(PDF) Fast Single-dish Scans Of The Sun Using ALMA

Log InSign Up

• Log In
• Sign Up
• more
• • About
  • Press
  • Papers
  • Terms
  • Privacy
  • Copyright
  • We're Hiring!
  • Help Center
  • less

Outline

keyboard_arrow_downTitleAbstractReferencesdownload

Download Free PDF

Download Free PDFFast single-dish scans of the Sun using ALMAH. Hudsonvisibility

…

description

3 pages

descriptionSee full PDFdownloadDownload PDF bookmarkSave to LibraryshareShareclose

Sign up for access to the world's latest research

Sign up for freearrow_forwardcheckGet notified about relevant paperscheckSave papers to use in your researchcheckJoin the discussion with peerscheckTrack your impact

Abstract

AI

This study presents the development of control and data-taking software for ALMA, enabling complex scanning patterns of solar observations. The fast-scan experiments yielded high-quality data, facilitating the characterization of signal fluctuations and noise. With a focus on rapid antenna movements, the paper highlights the capability to achieve near-Nyquist sampling over solar regions, promising advancements in monitoring microflares and nanoflares and providing insights into solar dynamics through enhanced mapping techniques.

... Read more

Related papers

Mid-frequency aperture arrays: the future of radio astronomyAndrew Faulkner

Proceedings of Resolving The Sky - Radio Interferometry: Past, Present and Future — PoS(RTS2012), 2012

downloadDownload free PDFView PDFchevron_rightThe astronomical low frequency array: A proposed explorer mission for radio astronomyRichard Woo

Geophysical Monograph Series, 2000

A radio interferometer array in space providing high dynamic range images with unprecedented angular resolution over the broad frequency range from 0.03-30 MHz will open new vistas in solar, terrestrial, galactic, and extragalactic astrophysics. The ALFA interferometer will image and track transient disturbances in the solar corona and interplanetary mediuma new capability which is crucial for understanding many aspects of solar-terrestrial interaction and space weather. ALFA will also produce the first sensitive, high-angular-resolution radio surveys of the entire sky at low frequencies. The radio sky will look entirely different below 30 MHz. As a result, ALFA will provide a fundamentally new view of the universe and an extraordinarily large and varied science return.

downloadDownload free PDFView PDFchevron_rightTracing large-scale structures in circumstellar disks with ALMAHubert Klahr

Astronomy & Astrophysics, 2013

Context. Planets are supposed to form in circumstellar disks. The additional gravitational potential of a planet perturbs the disk and leads to characteristic structures, i.e. spiral waves and gaps, in the disk's density profile. Aims. We perform a large-scale parameter study of the observability of these planet-induced structures in circumstellar disks in the (sub)mm wavelength range for the Atacama Large (Sub)Millimeter Array (ALMA). Methods. On the basis of hydrodynamical and magneto-hydrodynamical simulations of star-disk-planet models, we calculated the disk temperature structure and (sub)mm images of these systems. These were used to derive simulated ALMA images. Because appropriate objects are frequent in the Taurus-Auriga region, we focused on a distance of 140 pc and a declination of ≈20 • . The explored range of star-disk-planet configurations consists of six hydrodynamical simulations (including magnetic fields and different planet masses), nine disk sizes with outer radii ranging from 9 AU to 225 AU, 15 total disk masses in the range between 2.67 × 10 −7 M and 4.10 × 10 −2 M , six different central stars, and two different grain size distributions, resulting in 10 000 disk models.

downloadDownload free PDFView PDFchevron_rightSolar Observations with Single-Dish INAF Radio Telescopes: Continuum Imaging in the 18 – 26 GHz RangeA. Navarrini

Solar Physics

We present a new solar radio imaging system implemented through the upgrade of the large single-dish telescopes of the Italian National Institute for Astrophysics (INAF), not originally conceived for solar observations.During the development and early science phase of the project (2018 – 2020), we obtained about 170 maps of the entire solar disk in the 18 – 26 GHz band, filling the observational gap in the field of solar imaging at these frequencies. These solar images have typical resolutions in the 0.7 – 2 arcmin range and a brightness temperature sensitivity <10 K. Accurate calibration adopting the Supernova Remnant Cas A as a flux reference provided typical errors <3% for the estimation of the quiet-Sun level components and active regions flux measurements.As the first early scientific result of the project, we present a catalog of radio continuum solar imaging observations with Medicina 32-m and SRT 64-m radio telescopes, including the multi-wavelength identification of a...

downloadDownload free PDFView PDFchevron_rightMurchison Widefield array: Tracing solar disturbances from the sun to the earthIver Cairns

2011 30th URSI General Assembly and Scientific Symposium, URSIGASS 2011, 2011

The unique and powerful diagnostic capabilities of low radio frequencies for solar, heliospheric, and ionospheric science have long been recognized, but the challenges associated with high-fidelity low frequency radio imaging have limited their exploitation. The Murchison Widefield Array (MWA) is a pioneering new interferometer, currently under construction in the radio-quiet Western Australian outback, which exploits the recent advances in digital signal processing to rise to this challenge. We present an overview of the exciting new solar, heliospheric, and ionospheric science which this instrument will enable, along with early results from a prototype array.

downloadDownload free PDFView PDFchevron_rightSolar Physics with the Square Kilometre ArrayEduard Kontar

Advances in Space Research, 2019

The Square Kilometre Array (SKA) will be the largest radio telescope ever built, aiming to provide collecting area larger than 1 km 2. The SKA will have two independent instruments, SKA-LOW comprising of dipoles organized as aperture arrays in Australia and SKA-MID comprising of dishes in South Africa. Currently the phase-1 of SKA, referred to as SKA1, is in its late design stage and construction is expected to start in 2020. Both SKA1-LOW (frequency range of 50-350 MHz) and SKA1-MID Bands 1, 2, and 5 (frequency ranges of 350-1050, 950-1760, and 4600-15300 MHz, respectively) are important for solar observations. In this paper we present SKA's unique capabilities in terms of spatial, spectral, and temporal resolution, as well as sensitivity and show that they have the potential to provide major new insights in solar physics topics of capital importance including (i) the structure and evolution of the solar corona, (ii) coronal heating, (iii) solar flare dynamics including particle acceleration and transport, (iv) the dynamics and structure of coronal mass ejections, and (v) the solar aspects of space weather. Observations of the Sun jointly with the new generation of ground-based and space-borne instruments promise unprecedented discoveries.

downloadDownload free PDFView PDFchevron_rightThe Simons Observatory: Beam characterization for the Small Aperture TelescopesEdward J Wollack

HAL (Le Centre pour la Communication Scientifique Directe), 2023

We use time-domain simulations of Jupiter observations to test and develop a beam reconstruction pipeline for the Simons Observatory Small Aperture Telescopes. The method relies on a map maker that estimates and subtracts correlated atmospheric noise and a beam fitting code designed to compensate for the bias caused by the map maker. We test our reconstruction performance for four different frequency bands against various algorithmic parameters, atmospheric conditions and input beams. We additionally show the reconstruction quality as function of the number of available observations and investigate how different calibration strategies affect the beam uncertainty. For all of the

downloadDownload free PDFView PDFchevron_rightBeam Pattern Measurements and Observational Evaluations of the ALMA/ACA 12-m AntennaJose Puga

Publications of the Astronomical Society of Japan, 2009

We have evaluated the beam pattern of the ALMA/ACA 12-m antenna with total power observations of Jupiter and the Moon. Models of the expected beam pattern as it passes across Jupiter and the Moon were derived in consideration of the radiation pattern of the actual receiving system and the surface error of the main reflector. Since the profiles of the measured beam patterns were consistent with those of the models within the range from the peak to 20 dB, we confirmed that the antenna achieved the beam pattern expected from its optical design. After this confirmation, we performed astronomical observations. In addition to the detection of the CS J = 3-2 (146.969026 GHz) spectrum toward Orion KL, the change in the Moon intensity was successfully detected during the total lunar eclipse during 2008 February 20-21. A time lag longer than 10 min in the millimeter-wave eclipse relative to the corresponding optical eclipse ephemeris was detected. Mapping observations of the Sun revealed the structure of the chromospheric networks at 147 GHz. These astronomical observations confirmed that the ACA 12-m antenna could be successfully operated under various operating conditions.

downloadDownload free PDFView PDFchevron_rightPhased array feeds for the Square Kilometre ArrayJan Geralt Bij de Vaate

2011 XXXth URSI General Assembly and Scientific Symposium, 2011

A novel method to form multiple instantaneous beams on the sky with a reflector antenna is to employ a dense Phased Array Feed (PAF). This technology is currently being developed to greatly increase the survey speed of existing and future radio telescopes. This paper reviews the current state of PAF development projects for radio astronomy, the particular challenges and the potential for incorporation of PAFs into the ultimate radio survey instrument-the Square Kilometre Array.

downloadDownload free PDFView PDFchevron_rightStudy of solar brightness profiles in the 18-26 GHz frequency range with INAF radio telescopes I: solar radiusA. Navarrini

arXiv (Cornell University), 2024

The Sun is an extraordinary workbench, from which several fundamental astronomical parameters can be measured with high precision. Among these parameters, the solar radius $R_{\odot}$ plays an important role in several aspects, such as in evolutionary models. Despite the efforts in obtaining accurate measurements of $R_{\odot}$, the subject is still debated and measurements are puzzling and/or lacking in many frequency ranges. We aimed to determine the mean, equatorial, and polar radii of the Sun ($R_c$, $R_{eq}$, and $R_{pol}$) in the frequency range 18.1 - 26.1 GHz. We employed single-dish observations from the newly-appointed Medicina "Gavril Grueff" Radio Telescope and the Sardinia Radio Telescope (SRT) throughout 5 years, from 2018 to mid-2023, in the framework of the SunDish project for solar monitoring. Two methods to calculate the radius at radio frequencies are considered and compared. To assess the quality of our radius determinations, we also analysed the possible degrading effects of the antenna beam pattern on our solar maps, using two 2D-models. We carried out a correlation analysis with the evolution of the solar cycle through the calculation of Pearson's correlation coefficient $\rho$. We obtained several values for the solar radius - ranging between 959 and 994 arcsec - and $\rho$, with typical errors of a few arcsec. Our $R_{\odot}$ measurements, consistent with values reported in literature, suggest a weak prolatness of the solar limb ($R_{eq}$ > $R_{pol}$), although $R_{eq}$ and $R_{pol}$ are statistically compatible within 3$\sigma$ errors. The correlation analysis using the solar images from Grueff shows (1) a positive correlation between the solar activity and the temporal variation of $R_c$ (and $R_{eq}$) at all observing frequencies, and (2) a weak anti-correlation between the temporal variation of $R_{pol}$ and the solar activity at 25.8 GHz.

downloadDownload free PDFView PDFchevron_rightSee full PDFdownloadDownload PDF

Loading Preview

Sorry, preview is currently unavailable. You can download the paper by clicking the button above.

References (2)

1. Hudson, H. S. 1991, Solar Phys., 133, 357.
2. Kovács, A. 2008, in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, vol. 7020 of Society of Photo-Optical Instrumen- tation Engineers (SPIE) Conference Series (http://arxiv.org/abs/0806.4888).

Related papers

Observing the Sun with the Atacama Large Millimeter-submillimeter Array (ALMA): Fast-Scan Single-Dish MappingW. Kawasaki

2017

The Atacama Large Millimeter-submillimeter Array (ALMA) radio telescope has commenced science observations of the Sun starting in late 2016. Since the Sun is much larger than the field of view of individual ALMA dishes, the ALMA interferometer is unable to measure the background level of solar emission when observing the solar disk. The absolute temperature scale is a critical measurement for much of ALMA solar science, including the understanding of energy transfer through the solar atmosphere, the properties of prominences, and the study of shock heating in the chromosphere. In order to provide an absolute temperature scale, ALMA solar observing will take advantage of the remarkable fast-scanning capabilities of the ALMA 12m dishes to make single-dish maps of the full Sun. This article reports on the results of an extensive commissioning effort to optimize the mapping procedure, and it describes the nature of the resulting data. Amplitude calibration is discussed in detail: a path...

downloadDownload free PDFView PDFchevron_rightSolar radar astronomy with the low-frequency arrayPaul Rodriguez

Planetary and Space Science, 2004

Initial studies of the Sun's corona using a solar radar were done in the 1960s and provided measurements of the Sun's radar crosssection at about 38 MHz. These initial measurements were done at a time when the large-scale phenomenon known as a coronal mass ejection was unknown; however, these data suggest that coronal mass ejections (CMEs) may have been detected but were unrecognized. That solar radar facility, which was located at El Campo, TX, no longer exists. New solar radar investigations are motivated by our modern understanding of CMEs and their effects on the Earth. A radar echo from an Earthward-directed coronal mass ejection may be expected to have a frequency shift proportional to velocity; thus providing a good estimate of arrival time at Earth and the possible occurrence of geomagnetic storms. Solar radar measurements may also provide new information on electron densities in the corona. The frequencies of interest for solar radars fall in the range of about 10-100 MHz, corresponding to the lower range planned for the low-frequency array. In combination with existing or new high-power transmitters, it is possible to use the low-frequency array to re-initiate radar studies of the Sun's corona. In this report, we review the basic requirements of solar radars, as developed in past studies and as proposed for future investigations.

downloadDownload free PDFView PDFchevron_rightThe fastscanning observing technique for millimeter and submillimeter astronomyCatherine Turner

Astronomy and Astrophysics, 2001

Fastscanning is a new observing technique for millimeter and submillimeter astronomy from ground based telescopes. The atmosphere is eliminated by taking advantage of detector arrays. Instead of wobbling the secondary mirror with a fixed frequency of a few Hz to filter the atmospheric contribution, we sample the detector outputs at a much higher rate without a modulation by the secondary mirror. The atmospheric contribution is then removed later in the offline data reduction by correlation analysis between the detector pixels. In order to satisfy the AC requirement of the amplifiers in the absence of modulation, the telescope scans fast to convert the spatial frequencies of the sky into the detector frequency band. The acquired AC signals are then deconvolved with the corresponding filter function in order to reconstruct quasi-DC signals. This article describes the technique of this new method and shows simulations and preliminary test results.

downloadDownload free PDFView PDFchevron_rightScience at Very High Angular Resolution with the Square Kilometre ArrayR. Ekers

Publications of the Astronomical Society of Australia, 2012

Preliminary specifications for the Square Kilometre Array (SKA) call for 25% of the total collecting area of the dish array to be located at distances greater than 180 km from the core, with a maximum baseline of at least 3000 km. The array will provide angular resolution θ ≲ 40–2 mas at 0.5–10 GHz with image sensitivity reaching ≲50 nJy beam−1in an 8-hour integration with 500-MHz bandwidth. Given these specifications, the high-angular-resolution component of the SKA will be capable of detecting brightness temperatures ≲200K with milliarcsecond-scale angular resolution. The aim of this article is to bring together in one place a discussion of the broad range of new and important high-angular-resolution science that will be enabled by the SKA, and in doing so, address the merits of long baselines as part of the SKA. We highlight the fact that high angular resolution requiring baselines greater than 1000 km provides a rich science case with projects from many areas of astrophysics, in...

downloadDownload free PDFView PDFchevron_rightAllen Telescope Array Multi-frequency Observations of the SunGarrett Keating, Colby Gutierrez-kraybill

Solar Physics, 2012

We present the first observations of the Sun with the Allen Telescope Array (ATA). We used up to six frequencies, from 1.43 to 6 GHz, and baselines from 6 to 300 m. To our knowledge, these are the first simultaneous multifrequency full-Sun maps obtained at microwave frequencies without mosaicing. The observations took place when the Sun was relatively quiet, although at least one active region was present each time. We present multi-frequency flux budgets for each sources on the Sun. Outside of active regions, assuming optically thin bremsstrahlung (free-free) coronal emission on top of an optically thick ≈10 000 K chromosphere, the multi-frequency information can be condensed into a single, frequency-independent, "coronal bremsstrahlung contribution function" [EM/

downloadDownload free PDFView PDFchevron_rightTomography of Galactic star-forming regions and spiral arms with the Square Kilometer ArrayHuib van Langevelde

Very Long Baseline Interferometry (VLBI) at radio wavelengths can provide astrometry accurate to 10 micro-arcseconds or better (i.e. better than the target GAIA accuracy) without being limited by dust obscuration. This means that unlike GAIA, VLBI can be applied to star-forming regions independently of their internal and line-of-sight extinction. Low-mass young stellar objects (particularly T Tauri stars) are often non-thermal compact radio emitters, ideal for astrometric VLBI radio continuum experiments. Existing observations for nearby regions (e.g. Taurus, Ophiuchus, or Orion) demonstrate that VLBI astrometry of such active T Tauri stars enables the reconstruction of both the regions' 3D structure (through parallax measurements) and their internal kinematics (through proper motions, combined with radial velocities). The extraordinary sensitivity of the SKA telescope will enable similar tomographic mappings to be extended to regions located several kpc from Earth, in particular to nearby spiral arm segments. This will have important implications for Galactic science, galactic dynamics and spiral structure theories.

downloadDownload free PDFView PDFchevron_rightkeyboard_arrow_downView more papers

• Explore
• Papers
• Topics

• Features
• Mentions
• Analytics
• PDF Packages
• Advanced Search
• Search Alerts

• Journals
• Academia.edu Journals
• My submissions
• Reviewer Hub
• Why publish with us
• Testimonials

• Company
• About
• Careers
• Press
• Help Center
• Terms
• Privacy
• Copyright
• Content Policy

580 California St., Suite 400San Francisco, CA, 94104© 2025 Academia. All rights reserved