Astrophotonics will be central to the next generation of astronomical instrumentation, enabling lightweight, compact, and environmentally stable photonic integrated circuits for both ground-based observatories and future space missions. One key application is beam combination for nulling interferometry, which suppresses starlight to reveal exoplanets and companions. Compact, broadband photonic beam combiners are essential for enabling complex circuitry on a single chip and for scalable solutions for single- and multi-telescope instruments, and are investigated herein. Two-waveguide photonic combiners rely on symmetric evanescent coupling to interfere light, which is inherently chromatic and requires modification for broadband operation. A three-waveguide configuration, or tri-coupler, offers the potential for deeper, broader, and more stable achromatic nulls compared with two-waveguide approaches. This work compares the simulated performance of two evanescent tri-couplers and a multimode interference coupler (MMI) across the 1.5–1.8 µm band, evaluating exoplanet throughput, starlight attenuation, sensing characteristics, and estimations on fabrication tolerance. All three tri-couplers achieved >40 dB attenuation over a ≥270 nm bandwidth. However, the standard tri-coupler was outperformed by both a bespoke tapered tri-coupler and the MMI, each of which achieved exoplanet throughput >85% across the band, excluding component losses. Including component loss, the tapered tri-coupler has the highest total throughput, averaging ∼96%. The standard tri-coupler began with an equivalent exoplanet throughput, falling to 50% at the band edges. The tapered tri-coupler was further redesigned to achieve a non-degenerate sensing state. The MMI, while limited to a starlight attenuation of 40 dB (10−4) by uncoupled light, showed the greatest tolerance to fabrication errors, offering strong practical potential. Future designs aim to combine high exoplanet throughput, deep starlight attenuation, and non-degenerate sensing within a single integrated architecture. This work provides a simulation suite for three tri-couplers. They can be selected based on robustness to common fabrication tolerances (the MMI), exoplanet throughput (the tapered tri-coupler), and/or the sensing performance (the tapered tri-coupler).
\nThe photonic lantern nuller (PLN) is an instrument concept designed to characterize exoplanets within a single beam width from its host star. The PLN leverages the spatial symmetry of a mode-selective photonic lantern to create nulled ports, which cancel out on-axis starlight but allow off-axis exoplanet light to couple. The null depths are limited by wavefront aberrations in the system as well as by imperfections in the lantern. We show that the implicit electric field conjugation (iEFC) algorithm can be used to reduce the stellar coupling through the PLN by orders of magnitude while maintaining the majority of the off-axis light, leading to deeper null depths (∼10\u207b\u2074) and thus higher sensitivity to potential planet signals. We discuss a theory for the tradeoff we observed among the different ports, where iEFC improves the nulls of some ports at the expense of others, and show that targeting one port alone can lead to deeper starlight rejection through that port than when targeting all ports at once. We also observe different levels of stability depending on the port and discuss the implications of practically implementing this technique for scientific observations.
", "doi": "10.1117/1.jatis.11.2.025004", "issn": "2329-4124", "publisher": "SPIE-Intl Soc Optical Eng", "publication": "Journal of Astronomical Telescopes, Instruments, and Systems", "publication_date": "2025-05", "series_number": "02", "volume": "11", "issue": "02", "pages": "025004" }, { "id": "authors:bbnt6-sag19", "collection": "authors", "collection_id": "bbnt6-sag19", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190802-094555948", "type": "article", "title": "GROWTH on S190425z: Searching Thousands of Square Degrees to Identify an Optical or Infrared Counterpart to a Binary Neutron Star Merger with the Zwicky Transient Facility and Palomar Gattini-IR", "author": [ { "family_name": "Coughlin", "given_name": "Michael W.", "orcid": "0000-0002-8262-2924", "clpid": "Coughlin-M-W" }, { "family_name": "Ahumada", "given_name": "Tom\u00e1s", "orcid": "0000-0002-2184-6430", "clpid": "Ahumada-T" }, { "family_name": "Anand", "given_name": "Shreya", "orcid": "0000-0003-3768-7515", "clpid": "Anand-Shreya" }, { "family_name": "De", "given_name": "Kishalay", "orcid": "0000-0002-8989-0542", "clpid": "De-Kishalay" }, { "family_name": "Hankins", "given_name": "Matthew J.", "orcid": "0000-0001-9315-8437", "clpid": "Hankins-M-J" }, { "family_name": "Kasliwal", "given_name": "Mansi M.", "orcid": "0000-0002-5619-4938", "clpid": "Kasliwal-M-M" }, { "family_name": "Singer", "given_name": "Leo P.", "orcid": "0000-0001-9898-5597", "clpid": "Singer-L-P" }, { "family_name": "Bellm", "given_name": "Eric C.", "orcid": "0000-0001-8018-5348", "clpid": "Bellm-E-C" }, { "family_name": "Andreoni", "given_name": "Igor", "orcid": "0000-0002-8977-1498", "clpid": "Andreoni-I" }, { "family_name": "Cenko", "given_name": "S. Bradley", "orcid": "0000-0003-1673-970X", "clpid": "Cenko-S-B" }, { "family_name": "Cooke", "given_name": "Jeff", "orcid": "0000-0001-5703-2108", "clpid": "Cooke-J" }, { "family_name": "Copperwheat", "given_name": "Christopher M.", "orcid": "0000-0001-7983-8698", "clpid": "Copperwheat-C-M" }, { "family_name": "Dugas", "given_name": "Alison M.", "clpid": "Dugas-A-M" }, { "family_name": "Jencson", "given_name": "Jacob E.", "orcid": "0000-0001-5754-4007", "clpid": "Jencson-J-E" }, { "family_name": "Perley", "given_name": "Daniel A.", "orcid": "0000-0001-8472-1996", "clpid": "Perley-D-A" }, { "family_name": "Yu", "given_name": "Po-Chieh", "orcid": "0000-0001-8894-0854", "clpid": "Yu-Po-Chieh" }, { "family_name": "Bhalerao", "given_name": "Varun", "orcid": "0000-0002-6112-7609", "clpid": "Bhalerao-V-B" }, { "family_name": "Kumar", "given_name": "Harsh", "clpid": "Kumar-Harsh" }, { "family_name": "Bloom", "given_name": "Joshua S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Anupama", "given_name": "G. C.", "clpid": "Anupama-G-C" }, { "family_name": "Ashley", "given_name": "Michael C. B.", "orcid": "0000-0003-1412-2028", "clpid": "Ashley-M-C-B" }, { "family_name": "Bagdasaryan", "given_name": "Ashot", "clpid": "Bagdasaryan-A" }, { "family_name": "Biswas", "given_name": "Rahul", "orcid": "0000-0002-5741-7195", "clpid": "Biswas-R" }, { "family_name": "Buckley", "given_name": "David A. H.", "orcid": "0000-0002-7004-9956", "clpid": "Buckley-D-A-H" }, { "family_name": "Burdge", "given_name": "Kevin B.", "orcid": "0000-0002-7226-836X", "clpid": "Burdge-K-B" }, { "family_name": "Cook", "given_name": "David O.", "orcid": "0000-0002-6877-7655", "clpid": "Cook-D-O" }, { "family_name": "Cromer", "given_name": "John", "clpid": "Cromer-J-L" }, { "family_name": "Cunningham", "given_name": "Virginia", "orcid": "0000-0003-2292-0441", "clpid": "Cunningham-V" }, { "family_name": "D'A\u00ec", "given_name": "Antonino", "orcid": "0000-0002-5042-1036", "clpid": "D'A\u00ec-Antonio" }, { "family_name": "Dekany", "given_name": "Richard G.", "clpid": "Dekany-Richard" }, { "family_name": "Delacroix", "given_name": "Alexandre", "clpid": "Delacroix-A" }, { "family_name": "Dichiara", "given_name": "Simone", "clpid": "Dichiara-S" }, { "family_name": "Duev", "given_name": "Dmitry A.", "orcid": "0000-0001-5060-8733", "clpid": "Duev-D-A" }, { "family_name": "Dutta", "given_name": "Anirban", "clpid": "Dutta-A" }, { "family_name": "Feeney", "given_name": "Michael", "clpid": "Feeney-M-E" }, { "family_name": "Frederick", "given_name": "Sara", "orcid": "0000-0001-9676-730X", "clpid": "Frederick-S" }, { "family_name": "Gatkine", "given_name": "Pradip", "orcid": "0000-0002-1955-2230", "clpid": "Gatkine-P" }, { "family_name": "Ghosh", "given_name": "Shaon", "orcid": "0000-0001-9901-6253", "clpid": "Ghosh-Shaon" }, { "family_name": "Goldstein", "given_name": "Daniel A.", "orcid": "0000-0003-3461-8661", "clpid": "Goldstein-D-A" }, { "family_name": "Golkhou", "given_name": "V. Zach", "orcid": "0000-0001-8205-2506", "clpid": "Golkhou-V-Z" }, { "family_name": "Goobar", "given_name": "Ariel", "orcid": "0000-0002-4163-4996", "clpid": "Goobar-A" }, { "family_name": "Graham", "given_name": "Matthew J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Hanayama", "given_name": "Hidekazu", "orcid": "0000-0001-8221-6048", "clpid": "Hanayama-Hidekazu" }, { "family_name": "Horiuchi", "given_name": "Takashi", "clpid": "Horiuchi-Takashi" }, { "family_name": "Hung", "given_name": "Tiara", "orcid": "0000-0002-9878-7889", "clpid": "Hung-Tiara" }, { "family_name": "Jha", "given_name": "Saurabh W.", "orcid": "0000-0001-8738-6011", "clpid": "Jha-S-W" }, { "family_name": "Kong", "given_name": "Albert K. H.", "orcid": "0000-0002-5105-344X", "clpid": "Kong-Albert-K-H" }, { "family_name": "Giomi", "given_name": "Matteo", "clpid": "Giomi-M" }, { "family_name": "Kaplan", "given_name": "David L.", "orcid": "0000-0001-6295-2881", "clpid": "Kaplan-D-L" }, { "family_name": "Karambelkar", "given_name": "V. R.", "clpid": "Karambelkar-V-R" }, { "family_name": "Kowalski", "given_name": "Marek", "clpid": "Kowalski-M" }, { "family_name": "Kulkarni", "given_name": "Shrinivas R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Kupfer", "given_name": "Thomas", "orcid": "0000-0002-6540-1484", "clpid": "Kupfer-T" }, { "family_name": "Masci", "given_name": "Frank J.", "orcid": "0000-0002-8532-9395", "clpid": "Masci-F-J" }, { "family_name": "Mazzali", "given_name": "Paolo", "orcid": "0000-0001-6876-8284", "clpid": "Mazzali-P-A" }, { "family_name": "Moore", "given_name": "Anna M.", "orcid": "0000-0002-2894-6936", "clpid": "Moore-A-M" }, { "family_name": "Mogotsi", "given_name": "Moses", "clpid": "Mogotsi-M" }, { "family_name": "Neill", "given_name": "James D.", "orcid": "0000-0002-0466-1119", "clpid": "Neill-J-D" }, { "family_name": "Ngeow", "given_name": "Chow-Choong", "orcid": "0000-0001-8771-7554", "clpid": "Ngeow-Chow-Choong" }, { "family_name": "Mart\u00ednez-Palomera", "given_name": "Jorge", "orcid": "0000-0002-7395-4935", "clpid": "Mart\u00ednez-Palomera-J" }, { "family_name": "La Parola", "given_name": "Valentina", "orcid": "0000-0002-8087-6488", "clpid": "La-Parola-V" }, { "family_name": "Pavana", "given_name": "M.", "orcid": "0000-0002-0000-1543", "clpid": "Pavana-M" }, { "family_name": "Ofek", "given_name": "Eran O.", "orcid": "0000-0002-6786-8774", "clpid": "Ofek-E-O" }, { "family_name": "Patil", "given_name": "Atharva Sunil", "clpid": "Patil-A-S" }, { "family_name": "Riddle", "given_name": "Reed", "orcid": "0000-0002-0387-370X", "clpid": "Riddle-R-L" }, { "family_name": "Rigault", "given_name": "Mickael", "orcid": "0000-0002-8121-2560", "clpid": "Rigault-M" }, { "family_name": "Rusholme", "given_name": "Ben", "orcid": "0000-0001-7648-4142", "clpid": "Rusholme-B" }, { "family_name": "Serabyn", "given_name": "Eugene", "clpid": "Serabyn-E" }, { "family_name": "Shupe", "given_name": "David L.", "orcid": "0000-0003-4401-0430", "clpid": "Shupe-David-L" }, { "family_name": "Sharma", "given_name": "Yashvi", "clpid": "Sharma-Y" }, { "family_name": "Singh", "given_name": "Avinash", "clpid": "Singh-Avinash" }, { "family_name": "Sollerman", "given_name": "Jesper", "orcid": "0000-0003-1546-6615", "clpid": "Sollerman-J" }, { "family_name": "Soon", "given_name": "Jamie", "clpid": "Soon-Jamie" }, { "family_name": "Staats", "given_name": "Kai", "clpid": "Staats-K" }, { "family_name": "Taggart", "given_name": "Kirsty", "orcid": "0000-0002-5748-4558", "clpid": "Taggart-K" }, { "family_name": "Tan", "given_name": "Hanjie", "clpid": "Tan-Hanjie" }, { "family_name": "Travouillon", "given_name": "Tony", "clpid": "Travouillon-T-D" }, { "family_name": "Troja", "given_name": "Eleonora", "orcid": "0000-0002-1869-7817", "clpid": "Troja-E" }, { "family_name": "Waratkar", "given_name": "Gaurav", "orcid": "0000-0003-3630-9440", "clpid": "Waratkar-G" }, { "family_name": "Yatsu", "given_name": "Yoichi", "orcid": "0000-0003-1890-3913", "clpid": "Yatsu-Yoichi" } ], "abstract": "The third observing run by LVC has brought the discovery of many compact binary coalescences. Following the detection of the first binary neutron star merger in this run (LIGO/Virgo S190425z), we performed a dedicated follow-up campaign with the Zwicky Transient Facility (ZTF) and Palomar Gattini-IR telescopes. The initial skymap of this single-detector gravitational wave (GW) trigger spanned most of the sky observable from Palomar Observatory. Covering 8000 deg\u00b2 of the initial skymap over the next two nights, corresponding to 46% integrated probability, ZTF system achieved a depth of \u224821 m_(AB) in g- and r-bands. Palomar Gattini-IR covered 2200 square degrees in J-band to a depth of 15.5 mag, including 32% integrated probability based on the initial skymap. The revised skymap issued the following day reduced these numbers to 21% for the ZTF and 19% for Palomar Gattini-IR. We narrowed 338,646 ZTF transient \"alerts\" over the first two nights of observations to 15 candidate counterparts. Two candidates, ZTF19aarykkb and ZTF19aarzaod, were particularly compelling given that their location, distance, and age were consistent with the GW event, and their early optical light curves were photometrically consistent with that of kilonovae. These two candidates were spectroscopically classified as young core-collapse supernovae. The remaining candidates were ruled out as supernovae. Palomar Gattini-IR did not identify any viable candidates with multiple detections only after merger time. We demonstrate that even with single-detector GW events localized to thousands of square degrees, systematic kilonova discovery is feasible.", "doi": "10.3847/2041-8213/ab4ad8", "issn": "2041-8213", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "2019-11-01", "series_number": "1", "volume": "885", "issue": "1", "pages": "Art. No. L19" }, { "id": "authors:tr1t6-kgt55", "collection": "authors", "collection_id": "tr1t6-kgt55", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190619-081420386", "type": "article", "title": "GROWTH on S190510g: DECam Observation Planning and Follow-Up of a Distant Binary Neutron Star Merger Candidate", "author": [ { "family_name": "Andreoni", "given_name": "Igor", "orcid": "0000-0002-8977-1498", "clpid": "Andreoni-I" }, { "family_name": "Goldstein", "given_name": "Daniel A.", "orcid": "0000-0003-3461-8661", "clpid": "Goldstein-D-A" }, { "family_name": "Anand", "given_name": "Shreya", "orcid": "0000-0003-3768-7515", "clpid": "Anand-Shreya" }, { "family_name": "Coughlin", "given_name": "Michael W.", "orcid": "0000-0002-8262-2924", "clpid": "Coughlin-M-W" }, { "family_name": "Singer", "given_name": "Leo P.", "orcid": "0000-0001-9898-5597", "clpid": "Singer-L-P" }, { "family_name": "Ahumada", "given_name": "Tom\u00e1s", "orcid": "0000-0002-2184-6430", "clpid": "Ahumada-T" }, { "family_name": "Medford", "given_name": "Michael", "orcid": "0000-0002-7226-0659", "clpid": "Medford-M" }, { "family_name": "Kool", "given_name": "Erik C.", "orcid": "0000-0002-7252-3877", "clpid": "Kool-E-C" }, { "family_name": "Webb", "given_name": "Sara", "orcid": "0000-0003-2601-1472", "clpid": "Webb-S" }, { "family_name": "Bulla", "given_name": "Mattia", "orcid": "0000-0002-8255-5127", "clpid": "Bulla-M" }, { "family_name": "Bloom", "given_name": "Joshua S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Kasliwal", "given_name": "Mansi M.", "orcid": "0000-0002-5619-4938", "clpid": "Kasliwal-M-M" }, { "family_name": "Nugent", "given_name": "Peter E.", "orcid": "0000-0002-3389-0586", "clpid": "Nugent-P-E" }, { "family_name": "Bagdasaryan", "given_name": "Ashot", "clpid": "Bagdasaryan-A" }, { "family_name": "Barnes", "given_name": "Jennifer", "orcid": "0000-0003-3340-4784", "clpid": "Barnes-J" }, { "family_name": "Cook", "given_name": "David O.", "orcid": "0000-0002-6877-7655", "clpid": "Cook-D-O" }, { "family_name": "Cooke", "given_name": "Jeff", "orcid": "0000-0001-5703-2108", "clpid": "Cooke-J" }, { "family_name": "Duev", "given_name": "Dmitry A.", "orcid": "0000-0001-5060-8733", "clpid": "Duev-D-A" }, { "family_name": "Fremling", "given_name": "U. Christoffer", "orcid": "0000-0002-4223-103X", "clpid": "Fremling-C" }, { "family_name": "Gatkine", "given_name": "Pradip", "orcid": "0000-0002-1955-2230", "clpid": "Gatkine-P" }, { "family_name": "Golkhou", "given_name": "V. Zach", "orcid": "0000-0001-8205-2506", "clpid": "Golkhou-V-Z" }, { "family_name": "Kong", "given_name": "Albert K. H.", "orcid": "0000-0002-5105-344X", "clpid": "Kong-Albert-K-H" }, { "family_name": "Mahabal", "given_name": "Ashish", "orcid": "0000-0003-2242-0244", "clpid": "Mahabal-A-A" }, { "family_name": "Mart\u00ednez-Palomera", "given_name": "Jorge", "orcid": "0000-0002-7395-4935", "clpid": "Mart\u00ednez-Palomera-J" }, { "family_name": "Tao", "given_name": "Duo", "clpid": "Tao-Duo" }, { "family_name": "Zhang", "given_name": "Keming", "orcid": "0000-0002-9870-5695", "clpid": "Zhang-Keming" } ], "abstract": "The first two months of the third Advanced LIGO and Virgo observing run (2019 April\u2013May) showed that distant gravitational-wave (GW) events can now be readily detected. Three candidate mergers containing neutron stars (NS) were reported in a span of 15 days, all likely located more than 100 Mpc away. However, distant events such as the three new NS mergers are likely to be coarsely localized, which highlights the importance of facilities and scheduling systems that enable deep observations over hundreds to thousands of square degrees to detect the electromagnetic counterparts. On 2019 May 10 02:59:39.292 UT the GW candidate S190510g was discovered and initially classified as a binary neutron star (BNS) merger with 98% probability. The GW event was localized within an area of 3462 deg^2, later refined to 1166 deg^2 (90%) at a distance of 227 \u00b1 92 Mpc. We triggered Target-of-Opportunity observations with the Dark Energy Camera (DECam), a wide-field optical imager mounted at the prime focus of the 4 m Blanco Telescope at Cerro Tololo Inter-American Observatory in Chile. This Letter describes our DECam observations and our real-time analysis results, focusing in particular on the design and implementation of the observing strategy. Within 24 hr of the merger time, we observed 65% of the total enclosed probability of the final skymap with an observing efficiency of 94%. We identified and publicly announced 13 candidate counterparts. S190510g was reclassified 1.7 days after the merger, after our observations were completed, with a \"BNS merger\" probability reduced from 98% to 42% in favor of a \"terrestrial classification.", "doi": "10.3847/2041-8213/ab3399", "issn": "2041-8213", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "2019-08-10", "series_number": "1", "volume": "881", "issue": "1", "pages": "Art. No. L16" }, { "id": "authors:qzyxt-zw549", "collection": "authors", "collection_id": "qzyxt-zw549", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190617-141803504", "type": "article", "title": "GROWTH on S190426c: Real-time Search for a Counterpart to the Probable Neutron Star\u2013Black Hole Merger using an Automated Difference Imaging Pipeline for DECam", "author": [ { "family_name": "Goldstein", "given_name": "Daniel A.", "orcid": "0000-0003-3461-8661", "clpid": "Goldstein-D-A" }, { "family_name": "Andreoni", "given_name": "Igor", "orcid": "0000-0002-8977-1498", "clpid": "Andreoni-I" }, { "family_name": "Nugent", "given_name": "Peter E.", "orcid": "0000-0002-3389-0586", "clpid": "Nugent-P-E" }, { "family_name": "Kasliwal", "given_name": "Mansi M.", "orcid": "0000-0002-5619-4938", "clpid": "Kasliwal-M-M" }, { "family_name": "Coughlin", "given_name": "Michael W.", "orcid": "0000-0002-8262-2924", "clpid": "Coughlin-M-W" }, { "family_name": "Anand", "given_name": "Shreya", "orcid": "0000-0003-3768-7515", "clpid": "Anand-Shreya" }, { "family_name": "Bloom", "given_name": "Joshua S.", "orcid": "0000-0002-7777-216X", "clpid": "Bloom-J-S" }, { "family_name": "Mart\u00ednez-Palomera", "given_name": "Jorge", "orcid": "0000-0002-7395-4935", "clpid": "Mart\u00ednez-Palomera-J" }, { "family_name": "Zhang", "given_name": "Keming", "orcid": "0000-0002-9870-5695", "clpid": "Zhang-Keming" }, { "family_name": "Ahumada", "given_name": "Tom\u00e1s", "orcid": "0000-0002-2184-6430", "clpid": "Ahumada-T" }, { "family_name": "Bagdasaryan", "given_name": "Ashot", "clpid": "Bagdasaryan-A" }, { "family_name": "Cooke", "given_name": "Jeff", "orcid": "0000-0001-5703-2108", "clpid": "Cooke-J" }, { "family_name": "De", "given_name": "Kishalay", "orcid": "0000-0002-8989-0542", "clpid": "De-Kishalay" }, { "family_name": "Duev", "given_name": "Dmitry A.", "orcid": "0000-0001-5060-8733", "clpid": "Duev-D-A" }, { "family_name": "Fremling", "given_name": "U. Christoffer", "orcid": "0000-0002-4223-103X", "clpid": "Fremling-C" }, { "family_name": "Gatkine", "given_name": "Pradip", "orcid": "0000-0002-1955-2230", "clpid": "Gatkine-P" }, { "family_name": "Graham", "given_name": "Matthew", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Ofek", "given_name": "Eran O.", "orcid": "0000-0002-6786-8774", "clpid": "Ofek-E-O" }, { "family_name": "Singer", "given_name": "Leo P.", "orcid": "0000-0001-9898-5597", "clpid": "Singer-L-P" }, { "family_name": "Yan", "given_name": "Lin", "orcid": "0000-0003-1710-9339", "clpid": "Yan-Lin" } ], "abstract": "The discovery of a transient kilonova following the gravitational-wave (GW) event GW170817 highlighted the critical need for coordinated rapid and wide-field observations, inference, and follow-up across the electromagnetic spectrum. In the southern hemisphere, the Dark Energy Camera (DECam) on the Blanco 4 m telescope is well suited to this task, as it is able to cover wide fields quickly while still achieving the depths required to find kilonovae like the one accompanying GW170817 to ~500 Mpc, the binary neutron star (NS) horizon distance for current generation of LIGO/Virgo collaboration (LVC) interferometers. Here, as part of the multi-facility follow-up by the Global Relay of Observatories Watching Transients Happen collaboration, we describe the observations and automated data movement, data reduction, candidate discovery, and vetting pipeline of our target-of-opportunity DECam observations of S190426c, the first possible NS\u2013black hole merger detected in GWs. Starting 7.5 hr after S190426c, over 11.28 hr of observations, we imaged an area of 525 deg^2 (r band) and 437 deg^2 (z band); this was 16.3% of the total original localization probability, and nearly all of the probability visible from the southern hemisphere. The machine-learning-based pipeline was optimized for fast turnaround, delivering transients for human vetting within 17 minutes, on average, of shutter closure. We reported nine promising counterpart candidates 2.5 hr before the end of our observations. One hour after our data-taking ended (roughly 20 hr after the announcement of S190426c), LVC released a refined skymap that reduced the probability coverage of our observations to 8.0%, demonstrating a critical need for localization updates on shorter (~hour) timescales. Our observations yielded no detection of a bona fide counterpart to m_z = 21.7 and m_r = 22.2 at the 5\u03c3 level of significance, consistent with the refined LVC positioning. We view these observations and rapid inferencing as an important real-world test for this novel end-to-end wide-field pipeline.", "doi": "10.3847/2041-8213/ab3046", "issn": "2041-8213", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "2019-08-10", "series_number": "1", "volume": "881", "issue": "1", "pages": "Art. No. L7" }, { "id": "authors:177dx-hm503", "collection": "authors", "collection_id": "177dx-hm503", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190722-075111137", "type": "publication_whitepaper", "title": "Astro2020: Astrophotonics White Paper", "author": [ { "family_name": "Gatkine", "given_name": "Pradip", "orcid": "0000-0002-1955-2230", "clpid": "Gatkine-P" }, { "family_name": "Veilleux", "given_name": "Sylvain", "orcid": "0000-0002-3158-6820", "clpid": "Veilleux-S" }, { "family_name": "Mather", "given_name": "John", "clpid": "Mather-J-C" }, { "family_name": "Betters", "given_name": "Christopher", "clpid": "Betters-C" }, { "family_name": "Bland-Hawthorn", "given_name": "Jonathan", "orcid": "0000-0001-7516-4016", "clpid": "Bland-Hawthorn-J" }, { "family_name": "Bryant", "given_name": "Julia", "orcid": "0000-0003-1627-9301", "clpid": "Bryant-J-J" }, { "family_name": "Cenko", "given_name": "S. Bradley", "orcid": "0000-0003-1673-970X", "clpid": "Cenko-S-B" }, { "family_name": "Dagenais", "given_name": "Mario", "clpid": "Dagenais-M" }, { "family_name": "Deming", "given_name": "Drake", "orcid": "0000-0001-5727-4094", "clpid": "Deming-D" }, { "family_name": "Ellis", "given_name": "Simon", "clpid": "Ellis-S" }, { "family_name": "Greenhouse", "given_name": "Matthew", "clpid": "Greenhouse-M" }, { "family_name": "Harris", "given_name": "Andrew", "orcid": "0000-0001-6159-9174", "clpid": "Harris-A-I" }, { "family_name": "Jovanovic", "given_name": "Nemanja", "clpid": "Jovanovic-N" }, { "family_name": "Kuhlmann", "given_name": "Steve", "clpid": "Kuhlmann-S" }, { "family_name": "Kutyrev", "given_name": "Alexander", "orcid": "0000-0002-2715-8460", "clpid": "Kutyrev-A" }, { "family_name": "Leon-Saval", "given_name": "Sergio", "clpid": "Leon-Saval-S" }, { "family_name": "Madhav", "given_name": "Kalaga", "clpid": "Madhav-K" }, { "family_name": "Moseley", "given_name": "Samuel", "clpid": "Moseley-S-H" }, { "family_name": "Norris", "given_name": "Barnaby", "clpid": "Norris-B" }, { "family_name": "Rauscher", "given_name": "Bernard", "clpid": "Rauscher-B-J" }, { "family_name": "Roth", "given_name": "Martin", "clpid": "Roth-M" }, { "family_name": "Vogel", "given_name": "Stuart", "clpid": "Vogel-S-N" } ], "abstract": "Astrophotonics is the application of versatile photonic technologies to channel, manipulate, and disperse guided light from one or more telescopes to achieve scientific objectives in astronomy in an efficient and cost-effective way. The developments and demands from the telecommunication industry have driven a major boost in photonic technology and vice versa in the last 40 years. The photonic platform of guided light in fibers and waveguides has opened the doors to next-generation instrumentation for both ground- and space-based telescopes in optical and near/mid-IR bands, particularly for the upcoming extremely large telescopes (ELTs). The large telescopes are pushing the limits of adaptive optics to reach close to a near-diffraction-limited performance. The photonic devices are ideally suited for capturing this AO-corrected light and enabling new and exciting science such as characterizing exoplanet atmospheres. The purpose of this white paper is to summarize the current landscape of astrophotonic devices and their scientific impact, highlight the key issues, and outline specific technological and organizational approaches to address these issues in the coming decade and thereby enable new discoveries as we embark on the era of extremely large telescopes.", "doi": "10.48550/arXiv.1907.05904", "publisher": "arXiv", "publication_date": "2019-07-12" }, { "id": "authors:ak75k-t5750", "collection": "authors", "collection_id": "ak75k-t5750", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190618-090909587", "type": "article", "title": "Discovery of Highly Blueshifted Broad Balmer and Metastable Helium Absorption Lines in a Tidal Disruption Event", "author": [ { "family_name": "Hung", "given_name": "T.", "clpid": "Hung-T-K" }, { "family_name": "Cenko", "given_name": "S. B.", "orcid": "0000-0003-1673-970X", "clpid": "Cenko-S-B" }, { "family_name": "Roth", "given_name": "Nathaniel", "clpid": "Roth-N" }, { "family_name": "Gezari", "given_name": "S.", "orcid": "0000-0003-3703-5154", "clpid": "Gezari-S" }, { "family_name": "Veilleux", "given_name": "S.", "orcid": "0000-0002-3158-6820", "clpid": "Veilleux-S" }, { "family_name": "van Velzen", "given_name": "Sjoert", "orcid": "0000-0002-3859-8074", "clpid": "van-Velzen-S" }, { "family_name": "Gaskell", "given_name": "C. Martin", "clpid": "Gaskell-C-M" }, { "family_name": "Foley", "given_name": "Ryan J.", "clpid": "Foley-R-J" }, { "family_name": "Blagorodnova", "given_name": "N.", "orcid": "0000-0003-0901-1606", "clpid": "Blagorodnova-N" }, { "family_name": "Yan", "given_name": "Lin", "orcid": "0000-0003-1710-9339", "clpid": "Yan-Lin" }, { "family_name": "Graham", "given_name": "M. J.", "orcid": "0000-0002-3168-0139", "clpid": "Graham-M-J" }, { "family_name": "Brown", "given_name": "J. S.", "orcid": "0000-0002-1885-6419", "clpid": "Brown-J-S" }, { "family_name": "Siebert", "given_name": "M. R.", "clpid": "Siebert-M-R" }, { "family_name": "Frederick", "given_name": "Sara", "orcid": "0000-0001-9676-730X", "clpid": "Frederick-S" }, { "family_name": "Ward", "given_name": "Charlotte", "clpid": "Ward-C" }, { "family_name": "Gatkine", "given_name": "Pradip", "orcid": "0000-0002-1955-2230", "clpid": "Gatkine-P" }, { "family_name": "Gal-Yam", "given_name": "Avishay", "orcid": "0000-0002-3653-5598", "clpid": "Gal-Yam-A" }, { "family_name": "Yang", "given_name": "Yi", "clpid": "Yang-Yi" }, { "family_name": "Schulze", "given_name": "S.", "orcid": "0000-0001-6797-1889", "clpid": "Schulze-S" }, { "family_name": "Dimitriadis", "given_name": "G.", "clpid": "Dimitriadis-G" }, { "family_name": "Kupfer", "given_name": "Thomas", "orcid": "0000-0002-6540-1484", "clpid": "Kupfer-T" }, { "family_name": "Shupe", "given_name": "David L.", "orcid": "0000-0003-4401-0430", "clpid": "Shupe-David-L" }, { "family_name": "Rusholme", "given_name": "Ben", "orcid": "0000-0001-7648-4142", "clpid": "Rusholme-B" }, { "family_name": "Masci", "given_name": "Frank J.", "orcid": "0000-0002-8532-9395", "clpid": "Masci-F-J" }, { "family_name": "Riddle", "given_name": "Reed", "orcid": "0000-0002-0387-370X", "clpid": "Riddle-R-L" }, { "family_name": "Soumagnac", "given_name": "Maayane T.", "orcid": "0000-0001-6753-1488", "clpid": "Soumagnac-M-T" }, { "family_name": "van Roestel", "given_name": "J.", "orcid": "0000-0002-2626-2872", "clpid": "van-Roestel-J" }, { "family_name": "Dekany", "given_name": "Richard", "clpid": "Dekany-Richard" } ], "abstract": "We report the discovery of nonstellar hydrogen Balmer and metastable helium absorption lines accompanying a transient, high-velocity (0.05c) broad absorption line (BAL) system in the optical spectra of the tidal disruption event (TDE) AT2018zr (z = 0.071). In the Hubble Space Telescope UV spectra, absorption of high- and low-ionization lines is also present at this velocity, making AT2018zr resemble a low-ionization BALQSO. We conclude that these transient absorption features are more likely to arise in fast outflows produced by the TDE than absorbed by the unbound debris. In accordance with the outflow picture, we are able to reproduce the flat-topped H\u03b1 emission in a spherically expanding medium without invoking the typical prescription of an elliptical disk. We also report the appearance of narrow (~1000 kms^(\u22121)) N III \u03bb4640, He II \u03bb4686, H\u03b1, and H\u03b2 emission in the late-time optical spectra of AT2018zr, which may be a result of UV continuum hardening at late times, as observed by Swift. Including AT2018zr, we find a high association rate (three out of four) of BALs in the UV spectra of TDEs. This suggests that outflows may be ubiquitous among TDEs and less sensitive to viewing angle effects compared to QSO outflows.", "doi": "10.3847/1538-4357/ab24de", "issn": "1538-4357", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2019-07-10", "series_number": "2", "volume": "879", "issue": "2", "pages": "Art. No. 119" }, { "id": "authors:xh063-2en23", "collection": "authors", "collection_id": "xh063-2en23", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180910-104151114", "type": "article", "title": "A UV resonance line echo from a shell around a hydrogen-poor superluminous supernova", "author": [ { "family_name": "Lunnan", "given_name": "R.", "orcid": "0000-0001-9454-4639", "clpid": "Lunnan-R" }, { "family_name": "Fransson", "given_name": "C.", "orcid": "0000-0001-8532-3594", "clpid": "Fransson-C" }, { "family_name": "Vreeswijk", "given_name": "P. M.", "orcid": "0000-0002-7572-9088", "clpid": "Vreeswijk-P-M" }, { "family_name": "Woosley", "given_name": "S. E.", "clpid": "Woosley-S-E" }, { "family_name": "Leloudas", "given_name": "G.", "orcid": "0000-0002-8597-0756", "clpid": "Leloudas-G" }, { "family_name": "Perley", "given_name": "D. A.", "orcid": "0000-0001-8472-1996", "clpid": "Perley-D-A" }, { "family_name": "Quimby", "given_name": "R. M.", "orcid": "0000-0001-9171-5236", "clpid": "Quimby-R-M" }, { "family_name": "Yan", "given_name": "Lin", "orcid": "0000-0003-1710-9339", "clpid": "Yan-Lin" }, { "family_name": "Blagorodnova", "given_name": "N.", "orcid": "0000-0003-0901-1606", "clpid": "Blagorodnova-N" }, { "family_name": "Bue", "given_name": "B. D.", "orcid": "0000-0002-7856-3570", "clpid": "Bue-B-D" }, { "family_name": "Cenko", "given_name": "S. B.", "orcid": "0000-0003-1673-970X", "clpid": "Cenko-S-B" }, { "family_name": "De Cia", "given_name": "A.", "orcid": "0000-0003-2082-1626", "clpid": "De-Cia-A" }, { "family_name": "Cook", "given_name": "D. O.", "orcid": "0000-0002-6877-7655", "clpid": "Cook-D-O" }, { "family_name": "Fremling", "given_name": "C. U.", "orcid": "0000-0002-4223-103X", "clpid": "Fremling-C" }, { "family_name": "Gatkine", "given_name": "P.", "orcid": "0000-0002-1955-2230", "clpid": "Gatkine-P" }, { "family_name": "Gal-Yam", "given_name": "A.", "orcid": "0000-0002-3653-5598", "clpid": "Gal-Yam-A" }, { "family_name": "Kasliwal", "given_name": "M. M.", "orcid": "0000-0002-5619-4938", "clpid": "Kasliwal-M-M" }, { "family_name": "Kulkarni", "given_name": "S. R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Masci", "given_name": "F. J.", "orcid": "0000-0002-8532-9395", "clpid": "Masci-F-J" }, { "family_name": "Nugent", "given_name": "P. E.", "orcid": "0000-0002-3389-0586", "clpid": "Nugent-P-E" }, { "family_name": "Nyholm", "given_name": "A.", "clpid": "Nyholm-A" }, { "family_name": "Rubin", "given_name": "A.", "clpid": "Rubin-A-E" }, { "family_name": "Suzuki", "given_name": "N.", "clpid": "Suzuki-Naoyuki" }, { "family_name": "Wozniak", "given_name": "P.", "orcid": "0000-0002-9919-3310", "clpid": "Wo\u017aniak-P-R" } ], "abstract": "Hydrogen-poor superluminous supernovae (SLSN-I) are a class of rare and energetic explosions that have been discovered in untargeted transient surveys in the past decade. The progenitor stars and the physical mechanism behind their large radiated energies (about 10^(51)\u2009erg or 10^(44)\u2009J) are both debated, with one class of models primarily requiring a large rotational energy and the other requiring very massive progenitors that either convert kinetic energy into radiation through interaction with circumstellar material (CSM) or engender an explosion caused by pair-instability (loss of photon pressure due to particle\u2013antiparticle production). Observing the structure of the CSM around SLSN-I offers a powerful test of some scenarios, although direct observations are scarce. Here, we present a series of spectroscopic observations of the SLSN-I iPTF16eh, which reveal both absorption and time- and frequency-variable emission in the Mg IIresonance doublet. We show that these observations are naturally explained as a resonance scattering light echo from a circumstellar shell. Modelling the evolution of the emission, we infer a shell radius of 0.1\u2009pc and velocity of 3,300\u2009km\u2009s\u22121, implying that the shell was ejected three decades before the supernova explosion. These properties match theoretical predictions of shell ejections occurring because of pulsational pair-instability and imply that the progenitor had a helium core mass of about 50\u201355 M_\u2299, corresponding to an initial mass of about 115 M_\u2299.", "doi": "10.1038/s41550-018-0568-z", "issn": "2397-3366", "publisher": "Nature Publishing Group", "publication": "Nature Astronomy", "publication_date": "2018-11", "series_number": "11", "volume": "2", "issue": "11", "pages": "887-895" } ]