ORAC-DR: A generic data reduction pipeline infrastructure

Jenness, Tim; Economou, Frossie

doi:10.1016/j.ascom.2014.10.005

Cited by 34 publications

(26 citation statements)

References 23 publications

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“…Imaging and removal of the host contribution The LCOGT gri images were pre-processed using the Observatory Reduction and Acquisition Control Data Reduction pipeline 55 . To remove the host contribution, we performed image subtraction using the pre-discovery DECam gri images as templates.…”

Section: Low-ionisation Features Such As Fementioning

confidence: 99%

The superluminous transient ASASSN-15lh as a tidal disruption event from a Kerr black hole

et al. 2016

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3 When a star passes within the tidal radius of a supermassive black hole, it will be torn apart 1 .For a star with the mass of the Sun (M ) and a non-spinning black hole with a mass < 10 8 M , the tidal radius lies outside the black hole event horizon 2 and the disruption results in a luminous flare 3,4,5,6 . Here we report observations over a period of 10 months of a transient, hitherto interpreted 7 as a superluminous supernova 8 . Our data show that the transient rebrightened substantially in the ultraviolet and that the spectrum went through three different spectroscopic phases without ever becoming nebular. Our observations are more consistent with a tidal disruption event than a superluminous supernova because of the temperature evolution 6 , the presence of highly ionised CNO gas in the line of sight 9 and our improved localisation of the transient in the nucleus of a passive galaxy, where the presence of massive stars is highly unlikely 10,11 . While the supermassive black hole has a mass > 10 8 M 12, 13 , a star with the same mass as the Sun could be disrupted outside the event horizon if the black hole were spinning rapidly 14 . The rapid spin and high black hole mass can explain the high luminosity of this event.ASASSN-15lh was discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) on 14 June 2015 at a redshift of z = 0.2326. Its light curve peaked at V ∼ 17 mag implying an absolute magnitude of M = −23.5 mag, more than twice as luminous as any known supernova (SN) 7 . Our long-term spectroscopic follow-up reveals that ASASSN-15lh went through three different spectroscopic phases (Figure 1). During the first phase 7 , the spectra were dominated by two broad absorption features. While these features appear similar to those observed in superluminous supernovae (SLSNe; Supplementary Figure 1), their physical origin is different. The features in 4 SLSNe are due to O II 8, 15 , but this would produce an additional strong feature at ∼4,400Å (Supplementary Figure 2) . The feature at ∼4,100Å cannot be easily identified in the tidal disruption event (TDE) framework either. Two possibilities are that it could be due to absorption of Mg II or high-velocity He II 16 . After the initial broad absorption features disappeared, the spectra of ASASSN-15lh were dominated by two emission features. A possible identification for these features is He II λλ3, 202 and 4, 686Å, which are both consistently blueshifted by ∼15,000 km s −1 ( Supplementary Figure 3). He II emission is commonly seen in optically discovered TDEs 4, 5 at different blueshifts, albeit typically at lower velocities, but it has not been seen in H-poor SLSNe.These features disappeared after day +75 (measured in rest frame from peak) and the later spectra were mostly featureless, with the exception of two emission features at ∼4,000 and 5,200Å. The spectra remained much bluer than those of SLSNe 17 for many months after the peak and never revealed nebular features, even up to day +256.A UV spectrum obtained with the HST on day +168 does not sh...

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Section: Low-ionisation Features Such As Fementioning

confidence: 99%

The superluminous transient ASASSN-15lh as a tidal disruption event from a Kerr black hole

et al. 2016

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“…• Ingestion: The LCOGT network is a world-wide facility that is able to observe the full sky nearly continuously (Brown et al 2013). At the end of the night for each LCOGT site, the raw data are preprocessed using the lcogtorac pipeline (Brown et al 2013;Jenness & Economou 2015). The prereduced data are then sent to the IPAC archive, where LCOGT users can access them.…”

Section: Appendix B: Lcogtsnpipementioning

confidence: 99%

The diversity of Type II supernova versus the similarity in their progenitors

Valenti

Howell

Stritzinger

et al. 2016

Mon. Not. R. Astron. Soc.

303

381

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High-quality collections of Type II supernova (SN) light curves are scarce because they evolve for hundreds of days, making follow-up observations time consuming and often extending over multiple observing seasons. In light of these difficulties, the diversity of SNe II is not fully understood. Here we present ultraviolet and optical photometry of 12 SNe II monitored by the Las Cumbres Observatory Global Telescope Network (LCOGT) during 2013-2014, and compare them with previously studied SNe having well-sampled light curves. We explore SN II diversity by searching for correlations between the slope of the linear light-curve decay after maximum light (historically used to divide SNe II into IIL and IIP) and other measured physical properties. While SNe IIL are found to be on average more luminous than SNe IIP, SNe IIL do not appear to synthesize more 56 Ni than SNe IIP. Finally, optical nebular spectra obtained for several SNe in our sample are found to be consistent with models of red supergiant progenitors in the 12-16 M ⊙ range. Consequently, SNe IIL appear not to account for the deficit of massive red supergiants as SN II progenitors.

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“…23 The instrumental magnitudes were calibrated to several nearby stars from SDSS, which were transformed into the Landolt (1983) system using the empirical prescription measured by Robert Lupton. 24 LCOGT images were preprocessed using the Observatory Reduction and Acquisition Control Data Reduction pipeline (ORAC-DR; Jenness & Economou 2015). Photometry was then extracted using the PyRAF-based lcogtsnpipe pipeline (see Appendix B of Valenti et al 2016) to perform PSF fitting and calibration to the AAVSO Photometric All-Sky Survey (APASS; Henden et al 2009) for BV and SDSS Data Release 8 (Aihara et al 2011) for gri.…”

Section: Appendixmentioning

confidence: 99%

Type Ibn Supernovae Show Photometric Homogeneity and Spectral Diversity at Maximum Light

Hosseinzadeh

Arcavi

Valenti

et al. 2017

ApJ

100

186

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Type Ibn supernovae (SNe) are a small yet intriguing class of explosions whose spectra are characterized by lowvelocity helium emission lines with little to no evidence for hydrogen. The prevailing theory has been that these are the core-collapse explosions of very massive stars embedded in helium-rich circumstellar material (CSM). We report optical observations of six new SNe Ibn: PTF11rfh, PTF12ldy, iPTF14aki, iPTF15ul, SN2015G, and iPTF15akq. This brings the sample size of such objects in the literature to 22. We also report new data, including a near-infrared spectrum, on the Type Ibn SN 2015U. In order to characterize the class as a whole, we analyze the photometric and spectroscopic properties of the full TypeIbn sample. We find that, despite the expectation that CSM interaction would generate a heterogeneous set of light curves, as seen in SNe IIn, most TypeIbn light curves are quite similar in shape, declining at rates around 0.1 mag day −1 during the first month after maximum light, with a few significant exceptions. Early spectra of SNe Ibn come in at least two varieties, one that shows narrow PCygni lines and another dominated by broader emission lines, both around maximum light, which may be an indication of differences in the state of the progenitor system at the time of explosion. Alternatively, the spectral diversity could arise from viewing-angle effects or merely from a lack of early spectroscopic coverage. Together, the relative light curve homogeneity and narrow spectral features suggest that the CSM consists of a spatially confined shell of helium surrounded by a less dense extended wind.

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ORAC-DR: A generic data reduction pipeline infrastructure

Cited by 34 publications

References 23 publications

The superluminous transient ASASSN-15lh as a tidal disruption event from a Kerr black hole

The superluminous transient ASASSN-15lh as a tidal disruption event from a Kerr black hole

The diversity of Type II supernova versus the similarity in their progenitors

Type Ibn Supernovae Show Photometric Homogeneity and Spectral Diversity at Maximum Light

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