Wide-field Cameras for GRB Observations in X-rays and EUV

Recent observations of the ASCA satellite resulted in the first identification of a GB source (Murakami et al. 1994). This success confirmed the importance of simultaneous observations in different wavelength bands for GB studies. Besides the ASCA results, there were several observations of GBs in X-ray band with the Ginga (Yoshida et al,.1989), V 78/1 (Laros et al. 1984) and other satellites. It became clear that GBs emit 4 - 8% of their energy in the 2 - 10 keV range. The main task now is to have an equipment which will be able to monitor the sky in X-rays in a mode similar to that of GRO observations, i.e. the telescope should have an all-sky field-of-view (FoV) and should work continuously.A telescope with these features but operating at soft X-ray energies may directly determine the GB distance scale, due to interstellar absorption of the photons with energies less than 2 keV, as was pointed out first by Schaefer (1993). Flaring sources similar to GBs in time scale may be found also in the EUV (hundreds of angstroms) with the help of very wide-field cameras. Of course each such device - in X-ray, soft X-ray and EUV bands - will discover many transient objects, flaring events, will study time variability of bright “stationary” sources etc. In this paper we describe several instrumental approaches in these fields.

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Imaging in Hard X-ray Astronomy

Symposium - International Astronomical Union ◽

10.1017/s0074180900194173 ◽

2003 ◽

Vol 214 ◽

pp. 70-83 ◽

Cited By ~ 1

Author(s):

T. P. Li

Keyword(s):

Gamma Ray ◽

Signal To Noise Ratio ◽

High Energy ◽

High Signal ◽

Wide Field ◽

X Rays ◽

X Ray ◽

Energy Gamma ◽

High Resolution Images ◽

Energy Processes

The energy range of hard X-rays is a key waveband to the study of high energy processes in celestial objects, but still remains poorly explored. In contrast to direct imaging methods used in the low energy X-ray and high energy gamma-ray bands, currently imaging in the hard X-ray band is mainly achieved through various modulation techniques. A new inversion technique, the direct demodulation method, has been developed since early 90s. with this technique, wide field and high resolution images can be derived from scanning data of a simple collimated detector. The feasibility of this technique has been confirmed by experiment, balloon-borne observation and analyzing simulated and real astronomical data. Based the development of methodology and instrumentation, a high energy astrophysics mission – Hard X-ray Modulation Telescope (HXMT) has been proposed and selected in China for a four-year Phase-A study. The main scientific objectives are a full-sky hard X-ray (20–200 keV) imaging survey and high signal-to-noise ratio timing studies of high energy sources.

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A proposed X-ray focusing device with wide field of view for use in X-ray astronomy

Nuclear Instruments and Methods ◽

10.1016/0029-554x(75)90501-7 ◽

1975 ◽

Vol 127 (2) ◽

pp. 285-292 ◽

Cited By ~ 56

Author(s):

W.K.H. Schmidt

Keyword(s):

Field Of View ◽

Wide Field ◽

X Ray ◽

Wide Field Of View

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The Detection of High-Energy X-Rays from Ara XR-1 and Nor XR-1

Publications of the Astronomical Society of Australia ◽

10.1017/s1323358000011243 ◽

1968 ◽

Vol 1 (4) ◽

pp. 165-166

Author(s):

R. M. Thomas

Keyword(s):

Zenith Angle ◽

High Energy ◽

Azimuth Angle ◽

Field Of View ◽

X Rays ◽

Balloon Flight ◽

X Ray ◽

Energy Channels

This paper presents observations of weak X-ray sources at photon energies between 20 and 100 keV which were made during a balloon flight conducted from Mildura, Australia on 29 February 1968. Results obtained from Sco XR-1 and the Sagittarius region during this flight have been presented elsewhere, and here we report additional results obtained during a search of an area of sky in which several sources have been reported from rocket experiments at photon energies below about 10 keV. The detector used was an actively collimated and shielded NaI(T1) crystal, 2 mm thick and 54.3 cm2 in area. Incident photons were sorted into 16 energy channels between 7 and 167 keV (1.76 to 0.07 Å). The collimator field of view was 8°FWHM; the telescope axis was fixed at a zenith angle of 32° and its azimuth angle was varied by rotating the observatory below the balloon. This allowed the telescope to scan back and forth in azimuth across a source, the azimuth angle at any time being indicated by magnetometers.

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The Wide Field X-ray Telescope Mission—A Digital Sky Survey in X-rays

10.1063/1.3475337 ◽

2010 ◽

Cited By ~ 1

Author(s):

S. Murray ◽

R. Giacconi ◽

A. Ptak ◽

P. Rosati ◽

M. Weisskopf ◽

...

Keyword(s):

Wide Field ◽

X Rays ◽

X Ray ◽

Sky Survey

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A Search for the Signature of the Diffuse Soft X-ray Background in the ROSAT Wide-Field Camera All-Sky Survey

International Astronomical Union Colloquium ◽

10.1017/s0252921100036113 ◽

1996 ◽

Vol 152 ◽

pp. 289-293

Author(s):

R.G. West ◽

R. Willingale ◽

J.P. Pye ◽

T.J. Sumner

Keyword(s):

Charged Particles ◽

Field Of View ◽

Wide Field ◽

Galactic Latitude ◽

The Sun ◽

X Ray ◽

Cosmic Background ◽

Sky Survey ◽

Cosmic Abundance ◽

X Ray Background

We present the results of an attempt to locate the signature of the diffuse soft X-ray background in the ROSAT Wide-Field Camera (WFC) all-sky survey. After removal of non-cosmic background sources (eg. energetic charged particles), the field-of-view integrated count rate in the WFC S1a filter (90–185 eV) shows no consistent variation with Galactic latitude or longitude. We place limits on the signal from the soft X-ray background (SXRB) in the WFC, and show that these limits conflict with the observations of the Wisconsin Sky Survey if the SXRB in this energy range is assumed to be produced by a thermal plasma of cosmic abundance and a temperature T ~ 106 K within d ~ 100 pc of the Sun.

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Optical counterparts of an ultraluminous X-Ray Source X-1 in NGC 2500

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2160 ◽

2019 ◽

Vol 488 (4) ◽

pp. 5935-5940 ◽

Cited By ~ 1

Author(s):

N Aksaker ◽

A Akyuz ◽

S Avdan ◽

H Avdan

Keyword(s):

Hubble Space Telescope ◽

Optical Emission ◽

Spectral Energy ◽

Wide Field ◽

Nearby Galaxy ◽

X Rays ◽

Energy Distributions ◽

X Ray ◽

Photon Index ◽

Absolute Magnitudes

ABSTRACT We present the results of a search for optical counterparts of ultraluminous X-ray source (ULX) X-1 in the nearby galaxy NGC 2500 by using archival images taken with the Hubble Space Telescope Wide Field Camera (WFC3)/UVIS. We identified four optical sources as possible counterparts within the 2σ error radius of 0$^{\prime \prime }_{.}$3 in the images. However, only two of them were investigated as candidates for counterparts due to their point-like features and their identification in various filters. These two faint candidates have absolute magnitudes of MV ≈ −3.4 and −3.7. The spectral energy distributions of two candidates were modelled by a power-law spectrum with a photon index (α) ∼1.5, but the spectrum of one candidate shows a deviation. This may suggest that at least two components are responsible for the optical emission. The red part of the spectrum could arise from the companion star and the blue part could be interpreted as an evidence of reprocessing of the X-rays from the disc.

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Sudden changes in the intensity of high energy X-rays from Sco X-1

Symposium - International Astronomical Union ◽

10.1017/s0074180900004095 ◽

1970 ◽

Vol 37 ◽

pp. 104-106

Author(s):

P. C. Agrawal ◽

S. Biswas ◽

G. S. Gokhale ◽

V. S. Iyengar ◽

P. K. Kunte ◽

...

Keyword(s):

Counting Rate ◽

High Energy ◽

Field Of View ◽

X Rays ◽

Background Counting Rate ◽

X Ray ◽

The North ◽

Residual Atmosphere ◽

Flux Gate ◽

Background Counting

In this note we wish to report briefly the observation of sudden changes in the intensity of Sco X-1 by a factor of about 3 recorded in the energy interval 29.9–52.3 keV on December 22, 1968 between 04 h 27 m and 05 h 53 m UT. The observation was made with an X-ray telescope flown in a balloon from Hyderabad, India. The balloon was launched at 0200 hr UT and reached the ceiling of 7.5 g/cm2 of residual atmosphere at 0435 hr UT. The X-ray telescope consisted of a NaI(T1) crystal with an area of 97.3 cm2 and thickness 4 mm, surrounded by both active and passive collimators. The telescope was mounted on an oriented platform which was programmed to look in four specified directions successively, of azimuths, Φ=0°, 110°, 180° and 310° (Φ=0° being North and Φ=90°, West), spending about 4 min in each direction during a cycle of period of about 16 min. The axis of the telescope was inclined at an angle of 32° with respect to the zenith. A pair of crossed flux gate magnetometers provided information every 8.2 sec on the azimuth of the telescope. The pulse heights from the X-ray detector were sorted into several channels extending from 10 to 120 keV. An Am241 source came into the field of view of the telescope once in 15 min for about 30 sec to provide in-flight calibration of the detector. The meridian transit of Sco X-1 was at 0454 hr UT. Just before the balloon reached the ceiling Sco X-1 was in the field of view of the telescope for 3 min and 41 sec. After the balloon reached ceiling, Sco X-1 was in the field of view of the telescope on five occasions between 0443 and 0553 hr UT. During the last observation, however, the balloon had lost altitude by about 1 g/cm2. The excess counts due to Sco X-1 were obtained by subtracting the counting rates corresponding to the North direction which did not include any known X-ray sources. The observation on Sco X-1 in the 1st cycle was made while the balloon was still ascending and consequently the interposed grammage was changing from 10.5 to 9.7 g/cm2. However, for the energy range under consideration, the change in the background counting rate was not significant and there cannot be any doubt regarding the genuineness of the excess counts recorded.

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