New UV-source catalogs, UV spectral database, UV variables and science tools from the GALEX surveys

Bianchi, Luciana; Vega, Alexander de la; Shiao, B.; Bohlin, R. C.

doi:10.1007/s10509-018-3277-2

Cited by 9 publications

(8 citation statements)

References 22 publications

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“…We developed and tested a methodology to identify the artifacts and remove them from light curves using the Fourier transforms of the light curve and the dither during an observation. A future paper will be devoted to physical variations detected in GALEX time-resolved photometry (see examples in Bianchi et al 2018) including this sample and to a fainter sample. The current sample is mostly in the non-linear regime although some of the artifacts are also seen at our faintest magnitude of 14.…”

Section: Discussionmentioning

confidence: 99%

Searching for Short-timescale Variability in the Ultraviolet with the GALEX gPhoton Archive. I. Artifacts and Spurious Periodicities

Vega

Bianchi

2018

ApJS

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In order to develop and test a methodology to search for UV variability over the entire GALEX database down to the shortest time scales, we analyzed time-domain photometry of ∼ 5000 light curves of ∼ 300 bright (m FUV , m NUV ≤ 14) and blue (m FUV − m NUV < 0) GALEX sources. Using the gPhoton database tool, we discovered and characterized instrumentally-induced variabilities in time-resolved GALEX photometry, which may severely impact automated searches for short-period variations. The most notable artifact is a quasi-sinusoidal variation mimicking light curves typical of pulsators, seen occasionally in either one or both detectors, with amplitudes of up to 0.3 mag and periods corresponding to the periodicity of the spiral dithering pattern used during the observation (P∼120 sec). Therefore, the artifact may arise from small-scale response variations. Other artifacts include visit-long "sagging" or "hump" in flux, occurring when the dithering pattern is not a spiral, or a one-time change in flux level during the exposure. These instrumentally-caused variations were not reported before, and are not due to known (and flagged) artifacts such as hot spots, which can be easily eliminated. To characterize the frequency and causality of such artifacts, we apply Fourier transform analysis to both light curves and dithering patterns, and examine whether artificial brightness variations correlate with visit or instrumental parameters. Artifacts do not correlate with source position on the detector. We suggest methods to identify artifact variations and to correct them when possible.

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Section: Discussionmentioning

confidence: 99%

Searching for Short-timescale Variability in the Ultraviolet with the GALEX gPhoton Archive. I. Artifacts and Spurious Periodicities

Vega

Bianchi

2018

ApJS

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“…The individual light curves of the longest two runs (S8632 and S8635) are displayed in Figure 11, each being vertically offset for display purposes, and shows flaring of ∼ 0.5 mag. Matches to GALEX (Bianchi et al 2018) and Swift (Evans et al 2013) show the presence of UV and X-ray emission from ASASSN-15ev. The observations presented in this paper were taken over a month after the outburst recorded by Kato et al (2016), once the system was in quiescence.…”

Section: Asassn-15evmentioning

confidence: 99%

High-speed photometry of faint cataclysmic variables – IX. Targets from multiple transient surveys

Paterson

Woudt

Warner

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present high-speed photometric observations of 25 cataclysmic variables detected by the All Sky Automated Search for Super-Novae (ASAS-SN), the Mobile Astronomical System of the TElescope-Robot (MASTER) and the Catalina Real-Time Transient Survey (CRTS). From these observations we determine 16 new orbital periods and 1 new superhump period. Two systems (ASASSN-14ik and ASASSN-14ka) have outburst periods of approximately 1 month, with a third (ASASSN-14hv) having outbursts approximately every 2 months. Included in the sample are 11 eclipsing systems, one probable intermediate polar (ASASSN-15fm), 1 SW Sex-type star (MLS 0720+17), 1 WZ Sge-type star (ASASSN-17fz) and one system showing different photometric and spectroscopic periods (ASASSN-15kw).

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“…Many astronomical missions are available in ultraviolet wavelength, but Galaxy Evolution Explorer −50 cm telescope conducted the first all sky surveys in UV [16]. Ultraviolet imaging of planetary nebulae with GALEX was taken to illustrate the variety in UV morphology [17]. The current study that used the observations of GALEX in helix planetary nebula can explain the nature of ultraviolet emission A Study of the Extragalactic UV Radiation in Helix Nebula using GALEX Lakshmi S BOSE http://wjst.wu.ac.th and the UV flux distribution of extragalactic sources.…”

Section: Introductionmentioning

confidence: 99%

A Study of the Extragalactic UV Radiation in Helix Nebula using GALEX

Bose¹

2021

Walailak J Sci & Tech

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We have studied the ultraviolet sources using Galaxy Evolution Explorer medium imaging surveys in Helix Nebula and estimated UV fluxes by using aperture photometry in distant and near ultraviolet bands. The aperture photometric method produces reliable, accurate flux measurements and found inconsistent with the merged catalog of Galaxy Evolution Explorer. From the current results, the fluxes are consistent with brighter absolute magnitude up to 24.5 and the measurement error increases gradually to more than 50 % at the fainter magnitude side. Percentage of error in far UV is greater than near UV, due to the fact that brighter galaxies are more visible than the near UV sources. The diffuse UV contributors of zodiacal light, airglow contribution in the nebula were estimated. The total extragalactic UV radiation from the detected sources to the diffuse background in the nebula is of the order of 50 ± 14 photons cm-2sr-1s-1Å-1 in NUV band and 28 ±10 photons cm-2sr-1s-1Å-1 in FUV band. HIGHLIGHTS GALEX observations have the potential to find extragalactic UV sources Helix Nebula is first identified for distinct source detection Aperture photometric method can detect fainter sources up to the magnitude of 27 Extragalactic sources in the Helix nebula contribute to diffuse UV emission in the nebula GRAPHICAL ABSTRACT

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New UV-source catalogs, UV spectral database, UV variables and science tools from the GALEX surveys

Cited by 9 publications

References 22 publications

Searching for Short-timescale Variability in the Ultraviolet with the GALEX gPhoton Archive. I. Artifacts and Spurious Periodicities

Searching for Short-timescale Variability in the Ultraviolet with the GALEX gPhoton Archive. I. Artifacts and Spurious Periodicities

High-speed photometry of faint cataclysmic variables – IX. Targets from multiple transient surveys

A Study of the Extragalactic UV Radiation in Helix Nebula using GALEX

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