Precision of a Low-Cost InGaAs Detector for Near Infrared Photometry

We have designed, constructed, and tested an InGaAs near-infrared camera to explore whether low-cost detectors can make small (<1 m) telescopes capable of precise (<1 mmag) infrared photometry of relatively bright targets. The camera is constructed around the 640x512 pixel APS640C sensor built by FLIR Electro-Optical Components. We designed custom analog-to-digital electronics for maximum stability and minimum noise. The InGaAs dark current halves with every 7 deg C of cooling, and we reduce it to 840 e-/s/pixel (with a pixel-to-pixel variation of +/-200 e-/s/pixel) by cooling the array to -20 deg C. Beyond this point, glow from the readout dominates. The single-sample read noise of 149 e- is reduced to 54 e- through up-the-ramp sampling. Laboratory testing with a star field generated by a lenslet array shows that 2-star differential photometry is possible to a precision of 631 +/-205 ppm (0.68 mmag) hr^-0.5 at a flux of 2.4E4 e-/s. Employing three comparison stars and de-correlating reference signals further improves the precision to 483 +/-161 ppm (0.52 mmag) hr^-0.5. Photometric observations of HD80606 and HD80607 (J=7.7 and 7.8) in the Y band shows that differential photometry to a precision of 415 ppm (0.45 mmag) hr^-0.5 is achieved with an effective telescope aperture of 0.25 m. Next-generation InGaAs detectors should indeed enable Poisson-limited photometry of brighter dwarfs with particular advantage for late-M and L types. In addition, one might acquire near-infrared photometry simultaneously with optical photometry or radial velocity measurements to maximize the return of exoplanet searches with small telescopes.Comment: Accepted to PAS

Near-Infrared InGaAs Detectors for Background-limited Imaging and Photometry

Originally designed for night-vision equipment, InGaAs detectors are beginning to achieve background-limited performance in broadband imaging from the ground. The lower cost of these detectors can enable multi-band instruments, arrays of small telescopes, and large focal planes that would be uneconomical with high-performance HgCdTe detectors. We developed a camera to operate the FLIR AP1121 sensor using deep thermoelectric cooling and up-the-ramp sampling to minimize noise. We measured a dark current of 163$~e$- s$^{-1}$ pix$^{-1}$, a read noise of 87$~e$- up-the-ramp, and a well depth of 80k$~e$-. Laboratory photometric testing achieved a stability of 230 ppm hr$^{-1/2}$, which would be required for detecting exoplanet transits. InGaAs detectors are also applicable to other branches of near-infrared time-domain astronomy, ranging from brown dwarf weather to gravitational wave follow-up.Comment: Submitted to Proc. SPIE, Astronomical Telescopes + Instrumentation (2014

A 3 county planning program

"MP199 ... 5/71/2.5""Case study no. 2."Covers: Marion, Monroe, and Ralls counties."The community development process, as applied in the planning program, did help create situations in which micro-macro integration was facilitated. The success of the three-county planning program in this regard has been attested to by many people at various levels in the macroscene--the Corps of Engineers, the State Planner, State Legislators, professional planners, University staff members, and many others. Perhaps the strongest evidence that the community development process contributed to the successful micro-macro integration in this case is the unique nature of this planning program. This was the first cooperative planning activity-three counties and six cities-in Missouri..."--Summary.John A. Croll (Dept. of Regional and Community Affairs)Includes bibliographical references

Kepler Transit Depths Contaminated by a Phantom Star

We present ground-based observations from the Discovery Channel Telescope (DCT) of three transits of Kepler-445c---a supposed super-Earth exoplanet with properties resembling GJ 1214b---and demonstrate that the transit depth is approximately 50 percent shallower than the depth previously inferred from Kepler Spacecraft data. The resulting decrease in planetary radius significantly alters the interpretation of the exoplanet's bulk composition. Despite the faintness of the M4 dwarf host star, our ground-based photometry clearly recovers each transit and achieves repeatable 1-sigma precision of approximately 0.2 percent (2 millimags). The transit parameters estimated from the DCT data are discrepant with those inferred from the Kepler data to at least 17-sigma confidence. This inconsistency is due to a subtle miscalculation of the stellar crowding metric during the Kepler pre-search data conditioning (PDC). The crowding metric, or CROWDSAP, is contaminated by a non-existent "phantom star" originating in the USNO-B1 catalog and inherited by the Kepler Input Catalog (KIC). Phantom stars in the KIC are likely rare, but they have the potential to affect statistical studies of Kepler targets that use the PDC transit depths for a large number of exoplanets where individual follow-up observation of each is not possible. The miscalculation of Kepler-445c's transit depth emphasizes the importance of stellar crowding in the Kepler data, and provides a cautionary tale for the analysis of data from the Transiting Exoplanet Survey Satellite (TESS), which will have even larger pixels than Kepler.Comment: 11 pages, 10 figures, 5 tables. Accepted for publication in AJ. Transit light curves will be available from AJ as Db

The Planning Process and People

Planning takes place on many levels, ranging from the individual to the nation and beyond. It can be related to a tremendous variety of situations and time spans, so there is no reason to expect the planning process to be uniform in its application. The particular elements of planning, the structures and techniques used, and the degrees of complexity will vary widely, depending on the conditions, issues and units of concern. About the only elements common to any planning are the assumptions that what happens today has consequences in the future, and that people can do things in the present that will increase the probabilities of particular events and situations matching their expectations or aspirations in the future. In other words, the planning process is predicated on the notions that the present is the father of the future, and people can purposely intervene to give some direction to the flow of events.Reviewed October 1993

An Analysis of Cheliped Asymmetry in Three Species of Fiddler Crabs

Left-right cheliped asymmetry occurs in a variety of decapod species, Such asymmetries can be present in early development or can arise during sexual differentiation. Male fiddler crabs have a dimorphic enlargement of one of the two chelipeds. This major cheliped has been associated with male reproductive success as a result of female selection or advantage in male-male combat. Because the major cheliped occurs on either the right or the left side, selection pressure could produce populations with right or left cheliped dominance. To ascertain whether populations of dominantly enlarged right- or left-clawed males are present, three fiddler crab species, Uca longisignalis, U. minax and U. pugnax, from four North American marshes, two on the coast of the Atlantic Ocean, one on the coast of the Chesapeake Bay, and one on the coast of the Gulf of Mexico, were sampled. There were no significant differences in the number of males with right- or left-enlarged chelipeds within all species or marshes sampled. Similarly, when male crabs were grouped arbitrarily into two size classes (major chelipeds \u3c20 mm and 2:20 mm), the number of crabs with right or left major cheliped was similar among the size groups. Mean major propodus size for males was also similar for individuals with either right or left major chelipeds within each of the three species and four marshes. Comparison of morphometric parameters in each population indicated a strong correlation between claw size, carapace width, and carapace length, which was not affected by cheliped laterality. It appears that among these three species of Uca, there is no selection for males with cheliped enlargement on either the right or the left side within the geographical range of the species sampled

The GROUSE project II: Detection of the Ks-band secondary eclipse of exoplanet HAT-P-1b

Context: Only recently it has become possible to measure the thermal emission from hot-Jupiters at near-Infrared wavelengths using ground-based telescopes, by secondary eclipse observations. This allows the planet flux to be probed around the peak of its spectral energy distribution, which is vital for the understanding of its energy budget. Aims: The aim of the reported work is to measure the eclipse depth of the planet HAT-P-1b at 2.2micron. This planet is an interesting case, since the amount of stellar irradiation it receives falls in between that of the two best studied systems (HD209458 and HD189733), and it has been suggested to have a weak thermal inversion layer. Methods: We have used the LIRIS instrument on the William Herschel Telescope (WHT) to observe the secondary eclipse of HATP-1b in the Ks-band, as part of our Ground-based secondary eclipse (GROUSE) project. The observations were done in staring mode, while significantly defocusing the telescope to avoid saturation on the K=8.4 star. With an average cadence of 2.5 seconds, we collected 6520 frames during one night. Results: The eclipse is detected at the 4sigma level, the measured depth being 0.109+/-0.025%. The uncertainties are dominated by residual systematic effects, as estimated from different reduction/analysis procedures. The measured depth corresponds to a brightness temperature of 2136+150-170K. This brightness temperature is significantly higher than those derived from longer wavelengths, making it difficult to fit all available data points with a plausible atmospheric model. However, it may be that we underestimate the true uncertainties of our measurements, since it is notoriously difficult to assign precise statistical significance to a result when systematic effects are important.Comment: 7 pages, 10 figures, Accepted for publication in A&