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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 180510A: Swift/UVOT followup observations
  2. GRB 180510B: Swift-XRT refined Analysis
  3. GRB 180510A: Swift-XRT refined Analysis
  4. Swift trigger 831888: misidentification of 4U 1416-62
  5. GRB 180510B: Swift-BAT refined analysis
  6. GRB 180510B: VLT/X-shooter observations
  7. GRB 180510B: GROND detection in all bands
  8. GRB 180510B: TAROT La Silla observatory optical observations
  9. Swift Trigger 831888: a possible GRB or Galactic transient
  10. GRB 180510B: Enhanced Swift-XRT position
  11. GRB 180418A: 15 GHz upper limits from AMI
  12. GRB 180510B: Swift detection of a burst with an optical counterpart
  13. GRB 180510A: Swift detection of a burst
  14. GRB 180427A: AstroSat CZTI detection
  15. Chandra observations of GW170817 reveal a fading afterglow
  16. Chandra observations of GW170817 260 days since merger: first statistically significant evidence for an X-ray decay
  17. GRB 180504A: Swift/UVOT Upper Limits
  18. GRB 180504A: Swift-BAT refined analysis
  19. GRB 180505A: Fermi GBM detection
  20. GRB 180416A: AstroSat CZTI detection
  21. GRB 180504A: ePESSTO NTT NIR observations
  22. Correction to Swift-XRT light curve fit for GRB 180504A in GCN 22685
  23. GRB 180504A: Swift-XRT refined Analysis
  24. GRB 180504A: NOT afterglow candidate
  25. GRB 180504A: Prompt enhanced Swift-XRT position
  26. GRB 180504A: Swift detection of a burst
  27. GRB 180416B: AstroSat CZTI detection
  28. Konus-Wind observation of GRB 180427A
  29. IPN Triangulation of GRB 180427A
  30. GRB 180427A: Fermi GBM detection
  31. Swift Trigger 829046 is probably noise
  32. GRB 180425A: Swift-XRT refined Analysis
  33. GRB 180425A: Swift-BAT refined analysis
  34. GRB 180425A: Swift/UVOT Upper Limits
  35. GRB 180425A: Enhanced Swift-XRT position
  36. GRB 180425A: Swift detection of a burst
  37. GRB 180418A: TAROT La Silla observatory early optical observations
  38. GRB 180418A: MITSuME Ishigakijima Optical Observation
  39. Retraction of IceCube GCN/AMON NOTICE 71165249_130949
  40. GRB 180418A : SQUEAN observations
  41. Fermi GBM trigger 545979055/180421202 is not a GRB
  42. GRB 180418A: Further GROND observations
  43. GRB 180418A: Swift/UVOT Detection
  44. GRB 180418A: Continued RATIR Optical Observations
  45. GRB 180418A: Imaging of the optical afterglow with the 1.3 m DFOT and 3.6 m DOT in ARIES, India
  46. GRB 180418A GROND observations
  47. GRB 180418A: Xinglong TNT optical upper limit
  48. GRB 180418A: NOT optical observations
  49. GRB 180418A: Gemini-North imaging and spectroscopy
  50. GRB 180418A: Swift-BAT refined analysis
  51. GRB 180418A: 1.5m OSN optical observations
  52. GRB 180418A: Fermi GBM observation
  53. GRB 180418A: Swift-XRT refined Analysis
  54. GRB 180416B: CALET Gamma-Ray Burst Monitor detection
  55. GRB 180418A: RATIR Optical Observations
  56. LIGO/Virgo G299232: LOFAR follow-up
  57. GRB 180418A: Enhanced Swift-XRT position
  58. GRB 180418A: Swift-XRT observations
  59. GRB 180418A: LCO FTN afterglow confirmation
  60. GRB 180418A: KAIT Optical Afterglow Candidate
  61. GRB 180418A: Swift detection of a short burst
  62. GRB 180404B: AstroSat CZTI detection
  63. GRB 180416A: Fermi GBM detection
  64. GRB 180409A: Swift-XRT afterglow detection
  65. GRB 180411A: CALET Gamma-Ray Burst Monitor detection
  66. GRB 180411B: CALET Gamma-Ray Burst Monitor detection
  67. Konus-Wind observation of GRB 180411A
  68. GRB 180411A: Swift/UVOT Upper Limit
  69. GRB 180411A: Tautenburg observations
  70. GRB 180410A: Fermi GBM observation
  71. GRB 180409A CALET Gamma-Ray Burst Monitor detection
  72. GRB 180411A: Fermi GBM detection
  73. GRB 180411A: Swift-BAT refined analysis
  74. GRB 180411A: Swift-XRT refined Analysis
  75. GRB 180410A: RATIR Optical Observations
  76. GRB 180411A: Swift detection of a burst
  77. GRB 180410A: Swift-XRT refined Analysis
  78. GRB 180410A: Swift-BAT refined analysis
  79. GRB 180410A: Swift/UVOT Upper Limits
  80. GRB 180409A: Fermi GBM observation
  81. GRB 180409A: Swift-XRT observations
  82. Konus-Wind observation of GRB 180404C
  83. GRB 180410A: MITSuME Akeno optical upper limits
  84. GRB 180410A: Enhanced Swift-XRT position
  85. Konus-Wind observation of GRB 180409A
  86. GRB 180410A: Swift detection of a burst or a Galactic transient.
  87. IPN Triangulation of GRB 180409A
  88. GRB 180409A: Tiled Swift observations
  89. GRB 180402A: ISON-NM early optical limits
  90. GRB 180407A: Swift-BAT refined analysis
  91. Swift Trigger 823014: TAROT Calern observatory optical observations
  92. GRB 180407A: COATLI Upper Limits
  93. Swift Trigger 823014 is probably not a GRB
  94. GRB 180407A: Swift detection of a burst
  95. GRB 180404B: Swift/UVOT Detection
  96. IPN Triangulation of GRB 180404C (long)
  97. Konus-Wind observation of GRB 180404B
  98. Chandra observations of GRB161219B 400 days after the explosion
  99. GRB 180404C CALET Gamma-Ray Burst Monitor detection
  100. Fermi GBM triggers 544628550/180405571, 544542853/180404579, 544531428/180404447 are not GRBs

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