Calibration of the ROSAT High-Resolution Imager

Zombeck, Martin V.; Conroy, Maureen A.; Harnden, F. R.; Roy, Adrian G.; Braeuninger, Heinrich W.; Burkert, Wolfgang; Hasinger, G.; Predehl, P.

doi:10.1117/12.23255

Cited by 11 publications

(4 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…12 (as in Fig. 10 of Zombeck et al 1990). The corrected image is clearly more centrally peaked and more symmetric about the centroid.…”

Section: Characterization Of Errors In Thementioning

confidence: 94%

“…Photon arrival times are recorded to a precision of 61 /jls (with a position sensitive dead time of -1 ms). Zombeck et al (1990;and references 'The Image Reduction and Analysis Facility (IRAF) is distributed by the National Optical Astronomy Observatories, which is operated by the Association of Universities for Research in Astronomy, Inc., under contract to the National Science Foundation. The Post Reduction Off-line Software (pros) package was developed by the High Energy Astrophysics Division of the Smithsonian Astrophysical Observatory, with assistence from the Space Science Computing Division and the Laboratory for High Energy Astrophysics of the Goddard Space Flight Center.…”

Section: Rosat Hri Observationsmentioning

confidence: 99%

“…The observation was not wobbled consistently and the source occasionally languished in the middle position. The gaps along the lines 7 = 1920 and X=2175 are an artifact caused by the method for reading out photon events from the detector with the Cross Grid Charge Detector (CGCD), but are not caused by shadowing in the detector (see Murray and Chapell 1988;Zombeck et al 1990). Each bin is 10 pixels on a side (5"X5" at 0"5 pixel -1 ) and has a "rank" assigned to it which measures the average ellipticity of each of the subimages; more circular subimages have higher ranks, as discussed in the text.…”

Section: Characterization Of Errors In Thementioning

confidence: 99%

See 2 more Smart Citations

A method for correcting aspect solution errors in ROSAT HRI observations of compact sources

Morse¹

1994

PASP

View full text Add to dashboard Cite

X-ray point sources observed with the ROSAT High Resolution Imager (HRI) often appear elongated over scales of -5"-10" from the image core. This elongation has been attributed to errors in the attitude correction as the satellite is wobbled during the observations, and affects sources with both soft and hard X-ray spectra. In this paper, I report the results of an attempt to rid a high signal-to-noise observation of the soft X-ray point source HZ 43 of its characteristic elongation. I divided the observation into 181 separate images, each containing photons from only a small region on the detector through which the source passed during the satellite's wobble. By measuring the positions of the individual image centroids, I found clear evidence for systematic offsets from a common mean by up to -±3" in both right ascension and declination as a function of phase in the satellite wobble. Shifting the subimages to a common center and then restacking them into a single image measurably improved the symmetry of the point-spread function. HRI observations are wobbled primarily to smooth out variations in the pixel-to-pixel sensitivity of the detector and also to extend the lifetime of the microchannel plates in the detector since these decay at a given location as a function of the number of photons detected. However, the elongations introduced by the aspect errors inhibit the identification of possible extended X-ray emission associated with sources such as pulsars and active galactic nuclei. In light of these results, I suggest that until the aspect errors are understood, observations of compact sources, where this effect may be important, should not be wobbled.

show abstract

“…12 (as in Fig. 10 of Zombeck et al 1990). The corrected image is clearly more centrally peaked and more symmetric about the centroid.…”

Section: Characterization Of Errors In Thementioning

confidence: 94%

Section: Rosat Hri Observationsmentioning

confidence: 99%

Section: Characterization Of Errors In Thementioning

confidence: 99%

See 1 more Smart Citation

A method for correcting aspect solution errors in ROSAT HRI observations of compact sources

Morse¹

1994

PASP

View full text Add to dashboard Cite

show abstract

“…On the other hand, the HRI has a very crude spectral resolution in the 0.1-2.4 keV energy band (for more details see Prestwich et al 1996), it is less efficient than the PSPC (a factor of 3 to 8 for a plausible range of incident spectra) and it has a higher instrumental background. The ROSAT satellite, its X-ray telescope, and the HRI detector have been described in detail by Pfeffermann et al (1986), Zombeck et al (1990), Trümper et al (1991) and David et al (1998).…”

Section: Introductionmentioning

confidence: 99%

The Brera Multi-scale Wavelet ROSAT HRI source catalogue

Panzera

Campana

Covino

et al. 2003

A&A

View full text Add to dashboard Cite

Abstract. We present the Brera Multi-scale Wavelet ROSAT HRI source catalogue (BMW-HRI) derived from all ROSAT HRI pointed observations with exposure times longer than 100 s available in the ROSAT public archives. The data were analyzed automatically using a wavelet detection algorithm suited to the detection and characterization of both point-like and extended sources. This algorithm is able to detect and disentangle sources in very crowded fields and/or in the presence of extended or bright sources. Images have been also visually inspected after the analysis to ensure verification. The final catalogue, derived from 4303 observations, consists of 29 089 sources detected with a detection probability of ≥4.2σ. For each source, the primary catalogue entries provide name, position, count rate, flux and extension along with the relative errors. In addition, results of cross-correlations with existing catalogues at different wavelengths (FIRST, IRAS, 2MASS and GSC2) are also reported. Some information is available on the web via the DIANA Interface. As an external check, we compared our catalogue with the previously available ROSHRICAT catalogue (both in its short and long versions) and we were able to recover, for the short version, ∼90% of the entries. We computed the sky coverage of the entire HRI data set by means of simulations. The complete BMW-HRI catalogue provides a sky coverage of 732 deg 2 down to a limiting flux of ∼10 −12 erg s −1 cm −2 and of 10 deg 2 down to ∼10 −14 erg s −1 cm −2 . We were able to compute the cosmological log(N)-log(S ) distribution down to a flux of 1.2 × 10 −14 erg s −1 cm −2 .

show abstract

Ultrasensitive Detection

Siegmund¹

1995

Sensors Set

View full text Add to dashboard Cite

Calibration of the ROSAT High-Resolution Imager

Cited by 11 publications

References 2 publications

A method for correcting aspect solution errors in ROSAT HRI observations of compact sources

A method for correcting aspect solution errors in ROSAT HRI observations of compact sources

The Brera Multi-scale Wavelet ROSAT HRI source catalogue

Ultrasensitive Detection

Contact Info

Product

Resources

About