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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"

33628 results found.

  1. GRB 220706A : NICER detection of re-brightening 1 day after the Swift trigger
  2. GRB 220708A: Swift-XRT refined Analysis
  3. GRB 220706A: Swift/UVOT Upper Limits
  4. GRB 220708B: Swift-XRT afterglow detection
  5. GRB 220708A: BOOTES-5/JGT early optical upper limit
  6. GRB 220706A: Swift-BAT refined analysis
  7. GRB 220708A: Enhanced Swift-XRT position
  8. GRB 220708B: Swift ToO observations
  9. GRB 220708B: Swift/BAT-GUANO arcminute localization
  10. GRB 220708A: Swift-XRT observations
  11. GRB 220708A: Swift detection of a burst
  12. GRB 220706A: LCO Optical Upper Limits
  13. GRB 220627A: ATCA detection of radio counterpart
  14. GRB 220706A: Swift-XRT refined Analysis
  15. GRB 220706A, GROND observations
  16. GRB 220706A: Optical observations from NOT
  17. GRB 220706A: MAXI/GSC detection 84 minutes after the Swift Trigger
  18. GRB 220702B: AstroSat CZTI detection
  19. GRB 220706A: Nanshan/NEXT optical upper limits
  20. GRB 220706A: Enhanced Swift-XRT position
  21. Swift GRB 220706A: Global MASTER-Net observations report
  22. GRB 220706A: Zadko observatory - Gingin optical observations
  23. GRB 220706A: Prompt enhanced Swift-XRT position
  24. GRB 220706A: Swift detection of a burst
  25. GRB 220701A: Swift-BAT refined analysis
  26. GRB 220702B: Fermi GBM Final Localization
  27. GRB 220702A: Fermi GBM Final Localization
  28. GRB 220705A: Fermi GBM Final Localization
  29. GRB 220701A: MITSuME Akeno optical upper limits
  30. GRB 220701A: COATLI Optical Upper Limit
  31. GRB 220701A: AbAO optical upper limit
  32. GRB 220627A: AstroSat CZTI detection
  33. GRB 220701A: Keck/LRIS Optical Upper Limit
  34. GRB 220701A: Swift-XRT refined Analysis
  35. GRB 220701A: LCO Optical Upper Limits
  36. GRB 220701A: BOOTES-5/JGT early optical upper limit
  37. GRB 220701A: Swift/UVOT Upper Limits
  38. GRB 220701A: Lowell Discovery Telescope Optical Observations
  39. GRB 220701A: Enhanced Swift-XRT position
  40. GRB 200701A: KAIT Optical Upper Limit
  41. GRB 220701A: Swift detection of a burst
  42. GRB 220627A, GROND observations
  43. GRB 220624A: AGILE/GRID refined analysis
  44. GRB 220627A: Swift/UVOT Upper Limits
  45. GRB 220627A: Swift-XRT afterglow detection
  46. Konus-Wind detection of GRB 220627A
  47. GRB 220627A: VLT MUSE redshift
  48. GRB 220627A: MeerLICHT candidate optical afterglow
  49. GRB 220627A: Fermi GBM Detection of a possible Lensed or Ultra-long GRB
  50. GRB 220627A: Swift/BAT-GUANO detection outside the coded FOV
  51. Konus-Wind detection of GRB 220624A
  52. GRB 220627A: Swift ToO observations
  53. GRB 220627A: Fermi-LAT detection
  54. GRB 220627A: MeerLICHT detection of two afterglow candidates
  55. Fermi GRB 220627A: Global MASTER-Net observations report
  56. GRB 220627A: Fermi GBM Final Real-time Localization
  57. GRB 220623A: GIT optical upper limits.
  58. GRB 220624A: CALET Gamma-Ray Burst Monitor detection
  59. GRB 220623A: T193-OHP optical upper limit
  60. GRB 220624A: Fermi GBM Detection
  61. Fermi GRB 220623B: Global MASTER-Net observations report
  62. Fermi GRB 220624A: Global MASTER-Net observations report
  63. IPN triangulation of GRB 220624A
  64. GRB 220623A: Swift-BAT refined analysis
  65. GRB 220624A: Swift/BAT-GUANO detection outside the coded FOV
  66. GRB 220611A: X-ray afterglow Chandra sub-arcsecond localization
  67. GRB 220624A: AGILE/GRID analysis
  68. GRB 220624A: AGILE detection
  69. Konus-Wind detection of GRB 220623A
  70. GRB 220624B: Fermi GBM Final Real-time Localization
  71. GRB 220624A: Fermi GBM Final Real-time Localization
  72. GRB 220623A: AbAO optical upper limit
  73. GRB 220623A: Swift-XRT refined Analysis
  74. GRB 220623A: NOT optical observations
  75. GRB 220623A: Swift/UVOT Upper Limits
  76. GRB 220623A: BOOTES-5/JGT optical afterglow detection
  77. Konus-Wind detection of GRB 220609B
  78. GRB 220623B: Fermi GBM Final Real-time Localization
  79. GRB 220623A: Enhanced Swift-XRT position
  80. GRB 220623A: AGILE detection
  81. GRB 220623A: AstroSat CZTI detection
  82. GRB 220623A: iTelescope optical upper limit
  83. GRB 220623A: Swift-XRT observations
  84. GRB 220623A: Swift detection of a burst
  85. GRB 220618A: Fermi GBM detection
  86. GRB 220618A: Swift-BAT refined analysis
  87. GRB 220618A: iTelescope T-19 upper limit
  88. Konus-Wind detection of GRB 220617A
  89. Fermi GRB 220620B: Global MASTER-Net observations report
  90. Fermi GRB 220620A: Global MASTER-Net observations report
  91. GRB 220620B: Fermi GBM Final Real-time Localization
  92. GRB 220619A: AstroSat CZTI detection
  93. GRB 220620A: Fermi GBM Final Real-time Localization
  94. GRB 220611A: Continued Gemini Infrared Observations
  95. GRB 220617A: TNG optical observations
  96. GRB 220617A: Fermi GBM observation
  97. GRB 220611A optical counterpart
  98. GRB 220618A: Swift-XRT refined Analysis
  99. IPN triangulation of GRB 220617A (short)
  100. GRB 220618A: BOOTES-5/JGT early optical upper limit

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