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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"

43920 results found.

  1. GRB 241018A: Maidanak optical observations
  2. GRB 250620C: AstroSat CZTI detection
  3. Fermi GRB 250624A: Global MASTER-Net observations report
  4. GRB 250624A: Fermi GBM Final Real-time Localization
  5. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  6. Fermi GRB 250623A: Global MASTER-Net observations report
  7. GRB 250623A: Fermi GBM Final Real-time Localization
  8. GRB 250521A: VZLUSAT-2 detection
  9. GRB 250617B: Swift-BAT refined analysis
  10. Fermi trigger No 772190032: Global MASTER-Net observations report
  11. Konus-Wind detection of GRB 250620C
  12. IPN triangulation of GRB 250620C (long/bright)
  13. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  14. GRB 250620C: SVOM/GRM observation
  15. GRB 250620A: SVOM/GRM observation of a short burst
  16. GRB250620A: Fermi GBM Observation
  17. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  18. Fermi GRB 250621A: Global MASTER-Net observations report
  19. GRB 250619B: Fermi GBM Observation
  20. GRB 250621A: Fermi GBM Final Real-time Localization
  21. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  22. GRB250620C: Fermi GBM Observation
  23. GRB 250506A - SVOM/ECLAIRs Refined analysis
  24. The EP-WXT trigger 01709179071 is likely a flaring star
  25. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  26. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  27. GRB 250620C: Fermi GBM Final Real-time Localization
  28. Fermi trigger No 772128434: Global MASTER-Net observations report
  29. GRB 250620B: Fermi GBM Final Real-time Localization
  30. GRB 250620A: Fermi GBM Final Real-time Localization
  31. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  32. GRB 250617B: Nickel telescope optical observations
  33. GRB 250619B: Fermi GBM Final Real-time Localization
  34. Fermi trigger No 772058337: Global MASTER-Net observations report
  35. Fermi Gamma-ray Burst Monitor trigger 772058337/250619860 is not a GRB
  36. GRB 250615A: Kilonova-Catcher optical upper limits
  37. GRB 250619A: Fermi GBM Final Real-time Localization
  38. GRB 250617B: Assy AZT-20 Optical Observations
  39. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  40. Fermi GRB 250617A: Global MASTER-Net observations report
  41. GRB 250615A/EP250615a: FTW optical and NIR observations
  42. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  43. GRB 250617B: Swift/UVOT Detection
  44. GRB 250617B: Kilonova-Catcher optical afterglow detection
  45. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  46. GRB 250617B: COLIBRÍ optical observations
  47. GRB 250617B: NOT NIR observations of the afterglow
  48. GRB 250617B: Swift-XRT refined Analysis
  49. GRB 250617B: SVOM/VT optical observation
  50. GRB 250617B: NUTTelA-TAO early time optical observations
  51. Fermi trigger No 771886893: Global MASTER-Net observations report
  52. Swift GRB 250617B: Global MASTER-Net observations report
  53. GRB 250617B: GOTO optical upper limit
  54. GRB 250617B: Enhanced Swift-XRT position
  55. GRB 250617B: Fermi GBM Observation
  56. GRB 250615A: Swift-BAT refined analysis
  57. The EP-WXT trigger 01709178990 is likely a flaring star
  58. GRB 250617B: Fermi GBM Final Localization
  59. GRB 250617B: Ondrejov D50 optical afterglow detection
  60. GRB 250617B: SAO RAS optical observations
  61. GRB 250617B: Swift detection of a burst with an optical counterpart
  62. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  63. GRB 250617A: Fermi GBM Final Real-time Localization
  64. IPN triangulation of GRB 250612C (short/hard)
  65. EP#01709178975: Swift-XRT counterpart detection
  66. EP-WXT trigger 01709178975: GOTO optical upper limit
  67. The EP-WXT trigger 01709178975 is likely a flaring star
  68. Konus-Wind detection of GRB 250615A / EP250615a
  69. GRB 250615A / EP250615a: AstroSat CZTI detection
  70. Fermi Gamma-ray Burst Monitor trigger 771803204/250616907 is not a GRB
  71. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  72. GRB 250615A: COLIBRÍ optical upper limit
  73. GRB 250615A: DDOTI Optical Upper Limit
  74. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  75. GRB 250615A: Swift-XRT refined Analysis
  76. sb25061207/SVOM: T120 OHP optical upper limit
  77. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  78. Fermi trigger No 771752663: Global MASTER-Net observations report
  79. EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
  80. The EP-WXT trigger 01709178875 is likely a flaring star
  81. GRB 250615A: Enhanced Swift-XRT position
  82. Fermi Gamma-ray Burst Monitor trigger 771718064/250615922 is not a GRB
  83. GRB 250615A: Prompt enhanced Swift-XRT position
  84. GRB 250615A: Swift detection of a burst
  85. Swift GRB 250615A: Global MASTER-Net observations report
  86. Fermi trigger No 771718064: Global MASTER-Net observations report
  87. Fermi Gamma-ray Burst Monitor trigger 771704505/250615765 is not a GRB
  88. GRID detection of GRB 250612C
  89. sb25061207: Mephisto optical upper limits
  90. IceCube alert 141029_8144692 retraction
  91. Fermi Gamma-ray Burst Monitor trigger 771596290/250614513 is not a GRB
  92. GRB 250614A: Fermi GBM Final Real-time Localization
  93. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  94. Fermi Gamma-ray Burst Monitor trigger 771547945/250613953 is not a GRB
  95. Fermi Gamma-ray Burst Monitor trigger 771541927/250613883 is not a GRB
  96. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  97. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  98. Fermi trigger No 771494087: Global MASTER-Net observations report
  99. sb25061218: Swift-XRT observations
  100. EP250612a: refined analysis of the EP-WXT and EP-FXT observations

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