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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 180510B: VLT/X-shooter observations
  2. GRB 180510B: GROND detection in all bands
  3. GRB 180510B: TAROT La Silla observatory optical observations
  4. Swift Trigger 831888: a possible GRB or Galactic transient
  5. GRB 180510B: Enhanced Swift-XRT position
  6. GRB 180418A: 15 GHz upper limits from AMI
  7. GRB 180510B: Swift detection of a burst with an optical counterpart
  8. GRB 180510A: Swift detection of a burst
  9. GRB 180427A: AstroSat CZTI detection
  10. Chandra observations of GW170817 reveal a fading afterglow
  11. Chandra observations of GW170817 260 days since merger: first statistically significant evidence for an X-ray decay
  12. GRB 180504A: Swift/UVOT Upper Limits
  13. GRB 180504A: Swift-BAT refined analysis
  14. GRB 180505A: Fermi GBM detection
  15. GRB 180416A: AstroSat CZTI detection
  16. GRB 180504A: ePESSTO NTT NIR observations
  17. Correction to Swift-XRT light curve fit for GRB 180504A in GCN 22685
  18. GRB 180504A: Swift-XRT refined Analysis
  19. GRB 180504A: NOT afterglow candidate
  20. GRB 180504A: Prompt enhanced Swift-XRT position
  21. GRB 180504A: Swift detection of a burst
  22. GRB 180416B: AstroSat CZTI detection
  23. Konus-Wind observation of GRB 180427A
  24. IPN Triangulation of GRB 180427A
  25. GRB 180427A: Fermi GBM detection
  26. Swift Trigger 829046 is probably noise
  27. GRB 180425A: Swift-XRT refined Analysis
  28. GRB 180425A: Swift-BAT refined analysis
  29. GRB 180425A: Swift/UVOT Upper Limits
  30. GRB 180425A: Enhanced Swift-XRT position
  31. GRB 180425A: Swift detection of a burst
  32. GRB 180418A: TAROT La Silla observatory early optical observations
  33. GRB 180418A: MITSuME Ishigakijima Optical Observation
  34. Retraction of IceCube GCN/AMON NOTICE 71165249_130949
  35. GRB 180418A : SQUEAN observations
  36. Fermi GBM trigger 545979055/180421202 is not a GRB
  37. GRB 180418A: Further GROND observations
  38. GRB 180418A: Swift/UVOT Detection
  39. GRB 180418A: Continued RATIR Optical Observations
  40. GRB 180418A: Imaging of the optical afterglow with the 1.3 m DFOT and 3.6 m DOT in ARIES, India
  41. GRB 180418A GROND observations
  42. GRB 180418A: Xinglong TNT optical upper limit
  43. GRB 180418A: NOT optical observations
  44. GRB 180418A: Gemini-North imaging and spectroscopy
  45. GRB 180418A: Swift-BAT refined analysis
  46. GRB 180418A: 1.5m OSN optical observations
  47. GRB 180418A: Fermi GBM observation
  48. GRB 180418A: Swift-XRT refined Analysis
  49. GRB 180416B: CALET Gamma-Ray Burst Monitor detection
  50. GRB 180418A: RATIR Optical Observations
  51. LIGO/Virgo G299232: LOFAR follow-up
  52. GRB 180418A: Enhanced Swift-XRT position
  53. GRB 180418A: Swift-XRT observations
  54. GRB 180418A: LCO FTN afterglow confirmation
  55. GRB 180418A: KAIT Optical Afterglow Candidate
  56. GRB 180418A: Swift detection of a short burst
  57. GRB 180404B: AstroSat CZTI detection
  58. GRB 180416A: Fermi GBM detection
  59. GRB 180409A: Swift-XRT afterglow detection
  60. GRB 180411A: CALET Gamma-Ray Burst Monitor detection
  61. GRB 180411B: CALET Gamma-Ray Burst Monitor detection
  62. Konus-Wind observation of GRB 180411A
  63. GRB 180411A: Swift/UVOT Upper Limit
  64. GRB 180411A: Tautenburg observations
  65. GRB 180410A: Fermi GBM observation
  66. GRB 180409A CALET Gamma-Ray Burst Monitor detection
  67. GRB 180411A: Fermi GBM detection
  68. GRB 180411A: Swift-BAT refined analysis
  69. GRB 180411A: Swift-XRT refined Analysis
  70. GRB 180410A: RATIR Optical Observations
  71. GRB 180411A: Swift detection of a burst
  72. GRB 180410A: Swift-XRT refined Analysis
  73. GRB 180410A: Swift-BAT refined analysis
  74. GRB 180410A: Swift/UVOT Upper Limits
  75. GRB 180409A: Fermi GBM observation
  76. GRB 180409A: Swift-XRT observations
  77. Konus-Wind observation of GRB 180404C
  78. GRB 180410A: MITSuME Akeno optical upper limits
  79. GRB 180410A: Enhanced Swift-XRT position
  80. Konus-Wind observation of GRB 180409A
  81. GRB 180410A: Swift detection of a burst or a Galactic transient.
  82. IPN Triangulation of GRB 180409A
  83. GRB 180409A: Tiled Swift observations
  84. GRB 180402A: ISON-NM early optical limits
  85. GRB 180407A: Swift-BAT refined analysis
  86. Swift Trigger 823014: TAROT Calern observatory optical observations
  87. GRB 180407A: COATLI Upper Limits
  88. Swift Trigger 823014 is probably not a GRB
  89. GRB 180407A: Swift detection of a burst
  90. GRB 180404B: Swift/UVOT Detection
  91. IPN Triangulation of GRB 180404C (long)
  92. Konus-Wind observation of GRB 180404B
  93. Chandra observations of GRB161219B 400 days after the explosion
  94. GRB 180404C CALET Gamma-Ray Burst Monitor detection
  95. Fermi GBM triggers 544628550/180405571, 544542853/180404579, 544531428/180404447 are not GRBs
  96. GRB 180404A: Swift/UVOT Detection
  97. GRB 180404A: LCO FTS observations
  98. GRB 180404A: Swift-XRT refined Analysis
  99. GRB 180404B: Swift-BAT refined analysis
  100. GRB 180402A: Fermi GBM refined spectral analysis

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