Dr. Paul P. Plucinsky Profile

Dr. Paul P. Plucinsky

Sr Astrophysicist at Smithsonian Astrophysical Observatory

SPIE Involvement:

Author

Publications (33)

Proceedings Article | 6 July 2018

The complicated evolution of the ACIS contamination layer over the mission life of the Chandra X-ray Observatory

Paul Plucinsky, Akos Bogdan, Herman Marshall, Neil Tice

Proc. SPIE. 10699, Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray

KEYWORDS: Observatories, Optical filters, Contamination, Data modeling, Sensors, Calibration, X-rays, Charge-coupled devices, Space operations, Absorption

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The Chandra X-ray Observatory (CXO) was launched almost 19 years ago and has been delivering spectacular science over the course of its mission. The Advanced CCD Imager Spectrometer (ACIS) is the prime instrument on the satellite, conducting over 90% of the observations. The CCDs operate at a temperature of -120°C and the optical blocking filter (OBF) in front of the CCDs is at a temperature of approximately −60°C. The surface of the OBF has accumulated a layer of contamination over the course of the mission, as it is the coldest surface exposed to the interior to the spacecraft. We have been characterizing the thickness, chemical composition, and spatial distribution of the contamination layer as a function of time over the mission. All three have exhibited significant changes with time. There has been a dramatic decrease in the accumulation rate of the contaminant starting in 2017. The lower accumulation rate may be due to a decrease in the deposition rate or an increase in the vaporization rate or a combination of the two. We show that the current calibration file which models the additional absorption of the contamination layer is significantly overestimating that additional absorption by using the standard model spectrum for the supernova remnant 1E 0102.2-7219 developed by the International Astronomical Consortium for High Energy Calibration (IACHEC). In addition, spectral data from the cluster of galaxies known as Abell 1795 and the Blazar Markarian 421 are used to generate a model of the absorption produced by the contamination layer. The Chandra X-ray Center (CXC) calibration team is preparing a revised calibration file that more accurately represents the complex time dependence of the accumulation rate, the spatial dependence, and the chemical composition of the contaminant. Given the rapid changes in the contamination layer over the past year, future calibration observations at a higher cadence will be necessary to more accurately monitor such changes.

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Proceedings Article | 6 July 2018

Concept of the X-ray Astronomy Recovery Mission

Makoto Tashiro, Hironori Maejima, Kenichi Toda, Richard Kelley, Lillian Reichenthal, James Lobell, Robert Petre, Matteo Guainazzi, Elisa Costantini, Mark Edison, Ryuichi Fujimoto, Martin Grim, Kiyoshi Hayashida, Jan-Willem den Herder, Yoshitaka Ishisaki, Stéphane Paltani, Kyoko Matsushita, Koji Mori, Gary Sneiderman, Yoh Takei, Yukikatsu Terada, Hiroshi Tomida, Hiroki Akamatsu, Lorella Angelini, Yoshitaka Arai, Hisamitsu Awaki, Lurli Babyk, Aya Bamba, Peter Barfknecht, Kim Barnstable, Thomas Bialas, Branimir Blagojevic, Joseph Bonafede, Clifford Brambora, Laura Brenneman, Greg Brown, Kimberly Brown, Laura Burns, Edgar Canavan, Tim Carnahan, Meng Chiao, Brian Comber, Lia Corrales, Cor de Vries, Johannes Dercksen, Maria Diaz-Trigo, Tyrone Dillard, Michael DiPirro, Chris Done, Tadayasu Dotani, Ken Ebisawa, Megan Eckart, Teruaki Enoto, Yuichiro Ezoe, Carlo Ferrigno, Yasushi Fukazawa, Yutaka Fujita, Akihiro Furuzawa, Luigi Gallo, Steve Graham, Liyi Gu, Kohichi Hagino, Kenji Hamaguchi, Isamu Hatsukade, Dean Hawes, Takayuki Hayashi, Cailey Hegarty, Natalie Hell, Junko Hiraga, Edmund Hodges-Kluck, Matt Holland, Ann Hornschemeier, Akio Hoshino, Yuto Ichinohe, Ryo Iizuka, Kazunori Ishibashi, Manabu Ishida, Kumi Ishikawa, Kosei Ishimura, Bryan James, Timothy Kallman, Erin Kara, Satoru Katsuda, Steven Kenyon, Caroline Kilbourne, Mark Kimball, Takao Kitaguti, Shunji Kitamoto, Shogo Kobayashi, Takayoshi Kohmura, Shu Koyama, Aya Kubota, Maurice Leutenegger, Tom Lockard, Mike Loewenstein, Yoshitomo Maeda, Lynette Marbley, Maxim Markevitch, Hironori Matsumoto, Keiichi Matsuzaki, Dan McCammon, Brian McNamara, Joseph Miko, Eric Miller, Jon Miller, Kenji Minesugi, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Hideyuki Mori, Koji Mukai, Hiroshi Murakami, Richard Mushotzky, Hiroshi Nakajima, Hideto Nakamura, Shinya Nakashima, Kazuhiro Nakazawa, Chikara Natsukari, Kenichiro Nigo, Yusuke Nishioka, Kumiko Nobukawa, Masayoshi Nobukawa, Hirofumi Noda, Hirokazu Odaka, Mina Ogawa, Takaya Ohashi, Masahiro Ohno, Masayuki Ohta, Takashi Okajima, Atsushi Okamoto, Michitaka Onizuka, Naomi Ota, Masanobu Ozaki, Paul Plucinsky, F. Scott Porter, Katja Pottschmidt, Kosuke Sato, Rie Sato, Makoto Sawada, Hiromi Seta, Ken Shelton, Yasuko Shibano, Maki Shida, Megumi Shidatsu, Peter Shirron, Aurora Simionescu, Randall Smith, Kazunori Someya, Yang Soong, Yasuharu Suagawara, Andy Szymkowiak, Hiromitsu Takahashi, Toru Tamagawa, Takayuki Tamura, Takaaki Tanaka, Yuichi Terashima, Yohko Tsuboi, Masahiro Tsujimoto, Hiroshi Tsunemi, Takeshi Tsuru, Hiroyuki Uchida, Hideki Uchiyama, Yoshihiro Ueda, Shinichiro Uno, Thomas Walsh, Shin Watanabe, Brian Williams, Rob Wolfs, Michael Wright, Shinya Yamada, Hiroya Yamaguchi, Kazutaka Yamaoka, Noriko Yamasaki, Shigeo Yamauchi, Makoto Yamauchi, Keiichi Yanagase, Tahir Yaqoob, Susumu Yasuda, Nasa Yoshioka, Jaime Zabala, Zhuravleva Irina

Proc. SPIE. 10699, Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray

KEYWORDS: Iron, Stars, Spectroscopy, X-rays, Physics, Chemical elements, Galactic astronomy, X-ray astronomy, Galaxy groups and clusters, Plasma

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The ASTRO-H mission was designed and developed through an international collaboration of JAXA, NASA, ESA, and the CSA. It was successfully launched on February 17, 2016, and then named Hitomi. During the in-orbit verification phase, the on-board observational instruments functioned as expected. The intricate coolant and refrigeration systems for soft X-ray spectrometer (SXS, a quantum micro-calorimeter) and soft X-ray imager (SXI, an X-ray CCD) also functioned as expected. However, on March 26, 2016, operations were prematurely terminated by a series of abnormal events and mishaps triggered by the attitude control system. These errors led to a fatal event: the loss of the solar panels on the Hitomi mission. The X-ray Astronomy Recovery Mission (or, XARM) is proposed to regain the key scientific advances anticipated by the international collaboration behind Hitomi. XARM will recover this science in the shortest time possible by focusing on one of the main science goals of Hitomi,“Resolving astrophysical problems by precise high-resolution X-ray spectroscopy”.1 This decision was reached after evaluating the performance of the instruments aboard Hitomi and the mission’s initial scientific results, and considering the landscape of planned international X-ray astrophysics missions in 2020’s and 2030’s. Hitomi opened the door to high-resolution spectroscopy in the X-ray universe. It revealed a number of discrepancies between new observational results and prior theoretical predictions. Yet, the resolution pioneered by Hitomi is also the key to answering these and other fundamental questions. The high spectral resolution realized by XARM will not offer mere refinements; rather, it will enable qualitative leaps in astrophysics and plasma physics. XARM has therefore been given a broad scientific charge: “Revealing material circulation and energy transfer in cosmic plasmas and elucidating evolution of cosmic structures and objects”. To fulfill this charge, four categories of science objectives that were defined for Hitomi will also be pursued by XARM; these include (1) Structure formation of the Universe and evolution of clusters of galaxies; (2) Circulation history of baryonic matters in the Universe; (3) Transport and circulation of energy in the Universe; (4) New science with unprecedented high resolution X-ray spectroscopy. In order to achieve these scientific objectives, XARM will carry a 6 × 6 pixelized X-ray micro-calorimeter on the focal plane of an X-ray mirror assembly, and an aligned X-ray CCD camera covering the same energy band and a wider field of view. This paper introduces the science objectives, mission concept, and observing plan of XARM.

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Proceedings Article | 29 August 2017

Modeling contamination migration on the Chandra X-ray Observatory IV

Stephen O'Dell, Douglas Swartz, Neil Tice, Paul Plucinsky, Herman Marshall, Akos Bogdan, Catherine Grant, Allyn Tennant, Matthew Dahmer

Proc. SPIE. 10397, UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XX

KEYWORDS: Observatories, Contamination, X-rays, Imaging spectroscopy, Charge-coupled devices, Modeling and simulation, Geometrical optics, Space operations, X-ray imaging, X-ray astronomy

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Proceedings Article | 18 July 2016

Evolution of temperature-dependent charge transfer inefficiency correction for ACIS on the Chandra X-ray Observatory

Catherine Grant, Marshall Bautz, R. Nick Durham, Paul Plucinsky

Proc. SPIE. 9905, Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray

KEYWORDS: Optical filters, Metrology, Imaging systems, Sensors, Calibration, X-rays, X-rays, Extreme ultraviolet, Radiometry, Synchrotron radiation, Vacuum ultraviolet

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Proceedings Article | 18 July 2016

The evolution of the ACIS contamination layer over the 16-year mission of the Chandra X-ray Observatory

Paul Plucinsky, Akos Bogdan, Gregg Germain, Herman Marshall

Proc. SPIE. 9905, Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray

KEYWORDS: Observatories, Observatories, Mirrors, Contamination, Data modeling, Calibration, X-rays, X-rays, Charge-coupled devices, Neon, Space operations, Absorption

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Proceedings Article | 18 September 2015

Modeling contamination migration on the Chandra X-ray Observatory: III

Stephen O'Dell, Douglas Swartz, Neil Tice, Paul Plucinsky, Catherine Grant, Herman Marshall, Alexey Vikhlinin, Allyn Tennant, Matthew Dahmer

Proc. SPIE. 9601, UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XIX

KEYWORDS: Observatories, Telescopes, Optical filters, Contamination, Cameras, Spectroscopy, X-rays, Collimators, Charge-coupled devices, Thermal modeling

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Proceedings Article | 24 July 2014

Lessons we learned designing and building the Chandra telescope

Jonathan Arenberg, Gary Matthews, C. Atkinson, L. Cohen, C. Golisano, K. Havey, K. Hefner, C. Jones, J. Kegley, P. Knollenberg, T. Lavoie, J. Oliver, P. Plucinsky, H. Tananbaum, S. Texter, M. Weisskopf

Proc. SPIE. 9144, Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray

KEYWORDS: Observatories, Telescopes, Mirrors, Sensors, Calibration, X-rays, Interfaces, Space telescopes, Optical alignment, Optical instrument design

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Proceedings Article | 24 July 2014

Fifteen years of the Advanced CCD Imaging Spectrometer

Catherine Grant, Mark Bautz, Peter Ford, P. Plucinsky

Proc. SPIE. 9144, Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray

KEYWORDS: Observatories, Energy efficiency, Contamination, Calibration, Spectroscopy, Particles, X-rays, Bismuth, Charge-coupled devices, Space operations

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Proceedings Article | 27 September 2013

Modeling contamination migration on the Chandra X-ray Observatory II

Stephen O'Dell, Douglas Swartz, Neil Tice, Paul Plucinsky, Catherine Grant, Herman Marshall, Alexey Vikhlinin, Allyn Tennant

Proc. SPIE. 8859, UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XVIII

KEYWORDS: Observatories, Optical filters, Contamination, Cameras, Sensors, Spectroscopy, X-rays, Charge-coupled devices, Thermal modeling, Absorption

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Proceedings Article | 17 September 2012

The NASA X-ray Mission concepts study

R. Petre, J. Bregman, M. Bautz, D. Burrows, W. Cash, C. Jones-Forman, S. Murray, P. Plucinsky, B. Ramsey, R. Remillard, C. Wilson-Hodge, A. Ptak, J. Bookbinder, M. Garcia, R. Smith, G. Daelemans

Proc. SPIE. 8443, Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray

KEYWORDS: Observatories, Mirrors, Sensors, Spectroscopy, X-rays, Spectral resolution, Spatial resolution, Space operations, Electromagnetic coupling, X-ray astronomy

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Proceedings Article | 17 September 2012

Cross-calibration of the x-ray instruments onboard the Chandra, Suzaku, Swift, and XMM-Newton Observatories using the SNR 1E 0102.2-7219

Paul Plucinsky, Andrew Beardmore, Joseph DePasquale, Daniel Dewey, Adam Foster, Frank Haberl, Eric Miller, A. M. Pollock, Jennifer L. Posson-Brown, Steve Sembay, Randall Smith

Proc. SPIE. 8443, Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray

KEYWORDS: Signal to noise ratio, Roentgenium, Data modeling, Sensors, Calibration, X-rays, Charge-coupled devices, Neon, Molybdenum, Absorption

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Proceedings Article | 15 July 2008

The SMC SNR 1E0102.2-7219 as a calibration standard for x-ray astronomy in the 0.3-2.5 keV bandpass

Paul Plucinsky, Frank Haberl, Daniel Dewey, Andrew Beardmore, Joseph DePasquale, Olivier Godet, Victoria Grinberg, Eric Miller, A. Pollock, Steven Sembay, Randall Smith

Proc. SPIE. 7011, Space Telescopes and Instrumentation 2008: Ultraviolet to Gamma Ray

KEYWORDS: Signal to noise ratio, Magnesium, Iron, Roentgenium, Data modeling, Calibration, X-rays, Charge-coupled devices, Neon, Molybdenum

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The flight calibration of the spectral response of CCD instruments below 1.5 keV is difficult in general because of the lack of strong lines in the on-board calibration sources typically available. We have been using E0102, the brightest supernova remnant in the Small Magellanic Cloud, to evaluate the response models of the ACIS CCDs on the Chandra X-ray Observatory (CXO), the EPIC CCDs on the XMM-Newton Observatory, the XIS CCDs on the Suzaku Observatory, and the XRT CCD on the Swift Observatory. E0102 has strong lines of O, Ne, and Mg below 1.5 keV and little or no Fe emission to complicate the spectrum. The spectrum of E0102 has been well characterized using high-resolution grating instruments, namely the XMM-Newton RGS and the CXO HETG, through which a consistent spectral model has been developed that can then be used to fit the lower-resolution CCD spectra. Fits with this model are sensitive to any problems with the gain calibration and the spectral redistribution model of the CCD instruments. We have also used the measured intensities of the lines to investigate the consistency of the effective area models for the various instruments around the bright O (570 eV and 654 eV) and Ne (910 eV and 1022 eV) lines. We find that the measured fluxes of the O VII triplet, the O VIII Ly-a line, the Ne IX triplet, and the Ne X Ly-a line generally agree to within ±10% for all instruments, with 28 of our 32 fitted normalizations within ±10% of the RGS-determined value. The maximum discrepancies, computed as the percentage difference between the lowest and highest normalization for any instrument pair, are 23% for the O VII triplet, 24% for the O VIII Ly-a line, 13% for the Ne IX~triplet, and 19% for the Ne X Ly-a line. If only the CXO and XMM are compared, the maximum discrepancies are 22% for the O VII triplet, 16% for the O VIII Ly-a line, 4% for the Ne IX triplet, and 12% for the Ne X Ly-a line.

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Proceedings Article | 12 July 2008

Changing software philosophy for ACIS operations as Chandra ages

Nancy Adams-Wolk, Paul Plucinsky, Joseph DePasquale

Proc. SPIE. 7016, Observatory Operations: Strategies, Processes, and Systems II

KEYWORDS: Telescopes, Safety, Databases, Photons, X-rays, X-ray sources, Space telescopes, Solids, Charge-coupled devices, Space operations

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Proceedings Article | 18 September 2007

Managing radiation degradation of CCDs on the Chandra X-ray Observatory III

Stephen O'Dell, Thomas Aldcroft, William Blackwell, Sabina Bucher, Jon Chappell, Joseph DePasquale, Catherine Grant, Michael Juda, Eric Martin, Joseph Minow, Stephen Murray, Paul Plucinsky, Daniel Schwartz, Daniel Shropshire, Bradley Spitzbart, Paul Viens, Scott Wolk

Proc. SPIE. 6686, UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XV

KEYWORDS: Observatories, Solar radiation models, Sensors, X-rays, Bismuth, Charge-coupled devices, Back illuminated sensors, Space operations, Solar radiation, Solar processes

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Proceedings Article | 30 June 2006

An historical fluence analysis of the radiation environment of the Chandra X-ray Observatory and implications for continued radiation monitoring

J. DePasquale, P. Plucinsky, D. Schwartz

Proc. SPIE. 6270, Observatory Operations: Strategies, Processes, and Systems

KEYWORDS: Observatories, Environmental monitoring, Sensors, Databases, X-rays, Silicon, Charge-coupled devices, Helium, Space operations, Solar radiation

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Proceedings Article | 30 June 2006

The operational response to temporal changes in the gain of the ACIS instrument on the Chandra X-ray Observatory

Nancy Adams-Wolk, Royce Buehler, Paul Plucinksy

Proc. SPIE. 6270, Observatory Operations: Strategies, Processes, and Systems

KEYWORDS: Observatories, Calibration, Spectroscopy, X-rays, CCD cameras, Bismuth, Charge-coupled devices, X-ray imaging, Astrophysics, Data analysis

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Proceedings Article | 15 June 2006

Verifying the low-energy spectral response models of the CXO ACIS and the XMM-Newton EPIC CCDs

Paul Plucinsky, Joseph DePasquale, Steven Snowden

Proc. SPIE. 6266, Space Telescopes and Instrumentation II: Ultraviolet to Gamma Ray

KEYWORDS: Signal to noise ratio, Observatories, Data modeling, Sensors, Calibration, X-rays, Spectral calibration, Charge-coupled devices, Neon, Spectral models

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Proceedings Article | 31 August 2005

Modeling contamination migration on the Chandra X-ray Observatory

Stephen O'Dell, Douglas Swartz, Paul Plucinsky, Mark Freeman, Maxim Markevitch, Alexey Vikhlinin, Kenny Chen, Rino Giordano, Perry Knollenberg, Peter Morris, Hien Tran, Neil Tice, Scot Anderson

Proc. SPIE. 5898, UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XIV

KEYWORDS: Observatories, Contamination, Cameras, X-rays, Solids, Optical resonators, Thermal analysis, Space operations, Thermal modeling, Liquids

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Proceedings Article | 18 August 2005

Crab: the standard x-ray candle with all (modern) x-ray satellites

M. Kirsch, U. Briel, D. Burrows, S. Campana, G. Cusumano, K. Ebisawa, M. Freyberg, M. Guainazzi, F. Haberl, K. Jahoda, J. Kaastra, P. Kretschmar, S. Larsson, P. Lubinski, K. Mori, P. Plucinsky, A. Pollock, R. Rothschild, S. Sembay, J. Wilms, M. Yamamoto

Proc. SPIE. 5898, UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XIV

KEYWORDS: Roentgenium, Data modeling, Cameras, Sensors, Calibration, Satellites, X-rays, Charge-coupled devices, X-ray telescopes, Absorption

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Proceedings Article | 18 August 2005

Managing radiation degradation of CCDs on the Chandra X-ray Observatory II

Stephen O'Dell, Thomas Aldcroft, Bradley Bissell, William Blackwell, Robert Cameron, Jon Chappell, Joseph DePasquale, Kenneth Gage, Catherine Grant, Christine Harbison, Michael Juda, Kevin Marsh, Eric Martin, Joseph Minow, Stephen Murray, Paul Plucinsky, Daniel Schwartz, Daniel Shropshire, Bradley Spitzbart, Shanil Virani, Brent Williams, Scott Wolk

Proc. SPIE. 5898, UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XIV

KEYWORDS: Observatories, Solar radiation models, Sensors, X-rays, Bismuth, Charge-coupled devices, Space operations, Solar radiation, Magnetosphere, Solar processes

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Proceedings Article | 11 October 2004

An evaluation of a bake-out of the ACIS instrument on the Chandra X-Ray Observatory

Paul Plucinsky, Stephen O'Dell, Neil Tice, Douglas Swartz, Marshall Bautz, Joseph DePasquale, Richard Edgar, Gordon Garmire, Rino Giordano, Catherine Grant, Perry Knollenberg, Steve Kissel, Beverly LaMarr, Richard Logan, Martin Mach, Herman Marshall, Leon McKendrick, Gregory Prigozhin, Dan Schwartz, Norbert Schulz, Dan Shropshire, Tan Trinh, Alexey Vikhlinin, Shanil Virani

Proc. SPIE. 5488, UV and Gamma-Ray Space Telescope Systems

KEYWORDS: Observatories, Contamination, Aerospace engineering, Sensors, X-rays, Collimators, Charge-coupled devices, Space operations, Thermal modeling, Absorption

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Proceedings Article | 29 September 2004

Verifying the ACIS contamination model with 1E0102.2-7219

Joseph DePasquale, Paul Plucinsky, Alexey Vikhlinin, Herman Marshall, Norbert Schulz, Richard Edgar

Proc. SPIE. 5501, High-Energy Detectors in Astronomy

KEYWORDS: Observatories, Contamination, Data modeling, Calibration, X-rays, Imaging spectroscopy, Bismuth, Charge-coupled devices, Spectral models, Absorption

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Proceedings Article | 3 February 2004

Composition of the Chandra ACIS contaminant

Herman Marshall, Allyn Tennant, Catherine Grant, Adam Hitchcock, Stephen O'Dell, Paul Plucinsky

Proc. SPIE. 5165, X-Ray and Gamma-Ray Instrumentation for Astronomy XIII

KEYWORDS: Carbon, Contamination, Data modeling, Opacity, Calibration, Spectroscopy, X-rays, Quantum efficiency, Fluorine, Absorption

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Proceedings Article | 3 February 2004

Improving the science observing efficiency of the Chandra X-ray Observatory via the Chandra radiation model

Shanil Virani, Joseph DePasquale, Daniel Schwartz, Robert Cameron, Paul Plucinsky, Stephen O'Dell, Joseph Minow, William Blackwell

Proc. SPIE. 5165, X-Ray and Gamma-Ray Instrumentation for Astronomy XIII

KEYWORDS: Observatories, Data modeling, Databases, Satellites, X-rays, Magnetism, Charge-coupled devices, Magnetosphere, Solar processes, Instrument modeling

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The Chandra X-ray Observatory (CXO), NASA's latest "Great Observatory", was launched on July 23, 1999 and reached its final orbit on August 7, 1999. The CXO is in a highly elliptical orbit, with an apogee altitude of 120,000 km and a perigee altitude 20,000 km, and has a period of approximately 63.5 hours (≈ 2.65 days). It transits the Earth's Van Allen belts once per orbit during which no science observations can be performed due to the high radiation environment. The Chandra X-ray Observatory Center currently uses the National Space Science Data Center's "near Earth" AP-8/AE-8 radiation belt model to predict the start and end times of passage through the radiation belts. Our earlier analysis (Virani et al, 2000) demonstrated that our implementation of the AP-8/AE-8 model (a simple dipole model of the Earth's magnetic field) does not always give sufficiently accurate predictions of the start and end times of transit of the Van Allen belts. This led to a change in our operating procedure whereby we "padded" the start and end times of transit as determined by the AE-8 model by 10 ks so that ACIS, the Advanced CCD Imaging Spectrometer and the primary science instrument on-board Chandra, would not be exposed to the "fringes" of the Van Allen belts on ingress and egress for any given transit. This additional 20 ks per orbit during which Chandra is unable to perform science observations integrates to approximately 3 Ms of "lost" science time per year and therefore reduces the science observing efficiency of the Observatory. To address the need for a higher fidelity radiation model appropriate for the Chandra orbit, the Chandra Radiation Model (CRM) was developed. The CRM is an ion model for the outer magnetosphere and is based on data from the EPIC/ICS instrument on-board the Geotail satellite as well as data from the CEPPAD/IPS instrument on-board the Polar satellite. With the production and implementation of the CRM Version 2.3, we present the results of a study designed to investigate the science observing time that may be recovered by using the CRM for science mission planning purposes. In this paper, we present a scheme using the CRM such that for a modest increase in ACIS CTI, approximately 500 ks can be recovered each year for new science observations.

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Proceedings Article | 3 February 2004

A study of the seasonal variations of the Chandra X-ray Observatory radiation model

Joseph DePasquale, Shanil Virani, Daniel Schwartz, Robert Cameron, Paul Plucinsky, Stephen O'Dell, Joseph Minow, William Blackwell

Proc. SPIE. 5165, X-Ray and Gamma-Ray Instrumentation for Astronomy XIII

KEYWORDS: Observatories, Telescopes, Data modeling, Databases, X-rays, Spectrometers, Space telescopes, Charge-coupled devices, Magnetosphere, Solar processes

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The Chandra X-ray Observatory (CXO), launched in July of 1999, contains two focal-plane imaging detectors and two transmission-grating spectrometers. Maintaining an optimal performance level for the observatory is the job of the Chandra X-ray Center (CXC), located in Cambridge, MA. One very important aspect of the observatory's performance is the science observing efficiency. The single largest factor which reduces the observing efficiency of the observatory is the interruption of observations due to passage through the Earth's radiation belts approximately every 2 2/3 days. During radiation belt passages, observations are suspended on average for over 15 hours and the Advanced CCD Imaging Spectrometer (ACIS) is moved out of the focus of the telescope to minimize damage from low-energy (100-200 keV) protons. The CXC has been using the National Space Science Data Center's "near Earth" AE-8/AP-8 radiation belt model to predict the entry and exit from the radiation belts. However, it was discovered early in the mission that the AE-8/AP-8 model predictions were inadequate for science scheduling purposes and a 10ks "pad time" was introduced on ingress and egress of perigee to ensure protection from radiation damage. This pad time, totaling 20 ks per orbit, has recently been the subject of much analysis to determine if it can be reduced to maximize science observing efficiency. A recent analysis evaluating a possible correlation between the Chandra Radiation Model (CRM) and the Electron Proton Helium Instrument (EPHIN) found a greatest lower bound (GLB) in lieu of a correlation for the ingress and egress of each perigee. The GLB is a limit imposed on the CRM such that when the CRM exceeds this limit on ingress, this defines the new safing time and similarly for egress. We have shown that using this method we can regain a significant amount of lost science time at the expense of minimal radiation exposure. The GLB analysis also found that different GLB's produce varied results and hint that there could be a time dependence associated with the GLB, possibly related to the orientation of the Observatory's orbit. Utilizing CRM V2.3, we present the search for a seasonal dependence on the value of the GLB; we find a seasonal effect that appears to depend on the orientation of Chandra's orbit with respect to the Earth's magnetic field.

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Proceedings Article | 11 March 2003

Flight spectral response of the ACIS instrument

Paul Plucinsky, Norbert Schulz, Herman Marshall, Catherine Grant, George Chartas, Divas Sanwal, Marcus Teter, Alexey Vikhlinin, Richard Edgar, Michael Wise, Glenn Allen, Shanil Virani, Joseph DePasquale, Michael Raley

Proc. SPIE. 4851, X-Ray and Gamma-Ray Telescopes and Instruments for Astronomy

KEYWORDS: Contamination, Data modeling, Sensors, Calibration, X-rays, Spectral resolution, Bismuth, Charge-coupled devices, Manganese, Absorption

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We discuss the flight calibration of the spectral response of the Advanced CCD Imaging Spectrometer (ACIS) on-board the Chandra X-ray Observatory (CXO). The spectral resolution and sensitivity of the ACIS instrument have both been evolving over the course of the mission. The spectral resolution of the frontside-illuminated (FI) CCDs changed dramatically in the first month of the mission due to radiation damage. Since that time, the spectral resolution of the FI CCDs and the Backside-illuminated (BI) CCDs have evolved gradually with time. We demonstrate the efficacy of charge-transfer inefficiency (CTI) correction algorithms which recover some of the lost performance. The detection efficiency of the ACIS instrument has been declining throughout the mission, presumably due to a layer of contamination building up on the filter and/or CCDs. We present a characterization of the energy dependence of the excess absorption and demonstrate software which models the time dependence of the absorption from energies of 0.4 keV and up. The spectral redistribution function and the detection efficiency are well-characterized at energies from 1.5 to 8.0~keV primarily due to the existence of strong lines in the ACIS calibration source in that energy range. The calibration at energies below 1.5 keV is challenging because of the lack of strong lines in the calibration source and also because of the inherent non-linear dependence with energy of the CTI and the absorption by the contamination layer. We have been using data from celestial sources with relatively simple spectra to determine the quality of the calibration below 1.5 keV. We have used observations of 1E0102.2-7219 (the brightest supernova remnant in the SMC), PKS2155-304 (a bright blazar), and the pulsar PSR~0656+14 (nearby pulsar with a soft spectrum), since the spectra of these objects have been well-characterized by the gratings on the CXO. The analysis of these observations demonstrate that the CTI correction recovers a significant fraction of the spectral resolution of the FI CCDs and the models of the time-dependent absorption result in consistent measurements of the flux at low energies for data from a BI (S3) CCD.

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Proceedings Article | 2 January 2002

Optimizing the efficiency of command load inspection for the Advanced CCD Imaging Spectrometer (ACIS) on the Chandra X-ray Telescope

Joseph DePasquale, Shanil Virani, Paul Plucinsky

Proc. SPIE. 4844, Observatory Operations to Optimize Scientific Return III

KEYWORDS: Observatories, Safety, Sensors, Spectroscopy, X-rays, Inspection, Charge-coupled devices, Space operations, X-ray telescopes, Lawrencium

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Proceedings Article | 2 January 2002

Monitoring the health and safety of the ACIS instrument on board the Chandra X-ray Observatory

Shanil Virani, Peter Ford, Joseph DePasquale, Paul Plucinsky

Proc. SPIE. 4844, Observatory Operations to Optimize Scientific Return III

KEYWORDS: Actuators, Observatories, Safety, Sensors, Spectroscopy, X-rays, Charge-coupled devices, Analog electronics, Space operations, Data communications

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Proceedings Article | 6 March 2001

ACIS door failure investigation: technical details and mitigation procedures

Mark Kahan, Neil Tice, William Podgorski, Paul Plucinsky, Keith Doyle

Proc. SPIE. 4198, Optomechanical Engineering 2000

KEYWORDS: Actuators, Observatories, Switches, Contamination, Sensors, Calibration, X-rays, Inspection, Failure analysis, Temperature metrology

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Proceedings Article | 18 July 2000

Chandra X-ray Observatory's radiation environment and the AP-8/AE-8 model

Shanil Virani, Reinhold Mueller-Mellin, Paul Plucinsky, Yousaf Butt

Proc. SPIE. 4012, X-Ray Optics, Instruments, and Missions III

KEYWORDS: Observatories, Solar energy, Data modeling, Sensors, Particles, X-rays, Magnetism, Wind energy, Charge-coupled devices, Magnetosphere

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Proceedings Article | 18 July 2000

Observed on-orbit background of the ACIS instrument on the Chandra X-ray Observatory

Paul Plucinsky, Shanil Virani

Proc. SPIE. 4012, X-Ray Optics, Instruments, and Missions III

KEYWORDS: Observatories, Sensors, Spectroscopy, Particles, X-rays, Fourier transforms, Image enhancement, Bismuth, Charge-coupled devices, Information operations

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Proceedings Article | 18 July 2000

Absolute effective area of the Chandra high-resolution mirror assembly (HRMA)

Daniel Schwartz, Laurence David, R. Donnelly, Richard Edgar, Terrance Gaetz, Dale Graessle, Diab Jerius, Michael Juda, Edwin Kellogg, Brian McNamara, Paul Plucinsky, Leon Van Speybroeck, Bradford Wargelin, S. Wolk, Ping Zhao, Daniel Dewey, Herman Marshall, Norbert Schulz, Ronald Elsner, Jeffery Kolodziejczak, Stephen O'Dell, Douglas Swartz, Allyn Tennant, Martin Weisskopf

Proc. SPIE. 4012, X-Ray Optics, Instruments, and Missions III

KEYWORDS: Observatories, Mirrors, Sensors, Calibration, Photons, X-rays, Reflectivity, Optical testing, Synchrotrons, X-ray imaging

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Proceedings Article | 19 November 1998

Analysis of the AXAF HRMA+ACIS effective area measurements from the XRCF

Christopher Allen, Paul Plucinsky, Brian McNamara, Richard Edgar, Norbert Schulz, Jonathan Woo

Proc. SPIE. 3444, X-Ray Optics, Instruments, and Missions

KEYWORDS: Data modeling, Sensors, Calibration, X-rays, X-ray sources, Quantum efficiency, Bismuth, Charge-coupled devices, Data conversion, X-ray detectors

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Showing 5 of 33 publications

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