-
C. Mueller,
N. Akhter,
J. Ball,
D. A. Bramel,
J. Carson,
C. E. Covault,
D. Driscoll,
P. Fortin,
D M Gingrich,
D.S. Hanna,
A. Jarvis,
J. Kildea,
T. Lindner,
R Mukherjee,
R. A. Ong,
K. Ragan,
R. A. Scalzo,
D A Williams,
J. Zweerink
[show abstract]
[hide abstract]
ABSTRACT: We present results of very-high-energy gamma-ray observations (E > 160 GeV)
of two high-frequency-peaked BL Lac (HBL) objects, 1ES 1218+304 and H 1426+428,
with the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE). Both
sources are very-high-energy gamma-ray emitters above 100 GeV, detected using
ground-based Cherenkov telescopes. STACEE observations of 1ES 1218+304 and H
1426+428 did not produce detections; we present 99% CL flux upper limits for
both sources, assuming spectral indices measured mostly at higher energies.
04/2011;
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A. Jarvis,
R. A. Ong,
D. A. Williams,
T. Aune,
J. Ball,
J. E. Carson,
C. E. Covault,
D. D. Driscoll,
P. Fortin,
D. M. Gingrich,
D. S. Hanna,
J. Kildea,
T. Lindner,
R. Mukherjee, C. Mueller,
K. Ragan,
and J. Zweerink
[show abstract]
[hide abstract]
ABSTRACT: Gamma-ray bursts (GRBs) are the most powerful explosions known in the universe. Sensitive measurements of the high-energy spectra of GRBs can place important constraints on the burst environments and radiation processes. Until recently, there were no observations during the first few minutes of GRB afterglows in the energy range between 30 GeV and ~1 TeV. With the launch of the Swift GRB Explorer in late 2004, GRB alerts and localizations within seconds of the bursts became available. The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) was a ground-based, gamma-ray telescope with an energy threshold of ~150 GeV for sources at zenith. At the time of Swift's launch, STACEE was in a rare position to provide >150 GeV follow-up observations of GRBs as fast as three minutes after the burst alert. In addition, STACEE performed follow-up observations of several GRBs that were localized by the HETE-2 and INTEGRAL satellites. Between 2002 June and 2007 July, STACEE made follow-up observations of 23 GRBs. Upper limits are placed on the high-energy gamma-ray fluxes from 21 of these bursts.
The Astrophysical Journal 09/2010; 722(1):862. · 6.02 Impact Factor
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D S Hanna,
J Ball,
C E Covault,
J E Carson,
D D Driscoll,
P Fortin,
D M Gingrich,
A Jarvis,
J Kildea,
T Lindner, C Mueller,
R Mukherjee,
R A Ong,
K Ragan,
D A Williams,
J Zweerink
[show abstract]
[hide abstract]
ABSTRACT: We have used the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) high-energy gamma-ray detector to look for fast blue-green laser pulses from the vicinity of 187 stars. The STACEE detector offers unprecedented light-collecting capability for the detection of nanosecond pulses from such lasers. We estimate STACEE's sensitivity to be approximately 10 photons/m(2) at a wavelength of 420 nm. The stars have been chosen because their characteristics are such that they may harbor habitable planets, and they are relatively close to Earth. Each star was observed for 10 minutes, and we found no evidence for laser pulses in any of the data sets. Key Words: Search for extraterrestrial intelligence-Optical search for extraterrestrial intelligence-Interstellar communication-Laser.
Astrobiology 06/2009; 9(4):345-57. · 2.15 Impact Factor
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J. Zweerink,
J. Kildea,
J. Ball,
J. E. Carson,
C. E. Covault,
D. D. Driscoll,
P. Fortin,
D. M. Gingrich,
D. S. Hanna,
A. Jarvis,
T. Lindner, C. Mueller,
R. Mukherjee,
R. A. Ong,
K. Ragan,
and D. A. Williams
[show abstract]
[hide abstract]
ABSTRACT: The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is a ground-based telescope that uses the wave-front-sampling technique to detect very high energy (VHE) gamma rays. STACEE's sensitivity in the energy range near 100 GeV permits useful observations of pulsars with the potential to discriminate between various proposed mechanisms for pulsed gamma-ray emission. Based on the 11.3 hr of data taken during the 2005 and 2006 observing seasons, we derive an upper limit on the pulsed gamma-ray emission from PSR B1951+32 of <6.53 × 10–11 photons cm–2 s–1 above an energy threshold of 117 GeV.
The Astrophysical Journal 03/2009; 693(2):1128. · 6.02 Impact Factor
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L. M. Boone,
J. A. Hinton,
D. Bramel,
E. Chae,
C. E. Covault,
P. Fortin,
D. M. Gingrich,
D. S. Hanna,
R. Mukherjee, C. Mueller,
R. A. Ong,
K. Ragan,
R. A. Scalzo,
D. R. Schuette,
C. G. Théoret,
and D. A. Williams
[show abstract]
[hide abstract]
ABSTRACT: The active galaxy Markarian 421 underwent a substantial outburst in early 2001. Between January and May of that year, the STACEE detector was used to observe the source in γ-rays between the energies of 50 and 500 GeV. These observations represent the lowest energy γ-ray detection of this outburst by a ground-based experiment. Here we present results from these observations, which indicate an average integral γ-ray flux of (8.0 ± 0.7 ± 1.5) × 10-10 cm-2 s-1 above 140 GeV. We also present a light curve for Markarian 421 as observed by STACEE from March to May and compare our temporal, as well as spectral, measurements with those of other experiments.
The Astrophysical Journal 12/2008; 579(1):L5. · 6.02 Impact Factor
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R. A. Scalzo,
L. M. Boone,
D. Bramel,
J. Carson,
C. E. Covault,
P. Fortin,
G. Gauthier,
D. M. Gingrich,
D. Hanna,
A. Jarvis,
J. Kildea,
T. Lindner, C. Mueller,
R. Mukherjee,
R. A. Ong,
K. J. Ragan,
D. A. Williams,
J. Zweerink
[show abstract]
[hide abstract]
ABSTRACT: We report on observations of the blazar W Com (ON+231) with the Solar Tower Atmospheric Cerenkov Effect Experiment (STACEE), a wave front-sampling atmospheric Cerenkov telescope, in the spring of 2003. In a data set comprising 10.5 hr of on-source observing time, we detect no significant emission from W Com. We discuss the implications of our results in the context of the composition of the relativistic jet in W Com, examining both leptonic and hadronic models for the jet. We derive 95% confidence level upper limits on the flux at the level of (1.5-3.5) × 10-10 cm-2 s-1 above 100 GeV for the leptonic models, or (0.5-1.1) × 10-10 cm-2 s-1 above 150 GeV for the hadronic models.
The Astrophysical Journal 12/2008; 607(2):778. · 6.02 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: For some time, the Draco dwarf spheroidal galaxy has garnered interest as a possible source for the indirect detection of dark matter. Its large mass-to-light ratio and relative proximity to the Earth provide favorable conditions for the production of a detectable flux of gamma rays from dark matter self-annihilation in its core. The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is an atmospheric Cherenkov telescope located in Albuquerque, NM capable of detecting gamma rays at energies above 100 GeV. We present the results of the STACEE observations of Draco during the 2005–2006 observing season totaling 10.2 hours of live time after cuts. We do not detect a significant gamma-ray signal from Draco, and place an upper limit on a power-law spectrum of dN/dE|Draco<1.6×10-13(E/220 GeV)-2.2γ s-1 cm-2 GeV-1 Assuming a smooth Navarro-Frenk-White profile for the dark-matter halo and an annihilation spectrum, we also derive upper limits for the cross-section-velocity product (⟨σv⟩) for weakly interacting massive particles self-annihilation.
Phys. Rev. D. 10/2008; 78(8).
-
J. Kildea,
J. Zweerink,
J. Ball,
J. E. Carson,
C. E. Covault,
D. D. Driscoll,
P. Fortin,
D M Gingrich,
D.S. Hanna,
A. Jarvis,
T. Lindner, C. Mueller,
R Mukherjee,
R. A. Ong,
K. Ragan,
D A Williams
[show abstract]
[hide abstract]
ABSTRACT: We present the analysis and results of 12.5 hours of high-energy gamma-ray observations of the EGRET-detected pulsar PSR B1951+32 using the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE). STACEE is an atmospheric Cherenkov detector, in Albuquerque, New Mexico, that detects cosmic gamma rays using the shower-front-sampling technique. STACEE's sensitivity to astrophysical sources at energies around 100 GeV allows it to investigate emission from gamma-ray pulsars with expected pulsed emission cutoffs below 100 GeV. We discuss the observations and analysis of STACEE's PSR 1951+32 data, accumulated during the 2005 and 2006 observing seasons.
11/2007;
-
STACEE Collaboration: R. Mukherjee,
N. Akhter,
J. Ball,
J. E. Carson,
C. E. Covault,
D. D. Driscoll,
P. Fortin,
D M Gingrich,
D.S. Hanna,
A. Jarvis,
J. Kildea,
T. Lindner, C. Mueller,
R. A. Ong,
K. Ragan,
D A Williams,
J. Zweerink
[show abstract]
[hide abstract]
ABSTRACT: We present the analysis and results of recent high-energy gamma-ray observations of the high energy-peaked BL Lac (HBL) object 1ES 1218+304 with the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE). 1ES 1218+304 is an X-ray bright HBL at a redshift z=0.182. It has been predicted to be a gamma-ray emitter above 100 GeV, detectable by ground-based Cherenkov telescopes. Recently this source has been detected by MAGIC and VERITAS, confirming these predictions. STACEE's sensitivity to astrophysical sources at energies above 100 GeV allows it to explore high energy sources such as X-ray bright active galaxies and gamma-ray bursts. We present results from STACEE observations of 1ES 1218+304 in the 2006 and 2007 observing seasons.
11/2007;
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STACEE Collaboration: A. Jarvis,
J. Ball,
J. E. Carson,
C. E. Covault,
D. D. Driscoll,
P. Fortin,
D M Gingrich,
D.S. Hanna,
J. Kildea,
T. Lindner,
R Mukherjee, C. Mueller,
R. A. Ong,
K. Ragan,
D A Williams,
J. Zweerink
[show abstract]
[hide abstract]
ABSTRACT: The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is an atmospheric Cherenkov telescope (ACT) that uses a large mirror array to achieve a relatively low energy threshold. For sources with Crab-like spectra, at high elevations, the detector response peaks near 100 GeV. Gamma-ray burst (GRB) observations have been a high priority for the STACEE collaboration since the inception of the experiment. We present the results of 20 GRB follow-up observations at times ranging from 3 minutes to 15 hours after the burst triggers. Where redshift measurements are available, we place constraints on the intrinsic high-energy spectra of the bursts.
11/2007;
-
STACEE Collaboration: D. D. Driscoll,
J. Ball,
J. E. Carson,
C. E. Covault,
P. Fortin,
D M Gingrich,
D.S. Hanna,
A. Jarvis,
J. Kildea,
T. Lindner, C. Mueller,
R Mukherjee,
R. A. Ong,
K. Ragan,
D A Williams,
J. Zweerink
[show abstract]
[hide abstract]
ABSTRACT: For some time, the Draco dwarf spheroidal galaxy has garnered interest as a possible source for the indirect detection of dark matter. Its large mass-to-light ratio and relative proximity to the Earth provide favorable conditions for the production of detectable gamma rays from dark matter self-annihilation in its core. The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is an air-shower Cherenkov telescope located in Albuquerque, NM capable of detecting gamma rays at energies above 100 GeV. We present the results of the STACEE observations of Draco during the 2005-2006 observing season totaling 10 hours of livetime after cuts.
11/2007;
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T. Lindner,
D.S. Hanna,
J. Kildea,
J. Ball,
D. A. Bramel,
J. Carson,
C. E. Covault,
D. Driscoll,
P. Fortin,
D M Gingrich,
A. Jarvis, C. Mueller,
R Mukherjee,
R. A. Ong,
K. Ragan,
R. A. Scalzo,
D A Williams,
J. Zweerink
[show abstract]
[hide abstract]
ABSTRACT: Using the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE), we have observed the BL Lac objects 3C 66A and OJ 287. These are members of the class of low-frequency-peaked BL Lac objects (LBLs) and are two of the three LBLs predicted by Costamante and Ghisellini to be potential sources of very high energy (>100 GeV) gamma-ray emission. The third candidate, BL Lacertae, has recently been detected by the MAGIC collaboration. Our observations have not produced detections; we calculate a 99% CL upper limit of flux from 3C 66A of 0.15 Crab flux units and from OJ 287 our limit is 0.52 Crab. These limits assume a Crab-like energy spectrum with an effective energy threshold of 185 GeV.
08/2007;
-
J. E. Carson,
J. Kildea,
R. A. Ong,
J. Ball,
D. A. Bramel,
C. E. Covault,
D. Driscoll,
P. Fortin,
D M Gingrich,
D.S. Hanna,
T. Lindner, C. Mueller,
A. Jarvis,
R Mukherjee,
K. Ragan,
R. A. Scalzo,
D A Williams,
J. Zweerink
[show abstract]
[hide abstract]
ABSTRACT: Markarian 421 (Mrk 421) was the first blazar detected at gamma-ray energies above 300 GeV, and it remains one of only twelve TeV blazars detected to date. TeV gamma-ray measurements of its flaring activity and spectral variability have placed constraints on models of the high-energy emission from blazars. However, observations between 50 and 300 GeV are rare, and the high-energy peak of the spectral energy distribution (SED), predicted to be in this range, has never been directly detected. We present a detection of Mrk 421 above 100 GeV as made by the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) during a multiwavelength campaign in early 2004. STACEE is a ground-based atmospheric Cherenkov telescope using the wavefront sampling technique to detect gamma rays at lower energies than achieved by most imaging Cherenkov telescopes. We also outline a method for reconstructing gamma-ray energies using a solar heliostat telescope. This technique was applied to the 2004 data, and we present the differential energy spectrum of Mrk 421 above 130 GeV. Assuming a differential photon flux dN/dE proportional to E^-a, we measure a spectral index a = 2.1 +/- 0.2 (statistical) +0.2/-0.1 (systematic). Finally, we discuss the STACEE spectrum in the context of the multiwavelength results from the same epoch.
The Astrophysical Journal 01/2007; · 6.02 Impact Factor
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D.M. Gingrich,
L.M. Boone,
D. Bramel,
J. Carson,
C.E. Covault,
P. Fortin,
D.S. Hanna,
J.A. Hinton,
A. Jarvis,
J. Kildea,
T. Lindner, C. Mueller,
R. Mukherjee,
R.A. Ong,
K. Ragan,
R.A. Scalzo,
C.G. Theoret,
D.A. Williams,
J.A. Zweerink
[show abstract]
[hide abstract]
ABSTRACT: We describe the design and performance of the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) in its complete configuration. STACEE uses the heliostats of a solar energy research facility to collect and focus the Cherenkov photons produced in gamma-ray induced air showers. The light is concentrated onto an array of photomultiplier tubes located near the top of a tower. The large Cherenkov photon collection area of STACEE results in a gamma-ray energy threshold below that of previous ground-based detectors. STACEE is being used to observe pulsars, supernova remnants, active galactic nuclei, and gamma-ray bursts
IEEE Transactions on Nuclear Science 01/2006; · 1.45 Impact Factor
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D. A. Bramel,
J. Carson,
C. E. Covault,
P. Fortin,
D M Gingrich,
D.S. Hanna,
A. Jarvis,
J. Kildea,
T. Lindner,
R Mukherjee, C. Mueller,
R. A. Ong,
K. Ragan,
R. A. Scalzo,
D A Williams,
J. Zweerink
[show abstract]
[hide abstract]
ABSTRACT: We present the analysis and results of recent high-energy gamma-ray observations of the BL Lac object 3C 66A conducted with the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE). During the 2003-2004 observing season, STACEE extensively observed 3C 66A as part of a multiwavelength campaign on the source. A total of 33.7 hours of data was taken on the source, plus an equivalent-duration background observation. After cleaning the data set a total of 16.3 hours of live time remained, and a net on-source excess of 1134 events was seen against a background of 231742 events. At a significance of 2.2 standard deviations this excess is insufficient to claim a detection of 3C 66A, but is used to establish flux upper limits for the source.
The Astrophysical Journal 05/2005; · 6.02 Impact Factor
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STACEE Collaboration: R. A. Scalzo,
L. M. Boone,
D. Bramel,
J. Carson,
C. E. Covault,
P. Fortin,
G. Gauthier,
D M Gingrich,
D.S. Hanna,
A. Jarvis,
J. Kildea,
T. Lindner, C. Mueller,
R Mukherjee,
R. A. Ong,
K. J. Ragan,
D A Williams,
J. A. Zweerink
[show abstract]
[hide abstract]
ABSTRACT: We report on observations of the blazar W Comae (ON+231) with the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE), a wavefront-sampling atmospheric Cherenkov telescope, in the spring of 2003. In a data set comprising 10.5 hours of ON-source observing time, we detect no significant emission from W Comae. We discuss the implications of our results in the context of the composition of the relativistic jet in W Comae, examining both leptonic and hadronic models for the jet. We derive 95% confidence level upper limits on the flux at the level of 1.5--3.5 x 10^{-10} cm^{-2} s^{-1} above 100 GeV for the leptonic models, or 0.5--1.1 x 10^{-10} cm^{-2} s^{-1} above 150 GeV for the hadronic models.
04/2004;
-
C. E. Covault,
L.M. Boone,
D. Bramel,
J. Carson,
P. Fortin,
G. Gauthier,
D. Gingrich,
D. Hanna,
A. Jarvis,
J. Kildea, C. Mueller,
R. Mukherjee,
R.A. Ong,
K. Ragan,
R.A. Scalzo,
D.A. Williams,
J. Zweerink
[show abstract]
[hide abstract]
ABSTRACT: We present new results from observations of Active Galactic Nuclei (AGN)
by the STACEE experiment. STACEE is a detector for 50-500 GeV gamma rays
which uses the array of heliostat mirrors at the National Solar Thermal
Test Facility (NSTTF) located at Sandia Lab oratories, Albuquerque, New
Mexico, USA. STACEE uses 64 of these heliostats at night to collect
Cherenkov light from air showers due to high energy gamma rays. With a
large collecting area, STACEE has good sensitivity below 100 GeV. This
allow us to search for gamma rays from extragalactic sources at larger
redshift distances (to z of 0.2 or more) than can be studied by more
conventional imaging Cherenkov telescopes operating at higher energy
thresholds. We summarize recent STACEE observations of W Comae (also
known as ON+231), Markarian 421, and H 1426+428. Analysis of
observations on these sources in ongoing, and new results will be
presented at the conference. We also briefly describe plans for future
STACEE observations of AGN in the context of multiwavelength campaigns.
06/2003; 5:2551.
-
R. A. Scalzo,
L.M. Boone,
D. Bramel,
J. Carson,
C.E. Covault,
P. Fortin,
G. Gaunthier,
D. Gingrich,
D. Hanna,
A. Jarvis,
J. Kildea, C. Mueller,
R. Mukherjee,
R.A. Ong,
K. Ragan,
D.A. Williams,
J. Zweerink
[show abstract]
[hide abstract]
ABSTRACT: We discuss simulations of novel heliostat pointing configurations
designed to improve the angular and energy resolution of a solar tower
wavefront-sampling atmospheric Cherenkov telescope. One such
configuration will be tested via observations of the Crab Nebula with
the STACEE detector in the fall of 2003.
06/2003; 5:2799.
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STACEE Collaboration,
L. M. Boone,
D. Bramel,
E. Chae,
C. E. Covault,
P. Fortin,
D M Gingrich,
D.S. Hanna,
J. A. Hinton,
R Mukherjee, C. Mueller,
R. A. Ong,
K. Ragan,
R. A. Scalzo,
D. R. Schuette,
C. G. Theoret,
D A Williams
[show abstract]
[hide abstract]
ABSTRACT: STACEE is a ground based gamma-ray observatory that uses a heliostat array, built for solar energy research, to detect atmospheric Cherenkov radiation from gamma-ray initiated extensive air showers. During the first half of 2001, a prototype detector, STACEE-48, was used to detect the blazar Markarian 421, which was in an extremely active state. Observations from March to May of 2001 yielded an integral flux of (8.0+/-0.7_{stat}+/-1.5_{sys})x 10^-10 1/cm^2/s at energies above 140+/-20 GeV, and provide some evidence of correlated trends on time scales of a week or more in the GeV and X-ray bands.
02/2003;
-
R. Mukherjee,
L. M. Boone,
D. Bramel,
C. E. Covault,
P. Fortin,
D. Gingrich,
D. Hanna,
J. A. Hinton, C. Mueller,
R. A. Ong,
K. Ragan,
R. A. Scalzo,
D. R. Schuette,
D. A. Williams
[show abstract]
[hide abstract]
ABSTRACT: The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is a
ground-based gamma-ray telescope employing the atmospheric Cherenkov
technique. STACEE uses 64 large heliostats at a solar research facility
near Albuquerque NM, USA, to achieve a gamma-ray energy threshold below
traditional imaging telescopes. The full STACEE experiment started
regular observations in October, 2001. An earlier version of the
experiment using 48 heliostats took data between January and June of
2001. Here we report the results from STACEE observations of
extragalactic sources in 2001 and 2002. The sources observed include the
active galaxies Markarian 421, Markarian 501, 3C 66A, and W Comae. We
also summarize our future observing plan in the context of measuring the
absorbtion of high energy emission due to radiation fields at the
source, or in intergalactic space.
03/2002; -1:17112.
