The Swift mission, scheduled for launch in 2004, is a multiwavelength observatory for gamma-ray burst (GRB) astronomy. It is a first-of-its-kind autonomous rapid-slewing satellite for transient astronomy and pioneers the way for future rapid-reaction and multiwavelength missions. It will be far more powerful than any previous GRB mission, observing more than 100 bursts yr � 1 and performing detailed X-ray and UV/optical afterglow observations spanning timescales from 1 minute to several days after the burst. The objectives are to (1) determine the origin of GRBs, (2) classify GRBs and search for new types, (3) study the interaction of the ultrarelativistic outflows of GRBs with their surrounding medium, and (4) use GRBs to study the early universe out to z >10. The mission is being developed by a NASA-led international collaboration. It will carry three instruments: a newgeneration wide-field gamma-ray (15‐150 keV) detector that will detect bursts, calculate 1 0 ‐4 0 positions, and trigger autonomous spacecraft slews; a narrow-field X-ray telescope that will give 5 00 positions and perform spectroscopy in the 0.2‐10 keV band; and a narrow-field UV/optical telescope that will operate in the 170‐ 600 nm band and provide 0B3 positions and optical finding charts. Redshift determinations will be made for most bursts. In addition to the primary GRB science, the mission will perform a hard X-ray survey to a sensitivity of � 1m crab (� 2;10 � 11 ergs cm � 2 s � 1 in the 15‐150 keV band), more than an order of magnitude better than HEAO 1 A-4. A flexible data and operations system will allow rapid follow-up observations of all types of

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The Swift Gamma-Ray Burst Mission

he burst alert telescope (BAT) is one of three instruments on the
Swift MIDEX spacecraft to study gamma-ray bursts (GRBs). The BAT first detects the GRB and localizes the burst direction to an accuracy of 1–4 arcmin within 20 s after the start of the event. The GRB trigger initiates an autonomous spacecraft slew to point the two narrow field-of-view (FOV) instruments at the burst location within 20–70 s so to make follow-up X-ray and optical observations. The BAT is a wide-FOV, coded-aperture instrument with a CdZnTe detector plane. The detector plane is composed of 32,768 pieces of CdZnTe (4×4×2 mm), and the coded-aperture mask is composed of ∼52,000 pieces of lead (5×5×1 mm) with a 1-m separation between mask and detector plane. The BAT operates over the 15–150 keV energy range with ∼7 keV resolution, a sensitivity of ∼10−8 erg s−1 cm−2, and a 1.4 sr (half-coded) FOV. We expect to detect > 100 GRBs/year for a 2-year mission. The BAT also performs an all-sky hard X-ray survey with a sensitivity of ∼2 m Crab (systematic limit) and it serves as a hard X-ray transient monitor.

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The burst alert telescope (BAT) on the Swift MIDEX mission

The origin of the shallow decay segment in Swift XRT light curves remains a puzzle. We analyze the properties of this segment with a sample of 53 long Swift GRBs detected before 2007 February. We show that the distributions of the sample's characteristics are lognormal or normal, and its isotropic X-ray energy (E(iso),X) is linearly correlated with the prompt gamma-ray energy but with a steeper photon spectrum, aside from some X-ray flashes. No significant spectral evolution is observed from this phase to the following phase, and the latter is usually consistent with external shock models, implying that the shallow decay is also of external-shock origin, likely a refreshed external shock. Within the refreshed-shock model, the data are generally consistent with a roughly constant injection luminosity up to the end of this phase, t(b). A positive correlation between Eiso; X and tb also favors this scenario. Among the 13 bursts that have well-sampled optical light curves, six have an optical break around tb and the breaks are consistent with being achromatic. However, the other seven either do not show an optical break or have a break at an epoch different from tb. This raises a concern for the energy injection scenario, suggesting that the optical and X-ray emission may not be the same component, at least for some bursts. There are four significant outliers in the sample, GRBs 060413, 060522, 060607A, and 070110. The shallow decay phase in these bursts is immediately followed by a very steep decay after tb, which is inconsistent with any external-shock model. The optical data for these bursts evolve independently from the X-ray data. These X-ray plateaus likely have an internal origin and demand continuous operation of a long-term central engine. We conclude that the observed shallow decay phase likely has diverse physical origins.

https://iopscience.iop.org/article/10.1086/521870/pdf

A Comprehensive Analysis of Swift XRT Data. II. Diverse Physical Origins of the Shallow Decay Segment

Type Ia supernovae are destructive explosions of carbon-oxygen white dwarfs. Although they are used empirically to measure cosmological distances, the nature of their progenitors remains mysterious. One of the leading progenitor models, called the single degenerate channel, hypothesizes that a white dwarf accretes matter from a companion star and the resulting increase in its central pressure and temperature ignites thermonuclear explosion. Here we report observations with the Swift Space Telescope of strong but declining ultraviolet emission from a type Ia supernova within four days of its explosion. This emission is consistent with theoretical expectations of collision between material ejected by the supernova and a companion star, and therefore provides evidence that some type Ia supernovae arise from the single degenerate channel.

A strong ultraviolet pulse from a newborn type Ia supernova.

This paper discusses Swift observations of the � -ray burst GRB 050315 (z ¼ 1:949) from 80 s to 10 days after the onset of the burst. The X-ray light curve displayed a steep early decay (t � 5 ) for � 200 s and several breaks. However, both the prompt hard X-ray/� -ray emission (observed by the BAT) and the first � 300 s of X-ray emission (observed bytheXRT)canbeexplainedbyexponentialdecays,withsimilardecayconstants.ExtrapolatingtheBATlightcurve into the XRT band suggests that the rapidly decaying, early X-ray emission was simply a continuation of the fading promptemission;thisstrongsimilaritybetweentheprompt � -rayandearlyX-rayemissionmayberelatedtothesimple temporal and spectral character of this X-ray–rich GRB. Theprompt (BAT) spectrum was steep down to � 15keVand appeared to continue through the XRT bandpass, implying a low peak energy, inconsistent with the Amati relation. Following the initial steep decline, the X-ray afterglow did not fade for � 1:2 ; 10 4 s, after which time it decayed with at emporal index of� � 0:7, followed by a second break at � 2:5 ; 10 5 s to a slope of � � 2. The apparent ‘‘plateau’’ in the X-raylight curve, after the early rapid decay, makes this one of the most extreme examples of the steep-flat-steep X-ray light curves revealed by Swift. If the second afterglow break is identified with a jet break, then the jet opening

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Swift observations of the X-ray - Bright GRB 050315

The Swift Gamma-Ray Explorer is designed to make prompt multiwavelength observations of Gamma-Ray Bursts (GRBs) and GRB Afterglows. The X-ray Telescope (XRT) provides key capabilities that permit Swift to determine GRB positions with a few arcseconds accuracy within 100 seconds of the burst onset. The XRT utilizes a superb mirror set built for JET-X and a state-of-the-art XMM/EPIC MOS CCD detector to provide a sensitive broad-band (0.2-10 keV) X-ray imager with effective area of 135 cm2 at 1.5 keV, field of view of 23.6 x 23.6 arcminutes, and angular resolution of 18 arcseconds (HEW). The detection sensitivity is 2x10-14 erg/cm2/s in 104 seconds. The instrument is designed to provide automated source detection and position reporting within 5 seconds of target acquisition. It can also measure redshifts of GRBs for bursts with Fe line emission or other spectral features. The XRT will operate in an auto-exposure mode, adjusting the CCD readout mode automatically to optimize the science return for each frame as the source fades. The XRT will measure spectra and lightcurves of the GRB afterglow beginning about a minute after the burst and will follow each burst for days as it fades from view.

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The Swift X-Ray Telescope

Relationships of salivary cortisol and melatonin rhythms to sleep quality, emotion, and fatigue levels in patients with newly diagnosed lung cancer

The purpose of this study was to investigate the influence of rest-activity rhythm on the survival of cancer patients. This study collected data related to cancer patients experiencing pain who had been hospitalized for treatment between August 2006 and October 2007. Data included the Karnofsky Performance Status Index as a representation of functional condition as well as the Brief Pain Inventory and the Pittsburgh Sleep Quality Index. Actigraphic methods were used to record the dichotomy index (I < O) of patients' rest-activity rhythms over periods of three consecutive days. Patients were closely followed until 31 July 2013. Results were analyzed using Kaplan-Meier survival analysis, log-rank testing and Cox proportional hazards regression analysis to evaluate whether alterations in the rest-activity rhythm affected the survival rate of the patients. Of the 68 hospitalized cancer patients experiencing pain at the time of admission, 51 subsequently died within the study period. A significant difference was observed in the survival curves between the regular I < O group and the disrupted I < O group (log rank = 7.942, p = 0.005). A multivariable proportional hazard model was used for analysis of overall survival, revealing that the risk of death within the study period among patients with disrupted I < O was 4.59 times higher than that of patients with regular I < O (95% CI: 1.92-10.96, p = 0.001). Among patients with poor performance status, the risk of death among patients with disrupted I < O was 8.68 times higher than that of patients with regular I < O (95% CI: 2.50-30.09, p = 0.001). Disruptions in rest-activity rhythm were negatively correlated with the survival of hospitalized cancer patients experiencing pain. Effects were particularly pronounced in cancer patients with poor performance status.

Correlation between rest-activity rhythm and survival in cancer patients experiencing pain.

Use of opioid analgesics or sleeping medication and survival of cancer patients

The objective of this study was to understand the influence of rotating shifts and fixed night shifts on the sleep quality of nurses using a systematic literature review and meta-analysis and to determine whether the sleep quality of nurses working rotating shifts or fixed night shifts differs from that of nurses working fixed day shifts. We conducted a meta-analysis on literature that had used the Pittsburgh Sleep Quality Index (PSQI) to gauge sleep quality and had been published between 2000 and 2020 in the Cochrane Library, CINAHL, MEDLINE, and PubMed databases. This study was conducted in accordance with PRISMA, and the quality of the literature was assessed using the Joanna Briggs Institute Critical Appraisal Checklist for Analytical Cross Sectional Studies. CMA 3.0 was employed for data analysis, and meta-regression analysis was conducted to examine the differences between the PSQI scores of nurses working fixed day shifts and those working rotating shifts or fixed night shifts. Following assessment, a total of 29 papers (34 items of data) were analyzed. The papers included a total of 3,935 nurses who worked fixed day shifts, 3,777 nurses who worked rotating shifts, and 1,559 nurses who worked fixed night shifts. Our subgroup analysis indicated that the sleep quality of nurses working rotating shifts was poorer than the sleep quality of nurses working fixed day shifts; the standardized mean difference (SMD) was 0.38 (95% CI: 0.24-0.52, p< .001), and the meta-regression analysis found that the difference in sleep quality between nurses over 40 years old working rotating shifts and those working fixed day shifts was significantly smaller than the difference in sleep quality between nurses 40 years old or younger working rotating shifts and those working fixed day shifts (β = -0.368, p= .011). The sleep quality of nurses working fixed night shifts was also poorer than the sleep quality of nurses working fixed day shifts; the SMD was 0.58 (95% CI: 0.38-0.78, p< .001), and the meta-regression analysis revealed that the difference in sleep quality between nurses over 40 years old working fixed night shifts and those working fixed day shifts was not significantly different from the difference in sleep quality between nurses 40 years old or younger working fixed night shifts and those working fixed day shifts (β = -0.118, p= .608). This meta-analysis found that both nurses working rotating shifts and those working fixed night shifts had poorer sleep quality than those working fixed day shifts and that age influenced the difference in sleep quality only between nurses working rotating shifts and those working fixed day shifts; the difference in sleep quality between nurses 40 years old or younger working rotating shifts and those working fixed day shifts was greater than the difference in sleep quality between nurses over 40 years old working rotating shifts and those working fixed day shifts.

Wen Pei Chang

Papers

The Swift X-Ray Telescope

Relationships of salivary cortisol and melatonin rhythms to sleep quality, emotion, and fatigue levels in patients with newly diagnosed lung cancer

Correlation between rest-activity rhythm and survival in cancer patients experiencing pain.

Use of opioid analgesics or sleeping medication and survival of cancer patients

Influence of rotating shifts and fixed night shifts on sleep quality of nurses of different ages: a systematic literature review and meta-analysis.