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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"

43904 results found.

  1. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  2. Fermi GRB 250621A: Global MASTER-Net observations report
  3. GRB 250619B: Fermi GBM Observation
  4. GRB 250621A: Fermi GBM Final Real-time Localization
  5. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  6. GRB250620C: Fermi GBM Observation
  7. GRB 250506A - SVOM/ECLAIRs Refined analysis
  8. The EP-WXT trigger 01709179071 is likely a flaring star
  9. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  10. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  11. GRB 250620C: Fermi GBM Final Real-time Localization
  12. Fermi trigger No 772128434: Global MASTER-Net observations report
  13. GRB 250620B: Fermi GBM Final Real-time Localization
  14. GRB 250620A: Fermi GBM Final Real-time Localization
  15. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  16. GRB 250617B: Nickel telescope optical observations
  17. GRB 250619B: Fermi GBM Final Real-time Localization
  18. Fermi trigger No 772058337: Global MASTER-Net observations report
  19. Fermi Gamma-ray Burst Monitor trigger 772058337/250619860 is not a GRB
  20. GRB 250615A: Kilonova-Catcher optical upper limits
  21. GRB 250619A: Fermi GBM Final Real-time Localization
  22. GRB 250617B: Assy AZT-20 Optical Observations
  23. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  24. Fermi GRB 250617A: Global MASTER-Net observations report
  25. GRB 250615A/EP250615a: FTW optical and NIR observations
  26. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  27. GRB 250617B: Swift/UVOT Detection
  28. GRB 250617B: Kilonova-Catcher optical afterglow detection
  29. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  30. GRB 250617B: COLIBRÍ optical observations
  31. GRB 250617B: NOT NIR observations of the afterglow
  32. GRB 250617B: Swift-XRT refined Analysis
  33. GRB 250617B: SVOM/VT optical observation
  34. GRB 250617B: NUTTelA-TAO early time optical observations
  35. Fermi trigger No 771886893: Global MASTER-Net observations report
  36. Swift GRB 250617B: Global MASTER-Net observations report
  37. GRB 250617B: GOTO optical upper limit
  38. GRB 250617B: Enhanced Swift-XRT position
  39. GRB 250617B: Fermi GBM Observation
  40. GRB 250615A: Swift-BAT refined analysis
  41. The EP-WXT trigger 01709178990 is likely a flaring star
  42. GRB 250617B: Fermi GBM Final Localization
  43. GRB 250617B: Ondrejov D50 optical afterglow detection
  44. GRB 250617B: SAO RAS optical observations
  45. GRB 250617B: Swift detection of a burst with an optical counterpart
  46. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  47. GRB 250617A: Fermi GBM Final Real-time Localization
  48. IPN triangulation of GRB 250612C (short/hard)
  49. EP#01709178975: Swift-XRT counterpart detection
  50. EP-WXT trigger 01709178975: GOTO optical upper limit
  51. The EP-WXT trigger 01709178975 is likely a flaring star
  52. Konus-Wind detection of GRB 250615A / EP250615a
  53. GRB 250615A / EP250615a: AstroSat CZTI detection
  54. Fermi Gamma-ray Burst Monitor trigger 771803204/250616907 is not a GRB
  55. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  56. GRB 250615A: COLIBRÍ optical upper limit
  57. GRB 250615A: DDOTI Optical Upper Limit
  58. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  59. GRB 250615A: Swift-XRT refined Analysis
  60. sb25061207/SVOM: T120 OHP optical upper limit
  61. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  62. Fermi trigger No 771752663: Global MASTER-Net observations report
  63. EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
  64. The EP-WXT trigger 01709178875 is likely a flaring star
  65. GRB 250615A: Enhanced Swift-XRT position
  66. Fermi Gamma-ray Burst Monitor trigger 771718064/250615922 is not a GRB
  67. GRB 250615A: Prompt enhanced Swift-XRT position
  68. GRB 250615A: Swift detection of a burst
  69. Swift GRB 250615A: Global MASTER-Net observations report
  70. Fermi trigger No 771718064: Global MASTER-Net observations report
  71. Fermi Gamma-ray Burst Monitor trigger 771704505/250615765 is not a GRB
  72. GRID detection of GRB 250612C
  73. sb25061207: Mephisto optical upper limits
  74. IceCube alert 141029_8144692 retraction
  75. Fermi Gamma-ray Burst Monitor trigger 771596290/250614513 is not a GRB
  76. GRB 250614A: Fermi GBM Final Real-time Localization
  77. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  78. Fermi Gamma-ray Burst Monitor trigger 771547945/250613953 is not a GRB
  79. Fermi Gamma-ray Burst Monitor trigger 771541927/250613883 is not a GRB
  80. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  81. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  82. Fermi trigger No 771494087: Global MASTER-Net observations report
  83. sb25061218: Swift-XRT observations
  84. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  85. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  86. sb25061207: EP-FXT follow-up observation and afterglow candidate
  87. GRB 250612B: Fermi GBM Observation
  88. EP250612a / GRB 250612B: SVOM/VT optical candidate
  89. Fermi trigger No 771424081: Global MASTER-Net observations report
  90. EP250612a: Global MASTER-Net observations report
  91. GRB 250612C: Fermi GBM Observation
  92. sb25061218: SVOM detection of a X-ray transient
  93. sb25061207: Swift-XRT observations
  94. EP250612a/GRB 250612B: JinShan optical upper limit
  95. EP 250612a: AST3-3 Yaoan Optical Observation
  96. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  97. sb25061207: SVOM/VT optical counterpart
  98. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  99. GRB 250610B: Swift-XRT refined Analysis
  100. GRB 250612C: Fermi GBM Final Real-time Localization

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