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Haas, Michael R.

Publications and source records attributed to Haas, Michael R..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Kepler Data Validation I: Architecture, Diagnostic Tests, and Data Products for Vetting Transiting Planet Candidates

The Kepler Mission was designed to identify and characterize transiting planets in the Kepler Field of View and to determine their occurrence rates. Emphasis was placed on identification of Earth-size planets orbiting in the Habitable Zone of their host stars. Science data were acquired for a period of four years. Long-cadence data with 29.4 min sampling were obtained for approx. 200,000 individual stellar targets in at least one observing quarter in the primary Kepler Mission. Light curves for target stars are extracted in the Kepler Science Data Processing Pipeline, and are searched for transiting planet signatures. A Threshold Crossing Event is generated in the transit search for targets where the transit detection threshold is exceeded and transit consistency checks are satisfied. These targets are subjected to further scrutiny in the Data Validation (DV) component of the Pipeline. Transiting planet candidates are characterized in DV, and light curves are searched for additional planets after transit signatures are modeled and removed. A suite of diagnostic tests is performed on all candidates to aid in discrimination between genuine transiting planets and instrumental or astrophysical false positives. Data products are generated per target and planet candidate to document and display transiting planet model fit and diagnostic test results. These products are exported to the Exoplanet Archive at the NASA Exoplanet Science Institute, and are available to the community. We describe the DV architecture and diagnostic tests, and provide a brief overview of the data products. Transiting planet modeling and the search for multiple planets on individual targets are described in a companion paper. The final revision of the Kepler Pipeline code base is available to the general public through GitHub. The Kepler Pipeline has also been modified to support the Transiting Exoplanet Survey Satellite (TESS) Mission which is expected to commence in 2018.

data analysis↗
NASA NTRS2017

Kepler Certified False Positive Table

This document describes the Kepler Certied False Positive table hosted at the Exoplanet Archive1, herein referred to as the CFP table. This table is the result of detailed examination by the Kepler False Positive Working Group (FPWG) of declared false positives in the Kepler Object of Interest (KOI) tables (see, for example, Batalha et al. (2012); Burke et al.(2014); Rowe et al. (2015); Mullally et al. (2015); Coughlin et al. (2015b)) at the Exoplanet Archive. A KOI is considered a false positive if it is not due to a planet orbiting the KOI's target star. The CFP table contains all KOIs in the Exoplanet Archive cumulative KOI table. The purpose of the CFP table is to provide a list of certified false positive KOIs. A KOI is certified as a false positive when, in the judgement of the FPWG, there is no plausible planetary interpretation of the observational evidence, which we summarize by saying that the evidence for a false positive is compelling. This certification process involves detailed examination using all available data for each KOI, establishing a high-reliability ground truth set. The CFP table can be used to estimate the reliability of, for example, the KOI tables which are created using only Kepler photometric data, so the disposition of individual KOIs may differ in the KOI and CFP tables. Follow-up observers may find the CFP table useful to avoid observing false positives.

Kepler↗
NASA NTRS2016

Kepler Data Release 25 Notes (Q0-Q17)

These Data Release Notes provide information specific to the current reprocessing and re-export of the Q0-Q17 data. The data products included in this data release include target pixel files, light curve files, FFIs,CBVs, ARP, Background, and Collateral files. This release marks the final processing of the Kepler Mission Data. See Tables 1 and 2 for a list of the reprocessed Kepler cadence data. See Table 3 for a list of the available FFIs. The Long Cadence Data, Short Cadence Data, and FFI data are documented in these data release notes. The ancillary files (i.e., cotrending basis vectors, artifact removal pixels, background, and collateral data) are described in the Archive Manual (Thompson et al., 2016).

Data Release Notes↗
NASA NTRS2010

Selecting Pixels for Kepler Downlink

The Kepler mission monitors > 100,000 stellar targets using 42 2200 1024 pixel CCDs. Bandwidth constraints prevent the downlink of all 96 million pixels per 30-minute cadence, so the Kepler spacecraft downlinks a specified collection of pixels for each target. These pixels are selected by considering the object brightness, background and the signal-to-noise of each pixel, and are optimized to maximize the signal-to-noise ratio of the target. This paper describes pixel selection, creation of spacecraft apertures that efficiently capture selected pixels, and aperture assignment to a target. Diagnostic apertures, short-cadence targets and custom specified shapes are discussed.

Bryson, Stephen T.↗
NASA NTRS2010

Kepler Data Release 4 Notes

The Data Analysis Working Group have released long and short cadence materials, including FFIs and Dropped Targets for the Public. The Kepler Science Office considers Data Release 4 to provide "browse quality" data. These notes have been prepared to give Kepler users of the Multimission Archive at STScl (MAST) a summary of how the data were collected and prepared, and how well the data processing pipeline is functioning on flight data. They will be updated for each release of data to the public archive and placed on MAST along with other Kepler documentation, at http://archive.stsci.edu/kepler/documents.html. Data release 3 is meant to give users the opportunity to examine the data for possibly interesting science and to involve the users in improving the pipeline for future data releases. To perform the latter service, users are encouraged to notice and document artifacts, either in the raw or processed data, and report them to the Science Office.

Van Cleve, Jeffrey↗
NASA NTRS2004

On the Measurement of Elemental Abundance Ratios in Inner Galaxy H II Regions

Although abundance gradients in the Milky Way Galaxy certainly exist, details remain uncertain, particularly in the inner Galaxy, where stars and H II regions in the Galactic plane are obscured optically. In this paper we revisit two previously studied, inner Galaxy H II regions: G333.6-0.2 and W43. We observed three new positions in G333.6-0.2 with the Kuiper Airborne Observatory and reobserved the central position with the Infrared Space Observatory's Long Wavelength Spectrometer in far-infrared lines of S++, N++, N+, and O++. We also added the N+ lines at 122 and 205 microns to the suite of lines measured in W43 by Simpson et al.. The measured electron densities range from approx. 40 to over 4000 per cu cm in a single HII region, indicating that abundance analyses must consider density variations, since the critical densities of the observed lines range from 40 to 9000 per cu cm. We propose a method to handle density variations and make new estimates of the S/H and N/H abundance ratios. We find that our sulfur abundance estimates for G333.6-0.2 and W43 agree with the S/H abundance ratios expected for the gradient previously reported by Simpson et al., with the S/H values revised to be smaller owing to changes in collisional excitation cross sections. The estimated N/H, S/H, and N/S ratios are the most reliable because of their small corrections for unseen ionization states (< or approx. 10%). The estimated N/S ratios for the two sources are smaller than what would be calculated from the N/H and S/H ratios in our previous paper. If all low excitation H II regions had similar changes to their N/S ratios as a result of adding measurements of N+ to previous measurements of N++, there would be no or only a very small gradient in N/S. This is interesting because nitrogen is considered to be a secondary element and sulfur is a primary element in galactic chemical evolution calculations. We compute models of the two H II regions to estimate corrections for the other unseen ionization states. We find, with large uncertainties, that oxygen does not, have a high abundance, with the result that the N/O ratio is as high (approx. 0.35) as previously reported. The reasons for the uncertainty in the ionization corrections for oxygen are both the non-uniqueness of the H II region models and the sensitivity of these models to different input atomic data and stellar atmosphere models. We discuss these predictions and conclude that only a few of the latest models adequately reproduce H II region observations, including the well-known, relatively-large observed Ne++/O++ ratios in low- and moderate-excitation H II regions.

Simpson, Janet P.↗
NASA NTRS2003

The Shock Structure of Supernova Remnant IC443

We present and discuss ISO observations of IC443, a supernova remnant interacting with a molecular cloud. An SWS spectrum centered on molecular hydrogen clump R10E (RA(2000) = 6 17 7.6, Decl(2000) = 22 25 34.6) is dominated by strong [SiII] (34 microns) emission and the pure rotational transitions of molecular hydrogen ranging from 0-0 S(1) to 0-0 S(13). Fits to these H$-2$ lines imply a large column (approx. 7E19 cm$ {-2)$) of warm (T approx. 700 K) gas and an ortho/para ratio for hydrogen near 3. LWS Fabry-Perot spectra of [OI] (63 microns) and [CII] (158 microns) at positions R10E and C (RA(2000) = 6 17 42.8, Decl(2000) = 22 21 38.1) find broad (approx. 75 km/s), blue-shifted (-40 km/s) line profiles; their similarity strongly suggests a common, shock-generated origin for these two lines. The surprisingly large [CII]/[OI] ratio (approx. 0.1 to 0.2) confirms previous observations with the Kuiper Airborne Observatory. These [CII] and [OI] line intensities, the [SiII] intensity (above), and LWS grating measurements of OH (119 microns) and [OI] (145 microns) are all readily fit by a single, fast J-shock model. Although the [OI] (63) emission can alternatively be produced by a slow C-shock, this ensemble of lines can not be produced by such a shock and provides strong evidence for the existence of a J-shock. A 24-arcmin strip map shows that this far-infrared line emission is spatially correlated with the H$-2$ 1-0 S(1) emission, which most likely arises in an associated C-shock. In addition to this spatially correlated shock emission, the strip map identifies extended [CII] and [OI] emission with a significantly larger line ratio (approx. 0.6); this 'background' component is compared with current J-shock, C-shock, photo-dissociation region (PDR), and X-ray dissociation region (XDR) models in an effort to explain its origin.

Haas, Michael R.↗
NASA NTRS2002

Optical Alignment and Diffraction Analysis for AIRES: An Airborne Infrared Echelle Spectrometer

The optical design is presented for a long-slit grating spectrometer known as AIRES (Airborne InfraRed Echelle Spectrometer). The instrument employs two gratings in series: a small order sorter and a large steeply blazed echelle. The optical path includes four pupil and four field stops, including two narrow slits. A detailed diffraction analysis is performed using GLAD by Applied Optics Research to evaluate critical trade-offs between optical throughput, spectral resolution, and system weight and volume. The effects of slit width, slit length, oversizing the second slit relative to the first, on- vs off-axis throughput, and clipping at the pupil stops and other optical elements are discussed.

Haas, Michael R.↗
NASA NTRS2002

Diffraction Effects in a Grating Spectrometer

This paper describes a numerical study of diffraction effects in the AIRES optical system using GLAD by Applied Optics Research. AIRES (or Airborne Infrared Echelle Spectrometer) employs two gratings in series. The small, first-order (i.e., predisperser) grating sorts orders for the large, high-order echelle grating, thus providing moderately high spectral resolution over 3.6 octaves in wavelength. The AIRES' optical design includes three field stops (i.e., a circular aperture and two long, narrow slits) and four pupil stops. A detailed diffraction analysis is required to evaluate critical trade-offs between spectral resolution, optical throughput, detector background, scattered light, and system size and weight. Such an analysis must consider diffraction effects at the pupil stops (edge diffraction), at the field stops (spatial filtering), and at intermediate positions where other optical elements are located. The effects of slit width, slit length, oversizing of the second slit relative to the first, baffling at the Lyot stop and subsequent pupil stops, and the necessity for oversizing other optical elements are presented and discussed. It is found that for narrow slits, the downstream energy distribution is significantly broadened relative to that for large slits, where telescope diffraction dominates, leading to significantly more light loss than anticipated, unless other key optical elements are oversized. The importance of performing a proper diffraction analysis is emphasized and the suitability of GLAD for this task is discussed.

Haas, Michael R.↗
NASA NTRS2001

The AIRES Optical Design

AIRES (Airborne InfraRed Echelle Spectrometer) is the facility spectrometer for SOFIA (Stratospheric Observatory For Infrared Astronomy). AIRES is a long-slit (approximately 160 in) spectrometer designed to cover the 17 to 210-micron range with good sensitivity using three spectroscopic arrays. Initially, only the 30-130 micron, mid-wavelength array will be available. The instrument has a cryogenic K-mirror to perform field rotation and a slit-viewing camera (lambda < 28 microns, FOV = 160 in diameter) to image source morphology and verify telescope pointing. AIRES employs a large echelle grating to achieve a spectral resolving power (lambda/delta lambda) of approximately 1.0 x 10(exp 6)/lambda (sub mu), where lambda (sub mu) is the wavelength in microns. Hyperfine, Inc. has ruled and tested the AIRES' echelle; its wave-front error is 0.028 waves RMS (root mean square) at 10.6 microns. The instrument is housed in a liquid-helium cryostat which is constrained in diameter (approximately 1 m) and length (approximately 2 m) by the observatory. Hence, the length of the echelle (approximately 1.1 m) and the focal length of its collimator (approximately 5.2 m) severely drive the optical design and packaging. The final design uses diamond-turned aluminum optics and has up to 19 reflections inside the cryostat, depending on the optical path. This design was generated, optimized, and toleranced using Code V. The predicted performance is nearly diffraction-limited at 17 microns; the error budget is dominated by design residuals. Light loss due to slit rotation and slit curvature has been minimized. A thorough diffraction analysis with GLAD (G-Level Analysis Drawer) was used to size the mirrors and baffles; the internal light loss is shown to be a strong function of slit width.

Haas, Michael R.↗
NASA NTRS1999

AIRES: An Airborne Infra-Red Echelle Spectrometer for SOFIA

SOFIA will enable astronomical observations with unprecedented angular resolution at infrared wavelengths obscured from the ground. To help open this new chapter in the exploration of the infrared universe, we are building AIRES, an Airborne Infra-Red Echelle Spectrometer. AIRES will be operated as a first generation, general purpose facility instrument by USRA, NASA's prime contractor for SOFIA. AIRES is a long slit spectrograph operating from 17 - 210 microns. In high resolution mode the spectral resolving power is approx. 10(exp 6) microns/A or approx. 10(exp 4) at 100 microns. Unfortunately, since the conference, a low resolution mode with resolving power about 100 times lower has been deleted due to budgetary constraints. AIRES includes a slit viewing camera which operates in broad bands at 18 and 25 microns.

Dotson, Jessie J.↗
NASA NTRS1996

Design considerations for AIRES, an airborne infrared echelle spectrometer for SOFIA

The airborne infrared echelle spectrometer (AIRES) was proposed as a facility instrument for the stratospheric observatory for infrared astronomy (SOFIA) project. The preliminary AIRES design uses multiple two dimensional detector arrays and a 1.2 m long, 76 deg blaze angle echelle to combine high spectral resolution with diffraction limited imaging in the cross-dispersion direction. A preliminary optical design and the mechanical architecture are presented together with the analysis and prototyping of lightweight aluminum echelles. Instrument efficiencies are calculated and compared for different gratings, and the associated mechanical design tradeoffs are discussed.

Haas, Michael R.↗
NASA NTRS1996

Far-Infrared Hydrogen Lasers in the Peculiar Star MWC 349A

Far-infrared hydrogen recombination lines H15(alpha)(169.4 micrometers), H12(alpha)(88.8 micrometers), and H10(alpha)(52.5 micrometers) were detected in the peculiar luminous star MWC 349A from the Kuiper Airborne Observatory. Here it is shown that at least H15(alpha) is strongly amplified, with the probable amplification factor being greater than or about equal to 10(exp 3) and a brightness temperature that is greater than or about equal to 10(exp 7) kelvin. The other two lines also show signs of amplification, although to a lesser degree. Beyond H10(alpha) the amplification apparently vanishes. The newly detected amplified lines fall into the laser wavelength domain. These lasers, as well as the previously detected hydrogen masers may originate in the photoionized circumstellar disk of MWC 349A and constrain the disk's physics and structure.

Strelnitski, Vladimir↗
NASA NTRS1996

Infrared Observations of G0.18-0.04

The Galactic Center H(II) region, G0.18-0.04, the 'Sickle', is located where the nonthermal 'Arc' crosses the Galactic plane. The Sickle appears to be the ionized edge of a dense molecular cloud. The source of ionization has been ascribed to both the interaction of the cloud with the magnetic field of the Arc and to the hot stars in the adjacent cluster, AFGL 2004, also known as the 'Quintuplet Cluster'. This paper addresses the relative locations of the stars, the ionized and molecular gas, and the sources of gas excitation and dust heating. Using NASA's Kuiper Airborne Observatory, we have observed the far infrared forbidden lines of [S(III)] 18.7 and 33.5 micrometers, [Si(II)] 34.8 micrometers, [Ne(III)] 36.0 micrometers, [O(III)] 51.8 and 88.4 micrometers, [N(III)] 57.3 micrometers, [O(II)] 63.2 and 146 micrometers, [C(II)] 158 micrometers, and [N(II)] 205 micrometers and the adjacent continua at 11 positions around G0.18-0.04, including G0.15-0.05, the 'Pistol', in a beamsize of 40 - 60 arcsec. The electron density, the ionic abundances, and the ionization structure of the H(II) region are estimated from the doubly ionized line fluxes. The density and radiation field found in the photodissociation region (PDR) between the H(II) region and the molecular cloud are estimated from the [C(II)] and [O(I)] line fluxes and the far-infrared continuum. We compare the ionization structure and the PDR properties to shell models of H(II) regions with varying distances from their exciting stars. The agreement of observations and models indicates that the hot stars of AFGL 2004 are the likely source of ionization of the Sickle. Additional hot stars are necessary to ionize the more outlying positions. However, because of its low ionization and high PDR radiation field, the Pistol cannot be as close to AFGL 2004 as indicated by its close proximity on the sky. Instead, the Pistol is probably ionized by the luminous blue variable candidate, Pistol Source A. We estimated the extinction to the region from the distribution of the J, H, and K' magnitudes of the stars in the field that we measured from the Anglo-Australian telescope and from the IRAS LRS spectrum of AFGL 2004. The extinction is fairly uniform, with no enhancement from the molecular cloud. The strength of Brackett gamma, the 19-micrometer lines and continuum, and the IRAS 25-micrometer continuum are all consistent with the absence of a dense, foreground molecular cloud. We conclude that the H(II) region is on the near side of the dense cloud.

Simpson, Janet P.↗
NASA NTRS1995

Far-infrared lines from H II regions: Abundance variations in the galaxy

Far-infrared lines of (N III) (57 microns), (O III) (52, 88 microns), (Ne III) (36 microns), and (S III) (19, 33 microns) have been measured in the H II regions G1.13 - 0.11, W31B, G23.95 + 0.15, G25.38 - 0.18, G29.96 - 0.02, W43, W51e, S156, S158, NGC 3576, NGC 3603, and G298.22-0.34. These observations were made with the facility Cryogenic Grating Spectrometer on the Kuiper Airborne Observatory to examine variations in abundances throughout the Galaxy. Previously published observations of G0.095 + 0.012, G333.60 - 0.21, G45.13 + 0.14A, K3-50, and M17 are also discussed. The giant H II region 30 Doradus in the Large Magellanic Cloud (LMC) was observed for comparison. Fluxes for (Ne II) (12.8 microns), (S IV) (10.5 microns), and the radio free-free continuum were collected from the literature for those sources. Electron densities were estimated from FIR line-pair ratios, and ionic abundances were estimated from the FIR line and radio fluxes. The excitation was estimated from the O(2+)/S(2+) ratio. Corrections for unseen ionization stages were calculated with the use of constnat-density H II region models. The validity and range of applicability of such semiempirical ionization correction schemes are discussed. The abundances with respect to hydrogen exhibit gradients with R(sub G) comparable to those previously measured for our Galaxy and for other galaxies. The overall gradients are d (log N/H)/dR = -0.10 +/- 0.02 dex/kpc, d(log Ne/H)/dR = -0.08 +/- 0.02 dex/kpc and d(log S/H)/dR = 0.07 +/- 0.02 dex/kpc. Compared to the Orion Nebula, the intermediate R(sub G) H II regions with 6 is less than R(sub G) is less than 11 kpc have similar or lower S/H and N/O ratios. The N/O ratios in the inner Galaxy are more than twice those observed in the Orion Nebula and intermediate R(sub G) H II regions. In fact, all the abundance ratios are as well or better fitted by a step fit with two levels than by a linear gradient. As has been noted in previous studies, the N/O ratio estimated from infrared observations of the doubly ionized N and O lines in H II regions is larger than the ratio estimated from optical observations of the singly ionized N and O lines. The Ne(2+)/O(2+) ratio is observed to be essentially constant over a wide range of excitation. This contradicts predictions of model H II regions calculated with the use of Local Thermodynamic Equilibrium (LTE) model stellar atmospheres. We conclude that these stellar atmospheres significantly underestimate the actual emergent fluxes for energies greater than 41 eV.

Simpson, Janet P.↗
NASA NTRS1995

Airborne Astronomy Symposium on the Galactic Ecosystem: From Gas to Stars to Dust, volume 73

This symposium was organized to review the science related to NASA's Airborne Astronomy Program on the occasion of the twentieth anniversary of the Kuiper Airborne Observatory (KAO). The theme selected, 'The Galactic Ecosystem: From Gas to Stars to Dust,' was considered to capture the underlying commonality of much of the research discussed. The 8 sessions were as follows: The Interstellar Medium; The Life Cycle of the ISM in Other Galaxies; Star and Planetary System Formation; Our Planetary System: The Solar System; The Enrichment of the Interstellar Medium; The Galactic Center: A Unique Region of the Galactic Ecosystem; Instrumentation for Airborne Astronomy; KAO History and Education; and Missions and the Future of Infrared Astronomy.

Haas, Michael R.↗
NASA NTRS1995

Density determination from far-infrared lines

We demonstrate that when there are gas density variations within a nebula, various line ratios used to determine electron density (Ne) can give different results. When there are non-constant density conditions, it is shown that by using one (average) Ne, significant, systematic biases may occur in the derived chemical abundance ratios. The abundance ratio of a heavy element (when a collisionally excited line is used) to ionized hydrogen may be subject to a large underestimate in the presence of density fluctuations. The more Ne-diagnostic observations made, the more reliable will be the deciphering of the actual Ne variation throughout a nebula.

Rubin, Robert H.↗