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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"

3927 results found.

  1. LIGO/Virgo G275697: LOFAR follow-up
  2. LIGO/Virgo G277583: Konus-Wind observations
  3. LIGO/Virgo G277583: Fermi GBM Observations
  4. LIGO/Virgo G277583: INTEGRAL search for an X-ray and gamma-ray counterpart
  5. LIGO/Virgo G275697: AMI Large Array Search for a Radio Afterglow
  6. IPN Triangulation of GRB 170320A (long/intense)
  7. LIGO/Virgo G277583: CALET Observations
  8. LIGO/Virgo G277583: Asiago spectroscopic classification of ATLAS17byo and ATLAS17cgg
  9. LIGO/Virgo G277583 : MAXI/GSC observations
  10. LIGO/Virgo G275404: P200/DBSP Classification of iPTF Candidates
  11. LIGO/Virgo G277583: P200/DBSP Classification of ATLAS Candidates
  12. LIGO/Virgo G277583: AstroSat CZTI upper limits
  13. LIGO/Virgo G275697: Swift-XRT source 23 no longer fading
  14. LIGO/Virgo G277583: Swift/BAT data search
  15. LIGO/Virgo G277583: Discovery Channel Telescope Follow-Up of ATLAS17cck
  16. LIGO/Virgo G277583: ATLAS coverage and transients over the first 2 days
  17. LIGO/Virgo G277583: ATLAS17cck is likely a minor planet
  18. LIGO/Virgo G277583: GROND follow up of ATLAS17cck
  19. LIGO/Virgo G277583: ATLAS17cck - a fast declining transient
  20. LIGO/Virgo G275697: DLT40 follow-up observation
  21. LIGO/Virgo G274296: DLT40 follow-up observation
  22. LIGO/Virgo G275697: Fermi-LAT search for a high-energy gamma-ray counterpart
  23. LIGO/Virgo G277583: ERRATUM LV GCN 20871: TAROT Calern (TCA) observations
  24. LIGO/Virgo G277583: TAROT Calern (TCA) observations
  25. LIGO/Virgo G277583: SVOM/Mini-GWAC observations of the initial skymap
  26. LIGO/Virgo G275404: Medicina radio follow-up of near-infrared
  27. LIGO/Virgo G277583: INTEGRAL was inactive at the time of the event
  28. LIGO/Virgo G277583 ANTARES search
  29. LIGO/Virgo G277583: AGILE GRID observations
  30. LIGO/Virgo G277583: AGILE MCAL observations
  31. LIGO/Virgo G270580: optical observations and classification of PS and MASTER sources
  32. LIGO/Virgo G277583: IceCube neutrino observations
  33. LIGO/Virgo G277583: Identification of a GW Burst Candidate
  34. IPN Triangulation of GRB 170311B (long/very intense)
  35. LIGO/Virgo G275697: GRAWITA NOT optical observations of Swift/XRT Source 23
  36. SN MASTER OT J042250.16-820415.4 is the possible optical counterpart of the gravitational waves event LIGO/Virgo G274296
  37. LIGO/Virgo G275404: Swift-XRT observations of sources in the AGILE error region
  38. LIGO/Virgo G275697: Swift-XRT source 23 is fading
  39. LIGO/Virgo G275404: Updated localization from LIGO data
  40. LIGO/Virgo G275404 and AGL J1914+1043: INTEGRAL follow-up
  41. LIGO/Virgo G275697: Updated localization from LIGO data
  42. LIGO/Virgo G275697: Further Swift-XRT sources
  43. LIGO/Virgo G275697: P200/DBSP Classification of iPTF Candidates
  44. LIGO/Virgo G275404: P200/DBSP Classification of iPTF Candidates
  45. LIGO/Virgo G275697: Liverpool Telescope classification of EM candidates
  46. LIGO/Virgo G275404: Liverpool Telescope classification of EM candidates
  47. LIGO/Virgo G275697: Further Swift-XRT sources
  48. LIGO/Virgo G275404: HAWC follow-up
  49. LIGO/Virgo G275404: PIRATE Observations
  50. LIGO/Virgo G275404: Liverpool Telescope classification of EM candidates
  51. LIGO/Virgo G275697: Liverpool Telescope classification of EM candidates
  52. LIGO/Virgo G275697: Further Swift-XRT sources
  53. LIGO/Virgo G275697: MAXI/GSC observations
  54. LIGO/Virgo G275697: Additional iPTF Optical Transient Candidates
  55. LIGO/Virgo G275404: Additional iPTF Optical Transient Candidates
  56. LIGO/Virgo G275404: Nearby Galaxies in the Localization Volume
  57. LIGO/Virgo G275697: Further Swift-XRT sources
  58. LIGO/Virgo G275697: Fermi GBM Upper Limits
  59. LIGO/Virgo G275697: AstroSat CZTI upper limits
  60. LIGO/Virgo G275697: optical spectroscopy of Swift/XRT source 1
  61. LIGO/Virgo G268556, G270580, G274296, and G275404: Konus-Wind observations
  62. LIGO/Virgo G275697: SVOM/Mini-GWAC observations of the initial skymap
  63. LIGO/Virgo G275697: iPTF Optical Transient Candidates
  64. LIGO/Virgo G275404: iPTF Optical Transient Candidates
  65. LIGO/Virgo G275404: Fermi GBM Upper Limits
  66. LIGO/Virgo G275404: A near-infrared transient in the error circle of AGL J1914+1043
  67. LIGO/Virgo G275697: CALET Observations
  68. LIGO/Virgo G275697: MASTER automatic follow up detection
  69. LIGO/Virgo G275697: CNEOST optical observations
  70. LIGO/Virgo G274296 and G275404 : MAXI/GSC observations
  71. LIGO/Virgo G275404: Nearby galaxy observations by J-GEM collaboration
  72. LIGO/Virgo G275404: Nearby Galaxies in the Localization Region
  73. LIGO/Virgo G275697: Fermi-LAT search for a high-energy gamma-ray counterpart
  74. LIGO/Virgo G275697: REM optical/NIR observations
  75. LIGO/Virgo G275697: Konus-Wind observations
  76. LIGO/Virgo G275404: CNEOST optical observations
  77. LIGO/Virgo G275697: Swift-XRT sources
  78. LIGO/Virgo G275697: Swift/BAT data search
  79. LIGO/Virgo G275404: MASTER bright PSN detected on 27 Feb from the maximum of probability of LIGO localization
  80. LIGO/Virgo G275697: AGILE-GRID preliminary analysis
  81. LIGO/Virgo G275697: AGILE MCAL Observations
  82. LIGO/Virgo G275697: INTEGRAL search for a prompt gamma-ray counterpart
  83. LIGO/VIRGO G275697: Fermi GBM Observations
  84. LIGO/Virgo G275404: AstroSat CZTI upper limits
  85. LIGO/Virgo G275697 ANTARES search
  86. LIGO/Virgo G275697: IceCube neutrino observations
  87. LIGO/Virgo G275697: Identification of a GW CBC Candidate
  88. LIGO/Virgo G275404: Keck LRIS classification of MASTER PSN candidate
  89. LIGO/Virgo G274296: MASTER new PSN detected on 22 feb
  90. LIGO/Virgo G275404: REM optical/NIR observations
  91. LIGO/Virgo G275404: MASTER PSN detection from the maximal probability LIGO region
  92. LIGO/Virgo G275404: MASTER OT is outside LIGO error region
  93. LIGO/Virgo G275404: Keck spectrum of MASTER OT J105958.00-115756.5
  94. LIGO/Virgo G275404: Fermi-LAT search for a high-energy gamma-ray counterpart
  95. LIGO/Virgo G275404: INTEGRAL search for a prompt gamma-ray counterpart
  96. LIGO/Virgo G275404: AGILE-GRID detection of a possible gamma-ray transient
  97. LIGO/Virgo G275404: NOT Follow-up of MASTER OT
  98. LIGO/Virgo G275404: Swift-XRT sources
  99. LIGO/Virgo G275404 ANTARES search
  100. LIGO/Virgo G275404: Follow-up of MASTER OT J173532.70+103810.5

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