BYU Astronomy Research Group Joins the Astrophysical Research Consortium (ARC)

As of January 2021 BYU will be a member of the ARC Consortium (Link to Consortium) with access to the ARC 3.5-m telescope and the 0.5-m ARCSAT telescope.  The primary use of the ARC 3.5-m telescope time is for graduate student projects.  This provides a wide array of instrumentation that is currently being used to study objects in the solar system all the way to studies of the large scale structure of the Universe.

Other BYU Astronomy Facilities

In addition to our telescope time from the ARC consortium, we operate a number of our own astronomical facilities

West Mountain Observatory (West Mountain)

This is our mountain observatory at about 6600 ft above sea level.  This consists of three telescopes: 0.9-m, 0.5-m, and a 0.32-m. It is a 40 minute drive that ends in a 5 miles drive up a dirt road. The mountain itself can be seen from campus. We don't provide any tours of this facility.

Orson Pratt Observatory

The Orson Pratt Observatory is named for an early apostle of the Church of Jesus Christ of Latter-Day Saints.  It is our campus telescope facility and contains a wide variety of telescopes for student research and public outreach. We operate a 24" PlaneWave telescope in the main campus dome, plus a 16", two 12", one 8", and a 6" telescope on our observation deck.  The telescopes are all fully robotic. Beyond this we have a large sections of telescopes used on public nights.

Royden G. Derrick Planetarium (Planetarium)

This is a 119 seat, 39" dome planetarium with acoustically treated walls to allow it's use as a lecture room. Recently we upgraded to an E&S Digistar7 operating system with 4K projectors.  The planetarium is used for teaching classes, public outreach, and astronomy education research projects.





Selected Publications

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By D. C. Stephens (et al.)
Abstract: In the last few years a significant population of ultracool L and T dwarfs has been discovered. With effective temperatures ranging from similar to2200 to 700 K, these objects emit most of their radiation in the near-IR, and their spectral energy distributions are dominated by strong molecular absorption bands. These highly structured energy distributions lead to JHK magnitudes that are extremely sensitive to the exact filter bandpass used. In the case of the T dwarfs, the differences between commonly used photometric systems can be as large as 0.4 mag at J and 0.5 mag at J-K. Near-IR magnitudes have been published for L and T dwarfs using a variety of photometric systems. Currently, the data obtained with these systems cannot be accurately compared or combined, as transformations based on the colors of hotter stars are not valid for L and T dwarfs. To address this problem, we have synthesized J, H, and K magnitudes for some of the common photometric systems and present transformation equations with respect to the most atmospheric-independent system, the Mauna Kea Observatory filter set. If the spectral type of the dwarf is known, our transformations allow data to be converted between systems to 0.01 mag, which is better than the typical measurement uncertainty. Transforming on the basis of color alone is more difficult because of the degeneracy and intrinsic scatter in the near-IR colors of L and T dwarfs; in this case J magnitudes can only be transformed to less than or similar to0.05 mag and H and K to less than or similar to0.02 mag.
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By D. C. Stephens (et al.)
Abstract: From July 2001 to June 2002, an HST snapshot program obtained V, R and I photometry for 72 TNOs. The TNOs were sorted by dynamical class, and Spearman rank correlation statistics were calculated for each combination of color and orbital parameter. No strong correlations were found for the combined sample of TNOs, the resonant TNOs, or the non-resonant TNOs ( classical). The results presented here suggest that if correlations reported by other authors are real, they are evident only at shorter wavelengths than observed in our survey.
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By Denise C. Stephens (et al.)
Abstract: To better understand and model the atmospheres of L (Teff ˜2200 K to 1400 K) and T (Teff ⪉ 1300 K) dwarfs, we've obtained K- and L-band photometry with the Keck I telescope for a representative sample. These observations were motivated in part by our desire to understand the abundance of CH4 and H2O particularly at the L to T transition where CO reacts with H2 to produce these molecules. Here we present our most recent observations, discuss the trends we observe in color, and compare the Keck K and L' filters with the new Mauna Kea Observatory (MKO) K and L' filters.
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Abstract: A continuous L dwarf classification sequence requires the combined use of far optical (visible) and near infrared spectral indices. However, the visible and near infrared indices currently in use assign subtypes that differ by up to three subclasses due to differences in cloud opacity for objects with the same effective temperature. Therefore, it may be impossible to combine visible and near infrared spectral indices to create one L dwarf classification system, and two classification variables maybe necessary.
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By D. C. Stephens (et al.)
Abstract: Images of the trans-Neptunian objects 1997 CQ(29) and 2000 CF105 obtained with the Hubble Space Telescope WFPC2 camera show them to be binary. The two components of 1997 CQ29 were separated in our images by 0."20 +/- 0."03 in 2001 November and by 0."33 +/- 0."01 in 2002 June/July. The corresponding minimum physical distances are 6100 and 10,200 km. The companion to 2000 CF105 was 0."78 +/- 0."03 from the primary, at least 23,400 km. Six other objects in the trans-Neptunian region, including Pluto and its moon Charon, are known to be binaries; 1997 CQ29 and 2000 CF105 are the seventh and eighth known pair. Binarity appears to be a not uncommon characteristic in this region of the solar system, with detectable companions present in 4% +/- 2% of the objects we have examined.
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By D. C. Stephens (et al.)
Abstract: We present K- and L-band photometry obtained with the Keck I telescope for a representative sample of L and T dwarfs. These observations were motivated in part by the dominant role H(2)O and CH(4) play in shaping the flux near 2 and 3 mum and by the potential use of these bands as indicators of spectral class in the infrared. In addition, these observations aid the determination of the bolometric luminosity of L and T dwarfs. Here we report the K, L', and L(s) magnitudes of our objects and the trends observed in the (K-L') and (K-L(s)) colors as a function of L and T dwarf spectral class. We compare these colors with theoretical models, derive a relationship between effective temperature and L spectral class, and compare our temperature estimates with others.