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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 180614A: Swift/UVOT Upper Limits
  2. GRB 180614A: Swift-BAT refined analysis
  3. GRB 180529A: AstroSat CZTI detection
  4. GRB 180614A: NOT optical upper limits
  5. GRB 180614A: MASTER observation
  6. GRB 180614A: Swift-XRT refined Analysis
  7. GRB 180614A: Enhanced Swift-XRT position
  8. GRB 180614A: Swift detection of a burst
  9. GRB 180613A: Swift/UVOT Upper Limits
  10. GRB 180613A GROND observations: correction
  11. GRB 180613A GROND observations
  12. GRB 180613A, Swift-BAT refined analysis
  13. GRB 180613A: Possible IR afterglow
  14. GRB 180613A: Swift-XRT refined Analysis
  15. GRB 180613A: Enhanced Swift-XRT position
  16. GRB 180613A: Possible host galaxy at XRT position, or star
  17. GRB 180613A: Prompt enhanced Swift-XRT position
  18. Konus-Wind observation of GRB 180611A
  19. GRB 180613A: Swift detection of a burst
  20. GRB 180611A: Fermi GBM observation
  21. IPN Triangulation of GRB 180611A (long)
  22. GRB 180605A: Fermi GBM observation
  23. GRB 180605A: AstroSat CZTI detection
  24. IPN Triangulation of GRB 180605A (long)
  25. GW170817/GRB170817A: LBT optical detection
  26. GRB 180603A: AstroSat CZTI detection
  27. Fermi GBM trigger 180604900/549840956 likely not a GRB
  28. GRB 180602A: MITSuME Ishigakijima optical upper limits
  29. GRB 180602B: Fermi GBM detection
  30. GRB 180602A: Swift/UVOT Upper Limits
  31. GRB 180602A: MITSuME Akeno optical upper limits
  32. GRB 180602A: Swift-XRT refined Analysis
  33. GRB 180602A: Swift-BAT refined analysis
  34. GRB 180602A: MITSuME Okayama optical upper limits
  35. GRB 180602A: Enhanced Swift-XRT position
  36. GRB 180602A: Swift detection of a burst
  37. Fermi GBM trigger 549533811/180601345 is not a GRB
  38. Konus-Wind observation of GRB 180529A
  39. GRB 180529A: CALET Gamma-Ray Burst Monitor detection
  40. IPN Triangulation of GRB 180529A (short/hard)
  41. Swift Trigger 834937 is not a GRB
  42. Konus-Wind observation of GRB 180526A
  43. IPN Triangulation of GRB 180526A (long)
  44. GRB 180526A: CALET Gamma-Ray Burst Monitor detection
  45. Konus-Wind observation of GRB 180523A
  46. GRB 180526A: AstroSat CZTI detection
  47. AGILE/MCAL detection of GRB 180529 and a possible precursor
  48. IPN Triangulation of GRB 180523A
  49. GRB180523B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 548793993)
  50. GRB 180523A: CALET Gamma-Ray Burst Monitor detection
  51. Fermi GBM trigger 548829437/180524192 is not a GRB
  52. GRB 180514A: MITSuME Ishigakijima optical upper limits
  53. GRB 180514A: CrAO/ZTSH optical observations and afterglow candidate
  54. GRB 180505A: AstroSat CZTI detection
  55. GRB 180514A: Swift/UVOT Upper Limits
  56. GRB 180514A: MITSuME Akeno optical upper limits
  57. GRB 180514A: Detection limits from 2.5m NOT
  58. GRB 180510A: MITSuME Ishigakijima optical upper limits
  59. GRB 180514A: 1.5m OSN optical observations
  60. GRB 180514A: GOTO Optical Observations
  61. GRB 180514A: Swift-BAT refined analysis
  62. GRB 180514A: Swift-XRT refined Analysis
  63. GRB 180514A: Enhanced Swift-XRT position
  64. GRB 180512A: VLT/HAWK-I NIR Observations
  65. GRB 180514A: Swift detection of a burst
  66. Konus-Wind observation of GRB 180510A
  67. GRB 180512A: Swift-XRT refined Analysis
  68. GRB 180512A: Swift-BAT refined analysis
  69. GRB 180512A: RATIR Optical Observations
  70. GRB 180512A: LBT optical detection
  71. GRB 180512A: Swift/UVOT Upper Limits
  72. GRB 180512A: LT prompt observations
  73. GRB 180512A: Enhanced Swift-XRT position
  74. GRB 180512A: GROND upper limits
  75. GRB 180512A: NOT upper limits
  76. GRB 180512A: OASDG optical observations
  77. GRB 180512A: Upper limits from OSN
  78. GRB 180512A: Swift detection of a burst
  79. GRB 180510A: Swift/UVOT followup observations
  80. GRB 180510B: Swift-XRT refined Analysis
  81. GRB 180510A: Swift-XRT refined Analysis
  82. Swift trigger 831888: misidentification of 4U 1416-62
  83. GRB 180510B: Swift-BAT refined analysis
  84. GRB 180510B: VLT/X-shooter observations
  85. GRB 180510B: GROND detection in all bands
  86. GRB 180510B: TAROT La Silla observatory optical observations
  87. Swift Trigger 831888: a possible GRB or Galactic transient
  88. GRB 180510B: Enhanced Swift-XRT position
  89. GRB 180418A: 15 GHz upper limits from AMI
  90. GRB 180510B: Swift detection of a burst with an optical counterpart
  91. GRB 180510A: Swift detection of a burst
  92. GRB 180427A: AstroSat CZTI detection
  93. Chandra observations of GW170817 reveal a fading afterglow
  94. Chandra observations of GW170817 260 days since merger: first statistically significant evidence for an X-ray decay
  95. GRB 180504A: Swift/UVOT Upper Limits
  96. GRB 180504A: Swift-BAT refined analysis
  97. GRB 180505A: Fermi GBM detection
  98. GRB 180416A: AstroSat CZTI detection
  99. GRB 180504A: ePESSTO NTT NIR observations
  100. Correction to Swift-XRT light curve fit for GRB 180504A in GCN 22685

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