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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"
  1. GRB 160101B: Fermi-LAT detection
  2. GRB 160101B: Fermi GBM detection
  3. GRB 160101A: Swift/UVOT Detection
  4. GRB 160101A: Fermi GBM observation
  5. GRB 160101A: Swift-XRT afterglow detection
  6. GRB 160101A: Tiled Swift observations
  7. GRB 160101A: MAXI/GSC detection
  8. GRB 151227B: CALET Gamma-Ray Burst Monitor detection
  9. LIGO/Virgo G211117: Liverpool Telescope classification of EM candidates
  10. LIGO/Virgo G211117: FLOYDS Classification of SMTJ13331687-1607330 as a Two-Week-Old Type Ia Supernova
  11. LIGO/Virgo G211117: LBT follow-up imaging of iPTF15fhq
  12. GRB 151231B: Fermi GBM observation
  13. GRB 151231A: Fermi GBM observation
  14. LIGO/Virgo G211117: 44 transients from Pan-STARRS data during 2015-12-28/30
  15. Trigger 668949: Swift detection of V 404 Cyg
  16. LIGO/Virgo G211117: MAXI/GSC observations
  17. MASTER-NET observations of V404Cyg Swift Trigger 668877
  18. LIGO/Virgo G211117: Liverpool Telescope followup of EM candidates
  19. Konus-Wind observation of GRB 151227B
  20. LIGO/Virgo G211117: VLA follow-up
  21. LIGO/Virgo G211117: LBT Follow-up of iPTF15fen
  22. Trigger 668879: Swift detection of V 404 Cyg again
  23. Trigger 668877: Swift detection of V 404 Cyg
  24. LIGO/Virgo G211117: MAGIC very-high energy gamma-ray observations
  25. LIGO/Virgo G211117: INAF TNG follow-up of MASTER OT J020906.21+013800.1
  26. LIGO/Virgo G211117: OAO-WFC NIR follow-up observations
  27. IPN Triangulation of GRB 151227B
  28. GRB 151228A: Correction to GCN 18770
  29. LIGO/Virgo G211117: SkyMapper observations and transient candidate
  30. GRB 151228A: Swift-XRT refined Analysis
  31. V404Cyg Swift Trigger 668097: CrAO RT-22 radio observations
  32. LIGO/Virgo G211117: MASTER Observations of the 3 iPTF candidates
  33. V404Cyg Swift Trigger 668097: AbAO optical observations
  34. GRB 151228B: Swift/UVOT Detection
  35. GRB 151229A: MITSuME Akeno optical upper limits
  36. LIGO/Virgo G211117: Optical Observations with Kiso Schmidt telescope and KWFC
  37. LIGO/Virgo G211117: List of near-term future observation regions by Project Mini-GWAC of SVOM
  38. LIGO/Virgo G211117: iPTF Optical Transient Candidates
  39. GRB 151229A: MITSuME Okayama upper limits
  40. GRB 151229A Swift-BAT Spectral lag analysis
  41. LIGO/Virgo G211117: La Silla - QUEST observations 2015 Dec 28, 29
  42. GRB 151228B: MITSuME Akeno optical upper limits
  43. GRB 151229A: Swift-XRT refined Analysis
  44. GRB 151229A: Fermi GBM observation
  45. GRB 151228B: Fermi GBM observation
  46. GRB 151228A: Swift-BAT refined analysis
  47. GRB 151229A: Swift/UVOT observations
  48. GRB 151228B: Swift-BAT refined analysis
  49. GRB 151229A: Swift-BAT refined analysis
  50. GRB 151229A: Enhanced Swift-XRT position
  51. GRB 151228B: Swift-XRT refined Analysis
  52. LIGO/Virgo G211117: Further Swift-XRT sources
  53. GRB 151228A: MITSuME Akeno optical upper limits
  54. GRB 151228A: T60 observations
  55. GRB 151229A: Swift detection of a short burst
  56. LIGO/Virgo G211117: DESGW program observations with DECam
  57. GRB 151228B: Enhanced Swift-XRT position
  58. LIGO/Virgo G211117: Optical NIR observation with Kanata telescope
  59. LIGO/Virgo G211117: Fermi GBM Observations
  60. LIGO/Virgo G211117: Optical follow-up with Kanata telescope
  61. GRB 151228B: Swift detection of a burst with an optical detection
  62. LIGO/Virgo G211117: MASTER Observations and Inspection + OT
  63. LIGO/Virgo G211117: INTEGRAL was inactive at the time of the event
  64. GRB 151228A: Fermi GBM observation
  65. LIGO/Virgo G211117: Pan-STARRS1 observations 2015-12-28
  66. LIGO/Virgo G211117: INAF VST-ESO PARANAL observations
  67. LIGO/Virgo G211117: Further Swift-XRT sources
  68. LIGO/Virgo G211117: Swift-XRT sources
  69. GRB 151228A: Swift detection of a short burst
  70. LIGO/Virgo G211117: SWASP optical observations
  71. LIGO/Virgo G211117: MASTER possible OT detection at the begining of inspection
  72. LIGO/Virgo G211117: Identification of a GW CBC Candidate
  73. GRB 151227B: Fermi GBM detection
  74. GRB 151227A: Fermi GBM detection
  75. GRB 151212A iTelescope observation
  76. GRB 151225A: CALET Gamma-Ray Burst Monitor detection of a possible short GRB
  77. Konus-Wind observation of GRB 151222A
  78. Fermi GBM trigger 472694170/151224997 is not a GRB
  79. V404Cyg Swift Trigger 668097: TSHAO optical observations
  80. IPN Triangulation of GRB 151222A (short/hard)
  81. Fermi GBM trigger 151221730 is not a GRB
  82. V404Cyg Swift Trigger 668097: MASTER-Tunka optical wake up detection
  83. V404Cyg Swift Trigger 668097:
  84. Trigger 668097: Swift detection of V 404 Cyg
  85. GRB 151222A: Fermi GBM detection
  86. Fermi GBM trigger 151221690 is not a GRB
  87. Fermi GBM trigger 472271765/151220108 is not a GRB
  88. IBAS Alert 7313 is SGR J1935+2154
  89. GRB 151221A: INTEGRAL detection of a short burst or possible SGR
  90. Fermi GBM trigger 472166503/151218890 is not a GRB
  91. LIGO/Virgo G184098: Fermi-LAT search for high-energy gamma-ray counterpart
  92. GRB 151215A: TSHAO optical observations
  93. GRB151215A: Continued P60 Observations
  94. GRB 151212B: CALET Gamma-Ray Burst Monitor detection
  95. GRB 151216A: MAXI/GSC detection
  96. GRB 151210B: Fermi GBM observation
  97. GRB151215A: Early optical light curve from pt5m, La Palma
  98. GRB 151215A: MITSuME Akeno optical upper limits
  99. GRB 151210B: CALET Gamma-Ray Burst Monitor detection
  100. GRB 151215A: Swift-XRT refined Analysis

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