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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"

37619 results found.

  1. Fermi GRB 250623A: Global MASTER-Net observations report
  2. GRB 250623A: Fermi GBM Final Real-time Localization
  3. GRB 250521A: VZLUSAT-2 detection
  4. GRB 250617B: Swift-BAT refined analysis
  5. Fermi trigger No 772190032: Global MASTER-Net observations report
  6. Konus-Wind detection of GRB 250620C
  7. IPN triangulation of GRB 250620C (long/bright)
  8. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  9. GRB 250620C: SVOM/GRM observation
  10. GRB 250620A: SVOM/GRM observation of a short burst
  11. GRB250620A: Fermi GBM Observation
  12. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  13. Fermi GRB 250621A: Global MASTER-Net observations report
  14. GRB 250619B: Fermi GBM Observation
  15. GRB 250621A: Fermi GBM Final Real-time Localization
  16. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  17. GRB250620C: Fermi GBM Observation
  18. GRB 250506A - SVOM/ECLAIRs Refined analysis
  19. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  20. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  21. GRB 250620C: Fermi GBM Final Real-time Localization
  22. Fermi trigger No 772128434: Global MASTER-Net observations report
  23. GRB 250620B: Fermi GBM Final Real-time Localization
  24. GRB 250620A: Fermi GBM Final Real-time Localization
  25. GRB 250617B: Nickel telescope optical observations
  26. GRB 250619B: Fermi GBM Final Real-time Localization
  27. Fermi trigger No 772058337: Global MASTER-Net observations report
  28. Fermi Gamma-ray Burst Monitor trigger 772058337/250619860 is not a GRB
  29. GRB 250615A: Kilonova-Catcher optical upper limits
  30. GRB 250619A: Fermi GBM Final Real-time Localization
  31. GRB 250617B: Assy AZT-20 Optical Observations
  32. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  33. Fermi GRB 250617A: Global MASTER-Net observations report
  34. GRB 250615A/EP250615a: FTW optical and NIR observations
  35. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  36. GRB 250617B: Swift/UVOT Detection
  37. GRB 250617B: Kilonova-Catcher optical afterglow detection
  38. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  39. GRB 250617B: COLIBRÍ optical observations
  40. GRB 250617B: NOT NIR observations of the afterglow
  41. GRB 250617B: Swift-XRT refined Analysis
  42. GRB 250617B: SVOM/VT optical observation
  43. GRB 250617B: NUTTelA-TAO early time optical observations
  44. Fermi trigger No 771886893: Global MASTER-Net observations report
  45. Swift GRB 250617B: Global MASTER-Net observations report
  46. GRB 250617B: GOTO optical upper limit
  47. GRB 250617B: Enhanced Swift-XRT position
  48. GRB 250617B: Fermi GBM Observation
  49. GRB 250615A: Swift-BAT refined analysis
  50. GRB 250617B: Fermi GBM Final Localization
  51. GRB 250617B: Ondrejov D50 optical afterglow detection
  52. GRB 250617B: SAO RAS optical observations
  53. GRB 250617B: Swift detection of a burst with an optical counterpart
  54. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  55. GRB 250617A: Fermi GBM Final Real-time Localization
  56. IPN triangulation of GRB 250612C (short/hard)
  57. Konus-Wind detection of GRB 250615A / EP250615a
  58. GRB 250615A / EP250615a: AstroSat CZTI detection
  59. Fermi Gamma-ray Burst Monitor trigger 771803204/250616907 is not a GRB
  60. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  61. GRB 250615A: COLIBRÍ optical upper limit
  62. GRB 250615A: DDOTI Optical Upper Limit
  63. GRB 250615A: Swift/UVOT Upper Limits
  64. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  65. GRB 250615A: Swift-XRT refined Analysis
  66. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  67. Fermi trigger No 771752663: Global MASTER-Net observations report
  68. GRB 250615A: Enhanced Swift-XRT position
  69. Fermi Gamma-ray Burst Monitor trigger 771718064/250615922 is not a GRB
  70. GRB 250615A: Prompt enhanced Swift-XRT position
  71. GRB 250615A: Swift detection of a burst
  72. Swift GRB 250615A: Global MASTER-Net observations report
  73. Fermi trigger No 771718064: Global MASTER-Net observations report
  74. Fermi Gamma-ray Burst Monitor trigger 771704505/250615765 is not a GRB
  75. GRID detection of GRB 250612C
  76. Fermi Gamma-ray Burst Monitor trigger 771596290/250614513 is not a GRB
  77. GRB 250614A: Fermi GBM Final Real-time Localization
  78. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  79. Fermi Gamma-ray Burst Monitor trigger 771547945/250613953 is not a GRB
  80. Fermi Gamma-ray Burst Monitor trigger 771541927/250613883 is not a GRB
  81. Fermi trigger No 771494087: Global MASTER-Net observations report
  82. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  83. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  84. GRB 250612B: Fermi GBM Observation
  85. Fermi trigger No 771424081: Global MASTER-Net observations report
  86. GRB 250612C: Fermi GBM Observation
  87. EP250612a/GRB 250612B: JinShan optical upper limit
  88. EP 250612a: AST3-3 Yaoan Optical Observation
  89. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  90. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  91. GRB 250610B: Swift-XRT refined Analysis
  92. GRB 250612C: Fermi GBM Final Real-time Localization
  93. EP250610a: Upper limit from Fermi-GBM Observations
  94. GRB 250612B (250612519/771424081): Fermi GBM Final Localization
  95. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  96. GRB 250610B: Liverpool Telescope continued monitoring
  97. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  98. GRB 250610B - SVOM/ECLAIRs refined analysis
  99. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  100. Fermi GBM Sub-Threshold Detection of GRB 250610B

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