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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"

26232 results found.

  1. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  2. GRB 250702F: TRT Optical Observation
  3. GRB 250703A: DDOTI Optical Upper Limit
  4. GRB 250702F: REM optical afterglow detection
  5. EP250702a: Global MASTER-Net observations report
  6. GRB 250702F: DDOTI Optical Observation
  7. GRB 250703A: Fermi GBM Final Real-time Localization
  8. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  9. GRB 250702F: COLIBRÍ Observations of the Afterglow
  10. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  11. Fermi GRB 250702E: Global MASTER-Net observations report
  12. Fermi GRB 250702B: Global MASTER-Net observations report
  13. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  14. GRB 250702F: NOT observations of the optical afterglow
  15. Fermi GRB 250702F: Global MASTER-Net observations report
  16. Fermi GRB 250702C: Global MASTER-Net observations report
  17. GRB 250702F: GOTO optical counterpart detection
  18. GRB 250702F: Ondrejov D50 optical afterglow detection
  19. GRB 250702F: Swift detection of a burst with an optical counterpart
  20. Swift GRB 250702F: Global MASTER-Net observations report
  21. GRB 250702F: Fermi GBM Final Real-time Localization
  22. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  23. GRB 250702E: Fermi GBM Final Real-time Localization
  24. GRB 250702A: Fermi GBM Detection
  25. GRB 250702D: Fermi GBM Final Localization Correction
  26. GRB 250702C: Fermi GBM Final Real-time Localization
  27. GRB 250702B: Fermi GBM Final Real-time Localization
  28. GRB 250702A: BALROG localization (Fermi Trigger 773142852 / GRB 250702413)
  29. GRB 250702A: Fermi GBM Final Real-time Localization
  30. Fermi Gamma-ray Burst Monitor trigger 772838080/250628885 is not a GRB
  31. GRB 250628B: Swift-XRT observations
  32. Fermi Gamma-ray Burst Monitor trigger 772981768/250630548 is not a GRB
  33. GRB 250628B: SVOM/VT optical upper limit
  34. GRB 250628B: EP-FXT counterpart detection
  35. GRB 250627A: SVOM/GRM detection of a short burst
  36. GRB 250628A: REM optical/NIR upper limits
  37. GRB 250628C: Fermi GBM Final Real-time Localization
  38. GRB 250628B: SVOM detection of a long burst
  39. Fermi Gamma-ray Burst Monitor trigger 772811638/250628579 is not a GRB
  40. GRB 250628A: VLT/X-shooter upper limits
  41. GRB 250628A: Swift/UVOT Upper Limits
  42. GRB 250628A: Swift-XRT refined Analysis
  43. Fermi GRB 250626A: Global MASTER-Net observations report
  44. Swift GRB 250628A: Global MASTER-Net observations report
  45. GRB 250628A: Swift detection of a burst
  46. GRB 250625A: Swift-BAT refined analysis
  47. GRB 250625A: Leavitt Observatory afterglow detection
  48. Fermi Gamma-ray Burst Monitor trigger 772732642/250627665 is not a GRB
  49. Fermi Gamma-ray Burst Monitor trigger 772720540/250627525 is not a GRB
  50. The EP-WXT trigger 01709179435 is likely a new outburst of the CV SS Cyg
  51. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  52. GRB 250626A: Fermi GBM Final Real-time Localization
  53. Fermi Gamma-ray Burst Monitor trigger 772647532/250626680 is not a GRB
  54. GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  55. GRB 250625A: SVOM/C-GFT upper limit in early phase
  56. GRB 250625A: GECAM-B detection
  57. GRB 250625A: Swift/UVOT Upper Limits
  58. GRB 250625A: ABObservatory afterglow detection
  59. GRB 250625A: OHP/T193 optical detection
  60. GRB 250625A: COLIBRÍ optical observations
  61. GRB 250625A: Fermi-LAT detection
  62. GRB 250625A: Swift-XRT refined Analysis
  63. GRB 250625A: JinShan optical observations
  64. GRB250625A: Fermi GBM Observation
  65. Swift GRB 250625A: Global MASTER-Net observations report
  66. GRB 250625A: NOT z-band upper limit
  67. GRB 250625A: SVOM/VT optical confirmation
  68. GRB 250620B: Fermi GBM Observation
  69. Fermi GRB 250625A: Global MASTER-Net observations report
  70. GRB 250625A: Swift detection of a burst
  71. GRB 250625A: Fermi GBM Final Real-time Localization
  72. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580
  73. Fermi GRB 250624A: Global MASTER-Net observations report
  74. GRB 250624A: Fermi GBM Final Real-time Localization
  75. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  76. Fermi GRB 250623A: Global MASTER-Net observations report
  77. GRB 250623A: Fermi GBM Final Real-time Localization
  78. GRB 250521A: VZLUSAT-2 detection
  79. GRB 250617B: Swift-BAT refined analysis
  80. Fermi trigger No 772190032: Global MASTER-Net observations report
  81. IPN triangulation of GRB 250620C (long/bright)
  82. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  83. GRB 250620C: SVOM/GRM observation
  84. GRB 250620A: SVOM/GRM observation of a short burst
  85. GRB250620A: Fermi GBM Observation
  86. Fermi GRB 250621A: Global MASTER-Net observations report
  87. GRB 250619B: Fermi GBM Observation
  88. GRB 250621A: Fermi GBM Final Real-time Localization
  89. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  90. GRB250620C: Fermi GBM Observation
  91. GRB 250506A - SVOM/ECLAIRs Refined analysis
  92. The EP-WXT trigger 01709179071 is likely a flaring star
  93. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  94. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  95. GRB 250620C: Fermi GBM Final Real-time Localization
  96. Fermi trigger No 772128434: Global MASTER-Net observations report
  97. GRB 250620B: Fermi GBM Final Real-time Localization
  98. GRB 250620A: Fermi GBM Final Real-time Localization
  99. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  100. GRB 250619B: Fermi GBM Final Real-time Localization

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