometry of 18 Plutinos and determine sizes and albedos for these objects using thermal modeling. We analyze our results for correlations, draw conclusions on the Plutino size distribution, and compare to earlier results. Methods. Flux densities are derived from PACS mini scan-maps using specialized data reduction and photometry methods. In order to improve the quality of our results, we combine our PACS data with existing Spitzer MIPS data where possible, and refine existing absolute magnitudes for the targets. The physical characterization of our sample is done using a thermal model. Uncertainties of the physical parameters are derived using customized Monte Carlo methods. The correlation analysis is performed using a bootstrap Spearman rank analysis. Results. We find the sizes of our Plutinos to range from 150 to 730 km and geometric albedos to vary between 0.04 and 0.28. The average albedo of the sample is 0.08 ± 0.03, which is comparable to the mean albedo of Centaurs, Jupiter family comets and other TNOs. We were able to calibrate the Plutino size scale for the first time and find the cumulative Plutino size distribution to be best fit using a cumulative power law with q = 2 at sizes ranging from 120-400 km and q = 3 at larger sizes. We revise the bulk density of 1999 TC36 and find = 0.64. On the basis of a modified Spearman rank analysis technique our Plutino sample appears to be biased with respect to object size but unbiased with respect to albedo. Furthermore, we find biases based on geometrical aspects and color in our sample. There is qualitative evidence that icy Plutinos have higher albedos than the average of the sample.

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“…An exemplary case was with the du Pont telescope for C313.2 (see below) in which unpacking the system, mounting to the telescope, a full night of observing, dismounting, and repacking were accomplished in a 24-hour period. [7], Elliot et al [5], and Person et al [8]) Bottom: Normalized stellar flux from one POETS observation in the top panel is plotted as a function of distance from the shadow center -the break in the middle results from the chords not being central on the body. In 2005 the du Pont chord came within 11 km of shadow center and thus the break is not discernable in the plot.…”

Section: Stellar Occulation Observationsmentioning

confidence: 99%

Recent Stellar Occultation Observations Using High-Speed, Portable Camera Systems

Gulbis¹,

Elliot²,

Babcock³

et al. 2008

AIP Conference Proceedings

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Abstract.We have recently constructed six observing systems identified as POETS (Portable Occultation Eclipse and Transit System[1]). These systems are optimized for (i) high-speed, high signal-to-noise observations at visible wavelengths and (ii) easy transport, to allow mounting on telescopes worldwide. The Andor iXon cameras have e2v CCD97 (frame transfer) sensors: a 512 × 512 array of 16-micron pixels, back illuminated, with peak quantum efficiency > 90%. The maximum readout rate is 32 full frames per second, while binning and subframing can increase the cadence to a few hundred frames per second. Read noise in conventional modes goes below 6 electrons per pixel. Further, an electron-multiplying mode can effectively reduce the read noise to sub-electron levels, at the expense of dynamic range. The cameras are operated via a desktop computer that contains a 3 GHz Pentium 4 processor, 2 GB memory, and a 10,000 rpm hard disk. Images are triggered from a GPS receiver and have an approximately 50 nanosecond timing uncertainty. Each POETS can be transported as carry-on luggage. Here, we present instrument details, along with recent results from their use in stellar occultation observations by small bodies in the outer solar system. Occultations can produce data of the highest spatial resolution for any Earth-based observing method; therefore, they play a key role in determining diameters of distant solar-system bodies and probing the structure of atmospheres at the microbar level. We discuss POETS deployments in 2005-2007 to observe stellar occultations by Charon and Pluto (on 0.6-to 6.5-m telescopes) and future work on occultations by Kuiper Belt objects.

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Charon's radius and atmospheric constraints from observations of a stellar occultation

Cited by 45 publications

References 21 publications

Precise predictions of stellar occultations by Pluto, Charon, Nix, and Hydra for 2008–2015

Precise predictions of stellar occultations by Pluto, Charon, Nix, and Hydra for 2008–2015

TNOs are cool: A survey of the trans-Neptunian region

Recent Stellar Occultation Observations Using High-Speed, Portable Camera Systems

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