{"id":"https://openalex.org/W7096936183","doi":null,"title":"VLBI Observations of the Galactic Center Source Sgr A*","display_name":"VLBI Observations of the Galactic Center Source Sgr A*","publication_year":1998,"publication_date":"1998-01-01","ids":{"openalex":"https://openalex.org/W7096936183"},"language":"en","primary_location":{"id":"pmh:oai:CiteSeerX.psu:10.1.1.258.4220","doi":null,"is_oa":false,"landing_page_url":"http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.258.4220","pdf_url":null,"source":null,"license":null,"license_id":null,"version":"submittedVersion","is_accepted":false,"is_published":false,"raw_source_name":"http://arxiv.org/pdf/astro-ph/9812050v1.pdf","raw_type":"text"},"volume":null,"type":"preprint","is_traditional":true,"indexed_in":[],"open_access":{"is_oa":false,"oa_status":"closed","oa_url":null,"any_repository_has_fulltext":false},"authorships":[{"author_position":"first","author":{"id":null,"display_name":"At Ghz","orcid":null,"observed_orcids":[]},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"At Ghz","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":null,"display_name":"T. P. Krichbaum","orcid":null,"observed_orcids":[]},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"T. P. Krichbaum","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":null,"display_name":"A. Witzel","orcid":null,"observed_orcids":[]},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"A. Witzel","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"last","author":{"id":null,"display_name":"J. A. Zensus","orcid":null,"observed_orcids":[]},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"J. A. Zensus","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]}],"institutions":[],"countries_distinct_count":0,"institutions_distinct_count":0,"corresponding_author_ids":[],"corresponding_institution_ids":[],"apc_list":null,"apc_paid":null,"fwci":null,"has_fulltext":false,"cited_by_count":0,"citation_normalized_percentile":null,"cited_by_percentile_year":null,"biblio":{"volume":null,"issue":null,"first_page":null,"last_page":null},"is_retracted":false,"is_paratext":false,"is_xpac":true,"primary_topic":{"id":"https://openalex.org/T10744","display_name":"Astrophysical Phenomena and Observations","score":0.9887999892234802,"subfield":{"id":"https://openalex.org/subfields/3103","display_name":"Astronomy and Astrophysics"},"field":{"id":"https://openalex.org/fields/31","display_name":"Physics and Astronomy"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},"topics":[{"id":"https://openalex.org/T10744","display_name":"Astrophysical Phenomena and Observations","score":0.9887999892234802,"subfield":{"id":"https://openalex.org/subfields/3103","display_name":"Astronomy and Astrophysics"},"field":{"id":"https://openalex.org/fields/31","display_name":"Physics and Astronomy"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T10463","display_name":"Pulsars and Gravitational Waves Research","score":0.0026000000070780516,"subfield":{"id":"https://openalex.org/subfields/3103","display_name":"Astronomy and Astrophysics"},"field":{"id":"https://openalex.org/fields/31","display_name":"Physics and Astronomy"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T12450","display_name":"Radio Astronomy Observations and Technology","score":0.0017000000225380063,"subfield":{"id":"https://openalex.org/subfields/3103","display_name":"Astronomy and Astrophysics"},"field":{"id":"https://openalex.org/fields/31","display_name":"Physics and Astronomy"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}}],"keywords":[{"id":"https://openalex.org/keywords/sgr-a","display_name":"Sgr A*","score":0.9789999723434448},{"id":"https://openalex.org/keywords/galactic-center","display_name":"Galactic Center","score":0.9290000200271606},{"id":"https://openalex.org/keywords/supermassive-black-holes","display_name":"supermassive black holes","score":0.9229999780654907},{"id":"https://openalex.org/keywords/black-hole-size","display_name":"black hole size","score":0.597000002861023},{"id":"https://openalex.org/keywords/86-ghz","display_name":"86 GHz","score":0.8550000190734863},{"id":"https://openalex.org/keywords/closure-phases","display_name":"closure phases","score":0.8960000276565552},{"id":"https://openalex.org/keywords/schwarzschild-radius","display_name":"Schwarzschild radius","score":0.7250000238418579}],"concepts":[{"id":"https://openalex.org/C79896159","wikidata":"https://www.wikidata.org/wiki/Q1148351","display_name":"Very-long-baseline interferometry","level":2,"score":0.9419000148773193},{"id":"https://openalex.org/C132552067","wikidata":"https://www.wikidata.org/wiki/Q649112","display_name":"Galactic Center","level":3,"score":0.6607000231742859},{"id":"https://openalex.org/C121332964","wikidata":"https://www.wikidata.org/wiki/Q413","display_name":"Physics","level":0,"score":0.6524999737739563},{"id":"https://openalex.org/C44870925","wikidata":"https://www.wikidata.org/wiki/Q37547","display_name":"Astrophysics","level":1,"score":0.6049000024795532},{"id":"https://openalex.org/C1276947","wikidata":"https://www.wikidata.org/wiki/Q333","display_name":"Astronomy","level":1,"score":0.5613999962806702},{"id":"https://openalex.org/C115304011","wikidata":"https://www.wikidata.org/wiki/Q72755","display_name":"Schwarzschild radius","level":3,"score":0.5146999955177307},{"id":"https://openalex.org/C6260449","wikidata":"https://www.wikidata.org/wiki/Q41364","display_name":"Wavelength","level":2,"score":0.47040000557899475},{"id":"https://openalex.org/C109792285","wikidata":"https://www.wikidata.org/wiki/Q174789","display_name":"Millimeter","level":2,"score":0.45910000801086426},{"id":"https://openalex.org/C191486275","wikidata":"https://www.wikidata.org/wiki/Q210028","display_name":"Scattering","level":2,"score":0.39079999923706055},{"id":"https://openalex.org/C2779463800","wikidata":"https://www.wikidata.org/wiki/Q5062222","display_name":"Center (category theory)","level":2,"score":0.3253999948501587},{"id":"https://openalex.org/C153465967","wikidata":"https://www.wikidata.org/wiki/Q718647","display_name":"Angular diameter","level":3,"score":0.3068999946117401},{"id":"https://openalex.org/C50341732","wikidata":"https://www.wikidata.org/wiki/Q880302","display_name":"Black hole (networking)","level":5,"score":0.30649998784065247},{"id":"https://openalex.org/C44280652","wikidata":"https://www.wikidata.org/wiki/Q104837","display_name":"Phase (matter)","level":2,"score":0.3037000000476837},{"id":"https://openalex.org/C173120059","wikidata":"https://www.wikidata.org/wiki/Q40392","display_name":"Supermassive black hole","level":3,"score":0.28870001435279846},{"id":"https://openalex.org/C178635117","wikidata":"https://www.wikidata.org/wiki/Q747499","display_name":"RADIUS","level":2,"score":0.2793999910354614}],"mesh":[],"locations_count":1,"locations":[{"id":"pmh:oai:CiteSeerX.psu:10.1.1.258.4220","doi":null,"is_oa":false,"landing_page_url":"http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.258.4220","pdf_url":null,"source":null,"license":null,"license_id":null,"version":"submittedVersion","is_accepted":false,"is_published":false,"raw_source_name":"http://arxiv.org/pdf/astro-ph/9812050v1.pdf","raw_type":"text"}],"best_oa_location":null,"sustainable_development_goals":[],"study_designs":[],"awards":[],"funders":[],"has_content":{"grobid_xml":false,"pdf":false},"content_urls":null,"referenced_works_count":0,"referenced_works":[],"related_works":["https://openalex.org/W2783454374","https://openalex.org/W26425867","https://openalex.org/W2050959542","https://openalex.org/W1792164844","https://openalex.org/W2035538351","https://openalex.org/W2378381658","https://openalex.org/W2804413181","https://openalex.org/W1970353832","https://openalex.org/W2159376552","https://openalex.org/W2056728298"],"abstract_inverted_index":{"Abstract.":[0],"We":[1],"1":[2],"summarize":[3],"previous":[4],"VLBI":[5,19],"observations":[6,20],"of":[7,46,67,75,89,97],"Sgr":[8,60,98],"A":[9,61,99],"*":[10,62,100],"at":[11,21,25,91],"millimeter":[12],"wavelengths":[13],"and":[14,24],"present":[15],"new":[16],"results":[17],"from":[18],"86":[22,29],"GHz":[23,30,52],"215":[26,51],"GHz.":[27],"At":[28,50],"the":[31,56,86],"measured":[32],"closure":[33],"phase":[34],"is":[35,83],"close":[36],"to":[37,103,108],"zero,":[38],"consistent":[39],"with":[40,63],"a":[41,64,71,105,109,115],"point-like":[42],"or":[43],"symmetric":[44],"structure":[45],"190\u00b130":[47],"\u00b5as":[48],"size.":[49],"we":[53],"have":[54],"(for":[55,114],"first":[57],"time)":[58],"detected":[59],"signal-to-noise":[65],"ratio":[66],"6.":[68],"This":[69],"yields":[70],"tentative":[72],"size":[73,88,96],"estimate":[74],"50":[76],"\u2264":[77,79],"\u03b8":[78],"190":[80],"\u00b5as,":[81],"which":[82],"larger":[84],"than":[85],"scattering":[87],"20\u00b5as":[90],"this":[92],"frequency.":[93],"The":[94],"intrinsic":[95],"thus":[101],"appears":[102],"be":[104],"few":[106,110],"up":[107],"ten":[111],"Schwarzschild":[112],"radii":[113],"2.6":[116],"\u00b7":[117],"10":[118],"6":[119],"M":[120],"\u2299":[121],"black":[122],"hole).":[123],"1.":[124]},"counts_by_year":[],"updated_date":"2026-08-26T07:47:46.906454","created_date":"2025-10-27T00:00:00"}
