DOCSLIB.ORG

The Diffuse Ultraviolet Foreground

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Diffuse Ultraviolet Foreground The Diffuse Ultraviolet Foreground Jayant Murthy1 Abstract the Galaxy Evolution Explorer (GALEX ) in two bands Ultraviolet observations from low Earth orbit (LEO) (FUV: 1531 A˚ and NUV: 2321 A)˚ with observations far have to deal with a foreground comprised of airglow and from the Sun to minimize foreground emission. zodiacal light which depend on the look direction and Despite these drawbacks, we have used the GALEX on the date and time of the observation. We have used data to derive empirical formulae for the foreground all-sky observations from the GALEX spacecraft to find sources. Although our main interest is in better un- that the airglow may be divided into a baseline depen- derstanding the galactic and extragalactic diffuse radi- dent on the sun angle and a component dependent only ation, we hope that our results will also prove useful in on the time from local midnight. The zodiacal light is studies of the Earth's atmosphere and of the zodiacal observable only in the near ultraviolet band (2321 A)˚ light. They will certainly prove useful in mission plan- of GALEX and is proportional to the zodiacal light in ning for other space-borne instruments such as the Ul- the visible but with a color of 0.65 indicating that the traviolet Imaging Telescope (Kumar et al. 2012) which dust grains are less reflective in the UV. will observe the sky with large field of view instruments where diffuse radiation limits the observable sky. Keywords atmospheric effects; diffuse radiation; ul- traviolet: general; zodiacal dust 2 Observations & Data 1 Introduction 2.1 Observations Measurements of the diffuse ultraviolet (UV) radiation field have to contend with a number of contaminat- The GALEX spacecraft was launched in 2003 and has ing sources including atmospheric emission lines and since observed about 75% of the sky in two spectral the zodiacal light (Murthy 2009). These foreground bands (FUV: 1531 A˚ and NUV: 2321 A)˚ with a spatial sources are particularly important at high galactic lat- resolution of about 500 over a field of view of 0.6◦. The itudes where the Galactic contribution to the radiation arXiv:1307.5232v2 [astro-ph.IM] 8 Mar 2014 primary mission was described by Martin et al. (2005) field is relatively small and at longer wavelengths where and the software and data products by Morrissey et al. the zodiacal light, which follows the solar spectrum, be- (2007). Most of the GALEX observations were short comes increasingly important. It has been difficult to exposures of about 100 seconds in length (All-Sky Imag- disentangle these components, largely because of a lack ing Survey: AIS) but there were a number of longer of relevant observations. Ideally, these would be spec- observations of 10,000 seconds or more, either to ful- troscopic observations with moderate resolutions over fill specific mission objectives or taken as part of the a large part of the sky with different sun angles. How- Guest Investigator (GI) program. A single exposure ever, what we have is thousands of observations from was limited by the duration of the orbital night (about 1000 seconds) and longer observations were broken up Jayant Murthy into a series of exposures spread over a time period Indian Institute of Astrophysics, Bangalore 560034, India ranging from days to years. GALEX observations were [email protected] subject to severe selection effects due to brightness re- lated constraints from the diffuse radiation integrated 2 2300 we obtained the TLEs (two-line elements) from Space- ) Track.org (https://www.space-track.org/) and then -1 Å used STK (http://www.agi.com/default.aspx) to -1 2100 sr calculate the latitude and longitude of the spacecraft -1 s -2 ground track at a given UT. From this we calculated the 1900 local spacecraft time and cross-indexed with the TEC to obtain the total emission as a function of time. As a result of this rather painful experience, we would recom- 1700 FUV TEC (ph cm FUV mend that future missions include the local spacecraft coordinates as part of their standard data products. There were about 34,000 observations in each of the 1500 8.0 8.1 8.2 8.3 8.4 8.5 8.6 FUV and NUV bands in the GALEX GR6 data release Observation Time (UT) with close to 76,000 scst files and 14,000,000 individ- ual TEC measurements in each band. Note that the Fig. 1 The Total Event Counter (TEC) as a function of longer exposures were divided into multiple exposures UT. The minimum emission was at local (spacecraft) mid- night. and hence multiple scst files. 2.2 Airglow over the large field of view. Thus the Galactic plane and other high intensity regions such as Orion or the Naturally enough, most observations of the airglow Magellanic Clouds could not be observed in the origi- from space have been downward looking and have found nal mission. Recent observations have covered many of a number of different atomic and molecular lines (re- these but they will not help in refining the foreground viewed by Meier (1991)). There are many fewer ob- because of the brightness of the astrophysical emission. servations looking up from low-Earth orbit (LEO). The Observations were only taken at orbital night between only emission lines observable in the night spectrum are 20:00 and 04:00 (local time) and only in directions more the geocoronal O I lines at 1304 A˚ (0.013 kR) and 1356 ◦ than 90 from the Sun to minimize airglow and zodia- A˚ (0.001 kR) in the FUV band and 2471 A(˚ < 0:001 cal light. Hence, we only sampled a limited part of the kR) in the NUV band (Morrison et al. 1992; Feldman total phase space of observational parameters. et al. 1992; Boffi et al. 2007). The GALEX FUV band The diffuse background is the sum of the galactic rejected the 1304 A˚ line but with a 10% leak (Morrissey background, which depends only on the look direction, et al. 2007) and these values corresponded to expected and the foreground emission | airglow and zodiacal levels of about 200 photons cm−2 s−1 sr−1 A˚−1 in the light | which depends on the time and date of the ob- FUV band and 100 photons cm−2 s−1 sr−1 A˚−1 in the servation. The standard data products include a single NUV band. image of the targeted field for each of the two bands As mentioned above, we have adopted an empiri- (the FUV detector failed in May, 2009 following which cal approach in studying the foreground emission. We observations were made only with the NUV detector) noted that each observation could be separated into two and a merged catalog of point sources from both bands. parts; a minimum value at orbital midnight and a time- Because we are trying to derive the foreground emis- variable part which increased smoothly on either side of sion which is a function of time and date of the obser- orbital midnight (Figure 1). The only possible source vation, we used the spacecraft housekeeping files (scst for a signal that varies with the local time is airglow and files) which included the total count rate (TEC: Total we extracted this component of the foreground emission Event Count) in each of the two detectors. The TEC by subtracting a baseline calculated from the average of was tabulated every second and was tied to the UT the points within 15 minutes of local midnight, assum- (universal time) of the observation. A typical TEC is ing that the observation included this time span. This plotted with respect to UT in Figure 1. baseline is comprised of all other sources in the field, As implied by its name, the TEC includes all emis- including any residual airglow emission at midnight. sion in the field of view including starlight, diffuse back- There were approximately 5.8 million independent ground, airglow, and zodiacal light and each element points in the FUV channel and 6.6 million in the NUV had to be estimated separately. However, only the channel with an overlap of about 5 million points. We airglow would be expected to vary with the time of gridded the baseline-subtracted data to form a density day and, to anticipate our results, specifically with the plot for each band and these are shown in Figure 2. time from local midnight. Unfortunately, this was not These plots were created by gridding the data into bins readily available from the GALEX data products and 3 250 250 ) –1 ) Å -1 –1 Å -1 sr –1 sr s 150 –1 150 –2 s –2 50 50 FUV TEC (photons cm FUV NUV TEC (photons cm NUV –50 –50 –5 –3 –1 1 3 5 –5 –3 –1 1 3 5 Time from Midnight Time from Midnight Fig. 2 Distribution of FUV (a) and NUV (b) baseline-subtracted airglow. Plus signs (+) show the peak of the distribution and the contour lines represent the 1σ limits on the level of the airglow. The dark line is the parametrized fit to the peak airglow. of 10 minutes in time and 10 photons cm−2 s−1 sr−1 (Kelsall et al. 1998) from the Infrared Astronomy Satel- A˚−1 in flux. The plus signs show the peak airglow at lite (IRAS) mission. It is generally assumed that the a given time and the 1σ contour is shown as the closed spectrum of the zodiacal light follows the Solar spec- line; that is, 68% of the data points fall within the two trum; that is, the color of the zodiacal light is unity.
Load more

Recommended publications
  • Observation of the Airglow from the ISS by the IMAP Mission *Y
    2013/3/13(ANGWIN workshop, Tachikawa) Observation of the airglow from the ISS by the IMAP mission *Y. Akiya [1], A. Saito [1], T. Sakanoi [2], Y. Hozumi [1], A. Yamazaki [3], Y. Otsuka [4] [1] Graduation School of Science, Kyoto University , [2] PPARC, Tohoku University, [3] ISAS/JAXA, [4] STE Laboratory, Nagoya University ----- Outline ----- Introduction of the IMAP mission Visible and near-infrared spectrographic imager Samples of airglow observation by VISI Summary “ISS-IMAP” mission Ionosphere, Mesosphere, Upper atmosphere and Plasmasphere Imagers of the ISS-IMAP mapping mission from the mission International Space Station (ISS) Observational imagers were installed on the Exposure Facility of Japanese Experimental Module: August 9th, 2012. Initial checkout: August and September, 2012 Nominal observations: October, 2012 - [Pictures: Courtesy of JAXA/NASA] [this issue]. According to characteristics of airglow emissions, wavelength range from 630 to 762 nm. Typical total intensity of such as intensity, emission height, background continuum, etc., we airglow is 100 1000 R as listed in Table 1, and 10 % variation of selected the airglow emissions which will be measured with VISI, the total intensity must be detected in order to investigate the and determined the requirements for instrumental design. The airglow variation pattern. In addition, short exposure cycle less targets and requirements are summarized in Table 1. than several seconds is necessary to measure small-scale airglow Table 1. Scientific Targets of VISI signatures (see Table 1) considering the orbital speed of ISS (~8 km/s). Airglow Required Region Scientific Typical A sectional view of VISI and its specifications are given in (waele- spatial (height) target intensity Figure 4 and Table 2, respectively.
    [Show full text]
  • Hubble Space Telescope Primer for Cycle 25
    January 2017 Hubble Space Telescope Primer for Cycle 25 An Introduction to the HST for Phase I Proposers 3700 San Martin Drive Baltimore, Maryland 21218 [email protected] Operated by the Association of Universities for Research in Astronomy, Inc., for the National Aeronautics and Space Administration How to Get Started For information about submitting a HST observing proposal, please begin at the Cycle 25 Announcement webpage at: http://www.stsci.edu/hst/proposing/docs/cycle25announce Procedures for submitting a Phase I proposal are available at: http://apst.stsci.edu/apt/external/help/roadmap1.html Technical documentation about the instruments are available in their respective handbooks, available at: http://www.stsci.edu/hst/HST_overview/documents Where to Get Help Contact the STScI Help Desk by sending a message to [email protected]. Voice mail may be left by calling 1-800-544-8125 (within the US only) or 410-338-1082. The HST Primer for Cycle 25 was edited by Susan Rose, Senior Technical Editor and contributions from many others at STScI, in particular John Debes, Ronald Downes, Linda Dressel, Andrew Fox, Norman Grogin, Katie Kaleida, Matt Lallo, Cristina Oliveira, Charles Proffitt, Tony Roman, Paule Sonnentrucker, Denise Taylor and Leonardo Ubeda. Send comments or corrections to: Hubble Space Telescope Division Space Telescope Science Institute 3700 San Martin Drive Baltimore, Maryland 21218 E-mail:[email protected] CHAPTER 1: Introduction In this chapter... 1.1 About this Document / 7 1.2 What’s New This Cycle / 7 1.3 Resources, Documentation and Tools / 8 1.4 STScI Help Desk / 12 1.1 About this Document The Hubble Space Telescope Primer for Cycle 25 is a companion document to the HST Call for Proposals1.
    [Show full text]
  • [OI] 5577 in the Airglow and the Aurora
    Journal of Resea rch of the National Bureau of Sta ndards- D. Radio Propagation Vol. 63D, No.1, July-August 1959 Origin of [OlJ 5577 in the Airglow and the Aurora Franklin E. Roach, James W. McCaulley, and Edward Marovich (January 30, 1959) The distribution of 5577 zenith intensities at stations in the subauroral zone iB found to be unimodal with no discontinuity at the visual threshold. This is interpreted as evi­ dence that 5577 airglow and 5577 aurora may have a common origin. 1. Introduction origin hypothesis, their critical characteristic being the lack of any discontinuity. It i cu tomary to refer to [01] 5577 as airglow if In figure 2, a replot of the histogram of St. Amand it is invisible and as aurora if it is visible. Thus, and Ashburn is shown with a regroupillg of the data the physiological visual threshold (at approximately to correspond to class intervals of 50 R rather than the 10 R that they used. They put an approxi­ 1,000 myleighs 1 for extended objects) has been assumed to have a physical significance in the upper mately normal curve through the plot on the basis atmosphere with different mechanisms operative of which they were able to state that an intensity above and below the threshold. The purpose of correspondulg to a just visible aurora should occur this paper is to inquil'e into the existence of a only "once or twice in geologic time." Because physical criterion to distinguish between 5577 auroras do occur occasionally, though rarely, in southern California, the implication is that an aurora airglow and 5577 aurora.
    [Show full text]
  • + New Horizons
    Media Contacts NASA Headquarters Policy/Program Management Dwayne Brown New Horizons Nuclear Safety (202) 358-1726 [email protected] The Johns Hopkins University Mission Management Applied Physics Laboratory Spacecraft Operations Michael Buckley (240) 228-7536 or (443) 778-7536 [email protected] Southwest Research Institute Principal Investigator Institution Maria Martinez (210) 522-3305 [email protected] NASA Kennedy Space Center Launch Operations George Diller (321) 867-2468 [email protected] Lockheed Martin Space Systems Launch Vehicle Julie Andrews (321) 853-1567 [email protected] International Launch Services Launch Vehicle Fran Slimmer (571) 633-7462 [email protected] NEW HORIZONS Table of Contents Media Services Information ................................................................................................ 2 Quick Facts .............................................................................................................................. 3 Pluto at a Glance ...................................................................................................................... 5 Why Pluto and the Kuiper Belt? The Science of New Horizons ............................... 7 NASA’s New Frontiers Program ........................................................................................14 The Spacecraft ........................................................................................................................15 Science Payload ...............................................................................................................16
    [Show full text]
  • REMOTE SENSING of SEISMIC ACTIVITY on VENUS USING a SMALL SPACECRAFT: INITIAL MODELING RESULTS, A. Komjathy1, A. Didion1, B. Sutin1, B
    49th Lunar and Planetary Science Conference 2018 (LPI Contrib. No. 2083) 1731.pdf REMOTE SENSING OF SEISMIC ACTIVITY ON VENUS USING A SMALL SPACECRAFT: INITIAL MODELING RESULTS, A. Komjathy1, A. Didion1, B. Sutin1, B. Nakazono1, A. Karp1, M. Wallace1, G. Lan- toine1, S. Krishnamoorthy1, M. Rud1, J. Cutts, J. Makela2, M. Grawe2, P. Lognonné3, B. Kenda3, M. Drilleau3 and Jörn Helbert4 1Jet Propulsion Laboratory, California Institute of Technology, USA 2University of Illinois at Urbana-Champaign, USA 3Institut de Physique du Globe-Paris Sorbonne, France 4Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Germany Introduction: The planetary evolution and struc- other at 4.3 µm (visible on the dayside). The signifi- ture of Venus remain uncertain more than half a centu- cant advantage of observing nightglow on Venus is ry after the first visit by a robotic spacecraft. To under- that it is much brighter on Venus than on Earth [2] and stand how Venus evolved it is necessary to detect the that airglow lifetime (~4,000 sec) is significantly long- signs of seismic activity. Due to the adverse surface er than the period of seismic waves (10-30 sec). This conditions on Venus, with extremely high temperature makes it very attractive for directly detecting surface and pressure, it is infeasible with current technology, waves on Venus. This is in sharp contrast with Earth even using flagship missions, to place seismometers on where the lifetime of airglow is about one order of the surface for an extended period of time. Due to dy- magnitude smaller (~110 sec) than, e.g., the tsunami namic coupling between the solid planet and the at- waves we routinely observe on Earth with 630 nm air- mosphere, the waves generated by quakes propagate glow instruments [4].
    [Show full text]
  • Nighttime Photochemical Model and Night Airglow on Venus
    Planetary and Space Science 85 (2013) 78–88 Contents lists available at ScienceDirect Planetary and Space Science journal homepage: www.elsevier.com/locate/pss Nighttime photochemical model and night airglow on Venus Vladimir A. Krasnopolsky n a Department of Physics, Catholic University of America, Washington, DC 20064, USA b Moscow Institute of Physics and Technology, Dolgoprudnyy 141700 Russia article info abstract Article history: The photochemical model for the Venus nighttime atmosphere and night airglow (Krasnopolsky, 2010, Received 23 December 2012 Icarus 207, 17–27) has been revised to account for the SPICAV detection of the nighttime ozone layer and Received in revised form more detailed spectroscopy and morphology of the OH nightglow. Nighttime chemistry on Venus is 28 April 2013 induced by fluxes of O, N, H, and Cl with mean hemispheric values of 3 Â 1012,1.2Â 109,1010, and Accepted 31 May 2013 − − 1010 cm 2 s 1, respectively. These fluxes are proportional to column abundances of these species in the Available online 18 June 2013 daytime atmosphere above 90 km, and this favors their validity. The model includes 86 reactions of 29 Keywords: species. The calculated abundances of Cl2, ClO, and ClNO3 exceed a ppb level at 80–90 km, and Venus perspectives of their detection are briefly discussed. Properties of the ozone layer in the model agree Photochemistry with those observed by SPICAV. An alternative model without the flux of Cl agrees with the observed O Night airglow 3 peak altitude and density but predicts an increase of ozone to 4 Â 108 cm−3 at 80 km.
    [Show full text]
  • A Physically-Based Night Sky Model Henrik Wann Jensen1 Fredo´ Durand2 Michael M
    To appear in the SIGGRAPH conference proceedings A Physically-Based Night Sky Model Henrik Wann Jensen1 Fredo´ Durand2 Michael M. Stark3 Simon Premozeˇ 3 Julie Dorsey2 Peter Shirley3 1Stanford University 2Massachusetts Institute of Technology 3University of Utah Abstract 1 Introduction This paper presents a physically-based model of the night sky for In this paper, we present a physically-based model of the night sky realistic image synthesis. We model both the direct appearance for image synthesis, and demonstrate it in the context of a Monte of the night sky and the illumination coming from the Moon, the Carlo ray tracer. Our model includes the appearance and illumi- stars, the zodiacal light, and the atmosphere. To accurately predict nation of all significant sources of natural light in the night sky, the appearance of night scenes we use physically-based astronomi- except for rare or unpredictable phenomena such as aurora, comets, cal data, both for position and radiometry. The Moon is simulated and novas. as a geometric model illuminated by the Sun, using recently mea- The ability to render accurately the appearance of and illumi- sured elevation and albedo maps, as well as a specialized BRDF. nation from the night sky has a wide range of existing and poten- For visible stars, we include the position, magnitude, and temper- tial applications, including film, planetarium shows, drive and flight ature of the star, while for the Milky Way and other nebulae we simulators, and games. In addition, the night sky as a natural phe- use a processed photograph. Zodiacal light due to scattering in the nomenon of substantial visual interest is worthy of study simply for dust covering the solar system, galactic light, and airglow due to its intrinsic beauty.
    [Show full text]
  • Optical Radiation from the Atmosphere
    Utah State University DigitalCommons@USU Space Dynamics Lab Publications Space Dynamics Lab 1-1-1976 Optical Radiation from the Atmosphere Doran J. Baker Utah State University William R. Pendleton Jr. Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/sdl_pubs Recommended Citation Baker, Doran J. and Pendleton, William R. Jr., "Optical Radiation from the Atmosphere" (1976). Space Dynamics Lab Publications. Paper 2. https://digitalcommons.usu.edu/sdl_pubs/2 This Article is brought to you for free and open access by the Space Dynamics Lab at DigitalCommons@USU. It has been accepted for inclusion in Space Dynamics Lab Publications by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. cÌ E1 Baker, Doran J., and William R. Pendleton Jr. 1976. “Optical Radiation from the Atmosphere.” Proceedings of SPIE 0091: 50–62. doi:10.1117/12.955071. OPTICAL RADIATION FROM THE ATMOSPHERE Doran J. Baker and William R. Pendleton,Pendleton, Jr.Jr. Electro-Electro-Dynamics Dynamics Laboratories,Laboratories, UtahUtah StateState University Logan, Utah 84322 ABSTRACT The -interfaceinterface region which lies between the meteorological atmosphere of the Earth and "outer" space is a source ofof abundantabundant opticaloptical radiation.radiation. The purpose of thisthis paper isis toto provide the optical instrumentation engineer with a generalized understanding and a summary reference of naturally-naturally -occurring occurring aerospace radiation phenomena.phenomena. The colors of thethe radiationradiation extend over the full optical spectrum fromfrom ultravioletultraviolet throughthrough thethe infrared.infrared. The emissions, observed during both day and night times,times , areare richrich inin lineline andand bandband spectra.spectra. The parameter­parameter- ization of atmosphericatmospheric light by frequency (or photonphoton energy)energy) andand byby spectral radiance is discussed.
    [Show full text]
  • Modern Astronomical Optics 1
    Modern Astronomical Optics 1. Fundamental of Astronomical Imaging Systems OUTLINE: A few key fundamental concepts used in this course: Light detection: Photon noise Diffraction: Diffraction by an aperture, diffraction limit Spatial sampling Earth's atmosphere: every ground-based telescope's first optical element Effects for imaging (transmission, emission, distortion and scattering) and quick overview of impact on optical design of telescopes and instruments Geometrical optics: Pupil and focal plane, Lagrange invariant Astronomical measurements & important characteristics of astronomical imaging systems: Collecting area and throughput (sensitivity) flux units in astronomy Angular resolution Field of View (FOV) Time domain astronomy Spectral resolution Polarimetric measurement Astrometry Light detection: Photon noise Poisson noise Photon detection of a source of constant flux F. Mean # of photon in a unit dt = F dt. Probability to detect a photon in a unit of time is independent of when last photon was detected→ photon arrival times follows Poisson distribution Probability of detecting n photon given expected number of detection x (= F dt): f(n,x) = xne-x/(n!) x = mean value of f = variance of f Signal to noise ration (SNR) and measurement uncertainties SNR is a measure of how good a detection is, and can be converted into probability of detection, degree of confidence Signal = # of photon detected Noise (std deviation) = Poisson noise + additional instrumental noises (+ noise(s) due to unknown nature of object observed) Simplest case (often
    [Show full text]
  • Introducing the Bortle Dark-Sky Scale
    observer’s log Introducing the Bortle Dark-Sky Scale Excellent? Typical? Urban? Use this nine-step scale to rate the sky conditions at any observing site. By John E. Bortle ow dark is your sky? A Limiting Magnitude Isn’t Enough precise answer to this ques- Amateur astronomers usually judge their tion is useful for comparing skies by noting the magnitude of the observing sites and, more im- faintest star visible to the naked eye. Hportant, for determining whether a site is However, naked-eye limiting magnitude dark enough to let you push your eyes, is a poor criterion. It depends too much telescope, or camera to their theoretical on a person’s visual acuity (sharpness of limits. Likewise, you need accurate crite- eyesight), as well as on the time and ef- ria for judging sky conditions when doc- fort expended to see the faintest possible umenting unusual or borderline obser- stars. One person’s “5.5-magnitude sky” vations, such as an extremely long comet is another’s “6.3-magnitude sky.” More- tail, a faint aurora, or subtle features in over, deep-sky observers need to assess the galaxies. visibility of both stellar and nonstellar ob- On Internet bulletin boards and news- jects. A modest amount of light pollution groups I see many postings from begin- degrades diffuse objects such as comets, ners (and sometimes more experienced nebulae, and galaxies far more than stars. observers) wondering how to evaluate To help observers judge the true dark- the quality of their skies. Unfortunately, ness of a site, I have created a nine-level most of today’s stargazers have never scale.
    [Show full text]
  • Special Issue Editorial: Atmospheric Airglow—Recent Advances in Observations, Experimentations, and Modeling
    atmosphere Editorial Special Issue Editorial: Atmospheric Airglow—Recent Advances in Observations, Experimentations, and Modeling Tai-Yin Huang Department of Physics, Penn State Lehigh Valley, Center Valley, PA 18034, USA; [email protected] Airglow observations, experimentations, and theoretical studies have significantly advanced our understanding of airglow in recent decades. This Special Issue is a collec- tion of recent studies to showcase the latest results from studies in airglow observations, experimentations, and numerical modeling in the Mesosphere and Lower Thermosphere (MLT) and F regions of the terrestrial atmosphere. There are three main themes in this Special Issue. The first theme is focused on the use of satellite measurements to study the variabilities observed in the airglow emissions. The second theme is focused on ground- based observations of airglow to characterize gravity waves. The third theme is focused on airglow modeling. The recent (NASA) Global-scale Observations of the Limb and Disk (GOLD) mission provides a unique new view of the daytime thermosphere. Immel et al. [1] studied the daily variability in the UV airglow (OI and N2 in the 133–168-nm range) observed by the GOLD mission to characterize the behavior of these constituents of the thermosphere. Their results indicate that oxygen densities in the altitude range of 150–200 km vary independently from the variations in nitrogen. Yue et al. [2] performed a preliminary comparison between airglow-based Atmospheric Gravity Wave (AGW) observations from two space-borne Citation: Huang, T.-Y. Special Issue sensors, the Visible/Infrared Imaging Radiometer Suite/Day-Night Band (VIIRS/DNB) Editorial: Atmospheric Airglow— and the Ionosphere, Mesosphere, upper Atmosphere and Plasmasphere/Visible and near- Recent Advances in Observations, Infrared Spectral Imager (IMAP/VISI).
    [Show full text]
  • Three-Dimensional Tomographic Reconstruction of Mesospheric Airglow Structures Using Two-Station Ground-Based Image Measurements
    Three-dimensional tomographic reconstruction of mesospheric airglow structures using two-station ground-based image measurements Vern P. Hart,1,* Timothy E. Doyle,2 Michael J. Taylor,1,4 Brent L. Carruth,3 Pierre-Dominique Pautet,4 and Yucheng Zhao4 1Department of Physics, Utah State University, 4415 Old Main Hill, Logan, Utah 84322, USA 2Department of Physics, Utah Valley University, 800 West University Parkway, MS 179, Orem, Utah 84058, USA 3Department of Electrical and Computer Engineering, Utah State University, 4120 Old Main Hill, Logan, Utah 84322, USA 4Center for Atmospheric and Space Sciences, Utah State University, 4405 Old Main Hill, Logan, Utah 84322, USA *Corresponding author: [email protected] Received 15 June 2011; revised 4 November 2011; accepted 14 December 2011; posted 16 December 2011 (Doc. ID 149292); published 29 February 2012 A new methodology is presented to create two-dimensional (2D) and three-dimensional (3D) tomographic reconstructions of mesospheric airglow layer structure using two-station all-sky image measurements. A fanning technique is presented that produces a series of cross-sectional 2D reconstructions, which are combined to create a 3D mapping of the airglow volume. The imaging configuration is discussed and the inherent challenges of using limited-angle data in tomographic reconstructions have been analyzed using artificially generated imaging objects. An iterative reconstruction method, the partially constrained al- gebraic reconstruction technique (PCART), was used in conjunction with a priori information of the air- glow emission profile to constrain the height of the imaged region, thereby reducing the indeterminacy of the inverse problem. Synthetic projection data were acquired from the imaging objects and the forward problem to validate the tomographic method and to demonstrate the ability of this technique to accu- rately reconstruct information using only two ground-based sites.
    [Show full text]