Streak events are identified primarily on the basis of coincidence of > ν events occurring in a single chipy row of a single node within a single frame (Figure 1). The grade and fltgrade distributions of the streak events are similar to those of “good” events (Figure 2). The energy spectrum peaks at E ≈ 0.5 keV and shows weak line emission features, the strongest of which lies at 1.8 keV and is...

The MIT and CXC ACIS teams have explored a number of measures to ameliorate the effects of radiation damage suffered by the ACIS FI CCDs. One of these measures is a novel CCD read-out method called “squeegee mode”. A variety of different implementations of the squeegee mode have now been tested on the I0 CCD. Our results for the fitted FWHM at Al-Kα and Mn-Kα clearly demonstrate that all the sq...

We present the absolute measurement of the unresolved 0.5–8 keV X-ray background in the Chandra Deep Fields (CDF) North and South, the longest observations with Chandra (2 Ms and 1 Ms, respectively). We measure the unresolved CXB intensity by extracting spectra of the sky, removing all point and extended sources detected in the CDF. To model and subtract the instrumental background, we use obse...

It has been suggested that ingestion of polycyclic aromatic hydrocarbons (PAHs) may contribute to the high incidence and mortality of esophageal cancer in Linxian, China. To explore this relationship a semiquantitative immunohistochemical staining method was developed for localization of PAH-DNA adducts. Nuclear color intensity (bright field average pink intensity per nucleus for >1000 cells) w...

We report on Chandra ACIS observations of the ultracompact AM CVn binary ES Cet. This object has a 10.3 minute binary period and is the most compact of the confirmed AM CVn systems. We have, for the first time, unambiguously detected the X-ray counterpart to ES Cet. In a 20 ksec ACIS-S image a point-like X-ray source is found within 1 " of the catalogued optical position. The mean countrate in ...

We present here an overview of the status of the Chandra X-ray Observatory which has now been operating for five years. The Observatory is running smoothly, and the scientific return continues to be outstanding. We provide some details on the molecular contamination of the ACIS filters and its impact on observations. We review the observations with Chandra of the pulsar in the Crab Nebula and a...

We observed the " micro-quasar " GRS 1758–258 four times with Chandra. Two HRC-I observations were made in 2000 September-October spanning an intermediate-to-hard spectral transition (identified with RXTE). Another HRC-I and an ACIS/HETG observation were made in 2001 March following a hard-to-soft transition to a very low flux state. Based on the three HRC images and the HETG zero order image, ...