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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"

2974 results found.

  1. GRB 250103A: Fermi GBM Observation
  2. GRB 250103A: SVOM/C-GFT optical upper limit
  3. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  4. GRB 250101A: OASDG optical observations
  5. GRB 241228B: SAO RAS optical observations
  6. Konus-Wind detection of GRB 241228A
  7. GRB 241229B: Swift-BAT refined analysis
  8. Fermi GRB 241228B: Global MASTER-Net observations report
  9. GRB 241228A: Fermi GBM Observation
  10. GRB 241228B: TRT optical counterpart confirmation
  11. GRB 241228A: Swift detection of a burst
  12. Fermi trigger No 756678579: Global MASTER-Net observations report
  13. GRB 241217A/EP241217b: SOAR afterglow detection
  14. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  15. EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
  16. GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission.
  17. EP241217a: Liverpool Telescope optical follow-up
  18. EP241217a: Global MASTER-Net observations report
  19. GRB 241217A: GMG Optical Upper Limit
  20. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  21. EP241208a: Global MASTER-Net observations report
  22. Fermi GRB 241209E: Global MASTER-Net observations report
  23. Fermi GRB 241209A: Global MASTER-Net observations report
  24. Fermi GRB 241206A: Global MASTER-Net observations report
  25. Fermi GRB 241204A: Global MASTER-Net observations report
  26. Fermi GRB 241201A: Global MASTER-Net observations report
  27. LIGO/Virgo/KAGRA S241201ac: Identification of a GW compact binary merger candidate
  28. GRB 241127A: Swift-BAT refined analysis
  29. GRB 241026A: radio detection with the VLA
  30. GRB241120A: OHP/T193 optical observations
  31. GRB 241120A: Mondy and AbAO optical observations
  32. Fermi GRB 241118A: Global MASTER-Net observations report
  33. EP241113a: Global MASTER-Net observations report
  34. Fermi trigger No 753166198: Global MASTER-Net observations report
  35. Fermi-GBM Sub-Threshold Detection of GRB 241112B
  36. GRB 241112B: SVOM/GRM observation
  37. GRB 241112B : detection of a long GRB by SVOM/ECLAIRs
  38. Fermi trigger No 752990530: Global MASTER-Net observations report
  39. Fermi trigger No 752878030: Global MASTER-Net observations report
  40. EP241107a: AKO Optical Afterglow Follow-Up Observations
  41. GRB 240511A: LCO upper limits
  42. Fermi GRB 241105A: Global MASTER-Net observations report
  43. Fermi GRB 241104A: Global MASTER-Net observations report
  44. EP241101a: EP-FXT observations update
  45. Fermi trigger No 752365806: Global MASTER-Net observations report
  46. EP241103a: Swift XRT detection and improved X-ray position
  47. LIGO/Virgo/KAGRA S241102br: MASTER observations and OT detection
  48. GRB 241101A: Swift detection of a burst
  49. Fermi trigger No 752083996: Global MASTER-Net observations report
  50. EP EP241030a: Global MASTER-Net observations report
  51. Fermi trigger No 752006065: Global MASTER-Net observations report
  52. GRB 241030B: Swift detection of a burst
  53. GRB 240912A: radio detection with the VLA
  54. Fermi GRB 241030A: Global MASTER-Net observations report
  55. GRB 241026A: SAO RAS observations of possible optical afterglow
  56. Fermi GRB 241026A: Global MASTER-Net observations report
  57. GRB 241026A: Prompt enhanced Swift-XRT position
  58. EP241021a: optical follow-up observations with Xinglong Observatory
  59. Fermi GRB 241025A: Global MASTER-Net observations report
  60. IPN triangulation of GRB 241021A (long)
  61. GRB241017A: 1.3m DFOT optical upper limit
  62. Fermi trigger No 750788395: Global MASTER-Net observations report
  63. GRB 241017A : Detection of a weak and soft long duration GRB by SVOM/ECLAIRs
  64. Fermi GRB 241016A: Global MASTER-Net observations report
  65. GRB 240916A: radio detection with the VLA
  66. GRB241013A: REM observations
  67. Fermi trigger No 750211959: Global MASTER-Net observations report
  68. IceCube Alert 241006.94: Global MASTER-Net observations report
  69. EP EP240930a: Global MASTER-Net observations report
  70. Fermi GRB 240929A: Global MASTER-Net observations report
  71. LIGO/Virgo S240919bn: GOTO optical upper limits
  72. GRB 240918B: AstroSat CZTI detection
  73. EP240919a: EP-FXT follow-up observation update
  74. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  75. GRB 240918B: Fermi GBM Detection
  76. GRB 240912A: Swift-BAT refined analysis
  77. Fermi GRB 240908A: Global MASTER-Net observations report
  78. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  79. GRB 240902B: AstroSat CZTI detection of a long burst
  80. GRB 240825A: Montarrenti Observatory optical follow-up observations
  81. Fermi trigger No 746923430: Global MASTER-Net observations report
  82. Fermi trigger No 746587425: Global MASTER-Net observations report
  83. Swift GRB240829.16: Global MASTER-Net observations report
  84. Fermi trigger No 746438824: Global MASTER-Net observations report
  85. GRB 240824A: GIT optical upper limit
  86. GRB 240825A: AKO Optical Follow-Up Observations
  87. SGR 1E 1841-045 / Kes 73 (Trigger 1249878): Osservatorio Atronomico Nastro Verde optical upper limit
  88. SGR 1E 1841-045 / Kes 73 (Trigger 1249653) - Osservatorio Astronomico Nastro Verde upper limit
  89. SGR 1E 1841-045 / Kes 73: Leavitt Observatory optical upper limit
  90. Fermi GRB 240821B: Global MASTER-Net observations report
  91. Fermi trigger No 745866488: Global MASTER-Net observations report
  92. Trigger 1249878: Swift detection of another burst from SGR 1E 1841-045 / Kes 73
  93. EP240816a: EP detection of a fast X-ray transient and follow-up observation
  94. Fermi GRB 240814B: Global MASTER-Net observations report
  95. GRB 240808A: AstroSat CZTI detection
  96. GRB 240808A: SVOM/GRM observation
  97. EP EP240807a: Global MASTER-Net observations report
  98. EP EP240806a: Global MASTER-Net observations report
  99. GRB 240805B: Swift-BAT refined analysis
  100. Fermi trigger No 744629911: Global MASTER-Net observations report

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