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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"

27191 results found.

  1. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  2. EP250402a: Optical upper limit with PD 1.3m observations
  3. GRB 250404A / EP250404a: NOT optical observations
  4. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  5. EP250404a: REM optical/NIR observations
  6. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  7. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  8. EP250404a: LCO optical counterpart detection
  9. Fermi GRB 250404A: Global MASTER-Net observations report
  10. EP250404a: Xinglong decaying optical counterpart
  11. GRB 250404A: Fermi GBM Detection
  12. EP250404a: Global MASTER-Net observations report
  13. GRB 250403A: KAIT optical observations
  14. EP250404a: AKO Optical Afterglow Detection
  15. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  16. GRB 250403A: Fermi GBM observations
  17. EP250404a: Mephisto multi-band optical detection
  18. GRB 250331C Swift-BAT refined analysis
  19. GRB 250331B Swift-BAT refined analysis
  20. GRB 250330A Swift-BAT refined analysis
  21. EP250321A: J band upper limit by SYSU 80cm telescope
  22. EP250404a: Nanshan/HMT optical counterpart detection
  23. EP250404a: Einstein Probe detection of an X-ray transient
  24. GRB 250404A: Fermi GBM Final Real-time Localization
  25. EP250402a: Optical upper limit with Kinder observations
  26. GRB 250403A: SVOM/VT optical observation
  27. GRB 250403A: REM NIR afterglow detection
  28. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  29. GRB 250403A: JinShan optical observations
  30. GRB 250402A: EP-FXT afterglow detection
  31. GRB 250403A: Optical counterpart detection by LCO.
  32. EP250402a: EP-FXT follow-up observations
  33. GRB 250403A: Swift-XRT observations
  34. Fermi GRB 250403A: Global MASTER-Net observations report
  35. GRB 250402A: NUTTelA-TAO Early Optical Limits
  36. GRB 250403A: GMG Optical Observation
  37. GRB 250403A: 1.6m Mephisto multi-band optical detection
  38. GRB 250402A: Fermi GBM Observation
  39. GRB 250403A: SVOM/C-GFT optical observations
  40. GRB 250403A: GOTO detection of the optical afterglow
  41. GRB 250402A: Swift-XRT observations
  42. GRB 250403A : SVOM detection of a burst
  43. GRB 250403A: Fermi GBM Final Real-time Localization
  44. GRB 250225B: VLT host galaxy redshift z = 0.950
  45. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  46. GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
  47. GRB 250402A: REM optical/NIR upper limits
  48. GRB 250402A: LCO optical counterpart detection
  49. GRB 250402A: refined SVOM/MXT data analysis
  50. The EP-WXT trigger 01709133862 is a flaring star
  51. EP250402a: Einstein Probe detection of a fast X-ray transient
  52. GRB 250402A: SVOM/VT optical counterpart
  53. GRB 250402A: SVOM detection of a burst
  54. GRB 250329B: Swift/UVOT Upper Limit
  55. GRB 250329A: Swift/UVOT Upper Limit
  56. GRB 250327B: Swift/UVOT Detection
  57. GRB 250327A: Swift/UVOT Upper Limits
  58. GRB 250331E: SVOM/GRM observation
  59. GRB 250327B: Kilonova-Catcher Observations
  60. GRB 250331D: Fermi GBM observation
  61. GRB 250331C: Swift/UVOT Upper Limits
  62. GRB 250331B: Swift/UVOT Upper Limits
  63. GRB 250328A: AbAO AS-32 Optical Observations
  64. GRB 250331C: Swift-XRT refined Analysis
  65. GRB 250331B: Swift-XRT refined Analysis
  66. GRB 250331B: Swift-XRT refined Analysis
  67. GRB 250330B: SVOM/GRM observation of a short burst
  68. Fermi GRB 250331E: Global MASTER-Net observations report
  69. Fermi GRB 250331D: Global MASTER-Net observations report
  70. GRB 250331E: Fermi GBM Final Real-time Localization
  71. GRB 250327A Swift-BAT refined analysis
  72. Fermi trigger No 765078057: Global MASTER-Net observations report
  73. GRB 250329B: CAHA 2.2m telescope optical limit
  74. Swift GRB 250331C: Global MASTER-Net observations report
  75. Swift GRB 250331B: Global MASTER-Net observations report
  76. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  77. GRB 250320C : SVOM detection of a burst through offline search
  78. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  79. GRB 250330A: VLT/FORS2 Afterglow Detection
  80. GRB20250327B: 45th Parallel Observatory upper limit
  81. GRB 250328A: Swift/UVOT Detection
  82. GRB 250328A: Swift-XRT refined Analysis
  83. SVOM/sb25033102 is a false trigger
  84. GRB 250330A: Fermi GBM Observation
  85. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  86. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  87. GRB 250331D: Fermi GBM Final Real-time Localization
  88. GRB 250331C: Swift detection of a burst
  89. GRB 250331B: Swift detection of a burst
  90. GRB 250330A: SVOM/VT optical upper limit
  91. SVOM/sb25033102: SVOM detection of an X-ray transient
  92. Fermi GRB 250330B: Global MASTER-Net observations report
  93. GRB 250330B: Fermi GBM Final Real-time Localization
  94. Fermi GRB 250330A: Global MASTER-Net observations report
  95. GRB 250330A: BOOTES-7 early optical upper limit
  96. GRB 250330A: Swift/UVOT Upper Limits
  97. GRB 250328A: 1.6m Mephisto optical observations
  98. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  99. GRB 250330A: Fermi GBM Final Localization
  100. IceCube Alert 250330.35: Global MASTER-Net observations report

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