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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"

45451 results found.

  1. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  2. Fermi GRB 250617A: Global MASTER-Net observations report
  3. GRB 250615A/EP250615a: FTW optical and NIR observations
  4. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  5. GRB 250617B: Swift/UVOT Detection
  6. GRB 250617B: Kilonova-Catcher optical afterglow detection
  7. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  8. GRB 250617B: COLIBRÍ optical observations
  9. GRB 250617B: NOT NIR observations of the afterglow
  10. GRB 250617B: Swift-XRT refined Analysis
  11. GRB 250617B: SVOM/VT optical observation
  12. GRB 250617B: NUTTelA-TAO early time optical observations
  13. Fermi trigger No 771886893: Global MASTER-Net observations report
  14. Swift GRB 250617B: Global MASTER-Net observations report
  15. GRB 250617B: GOTO optical upper limit
  16. GRB 250617B: Enhanced Swift-XRT position
  17. GRB 250617B: Fermi GBM Observation
  18. GRB 250615A: Swift-BAT refined analysis
  19. The EP-WXT trigger 01709178990 is likely a flaring star
  20. GRB 250617B: Fermi GBM Final Localization
  21. GRB 250617B: Ondrejov D50 optical afterglow detection
  22. GRB 250617B: SAO RAS optical observations
  23. GRB 250617B: Swift detection of a burst with an optical counterpart
  24. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  25. GRB 250617A: Fermi GBM Final Real-time Localization
  26. IPN triangulation of GRB 250612C (short/hard)
  27. EP#01709178975: Swift-XRT counterpart detection
  28. EP-WXT trigger 01709178975: GOTO optical upper limit
  29. The EP-WXT trigger 01709178975 is likely a flaring star
  30. Konus-Wind detection of GRB 250615A / EP250615a
  31. GRB 250615A / EP250615a: AstroSat CZTI detection
  32. Fermi Gamma-ray Burst Monitor trigger 771803204/250616907 is not a GRB
  33. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  34. GRB 250615A: COLIBRÍ optical upper limit
  35. GRB 250615A: DDOTI Optical Upper Limit
  36. GRB 250615A: Swift/UVOT Upper Limits
  37. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  38. GRB 250615A: Swift-XRT refined Analysis
  39. sb25061207/SVOM: T120 OHP optical upper limit
  40. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  41. Fermi trigger No 771752663: Global MASTER-Net observations report
  42. EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
  43. The EP-WXT trigger 01709178875 is likely a flaring star
  44. GRB 250615A: Enhanced Swift-XRT position
  45. Fermi Gamma-ray Burst Monitor trigger 771718064/250615922 is not a GRB
  46. GRB 250615A: Prompt enhanced Swift-XRT position
  47. GRB 250615A: Swift detection of a burst
  48. Swift GRB 250615A: Global MASTER-Net observations report
  49. Fermi trigger No 771718064: Global MASTER-Net observations report
  50. Fermi Gamma-ray Burst Monitor trigger 771704505/250615765 is not a GRB
  51. GRID detection of GRB 250612C
  52. sb25061207: Mephisto optical upper limits
  53. IceCube alert 141029_8144692 retraction
  54. Fermi Gamma-ray Burst Monitor trigger 771596290/250614513 is not a GRB
  55. GRB 250614A: Fermi GBM Final Real-time Localization
  56. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  57. Fermi Gamma-ray Burst Monitor trigger 771547945/250613953 is not a GRB
  58. Fermi Gamma-ray Burst Monitor trigger 771541927/250613883 is not a GRB
  59. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  60. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  61. Fermi trigger No 771494087: Global MASTER-Net observations report
  62. sb25061218: Swift-XRT observations
  63. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  64. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  65. sb25061207: EP-FXT follow-up observation and afterglow candidate
  66. GRB 250612B: Fermi GBM Observation
  67. EP250612a: SVOM/VT optical candidate
  68. Fermi trigger No 771424081: Global MASTER-Net observations report
  69. EP250612a: Global MASTER-Net observations report
  70. GRB 250612C: Fermi GBM Observation
  71. sb25061218: SVOM detection of a X-ray transient
  72. sb25061207: Swift-XRT observations
  73. EP250612a/GRB 250612B: JinShan optical upper limit
  74. EP 250612a: AST3-3 Yaoan Optical Observation
  75. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  76. sb25061207: SVOM/VT optical counterpart
  77. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  78. GRB 250610B: Swift-XRT refined Analysis
  79. GRB 250612C: Fermi GBM Final Real-time Localization
  80. EP250610a: Upper limit from Fermi-GBM Observations
  81. GRB 250612B (250612519/771424081): Fermi GBM Final Localization
  82. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  83. EP250612a: Einstein Probe detection of an X-ray transient
  84. GRB 250610B: Liverpool Telescope continued monitoring
  85. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  86. sb25061207: SVOM detection of a X-ray transient
  87. EP250610a: continuous follow-up observations with EP-FXT
  88. GRB 250610B - SVOM/ECLAIRs refined analysis
  89. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  90. Swift GRB250612.04: Global MASTER-Net observations report
  91. Fermi GBM Sub-Threshold Detection of GRB 250610B
  92. GRB 250610B: Swift/UVOT Detection
  93. EP250610A: Swift/UVOT Upper limits
  94. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  95. EP250610a: TNG NIR upper limit
  96. GRB 250610B: REM optical/NIR observations
  97. EP250610a: Liverpool Telescope optical upper limits
  98. GRB 250610B: SVOM/VT optical shallow decay
  99. GRB 250610B: additional Liverpool Telescope optical observations
  100. GRB 250610B: SVOM/GRM analysis

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