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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

19548 results found.

  1. GRB 190511A: Enhanced Swift-XRT position
  2. LIGO/Virgo S190510g : Xinglong-60cm upper limit of the GRAWITA REM's OT
  3. LIGO/Virgo S190510g: Unconfirmed OT in PGC 094244
  4. LIGO/Virgo S190510g: Dabancheng/HMT Follow-Up Observations
  5. LIGO/Virgo S190510g: Xinglong/Schmidt Follow-Up Observations
  6. LIGO/Virgo S190510g: Pierre Auger Observatory follow-up
  7. GRB 190511A: Swift detection of a burst
  8. LIGO/Virgo S190510g: SOAR/Goodman follow-up observations
  9. LIGO/Virgo S190510g: CNEOST Follow-Up Observations
  10. LIGO/Virgo S190510g: J-GEM optical/NIR follow-up observations
  11. LIGO/Virgo S190510g: Lick/KAIT Follow-Up Observations
  12. LIGO/Virgo S190510g: Fermi-LAT search for a high-energy gamma-ray counterpart
  13. LIGO/Virgo S190510g: Swift/BAT Counterpart Search
  14. LIGO/Virgo S190510g: HSC Y-band follow-up observation
  15. LIGO/Virgo S190510g: ANTARES neutrino search
  16. LIGO/Virgo S190510g: HAWC follow-up
  17. LIGO/Virgo S190426c: Archival VLASS Observations of ZTF19aassfws 14 days prior to Merger
  18. GRB 190508A: GOTO optical search - no counterparts
  19. GRB 190508B: Fermi GBM Final Real-time Localization
  20. GRB 190508A: Fermi GBM Final Real-time Localization
  21. GRB 190507B: GOTO optical counterpart search
  22. LIGO/Virgo S190426c (BHNS candidate): Implications from Numerical Relativity
  23. GRB 190501A: Swift XRT and UVOT Observations
  24. IceCube-190504A: Swift-XRT Follow-up Observations
  25. IceCube-190503A: Swift-XRT Follow-up Observations
  26. LIGO/Virgo S190503bf: CALET Observations
  27. Fermi-LAT Gamma-ray Observations of IceCube-190504A
  28. LIGO/Virgo S190503bf: Swift/BAT Counterpart Search
  29. LIGO/Virgo S190503bf: Fermi-LAT search for a high-energy gamma-ray counterpart
  30. LIGO/Virgo S190503bf: ANTARES neutrino search
  31. LIGO/Virgo S190503bf: AGILE-GRID Observations
  32. IceCube-190503A: INTEGRAL prompt observation
  33. LIGO/Virgo S190503bf: INTEGRAL prompt observation
  34. GRB 190501A: Swift ToO observations
  35. GRB 190501A: GOTO optical counterpart search
  36. LIGO/Virgo S190425z: Insight-HXMT observation and counterpart search
  37. LIGO/Virgo S190426c: GROWTH India follow-up of GRAWITA transient
  38. LIGO/Virgo S190412m: Further J-GEM optical/NIR observations
  39. LIGO/Virgo S190425z: 1.3-m optical imaging of UVOT transient field
  40. Fermi GRB190429.74 Global MASTER-Net observations report
  41. LIGO/Virgo S190426c: Fermi-LAT search for a high-energy gamma-ray counterpart
  42. LIGO/Virgo S190426c: GRAWITA transients from Asiago Schmidt wide field observations
  43. LIGO/Virgo S190425z: DECam Observations of the UVOT Candidate Region
  44. LIGO/Virgo S190425z: VISTA K-band observations of the Swift/UVOT Transient
  45. GRB 190427A: Swift/UVOT Upper Limits
  46. LIGO/Virgo S190426c: Continued infrared wide-field search with Palomar Gattini-IR
  47. LIGO/Virgo S190425z: 1.5m OSN and 10.4m imaging of the UVOT source field
  48. LIGO/Virgo S190425z: NOT photometry of ZTF19aasckkq
  49. LIGO/Virgo S190426c: GROWTH India follow-up
  50. LIGO/Virgo S190426c: DDOTI/OAN Optical Observations
  51. LIGO/Virgo S190425z: No Optical Detection of the Swift/UVOT Transient with Las Cumbres Observatory
  52. LIGO/Virgo S190426c: J-GEM optical/NIR follow-up observations
  53. LIGO/Virgo S190426c: MMT Follow-Up Observations
  54. LIGO/Virgo S190426c: GOTO optical coverage - no notable counterparts
  55. GRB 190427A: Lick/Nickel telescope optical observations
  56. LIGO/Virgo S190426c: Lick/KAIT Follow-Up Observations
  57. GRB 190427A: COATLI Optical Observations
  58. LIGO/Virgo S190426c: CNEOST Optical Observations
  59. LIGO/Virgo S190425z: CNEOST Optical Observations
  60. LIGO/Virgo S190426c: Infrared Wide-field Search with Palomar Gattini-IR
  61. LIGO/Virgo S190426c: Optical Wide-field Search with the Zwicky Transient Facility
  62. GRB 190427A: RATIR Optical and NIR Observations
  63. LIGO/Virgo S190426c: Nanshan/NEXT Observation of Galaxies
  64. LIGO/Virgo S190426c: Hobby-Eberly Telescope VIRUS observations of target galaxies.
  65. ANTARES follow-up of the GW candidate S190426c
  66. LIGO/Virgo S190425z: Fermi-LAT search for a high-energy gamma-ray counterpart
  67. GRB 190427A: NOT optical observations
  68. GRB 190427A: Swift-XRT observations
  69. LIGO/Virgo S190426c: GROWTH India follow-up
  70. LIGO/Virgo S190425z: GRANDMA follow-up observations with Les Makes-T60, AZT-8 and Abastumani-T70
  71. LIGO/Virgo S190426c: Swift/BAT Counterpart Search
  72. LIGO/Virgo S190426c: AGILE-GRID Observations
  73. LIGO/Virgo S190425z: Further MMT Follow-Up Observations
  74. LIGO/Virgo S190426c: INTEGRAL prompt observation
  75. Baksan Neutrino Observatory Alert 190405.62: Global MASTER-Net:LIGO/Virgo S190425z: PanSTARR OT AT2019ebq/PS19qp
  76. LIGO/Virgo S190425z: Pierre Auger Observatory follow-up
  77. LIGO/Virgo S190426c: HAWC follow-up
  78. LIGO/Virgo S190425z: GROND observations of AT2019ebq/PS19qp
  79. LIGO/Virgo S190425z: GOTO observations
  80. LIGO/Virgo S190425z : IRSF/SIRIUS NIR photometry of ZTF19aarykkb and ZTF19aarzaod
  81. LIGO/Virgo S190425z - ePESSTO+ NTT observations
  82. LIGO/Virgo S190425z - GROWTH-India follow-up of two ZTF candidates
  83. LIGO/Virgo S190425z: OVRO-LWA simultaneous low frequency radio observations of localization region
  84. LIGO/Virgo S190425z: J-GEM optical follow-up observations with Subaru/FOCAS
  85. LIGO/Virgo S190425z: Xinglong/Schmidt follow-up observations
  86. LIGO/Virgo S190425z: Palomar Gattini-IR wide-field infrared follow-up
  87. LIGO/Virgo S190425z: AGILE-GRID Observations
  88. LIGO/Virgo S190425z: Swift/BAT Counterpart Search
  89. LIGO-Virgo S190425z: AGILE MCAL observation
  90. LIGO/Virgo S190425z: Lick/KAIT Follow-Up Observations
  91. LIGO/Virgo S190425z: Hobby-Eberly Telescope VIRUS observations of target galaxies.
  92. LIGO/Virgo S190421ar: Fermi-LAT search for a high-energy gamma-ray counterpart
  93. LIGO/VirgoS190425z: HAWC follow-up
  94. LIGO/Virgo S190425z: SAGUARO follow-up observations
  95. LIGO/Virgo S190425z: INTEGRAL SPI-ACS prompt observation
  96. LIGO/Virgo S190421ar: Lick/KAIT Follow-Up Observations
  97. GRB 190422A: Swift/UVOT Upper Limits
  98. LIGO/Virgo S190421ar: Swift/BAT Counterpart Search
  99. LIGO/Virgo S190421ar/G330308: ANTARES neutrino search
  100. LIGO/Virgo S190421ar: INTEGRAL prompt observation

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