摘要:

Astrometry using wide field coded aperture cameras is the most effective way to obtain prompt locations of gamma ray bursts for observations by narrow field instruments. However, the rate of burst detections using this method has been disappointing. In an attempt to understand this problem, I have been investigating the scaling relationships between instrument characteristics and instrument performance. The ideas are very simple, but the results are sometimes counter‐intuitive.I will discuss the effects of field of view and detector area on detected burst rate. I will also discuss the relationship between instrument architecture and instrument volume, a major limitation and cost driver. I will show how attention to these relationships could lead to an inexpensive mission capable of locating bursts at a very high rate. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810941

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

We present here the soft X‐ray All‐Sky Monitor (ASM). It is based on the current technological capabilities, sensitive in the ∼ 0.1 – 10.0 keV range with angular resolution of ∼ 3 – 4 arcmin, and has a limiting detectable flux ∼ 10−12erg/s/cm2for daily scans in the mentioned energy range. The ASM will play a key role in studying transient X‐ray sources like XRBs, GRBs, XRFs, X‐ray novae, as well as in the study of the long term variability of X‐ray sources like XRBs, AGN, or stellar X‐ray flares. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810942

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

With the coming launch of the Swift satellite, there will be many new opportunities to study the physics of the prompt optical emission from gamma ray bursts with robotic ground‐based telescopes. We discuss a new imaging system under development at Los Alamos National Laboratory that will provide simultaneous multicolor photometry of the rapidly evolving prompt optical emission in the first minutes after a burst trigger. This next generation system employs state‐of‐the‐art photon‐counting imaging technology at the focal plane of a rapidly slewing telescope. The imaging sensor is composed of an S‐20 photocathode, stacked microchannel plates, and crossed delay line readout electronics that together are capable of measuring the time of arrival and positions for individual optical photons with 200 picosecond time resolution. The imager is coupled with electronically tunable liquid‐crystal filters to provide essentially simultaneous linear polarization and multicolor photometric measurements of the prompt optical emission from a gamma ray bursts. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810943

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The 0.6‐m Super‐LOTIS (Livermore Optical Transient Imaging System) telescope is a fully robotic system dedicated to the search for prompt optical emission from gamma‐ray bursts. The telescope began routine operations from its Steward Observatory site atop Kitt Peak in April 2000. We summarize the current capabilities of the system and present some recent scientific results. A progress report is given on the upgrade of the system to allow for simultaneous near‐infrared (NIR) and optical imaging. This upgrade will be completed to coincide with the launch of the Swift GRB explorer mission in mid‐2004. Swift will have the capability of localizing very high redshift GRBs but absorption by the Ly‐&agr; forest prohibits optical detection ofz> 5 bursts. NIR observations can detect GRBs out toz∼ 10. Although Swift is a multi‐wavelength observatory capable of observing GRBs from the hard x‐rays to the optical it has no NIR capability. The upgraded Super‐LOTIS telescope will fill this NIR need. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810944

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

While it has been known for centuries that the optical sky is variable, monitoring the sky for optical transients with durations as short as a minute is an area of astronomical research that remains largely unexplored. Prompt follow‐up observations of Gamma Ray Bursts have shown that bright, explosive, optical transients exist. However, there are many reasons to suspect the existence of explosive optical transients that cannot be located through sky monitoring by high‐energy satellites. The RAPTOR sky monitoring system is an autonomous system of telescope arrays at Los Alamos National Laboratory that identifies fast optical transients as short as a minute and makes follow‐up observations in real time. The core of the RAPTOR system is composed of two arrays of telescopes, separated by 38 kilometers, that stereoscopically monitor a field of about 1300 square degrees for transients down to about 12.5th magnitude in 30 seconds. Both arrays are coupled to real‐time data analysis pipelines that are designed to identify transients on timescales of seconds. Each telescope array also contains a more sensitive higher resolution “fovea” telescope, capable of both measuring the light curve at a faster cadence and providing color information. In a manner analogous to human vision, each array is mounted on a rapidly slewing mount so that the “fovea” of the array can be rapidly directed for real‐time follow‐up observations of any interesting transient identified by the wide‐field system. We discuss the first results from RAPTOR and show that stereoscopic imaging and the absence of measurable parallax is a powerful tool for distinguishing real celestial transients in the “forest” of false positives. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810945

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The RAPTOR‐scan system mines data for optical transients associated with gamma‐ray bursts and is used to create a catalog for the RAPTOR telescope system. RAPTOR‐scan can detect and track individual astronomical objects across data sets containing millions of observed points.Accurately identifying a real object over many optical images (clusteringthe individual appearances) is necessary in order to analyze object light curves. To achieve this, RAPTOR telescope observations are sent in real time to a database. Each morning, a program based on the DBSCAN algorithm clusters the observations and labels each one with an object identifier. Once clustering is complete, the analysis program may be used to query the database and produce light curves, maps of the sky field, or other informative displays.Although RAPTOR‐scan was designed for the RAPTOR optical telescope system, it is a general tool designed to identify objects in a collection of astronomical data and facilitate quick data analysis. RAPTOR‐scan will be released as free software under the GNU General Public License. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810946

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The College of Charleston (CofC) is one of three institutions that belong to a consortium led by the Division of Science and Mathematics at the University of the Virgin Islands (UVI) to maintain and operate a research grade telescope at Etelman Observatory on the island of St. Thomas (18deg, 21′ N, 65deg W at an elevation ∼ 1325 ft with ⩽ 1″ seeing). The location provides 80&percent; sky coverage of the southern celestial hemisphere and, on average, ∼ 6 hours of clear sky per night, except during the peak of hurricane season. This makes the observatory an ideal facility for observing Gamma‐Ray Bursts (GRBs). The observatory will serve a variety of needs to the consortium members that include research, teaching, and public outreach. The primary research function of this facility will be to perform rapid, automated followup observations of Gamma‐Ray Bursts (GRBs) observed with NASA’s Swift spacecraft, to be launched in June 2004, via the GCN. The newly renovated observatory houses a new robotic 0.5 m Cassegrain telescope with a back‐illuminated Marconi 2024 × 2024 CCD42‐40 imaging array and 12‐position UBVRI filter wheel. Assuming 1.5″ seeing and a S/N=5, we can obtain a limiting (unfiltered) magnitude of ∼ 19 with a 10 s integration time. The slew rate is ⩾ 10deg per second.With the exceptional sky coverage at Etelman Observatory, we anticipate a detection rate of about 10–15&percent; of the Swift detection rate, and we anticipate making a significant contribution to the global network of small telescopes dedicated to GRB observations. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810947

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The Watcher telescope is planned to begin operation in Spring 2004 in South Africa.The system has been designed to respond primarily to very precise (arcminute) gamma‐ray burst locations distributed via the internet by the GCN. Watcher will be fully automatic and the planned response time for GRBs is ∼ 30 seconds or better. In addition, the telescope will be used for blazar monitoring and the photometric detection of extra‐solar planets when GRBs are not being observed. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810948

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

As the Swift era approaches, the University of Wyoming in Laramie has been preparing its two observatories for a robust GRB afterglow follow‐up program. The 2.3‐m Wyoming Infrared Observatory (WIRO) — first of its kind in collecting power and mid‐infrared optimization — is located on Jelm Mt. (2944‐m elevation) in a semi‐arid atmosphere, 40 km southwest of Laramie. On dry, cold winter nights, our estimates show that WIRO’s sensitivity in the K‐band is comparable to that of a 4‐m telescope at Mauna Kea observatory in Hawaii. Three instruments are currently in use at the observatory: WIRO‐Prime, WIRO‐Spec, and the Goddard IR camera. WIRO‐Prime is a 20482prime‐focus camera with a 20 arcmin diameter FOV (f/2.1). Its sensitivity for a 300‐s exposure will reach as faint as 24th(23rd) magnitude in V (R). WIRO‐Spec is an integral field, holographic spectrometer which utilizes Volume‐Phase‐Holographic gratings with a 20482detector. A bundle of 293 fiber optical cables (1 fiber ∼ 1 arcsec) connects the Cassegrain platform to the stationary spectrometer, optimizing the image by reduction from f/27 to f/9. At 20thmagnitude, a 700‐s exposure yields a S/N ratio of ∼ 10 at a resolution of ∼ 1 Angstrom, sufficient for resolving the MgII doublet [279.8 nm] in GRB host galaxies to determine a 0.4 <z< 2.5 for an operational wavelength range of ∼ 400–1000 nm (WIRO‐Prime and WIRO‐Spec). The Goddard IR Camera is a 2562InSb camera (FOV ∼ 108 arcsec) mounted at Cassegrain and operated at 15K. Available filters for GRB observations include R, I, J, H, and K’. WIRO slew timescale (∼ 120 s) is comparable to that of Swift. Red Buttes Observatory (RBO) is located 19 km south of Laramie in a dark site and houses a 0.6‐m f/8 Cassegrain DFM reflector. RBO’s Apogee AP8p 10242camera (18 arcmin FOV, sufficiently large for BAT localizations) is available for use with filters U, B, V, R and I. We are in the final stages of implementing fully automated response to Swift BAT alerts at RBO, and expect an average acquisition timescale to random sky positions of ∼ 25 s. Thus, rapid GRB detections by RBO can be forwarded to WIRO even while Swift’s pointed instruments are performing first integrations. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810949

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Many present and past gamma‐ray burst (GRB) detectors try to be not only a “scout”, discovering new GRBs, but also the “cavalry”, simultaneously optimizing on‐board science return. Recently, however, most GRB science return has moved out from the gamma‐ray energy bands where discovery usually occurs. Therefore a future gamma‐ray instrument that isonlya scout might best optimize future GRB science. Such a scout would specialize solely in the initial discovery of GRBs, determining only those properties that would allow an unambiguous handoff to waiting cavalry instruments. Preliminary general principles of scout design and cadence are discussed. Scouts could implement observing algorithms optimized for finding GRBs with specific attributes of duration, location, or energy. Scout sky‐scanning algorithms utilizing a return cadence near to desired durations of short GRBs are suggested as a method of discovering GRBs in the unexplored short duration part of the GRB duration distribution. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810950

出版商:AIP    

年代:1904

数据来源: AIP