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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

21469 results found.

  1. GRB 250823A: LCOGT Optical Detection
  2. GRB 250823A: BOOTES6/DPRT early optical detection
  3. GRB 250823A: Liverpool Telescope optical detection
  4. GRB 250823A: Swift detection of a burst
  5. Swift GRB250823.84: Global MASTER-Net observations report
  6. GRB 250821A: Kilonova-Catcher optical upper limits
  7. EP250821a: Swift/XRT counterpart fading
  8. GRB 250821A: Swift-BAT refined analysis
  9. EP250821a: Swift/UVOT further observations.
  10. GRB 250821A: VLT/FORS2 Optical Observation
  11. GRB 250821A: GECAM-B detection
  12. EP250821a: SVOM/VT optical observation
  13. GRB 250821A: NOT z-band upper limit
  14. GRB 250821A: KAIT optical upper limit
  15. GRB 250821A: Swift-XRT refined Analysis
  16. Swift GRB 250821A: Global MASTER-Net observations report
  17. GRB 250821A: Enhanced Swift-XRT position
  18. GRB 250821A: Swift/UVOT Upper Limits
  19. EP250821a: Rapidly fading optical source detected in Las Cumbres followup
  20. EP250821a: Swift XRT and UVOT counterpart detection
  21. GRB 250821A: LCOGT Optical Upper Limits
  22. GRB 250814A: CMO SAI and SAO RAS izJ observations.
  23. GRB 250821A: Prompt enhanced Swift-XRT position
  24. GRB 250821A: Swift detection of a burst
  25. LIGO/Virgo/KAGRA S250818k: Swift observations of AT 2025ulz
  26. GRB 250814A: Swift/UVOT Upper Limits
  27. GRB 250813B: Swift/UVOT Upper Limit
  28. IPN triangulation of GRB 250814C (short)
  29. IPN triangulation of GRB 250804B (short)
  30. GRB 250818B: Kilonova-Catcher optical afterglow detection
  31. GRB 250818A: AstroSat CZTI detection
  32. GRB 250818B: Swift/UVOT Detection
  33. GRB 250818B: SAO RAS optical observations
  34. Swift GRB 250818A: Global MASTER-Net observations report
  35. GRB 250818A: Swift-XRT refined Analysis
  36. GRB 250818A: Swift-BAT refined analysis
  37. GRB 250818B: Keck redshift of the optical afterglow
  38. GRB 250818A: Swift/UVOT Upper Limits
  39. GRB 250818A: Enhanced Swift-XRT position
  40. GRB 250818A: Fermi GBM Observation
  41. GRB 250818B: SVOM/VT optical observation
  42. GRB 250814A: Further GRAWITA TNG NIR observations
  43. GRB 250818B: Swift-XRT afterglow detection
  44. GRB 250818A: Swift detection of a burst
  45. sb25081602: Swift-XRT observations
  46. GRB 250814A: Swift-BAT refined analysis
  47. GRB 250814A: Further COLIBRÍ optical upper limit
  48. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  49. GRB 250814A: GRAWITA TNG NIR observations
  50. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  51. GRB250814A: TRT optical upper limits
  52. GRB 250814C: SVOM/GRM observation of a short burst
  53. LIGO/Virgo/KAGRA S250813k: Swift XRT observations, 2 X-ray sources
  54. GRB 250813B: SVOM/GRM observation
  55. GRB 250814A: P200/WIRC observations of the afterglow candidate
  56. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  57. GRB 250814A: KAIT optical upper limit
  58. GRB 250814A: Swift-XRT refined Analysis
  59. GRB 240814A: Fermi GBM Observation
  60. GRB 250814A: Possible afterglow candidate from P200/WIRC
  61. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  62. Swift GRB250814.32: Global MASTER-Net observations report
  63. GRB 250814A: J-band upper limit from WINTER
  64. GRB 250813B: SVOM/VT optical observations
  65. GRB 250814A: COLIBRÍ optical upper limit
  66. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  67. GRB 250814A: DDOTI Optical Upper Limit
  68. GRB 250813B: Swift-XRT afterglow detection
  69. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  70. EP250812a: NOT, NTT, and GS observations
  71. GRB 250812A: Swift/UVOT Detection
  72. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  73. EP250812a: SVOM/VT optical counterpart
  74. GRB 250812A: Swift ToO observations
  75. GRB 250807B: Swift-BAT refined analysis
  76. EP 250812a: GOTO optical upper limit
  77. GRB 250812A: Kilonova-Catcher optical afterglow detection
  78. EP250812a: Swift-XRT counterpart detection
  79. GRB 250812A: SVOM/VT optical afterglow confirmation
  80. GRB 250812A: Swift-XRT afterglow detection
  81. GRB 250809A: Swift-BAT refined analysis
  82. GRB 250807A: Swift-BAT refined analysis
  83. GRB 250809A: Swift/UVOT Detection
  84. Corrected Swift-XRT Refined Analysis of GRB 250809A
  85. GRB 250809A: Swift-XRT refined Analysis
  86. GRB 250807B: SVOM/VT optical observation
  87. GRB 250809A: LCOGT Optical Upper Limits
  88. GRB 250702B: Chandra X-ray Detection
  89. GRB 250808A: VLT X-shooter candidate counterpart
  90. GRB 250809A: Prompt enhanced Swift-XRT position
  91. GRB 250809A: Swift detection of a gamma ray burst
  92. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  93. GRB 250808A: Swift-XRT candidate counterpart detection
  94. GRB 250807A: SVOM/VT optical continued observation
  95. Konus-Wind detection of GRB 250807A
  96. GRB 250807B: Swift/UVOT Detection
  97. GRB 250807B: Kilonova-Catcher optical afterglow detection
  98. GRB 250807A: Swift/UVOT Detection
  99. GRB 250807A: Swift-XRT refined Analysis
  100. GRB 250807B: VLT/X-Shooter spectroscopic redshift z = 1.522

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