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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"

27162 results found.

  1. GRB 250625A: Fermi GBM Final Real-time Localization
  2. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580
  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. IPN triangulation of GRB 250620C (long/bright)
  12. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  13. GRB 250620C: SVOM/GRM observation
  14. GRB 250620A: SVOM/GRM observation of a short burst
  15. GRB250620A: Fermi GBM Observation
  16. Fermi GRB 250621A: Global MASTER-Net observations report
  17. GRB 250619B: Fermi GBM Observation
  18. GRB 250621A: Fermi GBM Final Real-time Localization
  19. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  20. GRB250620C: Fermi GBM Observation
  21. GRB 250506A - SVOM/ECLAIRs Refined analysis
  22. The EP-WXT trigger 01709179071 is likely a flaring star
  23. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  24. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  25. GRB 250620C: Fermi GBM Final Real-time Localization
  26. Fermi trigger No 772128434: Global MASTER-Net observations report
  27. GRB 250620B: Fermi GBM Final Real-time Localization
  28. GRB 250620A: Fermi GBM Final Real-time Localization
  29. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  30. GRB 250619B: Fermi GBM Final Real-time Localization
  31. Fermi trigger No 772058337: Global MASTER-Net observations report
  32. Fermi Gamma-ray Burst Monitor trigger 772058337/250619860 is not a GRB
  33. GRB 250615A: Kilonova-Catcher optical upper limits
  34. GRB 250619A: Fermi GBM Final Real-time Localization
  35. GRB 250617B: Assy AZT-20 Optical Observations
  36. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  37. Fermi GRB 250617A: Global MASTER-Net observations report
  38. GRB 250615A/EP250615a: FTW optical and NIR observations
  39. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  40. GRB 250617B: Swift/UVOT Detection
  41. GRB 250617B: Kilonova-Catcher optical afterglow detection
  42. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  43. GRB 250617B: COLIBRÍ optical observations
  44. GRB 250617B: NOT NIR observations of the afterglow
  45. GRB 250617B: Swift-XRT refined Analysis
  46. GRB 250617B: SVOM/VT optical observation
  47. GRB 250617B: NUTTelA-TAO early time optical observations
  48. Fermi trigger No 771886893: Global MASTER-Net observations report
  49. Swift GRB 250617B: Global MASTER-Net observations report
  50. GRB 250617B: GOTO optical upper limit
  51. GRB 250617B: Fermi GBM Observation
  52. GRB 250615A: Swift-BAT refined analysis
  53. The EP-WXT trigger 01709178990 is likely a flaring star
  54. GRB 250617B: Fermi GBM Final Localization
  55. GRB 250617B: Ondrejov D50 optical afterglow detection
  56. GRB 250617B: SAO RAS optical observations
  57. GRB 250617B: Swift detection of a burst with an optical counterpart
  58. GRB 250617A: Fermi GBM Final Real-time Localization
  59. IPN triangulation of GRB 250612C (short/hard)
  60. EP#01709178975: Swift-XRT counterpart detection
  61. EP-WXT trigger 01709178975: GOTO optical upper limit
  62. The EP-WXT trigger 01709178975 is likely a flaring star
  63. Fermi Gamma-ray Burst Monitor trigger 771803204/250616907 is not a GRB
  64. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  65. GRB 250615A: COLIBRÍ optical upper limit
  66. GRB 250615A: DDOTI Optical Upper Limit
  67. GRB 250615A: Swift/UVOT Upper Limits
  68. GRB 250615A: Swift-XRT refined Analysis
  69. sb25061207/SVOM: T120 OHP optical upper limit
  70. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  71. Fermi trigger No 771752663: Global MASTER-Net observations report
  72. EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
  73. The EP-WXT trigger 01709178875 is likely a flaring star
  74. Fermi Gamma-ray Burst Monitor trigger 771718064/250615922 is not a GRB
  75. GRB 250615A: Swift detection of a burst
  76. Swift GRB 250615A: Global MASTER-Net observations report
  77. Fermi trigger No 771718064: Global MASTER-Net observations report
  78. Fermi Gamma-ray Burst Monitor trigger 771704505/250615765 is not a GRB
  79. GRID detection of GRB 250612C
  80. sb25061207: Mephisto optical upper limits
  81. Fermi Gamma-ray Burst Monitor trigger 771596290/250614513 is not a GRB
  82. GRB 250614A: Fermi GBM Final Real-time Localization
  83. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  84. Fermi Gamma-ray Burst Monitor trigger 771547945/250613953 is not a GRB
  85. Fermi Gamma-ray Burst Monitor trigger 771541927/250613883 is not a GRB
  86. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  87. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  88. Fermi trigger No 771494087: Global MASTER-Net observations report
  89. sb25061218: Swift-XRT observations
  90. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  91. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  92. sb25061207: EP-FXT follow-up observation and afterglow candidate
  93. GRB 250612B: Fermi GBM Observation
  94. EP250612a: SVOM/VT optical candidate
  95. Fermi trigger No 771424081: Global MASTER-Net observations report
  96. EP250612a: Global MASTER-Net observations report
  97. GRB 250612C: Fermi GBM Observation
  98. sb25061218: SVOM detection of a X-ray transient
  99. sb25061207: Swift-XRT observations
  100. EP250612a/GRB 250612B: JinShan optical upper limit

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