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  • 1. Adams, S. M.
    et al.
    Blagorodnova, N.
    Kasliwal, M. M.
    Amanullah, Rahman
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Barlow, T.
    Bue, B.
    Bulla, Mattia
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Cao, Y.
    Cenko, S. B.
    Cook, D. O.
    Ferretti, Raphael
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Fox, O. D.
    Fremling, Christoffer
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Gezari, S.
    Goobar, Ariel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ho, A. Y. Q.
    Hung, Tiara
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Karamehmetoglu, Emir
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Kulkarni, S. R.
    Kupfer, T.
    Laher, R. R.
    Masci, F. J.
    Miller, A. A.
    Neill, J. D.
    Nugent, P. E.
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Taddia, Francesco
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Walters, R.
    iPTF Survey for Cool Transients2018In: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 130, no 985, article id 034202Article in journal (Refereed)
    Abstract [en]

    We performed a wide-area (2000 deg2) g and I band experiment as part of a two month extension to the Intermediate Palomar Transient Factory. We discovered 36 extragalactic transients including iPTF17lf, a highly reddened local SN Ia, iPTF17bkj, a new member of the rare class of transitional Ibn/IIn supernovae, and iPTF17be, a candidate luminous blue variable outburst. We do not detect any luminous red novae and place an upper limit on their rate. We show that adding a slow-cadence I band component to upcoming surveys such as the Zwicky Transient Facility will improve the photometric selection of cool and dusty transients.

  • 2. Ashcraft, Teresa A.
    et al.
    Windhorst, Rogier A.
    Jansen, Rolf A.
    Cohen, Seth H.
    Grazian, Andrea
    Paris, Diego
    Fontana, Adriano
    Giallongo, Emanuele
    Speziali, Roberto
    Testa, Vincenzo
    Boutsia, Konstantina
    O'Connell, Robert W.
    Rutkowski, Michael J.
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ryan, Russell E.
    Scarlata, Claudia
    Weiner, Benjamin
    Ultra-deep Large Binocular Camera U-band Imaging of the GOODS-North Field: Depth Versus Resolution2018In: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 130, no 988, article id 064102Article in journal (Refereed)
    Abstract [en]

    We present a study of the trade-off between depth and resolution using a large number of U-band imaging observations in the GOODS-North field from the Large Binocular Camera (LBC) on the Large Binocular Telescope (LBT). Having acquired over 30 hr of data (315 images with 5-6 minutes exposures), we generated multiple image mosaics, starting with the best atmospheric seeing images (FWHM less than or similar to 0 ''.8), which constitute similar to 10% of the total data set. For subsequent mosaics, we added in data with larger seeing values until the final, deepest mosaic included all images with FWHM less than or similar to 1 ''.8 (similar to 94% of the total data set). From the mosaics, we made object catalogs to compare the optimal-resolution, yet shallower image to the lower-resolution but deeper image. We show that the number counts for both images are similar to 90% complete to U-AB less than or similar to 26 mag. Fainter than U-AB similar to 27 mag, the object counts from the optimal-resolution image start to drop-off dramatically (90% between U-AB = 27 and 28 mag), while the deepest image with better surface-brightness sensitivity (mu(AB)(U) less than or similar to 32 mag arcsec(-2)) show a more gradual drop (10% between U-AB similar or equal to 27 and 28 mag). For the brightest galaxies within the GOODS-N field, structure and clumpy features within the galaxies are more prominent in the optimal-resolution image compared to the deeper mosaics. We conclude that for studies of brighter galaxies and features within them, the optimal-resolution image should be used. However, to fully explore and understand the faintest objects, the deeper imaging with lower resolution are also required. Finally, we find-for 220 brighter galaxies with U-AB less than or similar to 23 mag-only marginal differences in total flux between the optimal-resolution and lower-resolution light-profiles to mu(AB)(U) less than or similar to 32 mag arcsec(-2). In only 10% of the cases are the total-flux differences larger than 0.5 mag. This helps constrain how much flux can be missed from galaxy outskirts, which is important for studies of the Extragalactic Background Light.

  • 3. Bellm, Eric C.
    et al.
    Kulkarni, Shrinivas R.
    Graham, Matthew J.
    Dekany, Richard
    Smith, Roger M.
    Riddle, Reed
    Masci, Frank J.
    Helou, George
    Prince, Thomas A.
    Adams, Scott M.
    Barbarino, Cristina
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Barlow, Tom
    Bauer, James
    Beck, Ron
    Belicki, Justin
    Biswas, Rahul
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Blagorodnova, Nadejda
    Bodewits, Dennis
    Bolin, Bryce
    Brinnel, Valery
    Brooke, Tim
    Bue, Brian
    Bulla, Mattia
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Burruss, Rick
    Cenko, S. Bradley
    Chang, Chan-Kao
    Connolly, Andrew
    Coughlin, Michael
    Cromer, John
    Cunningham, Virginia
    De, Kishalay
    Delacroix, Alex
    Desai, Vandana
    Duev, Dmitry A.
    Eadie, Gwendolyn
    Farnham, Tony L.
    Feeney, Michael
    Feindt, Ulrich
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Flynn, David
    Franckowiak, Anna
    Frederick, S.
    Fremling, C.
    Gal-Yam, Avishay
    Gezari, Suvi
    Giomi, Matteo
    Goldstein, Daniel A.
    Golkhou, V. Zach
    Goobar, Ariel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Groom, Steven
    Hacopians, Eugean
    Hale, David
    Henning, John
    Ho, Anna Y. Q.
    Hover, David
    Howell, Justin
    Hung, Tiara
    Huppenkothen, Daniela
    Imel, David
    Ip, Wing-Huen
    Ivezic, Zeljko
    Jackson, Edward
    Jones, Lynne
    Juric, Mario
    Kasliwal, Mansi M.
    Kaspi, S.
    Kaye, Stephen
    Kelley, Michael S. P.
    Kowalski, Marek
    Kramer, Emily
    Kupfer, Thomas
    Landry, Walter
    Laher, Russ R.
    Lee, Chien-De
    Lin, Hsing Wen
    Lin, Zhong-Yi
    Lunnan, Ragnhild
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Giomi, Matteo
    Mahabal, Ashish
    Mao, Peter
    Miller, Adam A.
    Monkewitz, Serge
    Murphy, Patrick
    Ngeow, Chow-Choong
    Nordin, Jakob
    Nugent, Peter
    Ofek, Eran
    Patterson, Maria T.
    Penprase, Bryan
    Porter, Michael
    Rauch, Ludwig
    Rebbapragada, Umaa
    Reiley, Dan
    Rigault, Mickael
    Rodriguez, Hector
    van Roestel, Jan
    Rusholme, Ben
    van Santen, Jakob
    Schulze, S.
    Shupe, David L.
    Singer, Leo P.
    Soumagnac, Maayane T.
    Stein, Robert
    Surace, Jason
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Szkody, Paula
    Taddia, Francesco
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Terek, Scott
    Van Sistine, Angela
    van Velzen, Sjoert
    Vestrand, W. Thomas
    Walters, Richard
    Ward, Charlotte
    Ye, Quan-Zhi
    Yu, Po-Chieh
    Yan, Lin
    Zolkower, Jeffry
    The Zwicky Transient Facility: System Overview, Performance, and First Results2019In: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 131, no 995, article id 018002Article in journal (Refereed)
    Abstract [en]

    The Zwicky Transient Facility (ZTF) is a new optical time-domain survey that uses the Palomar 48 inch Schmidt telescope. A custom-built wide-field camera provides a 47 deg(2) field of view and 8 s readout time, yielding more than an order of magnitude improvement in survey speed relative to its predecessor survey, the Palomar Transient Factory. We describe the design and implementation of the camera and observing system. The ZTF data system at the Infrared Processing and Analysis Center provides near-real-time reduction to identify moving and varying objects. We outline the analysis pipelines, data products, and associated archive. Finally, we present on-sky performance analysis and first scientific results from commissioning and the early survey. ZTF's public alert stream will serve as a useful precursor for that of the Large Synoptic Survey Telescope.

  • 4. Boldt, Luis N.
    et al.
    Stritzinger, Maximilian D.
    Burns, Chris
    Hsiao, Eric
    Phillips, M. M.
    Goobar, Ariel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Marion, G. H.
    Stanishev, Vallery
    Near-Infrared K Corrections of Type Ia Supernovae and their Errors2014In: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 126, no 938, p. 324-337Article in journal (Refereed)
    Abstract [en]

    In this paper we use near-infrared (NIR) spectral observations of Type Ia supernovae (SNe Ia) to study the uncertainties inherent in NIR K corrections. To do so, 75 previously published NIR spectra of 33 SNe Ia are employed to determine K-correction uncertainties in the YJHK(s) passbands as a function of temporal phase and redshift. The resultant K corrections are then fed into an interpolation algorithm that provides mean K corrections as a function of temporal phase and robust estimates of the associated errors. These uncertainties are both statistical and intrinsic-i.e., due to the diversity of spectral features from object to object and must be included in the overall error budget of cosmological parameters constrained through the use of NIR observations of SNe Ia. Intrinsic variations are likely the dominant source of error for all four passbands at maximum light. Given the present data, the total Y-band K-correction uncertainties at maximum are smallest, amounting to +/- 0.04 mag at a redshift of z = 0.08. The J-band K-term errors are also reasonably small (+/- 0.06 mag), but intrinsic variations of spectral features and noise introduced by telluric corrections in the H-band currently limit its total K-correction errors at maximum to +/- 0.10 mag at z = 0.08. Finally, uncertainties in the K-s-band K terms at maximum amount to +/- 0.07 mag at this same redshift. These results are largely constrained by the small number of published NIR spectra of SNe Ia, which do not yet allow spectral templates to be constructed as a function of the light curve decline rate.

  • 5. Branch, David
    et al.
    Jeffery, David J.
    Parrent, Jerod
    Baron, E.
    Troxel, M. A.
    Stanishev, Vallery
    Stockholm University, Faculty of Science, Department of Physics.
    Keithley, Melissa
    Harrison, Joshua
    Bruner, Christopher
    Comparative direct analysis of type Ia supernova spectra. IV. Postmaximum2008In: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 120, no 864, p. 135-149Article in journal (Refereed)
    Abstract [en]

    A comparative study of optical spectra of Type Ia supernovae ( SNe Ia) obtained near 1 week, 3 weeks, and 3 months after maximum light is presented. Most members of the four groups that were defined on the basis of maximum light spectra in Paper II ( core normal, broad line, cool, and shallow silicon) develop highly homogeneous postmaximum spectra, although there are interesting exceptions. Comparisons with SYNOW synthetic spectra show that most of the spectral features can be accounted for in a plausible way. The fits show that 3 months after maximum light, when SN Ia spectra are often said to be in the nebular phase and to consist of forbidden emission lines, the spectra actually remain dominated by resonance- scattering features of permitted lines, primarily those of Fe II. Even in SN 1991bg, which is said to have made a very early transition to the nebular phase, there is no need to appeal to forbidden lines at 3 weeks postmaximum, and at 3 months postmaximum the only clear identification of a forbidden line is [Ca II]lambda lambda 7291, 7324. Recent studies of SN Ia rates indicate that most of the SNe Ia that have ever occurred have been "" prompt"" SNe Ia, produced by young (similar to 10(8) yr) stellar populations, while most of the SNe Ia that occur at low redshift today are "" tardy,"" produced by an older ( several Gyr) population. We suggest that the shallow silicon SNe Ia tend to be the prompt ones.

  • 6. Clocchiatti, Alejandro
    et al.
    Wheeler, J. Craig
    Kirshner, Robert P.
    Branch, David
    Challis, Peter
    Chevalier, Roger A.
    Filippenko, Alexei V.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy.
    Garnavich, Peter
    Leibundgut, Bruno
    Panagia, Nino
    Phillips, Mark M.
    Suntzeff, Nicholas B.
    Hoeflich, Peter A.
    Gallardo, Jose
    Late-time HST photometry of SN1994I: Hints of positron annihilation energy deposition2008In: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 120, no 865, p. 290-300Article in journal (Refereed)
    Abstract [en]

    We present multicolor Hubble Space Telescope ( HST) WFPC2 broadband observations of the Type Ic SN 1994I obtained similar to 280 d after maximum light. We measure the brightness of the SN and, relying on the detailed spectroscopic database of SN 1994I, we transform the ground-based photometry obtained at early times to the HST photometric system, deriving light curves for the WFPC2 F439W, F555W, F675W, and F814W passbands that extend from 7 days before to 280 days after maximum. We use the multicolor photometry to build a quasi-bolometric light curve of SN 1994I, and compare it with similarly constructed light curves of other supernovae. In doing so, we propose and test a scaling in energy and time that allows for a more meaningful comparison of the exponential tails of different events. Through comparison with models, we find that the late-time light curve of SN 1994I is consistent with that of spherically symmetric ejecta in homologous expansion, for which the ability to trap the gamma-rays produced by the radioactive decay of Co-56 diminishes roughly as the inverse of time squared. We also find that by the time of the HST photometry, the light curve was significantly energized by the annihilation of positrons.

  • 7. Coughlin, Michael W.
    et al.
    Ahumada, Tomas
    Cenko, S. Bradley
    Cunningham, Virginia
    Ghosh, Shaon
    Singer, Leo P.
    Bellm, Eric C.
    Burns, Eric
    De, Kishalay
    Goldstein, Adam
    Golkhou, V. Zach
    Kaplan, David L.
    Kasliwal, Mansi M.
    Perley, Daniel A.
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bagdasaryan, Ashot
    Dekany, Richard G.
    Duev, Dmitry A.
    Feeney, Michael
    Graham, Matthew J.
    Hale, David
    Kulkarni, Shri R.
    Kupfer, Thomas
    Laher, Russ R.
    Mahabal, Ashish
    Masci, Frank J.
    Miller, Adam A.
    Neill, James D.
    Patterson, Maria T.
    Riddle, Reed
    Rusholme, Ben
    Smith, Roger
    Tachibana, Yutaro
    Walters, Richard
    2900 Square Degree Search for the Optical Counterpart of Short Gamma-Ray Burst GRB 180523B with the Zwicky Transient Facility2019In: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 131, no 998, article id 048001Article in journal (Refereed)
    Abstract [en]

    There is significant interest in the models for production of short gamma-ray bursts (GRBs). Until now, the number of known short GRBs with multi-wavelength afterglows has been small. While the Fermi GRB Monitor detects many GRBs relative to the Neil Gehrels Swift Observatory, the large localization regions makes the search for counterparts difficult. With the Zwicky Transient Facility (ZTF) recently achieving first light, it is now fruitful to use its combination of depth (m(AB) similar to 20.6), field of view (approximate to 47 square degrees), and survey cadence (every similar to 3 days) to perform Target of Opportunity observations. We demonstrate this capability on GRB 180523B, which was recently announced by the Fermi GRB Monitor as a short GRB. ZTF imaged approximate to 2900 square degrees of the localization region, resulting in the coverage of 61.6% of the enclosed probability over two nights to a depth of m(AB) similar to 20.5. We characterized 14 previously unidentified transients, and none were found to be consistent with a short GRB counterpart. This search with the ZTF shows it is an efficient camera for searching for coarsely localized short GRB and gravitational-wave counterparts, allowing for a sensitive search with minimal interruption to its nominal cadence.

  • 8. Hsiao, E. Y.
    et al.
    Phiilips, M. M.
    Marion, G. H.
    Kirshner, R. P.
    Morrell, N.
    Sand, D. J.
    Burns, C. R.
    Contreras, C.
    Hoeflich, P.
    Stritzinger, M. D.
    Valenti, S.
    Anderson, J. P.
    Ashall, C.
    Baltay, C.
    Baron, E.
    Banerjee, D. P. K.
    Davis, S.
    Diamond, T. R.
    Folatelli, G.
    Freedman, Wendy L.
    Forster, F.
    Galbany, L.
    Gall, C.
    Gonzalez-Gaitan, S.
    Goobar, Ariel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hamuy, M.
    Holmbo, S.
    Kasliwal, M. M.
    Krisciunas, K.
    Kumar, S.
    Lidman, C.
    Lu, J.
    Nugent, P. E.
    Perlmutter, S.
    Persson, S. E.
    Piro, A. L.
    Rabinowitz, D.
    Roth, M.
    Ryder, S. D.
    Schmidt, B. P.
    Shahbandeh, M.
    Suntzeff, N. B.
    Taddia, Francesco
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Uddin, S.
    Wang, L.
    Carnegie Supernova Project-II: The Near-infrared Spectroscopy Program2019In: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 131, no 995, article id 014002Article in journal (Refereed)
    Abstract [en]

    Shifting the focus of Type Ia supernova (SN Ia) cosmology to the near infrared (NIR) is a promising way to significantly reduce the systematic errors, as the strategy minimizes our reliance on the empirical width-luminosity relation and uncertain dust laws. Observations in the NIR are also crucial for our understanding of the origins and evolution of these events, further improving their cosmological utility. Any future experiments in the rest-frame NIR will require knowledge of the SN Ia NIR spectroscopic diversity, which is currently based on a small sample of observed spectra. Along with the accompanying paper, Phillips et al., we introduce the Carnegie Supernova Project-II (CSP-II), to follow-up nearby SNe Ia in both the optical and the NIR. In particular, this paper focuses on the CSP-II NIR spectroscopy program, describing the survey strategy, instrumental setups, data reduction, sample characteristics, and future analyses on the data set. In collaboration with the Harvard-Smithsonian Center for Astrophysics (CfA) Supernova Group, we obtained 661 NIR spectra of 157 SNe Ia. Within this sample, 451 NIR spectra of 90 SNe Ia have corresponding CSP-II follow-up light curves. Such a sample will allow detailed studies of the NIR spectroscopic properties of SNe Ia, providing a different perspective on the properties of the unburned material; the radioactive and stable nickel produced; progenitor magnetic fields; and searches for possible signatures of companion stars.

  • 9. Kasliwal, M. M.
    et al.
    Cannella, C.
    Bagdasaryan, A.
    Hung, T.
    Feindt, Ulrich
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Singer, L. P.
    Coughlin, M.
    Fremling, C.
    Walters, R.
    Duev, D.
    Itoh, R.
    Quimby, R. M.
    The GROWTH Marshal: A Dynamic Science Portal for Time-domain Astronomy2019In: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 131, no 997, article id 038003Article in journal (Refereed)
    Abstract [en]

    We describe a dynamic science portal called the GROWTH Marshal that allows time-domain astronomers to define science programs; program filters to save sources from different discovery streams; coordinate follow-up with various robotic or classical telescopes; analyze the panchromatic follow-up data; and generate summary tables for publication. The GROWTH marshal currently serves 137 scientists, 38 science programs, and 67 telescopes. Every night, in real time, several science programs apply various customized filters to the 105 nightly alerts from the Zwicky Transient Facility. Here, we describe the schematic and explain the functionality of the various components of this international collaborative platform.

  • 10. Kattner, ShiAnne
    et al.
    Leonard, Douglas C.
    Burns, Christopher R.
    Phillips, M. M.
    Folatelli, Gaston
    Morrell, Nidia
    Stritzinger, Maximilian
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hamuy, Mario
    Freedman, Wendy L.
    Persson, Sven E.
    Roth, Miguel
    Suntzeff, Nicholas B.
    The Standardizability of Type Ia Supernovae in the Near-Infrared: Evidence for a Peak-Luminosity Versus Decline-Rate Relation in the Near-Infrared2012In: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 124, no 912, p. 114-127Article in journal (Refereed)
    Abstract [en]

    We analyze the standardizability of Type Ia supernovae (SNe Ia) in the near-infrared (NIR) by investigating the correlation between observed peak NIR (Y JH) absolute magnitude and postmaximum B-band decline rate [Delta m(15)(B)]. A sample of 27 low-redshift SNe Ia with well-observed NIR light curves observed by the Carnegie Supernova Project (CSP) between 2004 and 2007 is used. All 27 objects have premaximum coverage in optical bands, with a subset of 13 having premaximum NIR observations as well; coverage of the other 14 begins shortly after NIR maximum brightness. We describe the methods used to derive light-curve parameters (absolute peak magnitudes and decline rates) from both spline-and template-fitting procedures, and we confirm prior findings that fitting templates to SNe Ia light curves in the NIR is problematic due to the diversity of postmaximum behavior of objects that are characterized by similar Delta m(15)(B) values, especially at high decline rates. Nevertheless, we show that NIR light curves can be reasonably fit with a template, especially if the observations begin within 5 days after NIR maximum. SNe Ia appear to be better standardizable candles in the NIR bands than in the optical bands. For the subset of 13 objects in our data set that excludes the highly reddened and fast-declining SNe Ia and includes only those objects for which NIR observations began prior to 5 days after maximum light, we find modest (1.7 sigma) evidence for a peak-luminosity versus decline-rate relation in Y, and stronger evidence (2.8 sigma) in J and H. Using R-V values differing from the canonical value (R-V = 3.1) is shown to have little effect on the results. A Hubble diagram is presented for the NIR bands and the B band. The resulting scatter for the combined NIR bands is 0.13 mag, while the B band produces a scatter of 0.22 mag. Finally, we find evidence for a bimodal distribution in the NIR absolute magnitudes of fast-declining SNe Ia [Delta m(15)(B) > 1.7]. These data suggest that applying a correction to SNe Ia peak luminosities for decline rate is likely to be beneficial in the J and H bands to make SNe Ia more precise distance indicators, but of only marginal importance in the Y band.

  • 11. Kessler, Richard
    et al.
    Bassett, Bruce
    Belov, Pavel
    Bhatnagar, Vasudha
    Campbell, Heather
    Conley, Alex
    Frieman, Joshua A.
    Glazov, Alexandre
    Gonzalez-Gaitan, Santiago
    Hlozek, Renee
    Jha, Saurabh
    Kuhlmann, Stephen
    Kunz, Martin
    Lampeitl, Hubert
    Mahabal, Ashish
    Newling, James
    Nichol, Robert C.
    Parkinson, David
    Philip, Ninan Sajeeth
    Poznanski, Dovi
    Richards, Joseph W.
    Rodney, Steven A.
    Sako, Masao
    Schneider, Donald P.
    Smith, Mathew
    Stritzinger, Maximilian
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Varughese, Melvin
    Results from the Supernova Photometric Classification Challenge2010In: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 122, no 898, p. 1415-1431Article in journal (Refereed)
    Abstract [en]

    We report results from the Supernova Photometric Classification Challenge (SNPhotCC), a publicly released mix of simulated supernovae (SNe), with types (Ia, Ibc, and II) selected in proportion to their expected rates. The simulation was realized in the griz filters of the Dark Energy Survey (DES) with realistic observing conditions (sky noise, point-spread function, and atmospheric transparency) based on years of recorded conditions at the DES site. Simulations of non-Ia-type SNe are based on spectroscopically confirmed light curves that include unpublished non-Ia samples donated from the Carnegie Supernova Project (CSP), the Supernova Legacy Survey (SNLS), and the Sloan Digital Sky Survey-II (SDSS-II). A spectroscopically confirmed subset was provided for training. We challenged scientists to run their classification algorithms and report a type and photo-z for each SN. Participants from 10 groups contributed 13 entries for the sample that included a host-galaxy photo-z for each SN and nine entries for the sample that had no redshift information. Several different classification strategies resulted in similar performance, and for all entries the performance was significantly better for the training subset than for the unconfirmed sample. For the spectroscopically unconfirmed subset, the entry with the highest average figure of merit for classifying SNe Ia has an efficiency of 0.96 and an SN Ia purity of 0.79. As a public resource for the future development of photometric SN classification and photo-z estimators, we have released updated simulations with improvements based on our experience from the SNPhotCC, added samples corresponding to the Large Synoptic Survey Telescope (LSST) and the SDSS-II, and provided the answer keys so that developers can evaluate their own analysis.

  • 12. Mahabal, Ashish
    et al.
    Rebbapragada, Umaa
    Walters, Richard
    Masci, Frank J.
    Blagorodnova, Nadejda
    van Roestel, Jan
    Ye, Quan-Zhi
    Biswas, Rahul
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Burdge, Kevin
    Chang, Chan-Kao
    Duev, Dmitry A.
    Golkhou, V. Zach
    Miller, Adam A.
    Nordin, Jakob
    Ward, Charlotte
    Adams, Scott
    Bellm, Eric C.
    Branton, Doug
    Bue, Brian
    Cannella, Chris
    Connolly, Andrew
    Dekany, Richard
    Feindt, Ulrich
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hung, Tiara
    Fortson, Lucy
    Frederick, Sara
    Fremling, C.
    Gezari, Suvi
    Graham, Matthew
    Groom, Steven
    Kasliwal, Mansi M.
    Kulkarni, Shrinivas
    Kupfer, Thomas
    Lin, Hsing Wen
    Lintott, Chris
    Lunnan, Ragnhild
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Parejko, John
    Prince, Thomas A.
    Riddle, Reed
    Rusholme, Ben
    Saunders, Nicholas
    Sedaghat, Nima
    Shupe, David L.
    Singer, Leo P.
    Soumagnac, Maayane T.
    Szkody, Paula
    Tachibana, Yutaro
    Tirumala, Kushal
    van Velzen, Sjoert
    Wright, Darryl
    Machine Learning for the Zwicky Transient Facility2019In: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 131, no 997, article id 038002Article in journal (Refereed)
    Abstract [en]

    The Zwicky Transient Facility is a large optical survey in multiple filters producing hundreds of thousands of transient alerts per night. We describe here various machine learning (ML) implementations and plans to make the maximal use of the large data set by taking advantage of the temporal nature of the data, and further combining it with other data sets. We start with the initial steps of separating bogus candidates from real ones, separating stars and galaxies, and go on to the classification of real objects into various classes. Besides the usual methods (e.g., based on features extracted from light curves) we also describe early plans for alternate methods including the use of domain adaptation, and deep learning. In a similar fashion we describe efforts to detect fast moving asteroids. We also describe the use of the Zooniverse platform for helping with classifications through the creation of training samples, and active learning. Finally we mention the synergistic aspects of ZTF and LSST from the ML perspective.

  • 13. Phillips, M. M.
    et al.
    Contreras, Carlos
    Hsiao, E. Y.
    Morrell, Nidia
    Burns, Christopher R.
    Stritzinger, Maximilian
    Ashall, C.
    Freedman, Wendy L.
    Hoeflich, P.
    Persson, S. E.
    Piro, Anthony L.
    Suntzeff, Nicholas B.
    Uddin, Syed A.
    Anais, Jorge
    Baron, E.
    Busta, Luis
    Campillay, Abdo
    Castellon, Sergio
    Corco, Carlos
    Diamond, T.
    Gall, Christa
    Gonzalez, Consuelo
    Holmbo, Simon
    Krisciunas, Kevin
    Roth, Miguel
    Seron, Jacqueline
    Taddia, Francesco
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Torres, Simon
    Anderson, J. P.
    Baltay, C.
    Folatelli, Gaston
    Galbany, L.
    Goobar, Ariel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hadjiyska, Ellie
    Hamuy, Mario
    Kasliwal, Mansi
    Lidman, C.
    Nugent, Peter E.
    Perlmutter, S.
    Rabinowitz, David
    Ryder, Stuart D.
    Schmidt, Brian P.
    Shappee, B. J.
    Walker, Emma S.
    Carnegie Supernova Project-II: Extending the Near-infrared Hubble Diagram for Type Ia Supernovae to z similar to 0.12019In: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 131, no 995, article id 014001Article in journal (Refereed)
    Abstract [en]

    The Carnegie Supernova Project-II (CSP-II) was an NSF-funded, four-year program to obtain optical and near-infrared observations of a Cosmology sample of similar to 100 Type. Ia supernovae located in the smooth Hubble flow (0.03 less than or similar to z less than or similar to 0.10). Light curves were also obtained of a Physics sample composed of 90 nearby Type. Ia supernovae at z <= 0.04 selected for near-infrared spectroscopic timeseries observations. The primary emphasis of the CSP-II is to use the combination of optical and near-infrared photometry to achieve a distance precision of better than 5%. In this paper, details of the supernova sample, the observational strategy, and the characteristics of the photometric data are provided. In a companion paper, the near-infrared spectroscopy component of the project is presented.

  • 14. Sako, Masao
    et al.
    Bassett, Bruce
    Becker, Andrew C.
    Brown, Peter J.
    Campbell, Heather
    Wolf, Rachel
    Cinabro, David
    D'Andrea, Chris B.
    Dawson, Kyle S.
    DeJongh, Fritz
    Depoy, Darren L.
    Dilday, Ben
    Doi, Mamoru
    Filippenko, Alexei V.
    Fischer, John A.
    Foley, Ryan J.
    Frieman, Joshua A.
    Galbany, Lluis
    Garnavich, Peter M.
    Goobar, Ariel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Gupta, Ravi R.
    Hill, Gary J.
    Hayden, Brian T.
    Hlozek, Renee
    Holtzman, Jon A.
    Hopp, Ulrich
    Jha, Saurabh W.
    Kessler, Richard
    Kollatschny, Wolfram
    Leloudas, Giorgos
    Marriner, John
    Marshall, Jennifer L.
    Miquel, Ramon
    Morokuma, Tomoki
    Mosher, Jennifer
    Nichol, Robert C.
    Nordin, Jakob
    Olmstead, Matthew D.
    Östman, Linda
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Prieto, Jose L.
    Richmond, Michael
    Romani, Roger W.
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Stritzinger, Max
    Schneider, Donald P.
    Smith, Mathew
    Wheeler, J. Craig
    Yasuda, Naoki
    Zheng, Chen
    The Data Release of the Sloan Digital Sky Survey-II Supernova Survey2018In: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 130, no 988, article id 064002Article in journal (Refereed)
    Abstract [en]

    This paper describes the data release of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey conducted between 2005 and 2007. Light curves, spectra, classifications, and ancillary data are presented for 10,258 variable and transient sources discovered through repeat ugriz imaging of SDSS Stripe 82, a 300 deg(2) area along the celestial equator. This data release is comprised of all transient sources brighter than r similar or equal to 22.5 mag with no history of variability prior to 2004. Dedicated spectroscopic observations were performed on a subset of 889 transients, as well as spectra for thousands of transient host galaxies using the SDSS-III BOSS spectrographs. Photometric classifications are provided for the candidates with good multi-color light curves that were not observed spectroscopically, using host galaxy redshift information when available. From these observations, 4607 transients are either spectroscopically confirmed, or likely to be, supernovae, making this the largest sample of supernova candidates ever compiled. We present a new method for SN host-galaxy identification and derive host-galaxy properties including stellar masses, star formation rates, and the average stellar population ages from our SDSS multi-band photometry. We derive SALT2 distance moduli for a total of 1364 SN. Ia with spectroscopic redshifts as well as photometric redshifts for a further 624 purely photometric SN. Ia candidates. Using the spectroscopically confirmed subset of the three-year SDSS-II SN. Ia sample and assuming a flat.CDM cosmology, we determine Omega(M) = 0.315 +/- 0.093 (statistical error only) and detect a non-zero cosmological constant at 5.7 sigma.

  • 15. van Dishoeck, E. F.
    et al.
    Kristensen, L. E.
    Benz, A. O.
    Bergin, E. A.
    Caselli, P.
    Cernicharo, J.
    Herpin, F.
    Hogerheijde, M. R.
    Johnstone, D.
    Liseau, R.
    Nisini, B.
    Shipman, R.
    Tafalla, M.
    van der Tak, F.
    Wyrowski, F.
    Aikawa, Y.
    Bachiller, R.
    Baudry, A.
    Benedettini, M.
    Bjerkeli, P.
    Blake, G. A.
    Bontemps, S.
    Braine, J.
    Brinch, C.
    Bruderer, S.
    Chavarria, L.
    Codella, C.
    Daniel, F.
    de Graauw, Th.
    Deul, E.
    di Giorgio, A. M.
    Dominik, C.
    Doty, S. D.
    Dubernet, M. L.
    Encrenaz, P.
    Feuchtgruber, H.
    Fich, M.
    Frieswijk, W.
    Fuente, A.
    Giannini, T.
    Goicoechea, J. R.
    Helmich, F. P.
    Herczeg, G. J.
    Jacq, T.
    Jorgensen, J. K.
    Karska, A.
    Kaufman, M. J.
    Keto, E.
    Larsson, Bengt
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lefloch, B.
    Lis, D.
    Marseille, M.
    McCoey, C.
    Melnick, G.
    Neufeld, D.
    Olberg, M.
    Pagani, L.
    Panic, O.
    Parise, B.
    Pearson, J. C.
    Plume, R.
    Risacher, C.
    Salter, D.
    Santiago-Garcia, J.
    Saraceno, P.
    Staeuber, P.
    van Kempen, T. A.
    Visser, R.
    Viti, S.
    Walmsley, M.
    Wampfler, S. F.
    Yildiz, U. A.
    Water in Star-forming Regions with the Herschel Space Observatory (WISH). I. Overview of Key Program and First Results2011In: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 123, no 900, p. 138-170Article in journal (Refereed)
    Abstract [en]

    Water In Star-forming regions with Herschel (WISH) is a key program on the Herschel Space Observatory designed to probe the physical and chemical structures of young stellar objects using water and related molecules and to follow the water abundance from collapsing clouds to planet-forming disks. About 80 sources are targeted, covering a wide ranee of luminosities-from low (< 1 L(circle dot)) to high (> 10(5) L(circle dot))-and a wide range of evolutionary stages-from cold prestellar cores to warm protostellar envelopes and outflows to disks around young stars. Both the HIFI and PACS instruments are used to observe a variety of lines of H(2)O, H(2)(18)O and chemically related species at the source position and in small maps around the protostars and selected outflow positions. In addition, high-frequency lines of CO, (13)CO, and C(18)O are obtained with Herschel and are complemented by ground-based observations of dust continuum, HDO, CO and its isotopologs, and other molecules to ensure a self-consistent data set for analysis. An overview of the scientific motivation and observational strategy of the program is given, together with the modeling approach and analysis tools that have been developed. Initial science results are presented. These include a lack of water in cold gas at abundances that are lower than most predictions, strong water emission from shocks in protostellar environments, the importance of UV radiation in heating the gas along outflow walls across the full range of luminosities, and surprisingly widespread detection of the chemically related hydrides OH(+) and H(2)O(+) in outflows and foreground gas. Quantitative estimates of the energy budget indicate that H(2)O is generally not the dominant coolant in the warm dense gas associated with protostars. Very deep limits on the cold gaseous water reservoir in the outer regions of protoplanetary disks are obtained that have profound implications for our understanding of grain growth and mixing in disks.

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