The CANDLE Engineering Demonstration Unit (EDU) was selected by the 2022 APRA program to develop and demonstrate the ability to reach the flux accuracy and range required for an artificial flux calibration star. A critical issue in producing accurate and reliable flux calibration is systematic effects; this EDU is providing a path to deploying an artificial star calibration payload outside Earth’s atmosphere with SI-traceable calibration that enables accurate throughput characterization of astronomical and earth science observatories in space and on the ground. Such a payload could be carried independently on a dedicated platform such as an orbiting satellite, e.g. the Orbiting Configurable Artificial Star (ORCAS), by a star shade at L2, or some other independent platform to enable accurate end-to-end throughput vs. wavelength calibration that can be measured repeatedly throughout the operational lifetime of an observatory. Once calibrated, the observatory is enabled to carry out astrophysical programs whose science objectives demand high accuracy and/or high precision observations. One specific and immediate application is establishing SI-traceable standard stars beyond the current limited set. We show in this paper the progress made in developing this EDU.
The Orbiting Configurable Artificial Star (ORCAS) mission in collaboration with the W. M. Keck Observatory (WMKO) is poised to deliver near diffraction limited observations in visible light. The ability to conduct such observations will enable significant scientific discoveries in fields related to Active Galactic Nuclei (AGN), Dark Energy, Flux Calibration, the High Redshift Universe, Exoplanets, and the Solar System. The ORCAS team has successfully completed three primary mission development goals to enable such observations. The performance demonstration with the ORCAS Keck Instrument Demonstrator (ORKID) captured arguably the highest resolution image at visible wavelengths from a large (10 meter) segmented telescope on the ground to date. High resolution AO imaging of the galaxy UGC 4729 in Natural Guide Star (NGS) mode was performed by locking onto a foreground asteroid passing nearby, which simulated an observation with a moving guide star validating post processing capabilities and demonstrating how regions unreachable by NGS and LGS could be explored. Additionally, the ORCAS team has successfully locked onto a laser source onboard the Laser Communications Relay Demonstration (LCRD) and closed the adaptive optics loop to perform near diffraction limited imaging at 1550 nm with the Keck 10 meter, the first demonstration of such capability with a large segmented telescope. All of these results validate the feasibility of the ORCAS mission. Following these accomplishments, ORCAS will be strongly positioned to propose a full-scale mission to upcoming opportunities.
KEYWORDS: Space telescopes, Design and modelling, Telescopes, Observatories, Mirrors, James Webb Space Telescope, Space mirrors, Equipment, Astronomy, Coronagraphy
New development approaches, including launch vehicles and advances in sensors, computing, and software, have lowered the cost of entry into space, and have enabled a revolution in low-cost, high-risk Small Satellite (SmallSat) missions. To bring about a similar transformation in larger space telescopes, it is necessary to reconsider the full paradigm of space observatories. Here we will review the history of space telescope development and cost drivers, and describe an example conceptual design for a low cost 6.5 m optical telescope to enable new science when operated in space at room temperature. It uses a monolithic primary mirror of borosilicate glass, drawing on lessons and tools from decades of experience with ground-based observatories and instruments, as well as flagship space missions. It takes advantage, as do large launch vehicles, of increased computing power and space-worthy commercial electronics in low-cost active predictive control systems to maintain stability. We will describe an approach that incorporates science and trade study results that address driving requirements such as integration and testing costs, reliability, spacecraft jitter, and wavefront stability in this new risk-tolerant “LargeSat” context.
Here we present the methodology and results of transferring UV–NIR flux calibration from NIST photodiodes to a set of 20 picoammeters. These are to be deployed as flux reference sensors on the SCALA calibration system at the University of Hawaii 2.2m telescope on Maunakea as part of a systematic upgrade aimed at improving the existing flux calibration for dark energy and exoplanet host star measurements beyond the ∼ 4 mmag / 100 nm we have already achieved at optical wavelengths with SCALA. Our robotic light source for performing the photodiode calibration transfer provides monochromatic light spanning 230 to 1200 nm with a dynamic range of 106 , while our new picoammeters have a noise floor of 10 fA in 4 s at 25 ◦C, with saturation around 400 pA. Our robotic gantry enabled the measurement of the spatial and angular response of our picoammeters. In preparation for the calibration transfer, a number of tests were performed to establish the measurement uncertainties, and these tests revealed subtle systematic effects that required correction. These includes polarization effects, leading to the redesign of part of the optics in the gantry head, implementation of a Holmium-Didymium filter as a precision wavelength transfer between arc and continuum light sources, and further suppression of stray light. We find that our calibration transfers are consistent with the NIST calibration to within ∼0.1%
The SCALA system provides a physical flux calibration for the SuperNova Integral Field Spectrograph (SNIFS) mounted to the University of Hawaii 2.2m telescope on Mauna Kea by transferring the flux scale from a NIST- traceable photodiode to SNIFS. This calibration is then applied to CALSPEC standard stars. We thereby remove stellar atmospheric models from the calibration chain. Measurement results for supernova cosmology are directly improved, as systematic uncertainties in the flux calibration limit them. Using the existing SCALA setup we achieved a calibration that agrees with the CALSPEC and Hayes6 systems to within ~4 mmag / 1000 A over a wavelength range from 4500 A to 9000 A. We are now upgrading the SCALA system to reach measurement uncertainties below 0.5 %. To provide the flux references for the new system and to perform tests of the improved components, we have built a laboratory light source enabling measurements with sub-percent uncertainties. The light source provides monochromatic light (FWHM 1.8/3.6 nm) spanning UV to IR, with wavelength accuracy and reproducibility of ≤ 1A. Neutral density filters enable fluxes that induce photodiode currents between fA and µA. A subsystem allows linearity testing for detectors with their readout system. Using a gantry robot, we can measure our detectors’ spatial response and angular acceptance with active areas up to 0.5 m2.
The SNIFS CALibration Apparatus (SCALA), a device to calibrate the Supernova Integral Field Spectrograph on the University Hawaii 2.2m telescope, was developed and installed in Spring 2014. SCALA produces an artificial planet with a diameter of 1° and a constant surface brightness. The wavelength of the beam can be tuned between 3200 Å and 10000 Å and has a bandwidth of 35 Å. The amount of light injected into the telescope is monitored with NIST calibrated photodiodes. SCALA was upgraded in 2015 with a mask installed at the entrance pupil of the UH88 telescope, ensuring that the illumination of the telescope by stars is similar to that of SCALA. With this setup, a first calibration run was performed in conjunction with the spectrophotometric observations of standard stars. We present first estimates for the expected systematic uncertainties of the in-situ calibration and discuss the results of tests that examine the influence of stray light produced in the optics.
Observational cosmology employing optical surveys often require precise flux calibration. In this context we present SNIFS Calibration Apparatus (SCALA), a flux calibration system developed for the SuperNova Integral Field Spectrograph (SNIFS), operating at the University of Hawaii 2.2 m telescope. SCALA consists of a hexagonal array of 18 small parabolic mirrors distributed over the face of, and feeding parallel light to, the telescope entrance pupil. The mirrors are illuminated by integrating spheres and a wavelength-tunable (from UV to IR) light source, generating light beams with opening angles of 1°. These nearly parallel beams are flat and flux-calibrated at a subpercent level, enabling us to calibrate our “telescope + SNIFS system” at the required precision.
P. Antilogus, R. Thomas, G. Aldering, C. Aragon, Y. Copin, E. Gangler, E. Hornero, A. Pecontal, S. Poon, K. Runge, R. Scalzo, S. Bailey, C. Baltay, C. Buton, S. Bongard, M. Childress, S. Loken, P. Nugent, R. Pain, E. Pecontal, R. Pereira, S. Perlmutter, D. Rabinowitz, G. Rigaudier, G. Smadja, C. Tao, C. Wu
Virtual Control Room allows a team of people in various locations to contribute fully to an instrument acquisition:
a reduced support is required on site but, due to the large support available off site, the data taking quality can be
still better compared to the usual on-site support scheme. The acquisition of the SNfactory spectro-photometric
follow-up is based on such data taking model. This acquisition and its performances are presented here.
We present new characterization results for a large format, 15 um pixel pitch, 2kx4k format, p-channel CCD fabricated on high resistivity silicon at Lawrence Berkeley National Laboratory. The fully-depleted device is 300 um thick and backside illuminated utilizing 4-side buttable packaging. We report on measurements of standard operating characteristics including charge transfer efficiency, readout noise, cosmetics performance, dark current, and well depth. We have also made preliminary measurements of the device's X-Ray energy resolution and tests of device linearity.
Michael Sholl, Michael Lampton, Greg Aldering, W. Althouse, R. Amanullah, James Annis, Pierre Astier, Charles Baltay, E. Barrelet, Stephane Basa, Christopher Bebek, Lars Bergstrom, Gary Bernstein, Manfred Bester, Bruce Bigelow, Roger Blandford, Ralph Bohlin, Alain Bonissent, Charles Bower, Mark Brown, Myron Campbell, William Carithers, Eugene Commins, W. Craig, C. Day, F. DeJongh, Susana Deustua, T. Diehl, S. Dodelson, Anne Ealet, Richard Ellis, W. Emmet, D. Fouchez, Josh Frieman, Andrew Fruchter, D. Gerdes, L. Gladney, Gerson Goldhaber, Ariel Goobar, Donald Groom, Henry Heetderks, M. Hoff, Stephen Holland, M. Huffer, L. Hui, Dragan Huterer, B. Jain, Patrick Jelinsky, Armin Karcher, Steven Kahn, Steven Kent, Alex Kim, William Kolbe, B. Krieger, G. Kushner, N. Kuznetsova, Robin Lafever, J. Lamoureux, Olivier Le Fevre, Michael Levi, P. Limon, Huan Lin, Eric Linder, Stewart Loken, W. Lorenzon, Roger Malina, J. Marriner, P. Marshall, R. Massey, Alain Mazure, Timothy McKay, Shawn McKee, Ramon Miquel, Nicholas Morgan, E. Mörtsell, Nick Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nick Palaio, David Pankow, John Peoples, Saul Perlmutter, Eric Prieto, David Rabinowitz, Alexandre Refregier, Jason Rhodes, Natalie Roe, D. Rusin, V. Scarpine, Michael Schubnell, Gérard Smadja, Roger Smith, George Smoot, Jeffrey Snyder, Anthony Spadafora, A. Stebbins, Christopher Stoughton, Andrew Szymkowiak, Gregory Tarlé, Keith Taylor, A. Tilquin, Andrew Tomasch, Douglas Tucker, D. Vincent, Henrik von der Lippe, Jean-Pierre Walder, Guobin Wang, W. Wester
Mission requirements, the baseline design, and optical systems budgets for the SuperNova/Acceleration Probe (SNAP) telescope are presented. SNAP is a proposed space-based experiment designed to study dark energy and alternate explanations of the acceleration of the universe’s expansion by performing a series of complementary systematics-controlled astrophysical measurements. The goals of the mission are a Type Ia supernova Hubble diagram and a wide-field weak gravitational lensing survey. A 2m widefield three-mirror telescope feeds a focal plane consisting of 36 CCDs and 36 HgCdTe detectors and a high-efficiency, low resolution integral field spectrograph. Details of the maturing optical system, with emphasis on structural stability during terrestrial testing as well as expected environments during operations at L2 are discussed. The overall stray light mitigation system, including illuminated surfaces and visible objects are also presented.
Anne Ealet, Eric Prieto, Alain Bonissent, Roger Malina, Gérard Smadja, A. Tilquin, Gary Bernstein, Stephane Basa, D. Fouchez, Olivier Le Fevre, Alain Mazure, Greg Aldering, R. Amanullah, Pierre Astier, E. Barrelet, Christopher Bebek, Lars Bergstrom, Manfred Bester, Roger Blandford, Ralph Bohlin, Charles Bower, Mark Brown, Myron Campbell, William Carithers, Eugene Commins, W. Craig, C. Day, F. DeJongh, Susana Deustua, H. Diehl, S. Dodelson, Richard Ellis, M. Emmet, Josh Frieman, Andrew Fruchter, D. Gerdes, L. Gladney, Gerson Goldhaber, Ariel Goobar, Donald Groom, Henry Heetderks, M. Hoff, Stephen Holland, M. Huffer, L. Hui, Dragan Huterer, B. Jain, Patrick Jelinsky, Armin Karcher, Steven Kent, Steven Kahn, Alex Kim, William Kolbe, B. Krieger, G. Kushner, N. Kuznetsova, Robin Lafever, J. Lamoureux, Michael Lampton, Michael Levi, P. Limon, Huan Lin, Eric Linder, Stewart Loken, W. Lorenzon, J. Marriner, P. Marshall, R. Massey, Timothy McKay, Shawn McKee, Ramon Miquel, Nicholas Morgan, E. Mörtsell, Nick Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nick Palaio, David Pankow, John Peoples, Saul Perlmutter, David Rabinowitz, Alexandre Refregier, Jason Rhodes, Natalie Roe, D. Rusin, V. Scarpine, Michael Schubnell, Michael Sholl, Roger Smith, George Smoot, Jeffrey Snyder, Anthony Spadafora, A. Stebbins, Christopher Stoughton, Andrew Szymkowiak, Gregory Tarlé, Keith Taylor, Andrew Tomasch, Douglas Tucker, Henrik von der Lippe, D. Vincent, Jean-Pierre Walder, Guobin Wang, W. Wester
A well-adapted spectrograph concept has been developed for the SNAP (SuperNova/Acceleration Probe) experiment. The goal is to ensure proper identification of Type Iz supernovae and to standardize the magnitude of each candidate by determining explosion parameters. The spectrograph is also a key element for the calibration of the science mission. An instrument based on an integral field method with the powerful concept of imager slicing has been designed and is presented in this paper. The spectrograph concept is optimized to have high efficiency and low spectral resolution (R~100), constant through the wavelength range (0.35-1.7μm), adapted to the scientific goals of the mission.
SNIFS is an integral field spectrograph devoted to the observation of supernovae. This instrument is today in the manufacturing phase and should be able to observe supernovae at the end of this year (2003) on the 2.2m telescope of University Hawaii. The concept of SNIFS is to split the 6” x 6” field of view into 225 samples of 0.4” x 0.4” through a microlens array. Then the spectral decomposition of each sample is imaged on a 2k x 4k CCD. In order to cover all the large spectral range with a high resolution, the spectrograph is composed of two modules, one for the blue wavelengths (320 nm to 560nm)with a resolution around 1000 at 430 nm and one for the red wavelengths (520 nm to 1 µm) with a resolution around 1300 at 760 nm. First we will present the optical design and detail the function of each optical component. Then the mechanical design will be shown with some maps of the structure. Finally the first pictures taken during the alignments will be displayed.
Michael Lampton, Michael Sholl, Michael Krim, R. Besuner, Carl Akerlof, Greg Aldering, R. Amanullah, Pierre Astier, Charles Baltay, E. Barrelet, Stephane Basa, Christopher Bebek, John Bercovitz, Lars Bergstrom, Gary Berstein, Manfred Bester, Ralph Bohlin, Alain Bonissent, Charles Bower, Myron Campbell, William Carithers, Eugene Commins, C. Day, Susana Deustua, Richard DiGennaro, Anne Ealet, Richard Ellis, William Emmett, Mikael Eriksson, D. Fouchez, Andrew Fruchter, Jean-Francois Genat, Gerson Goldhaber, Ariel Goobar, Donald Groom, Henry Heetderks, Stephen Holland, Dragan Huterer, William Johnston, Richard Kadel, Armin Karcher, Alex Kim, William Kolbe, Robin Lafever, J. Lamoureux, Oliver LeFevre, Michael Levi, Daniel Levin, Eric Linder, Stewart Loken, Roger Malina, Alain Mazure, Timothy McKay, Shawn McKee, Ramon Miquel, Nicholas Morgan, E. Mortsell, Nick Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nick Palaio, David Pankow, Saul Perlmutter, Eric Prieto, David Rabinowitz, Alexandre Refregier, Jason Rhodes, Natalie Roe, Michael Schubnell, G. Smadja, R. Smith, George Smoot, Jeffrey Snyder, Anthony Spadafora, Andrew Szymkowiak, Gregory Tarle, Keith Taylor, A. Tilquin, Andrew Tomasch, D. Vincent, Henrik von der Lippe, Jean-Pierre Walder, Guobin Wang
We present the baseline telescope design for the telescope for the SuperNova/Acceleration Probe (SNAP) space mission. SNAP’s purpose is to determine expansion history of the Universe by measuring the redshifts, magnitudes, and spectral classifications of thousands of supernovae with unprecedented accuracy. Discovering and measuring these supernovae demand both a wide optical field and a high sensitivity throughout the visible and near IR wavebands. We have adopted the annular-field three-mirror anastigmat (TMA) telescope configuration, whose classical aberrations (including chromatic) are zero. We show a preliminary optmechanical design that includes important features for stray light control and on-orbit adjustment and alignment of the optics. We briefly discuss stray light and tolerance issues, and present a preliminary wavefront error budget for the SNAP Telescope. We conclude by describing some of the design tasks being carried out during the current SNAP research and development phase.
Christopher Bebek, Carl Akerlof, Greg Aldering, R. Amanullah, Pierre Astier, Charles Baltay, E. Barrelet, Stephane Basa, John Bercovitz, Lars Bergstrom, Gary Berstein, Manfred Bester, Ralph Bohlin, Alain Bonissent, Charles Bower, Myron Campbell, William Carithers, Eugene Commins, C. Day, Susana Deustua, Richard DiGennaro, Anne Ealet, Richard Ellis, William Emmett, Mikael Eriksson, D. Fouchez, Andrew Fruchter, Jean-Francois Genat, Gerson Goldhaber, Ariel Goobar, Donald Groom, Henry Heetderks, Stephen Holland, Dragan Huterer, William Johnston, Richard Kadel, Armin Karcher, Alex Kim, William Kolbe, Robin Lafever, J. Lamoureux, Michael Lampton, Oliver LeFevre, Michael Levi, Daniel Levin, Eric Linder, Stewart Loken, Roger Malina, Alain Mazure, Timothy McKay, Shawn McKee, Ramon Miquel, Nicholas Morgan, E. Mortsell, N. Mostek, Stuart Mufson, J. Musser, Natalie Roe, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nicholas Palaio, David Pankow, Saul Perlmutter, Eric Prieto, David Rabinowitz, Alexandre Refregier, Jason Rhodes, Michael Schubnell, Michael Sholl, G. Smadja, R. Smith, George Smoot, Jeffrey Snyder, Anthony Spadafora, Andrew Szymkowiak, Gregory Tarle, Keith Taylor, A. Tilquin, Andrew Tomasch, D. Vincent, Henrik von der Lippe, Jean-Pierre Walder, Guobin Wang
The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square degree field in the visible and near-infrared wavelength regime. The requirements for the instrument suite and the present configuration of the focal plane concept are presented. A two year R&D phase, largely supported by the Department of Energy, is just beginning. We describe the development activities that are taking place to advance our preparedness for mission proposal in the areas of detectors and electronics.
Gregory Tarle, Carl Akerlof, Greg Aldering, R. Amanullah, Pierre Astier, E. Barrelet, Christopher Bebek, Lars Bergstrom, John Bercovitz, Gary Bernstein, Manfred Bester, Alain Bonissent, C. Bower, Mark Brown, William Carithers, Eugene Commins, C. Day, Susana Deustua, Richard DiGennaro, Anne Ealet, Richard Ellis, Mikael Eriksson, Andrew Fruchter, Jean-Francois Genat, Gerson Goldhaber, Ariel Goobar, Donald Groom, Stewart Harris, Peter Harvey, Henry Heetderks, Steven Holland, Dragan Huterer, Armin Karcher, Alex Kim, William Kolbe, B. Krieger, R. Lafever, J. Lamoureux, Michael Lampton, Michael Levi, Daniel Levin, Eric Linder, Stewart Loken, Roger Malina, R. Massey, Ramon Miquel, Timothy McKay, Shawn McKee, E. Moertsell, N. Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nicholas Palaio, David Pankow, Saul Perlmutter, R. Pratt, Eric Prieto, Alexandre Refregier, Jason Rhodes, Kem Robinson, N. Roe, Michael Schubnell, Michael Sholl, G. Smadja, George Smoot, Anthony Spadafora, Andrew Tomasch, D. Vincent, H. von der Lippe, J.-P. Walder, Guobin Wang
The SuperNova/Acceleration Probe (SNAP) will measure precisely the cosmological expansion history over both the acceleration and deceleration epochs and thereby constrain the nature of the dark energy that dominates our universe today. The SNAP focal plane contains equal areas of optical CCDs and NIR sensors and an integral field spectrograph. Having over 150 million pixels and a field-of-view of 0.34 square degrees, the SNAP NIR system will be the largest yet constructed. With sensitivity in the range 0.9-1.7 μm, it will detect Type Ia supernovae between z = 1 and 1.7 and will provide follow-up precision photometry for all supernovae. HgCdTe technology, with a cut-off tuned to 1.7 μm, will permit passive cooling at 140 K while maintaining noise below zodiacal levels. By dithering to remove the effects of intrapixel variations and by careful attention to other instrumental effects, we expect to control relative photometric accuracy below a few hundredths of a magnitude. Because SNAP continuously revisits the same fields we will be able to achieve outstanding statistical precision on the photometry of reference stars in these fields, allowing precise monitoring of our detectors. The capabilities of the NIR system for broadening the science reach of SNAP are discussed.
Anne Ealet, Eric Prieto, Alain Bonissent, Roger Malina, G. Bernstein, Stephane Basa, Oliver LeFevre, Alain Mazure, Christophe Bonneville, Carl Akerlof, Greg Aldering, R. Amanullah, Pierre Astier, E. Barrelet, Christopher Bebek, Lars Bergstrom, John Bercovitz, Manfred Bester, C. Bower, William Carithers, Eugene Commins, C. Day, Susana Deustua, Richard DiGennaro, R. Ellis, Mikael Eriksson, Andrew Fruchter, Jean-Francois Genat, Gerson Goldhaber, Ariel Goobar, Donald Groom, Stewart Harris, Peter Harvey, Henry Heetderks, Steven Holland, Dragan Huterer, Armin Karcher, Alex Kim, William Kolbe, B. Krieger, R. Lafever, J. Lamoureux, Michael Lampton, Michael Levi, Daniel Levin, Eric Linder, Stewart Loken, R. Massey, Timothy McKay, Shawn McKee, Ramon Miquel, E. Moertsell, N. Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nicholas Palaio, David Pankow, Saul Perlmutter, R. Pratt, Alexandre Refregier, J. Rhodes, Kem Robinson, N. Roe, Michael Sholl, Michael Schubnell, G. Smadja, George Smoot, Anthony Spadafora, Gregory Tarle, Andrew Tomasch, H. von der Lippe, D. Vincent, J.-P. Walder, Guobin Wang
A well-adapted spectrograph concept has been developed for the SNAP (SuperNova/Acceleration Probe) experiment. The goal is to ensure proper identification of Type Ia supernovae and to standardize the magnitude of each candidate by determining explosion parameters. An instrument based on an integral field method with the powerful concept of imager slicing has been designed and is presented in this paper. The spectrograph concept is optimized to have very high efficiency and low spectral resolution (R~100), constant through the wavelength range (0.35-1.7μm), adapted to the scientific goals of the mission.
Michael Lampton, Christopher Bebek, Carl Akerlof, Greg Aldering, R. Amanullah, Pierre Astier, E. Barrelet, Lars Bergstrom, John Bercovitz, Gary Bernstein, Manfred Bester, Alain Bonissent, C. Bower, William Carithers, Eugene Commins, C. Day, Susana Deustua, Richard DiGennaro, Anne Ealet, Richard Ellis, Mikael Eriksson, Andrew Fruchter, Jean-Francois Genat, Gerson Goldhaber, Ariel Goobar, Donald Groom, Stewart Harris, Peter Harvey, Henry Heetderks, Steven Holland, Dragan Huterer, Armin Karcher, Alex Kim, William Kolbe, B. Krieger, R. Lafever, J. Lamoureux, Michael Levi, Daniel Levin, Eric Linder, Stewart Loken, Roger Malina, R. Massey, Timothy McKay, Steven McKee, Ramon Miquel, E. Moertsell, N. Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nicholas Palaio, David Pankow, Saul Perlmutter, R. Pratt, Eric Prieto, Alexandre Refregier, J. Rhodes, Kem Robinson, N. Roe, Michael Sholl, Michael Schubnell, G. Smadja, George Smoot, Anthony Spadafora, Gregory Tarle, Andrew Tomasch, H. von der Lippe, D. Vincent, J.-P. Walder, Guobin Wang
The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square-degree field sensitive in the visible and near-infrared wavelength regime. We describe the requirements for the instrument suite and the evolution of the focal plane design to the present concept in which all the instrumentation -- visible and near-infrared imagers, spectrograph, and star guiders -- share one common focal plane.
Greg Aldering, G. Adam, P. Antilogus, Pierre Astier, R. Bacon, S. Bongard, C. Bonnaud, Y. Copin, Delphine Hardin, Francois Henault, Dale Howell, Jean-Pierre Lemonnier, Jean-Michel Levy, Stewart Loken, Peter Nugent, Reynald Pain, A. Pecontal, E. Pecontal, Saul Perlmutter, Robert Quimby, K. Schahmaneche, G. Smadja, W. Michael Wood-Vasey
The Nearby Supernova Factory (Snfactory) is an international experiment designed to lay the foundation for the next generation of cosmology experiments (such as CFHTLS, wP, SNAP and LSST) which will measure the expansion history of the Universe using Type Ia supernovae. The Snfactory will discover and obtain frequent lightcurve spectrophotometry covering 3200-10000Å for roughly 300 Type Ia supernovae at the low-redshift end of the smooth Hubble flow. The quantity, quality, breadth of galactic environments, and homogeneous nature of the Snfactory dataset will make it the premier source of calibration for the Type Ia supernova width-brightness relation and the intrinsic supernova colors used for K-correction and correction for extinction by host-galaxy dust. This dataset will also allow an extensive investigation of additional parameters which possibly influence the quality of Type Ia supernovae as cosmological probes. The Snfactory search capabilities and follow-up instrumentation include wide-field CCD imagers on two 1.2-m telescopes (via collaboration with the Near Earth Asteroid Tracking team at JPL and the QUEST team at Yale), and a two-channel integral-field-unit optical spectrograph/imager being fabricated for the University of Hawaii 2.2-m telescope. In addition to ground-based follow-up, UV spectra for a subsample of these supernovae will be obtained with HST. The pipeline to obtain, transfer via wireless and standard internet, and automatically process the search images is in operation. Software and hardware development is now underway to enable the execution of follow-up spectroscopy of supernova candidates at the Hawaii 2.2-m telescope via automated remote control of the telescope and the IFU spectrograph/imager.
Alex Kim, Carl Akerlof, Greg Aldering, R. Amanullah, Pierre Astier, E. Barrelet, Christopher Bebek, Lars Bergstrom, J. Bercovitz, Gary Bernstein, M. Bester, A. Bonissent, C. Bower, William Carithers, Eugene Commins, C. Day, Susana Deustua, R. DiGennaro, A. Ealet, Richard Ellis, M. Eriksson, Andrew Fruchter, Jean-Francois Genat, Gerson Goldhaber, Ariel Goobar, Donald Groom, Stewart Harris, Peter Harvey, Henry Heetderks, Steven Holland, Dragan Huterer, Armin Karcher, William Kolbe, B. Krieger, Robin Lafever, J. Lamoureux, Michael Lampton, Michael Levi, Daniel Levin, Eric Linder, Stewart Loken, Roger Malina, R. Massey, Timothy McKay, Shawn McKee, Ramon Miquel, E. Mortsell, N. Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nicholas Palaio, David Pankow, Saul Perlmutter, R. Pratt, Eric Prieto, Alexandre Refregier, Jason Rhodes, Kem Robinson, N. Roe, Michael Sholl, Michael Schubnell, G. Smadja, George Smoot, Anthony Spadafora, Gregory Tarle, Andrew Tomasch, H. von der Lippe, D. Vincent, J.-P. Walder, Guobin Wang
The Supernova / Acceleration Probe (SNAP) is a proposed space-borne observatory that will survey the sky with a wide-field optical/near-infrared (NIR) imager. The images produced by SNAP will have an unprecedented combination of depth, solid-angle, angular resolution, and temporal sampling. For 16 months each, two 7.5 square-degree fields will be observed every four days to a magnitude depth of AB=27.7 in each of the SNAP filters, spanning 3500-17000Å. Co-adding images over all epochs will give AB=30.3 per filter. In addition, a 300 square-degree field will be surveyed to AB=28 per filter, with no repeated temporal sampling. Although the survey strategy is tailored for supernova and weak gravitational lensing observations, the resulting data will support a broad range of auxiliary science programs.
Michael Lampton, Carl Akerlof, Greg Aldering, R. Amanullah, Pierre Astier, E. Barrelet, Christopher Bebek, Lars Bergstrom, John Bercovitz, G. Bernstein, Manfred Bester, Alain Bonissent, C. Bower, William Carithers, Eugene Commins, C. Day, Susana Deustua, Richard DiGennaro, Anne Ealet, Richard Ellis, Mikael Eriksson, Andrew Fruchter, Jean-Francois Genat, Gerson Goldhaber, Ariel Goobar, Donald Groom, Stewart Harris, Peter Harvey, Henry Heetderks, Steven Holland, Dragan Huterer, Armin Karcher, Alex Kim, William Kolbe, B. Krieger, R. Lafever, J. Lamoureux, Michael Levi, Daniel Levin, Eric Linder, Stewart Loken, Roger Malina, R. Massey, Timothy McKay, Shawn McKee, Ramon Miquel, E. Mortsell, N. Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nicholas Palaio, David Pankow, Saul Perlmutter, R. Pratt, Eric Prieto, Alexandre Refregier, J. Rhodes, Kem Robinson, N. Roe, Michael Sholl, Michael Schubnell, G. Smadja, George Smoot, A. Spadafora, Gregory Tarle, Andrew Tomasch, H. von der Lippe, R. Vincent, J.-P. Walder, Guobin Wang
The SuperNova/Acceleration Probe (SNAP) mission will require a two-meter class telescope delivering diffraction limited images spanning a one degree field in the visible and near infrared wavelength regime. This requirement, equivalent to nearly one billion pixel resolution, places stringent demands on its optical system in terms of field flatness, image quality, and freedom from chromatic aberration. We discuss the advantages of annular-field three-mirror anastigmat (TMA) telescopes for applications such as SNAP, and describe the features of the specific optical configuration that we have baselined for the SNAP mission. We discuss the mechanical design and choice of materials for the telescope. Then we present detailed ray traces and diffraction calculations for our baseline optical design. We briefly discuss stray light and tolerance issues, and present a preliminary wavefront error budget for the SNAP Telescope. We conclude by describing some of tasks to be carried out during the upcoming SNAP research and development phase.
Greg Aldering, Carl Akerlof, R. Amanullah, Pierre Astier, E. Barrelet, Christopher Bebek, Lars Bergstrom, John Bercovitz, Gary Bernstein, Manfred Bester, Alain Bonissent, Charles Bower, William Carithers, Eugene Commins, C. Day, Susana Deustua, Richard DiGennaro, Anne Ealet, Richard Ellis, Mikael Eriksson, Andrew Fruchter, Jean-Francois Genat, Gerson Goldhaber, Ariel Goobar, Donald Groom, Stewart Harris, Peter Harvey, Henry Heetderks, Steven Holland, Dragan Huterer, Armin Karcher, Alex Kim, William Kolbe, B. Krieger, R. Lafever, James Lamoreux, Michael Lampton, Michael Levi, Daniel Levin, Eric Linder, Stewart Loken, Roger Malina, R. Massey, Timothy McKay, Shawn McKee, Ramon Miquel, E. Moertsell, N. Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nicholas Palaio, David Pankow, Saul Perlmutter, R. Pratt, Eric Prieto, Alexandre Refregier, J. Rhodes, Kem Robinson, N. Roe, Michael Sholl, Michael Schubnell, G. Smadja, George Smoot, Anthony Spadafora, Gregory Tarle, Andrew Tomasch, H. von der Lippe, D. Vincent, J.-P. Walder, Guobin Wang
The SuperNova / Acceleration Probe (SNAP) is a space-based experiment to measure the expansion history of the Universe and study both its dark energy and the dark matter. The experiment is motivated by the startling discovery that the expansion of the Universe is accelerating. A 0.7~square-degree imager comprised of 36 large format fully-depleted n-type CCD's sharing a focal plane with 36 HgCdTe detectors forms the heart of SNAP, allowing discovery and lightcurve measurements simultaneously for many supernovae. The imager and a high-efficiency low-resolution integral field spectrograph are coupled to a 2-m three mirror anastigmat wide-field telescope, which will be placed in a high-earth orbit. The SNAP mission can obtain high-signal-to-noise calibrated light-curves and spectra for over 2000 Type Ia supernovae at redshifts between z = 0.1 and 1.7. The resulting data set can not only determine the amount of dark energy with high precision, but test the nature of the dark energy by examining its equation of state. In particular, dark energy due to a cosmological constant can be differentiated from alternatives such as "quintessence", by measuring the dark energy's equation of state to an accuracy of ± 0.05, and by studying its time dependence.
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