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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"

27160 results found.

  1. GRB 250704A: Swift-XRT afterglow detection
  2. EP250704a / GRB 250704B - REM observations
  3. GRB 250702F: GROWTH-India Telescope optical observations
  4. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  5. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  6. EP250702a: WFST optical observations
  7. EP250704a: COLIBRÍ optical counterpart candidate
  8. EP250704a: Einstein Probe detection of an X-ray transient
  9. GRB 250704B: SVOM/GRM observation of a short burst
  10. GRB 250702F: optical photometry from Konkoly
  11. GRB 250704A: REM detection of the optical afterglow
  12. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  13. GRB 250702F: SVOM/VT optical observation
  14. GRB 250704A: SVOM detection of a burst
  15. GRB 250702F: Swift/UVOT Detection
  16. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  17. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  18. Fermi GRB 250703A: Global MASTER-Net observations report
  19. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  20. GRB 250702F: Swift-XRT refined Analysis
  21. GRB 250702F: Fermi GBM Observation
  22. GRB 250702F: Leavitt Observatory optical observations
  23. GRB 250702F: AKO Optical Afterglow Detection
  24. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  25. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  26. GRB 250702A: GECAM-B detection
  27. GRB 250702F: Skynet Optical Observations
  28. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  29. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  30. GRB 250702F: TRT Optical Observation
  31. GRB 250703A: DDOTI Optical Upper Limit
  32. GRB 250702F: REM optical afterglow detection
  33. EP250702a: Global MASTER-Net observations report
  34. GRB 250702F: DDOTI Optical Observation
  35. GRB 250703A: Fermi GBM Final Real-time Localization
  36. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  37. GRB 250702F: COLIBRÍ Observations of the Afterglow
  38. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  39. Fermi GRB 250702E: Global MASTER-Net observations report
  40. Fermi GRB 250702B: Global MASTER-Net observations report
  41. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  42. GRB 250702F: NOT observations of the optical afterglow
  43. Fermi GRB 250702F: Global MASTER-Net observations report
  44. Fermi GRB 250702C: Global MASTER-Net observations report
  45. GRB 250702F: GOTO optical counterpart detection
  46. GRB 250702F: Ondrejov D50 optical afterglow detection
  47. GRB 250702F: Swift detection of a burst with an optical counterpart
  48. Swift GRB 250702F: Global MASTER-Net observations report
  49. GRB 250702F: Fermi GBM Final Real-time Localization
  50. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  51. GRB 250702E: Fermi GBM Final Real-time Localization
  52. GRB 250702A: Fermi GBM Detection
  53. GRB 250702D: Fermi GBM Final Localization Correction
  54. GRB 250702C: Fermi GBM Final Real-time Localization
  55. GRB 250702B: Fermi GBM Final Real-time Localization
  56. GRB 250702A: BALROG localization (Fermi Trigger 773142852 / GRB 250702413)
  57. GRB 250702A: Fermi GBM Final Real-time Localization
  58. Fermi Gamma-ray Burst Monitor trigger 772838080/250628885 is not a GRB
  59. GRB 250628B: Swift-XRT observations
  60. Fermi Gamma-ray Burst Monitor trigger 772981768/250630548 is not a GRB
  61. GRB 250628B: SVOM/VT optical upper limit
  62. GRB 250628B: EP-FXT counterpart detection
  63. GRB 250627A: SVOM/GRM detection of a short burst
  64. GRB 250628A: REM optical/NIR upper limits
  65. GRB 250628C: Fermi GBM Final Real-time Localization
  66. GRB 250628B: SVOM detection of a long burst
  67. Fermi Gamma-ray Burst Monitor trigger 772811638/250628579 is not a GRB
  68. GRB 250628A: VLT/X-shooter upper limits
  69. GRB 250628A: Swift/UVOT Upper Limits
  70. GRB 250628A: Swift-XRT refined Analysis
  71. Fermi GRB 250626A: Global MASTER-Net observations report
  72. Swift GRB 250628A: Global MASTER-Net observations report
  73. GRB 250628A: Swift detection of a burst
  74. GRB 250625A: Swift-BAT refined analysis
  75. GRB 250625A: Leavitt Observatory afterglow detection
  76. Fermi Gamma-ray Burst Monitor trigger 772732642/250627665 is not a GRB
  77. Fermi Gamma-ray Burst Monitor trigger 772720540/250627525 is not a GRB
  78. The EP-WXT trigger 01709179435 is likely a new outburst of the CV SS Cyg
  79. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  80. GRB 250626A: Fermi GBM Final Real-time Localization
  81. Fermi Gamma-ray Burst Monitor trigger 772647532/250626680 is not a GRB
  82. GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  83. GRB 250625A: SVOM/C-GFT upper limit in early phase
  84. GRB 250625A: GECAM-B detection
  85. GRB 250625A: Swift/UVOT Upper Limits
  86. GRB 250625A: ABObservatory afterglow detection
  87. GRB 250625A: OHP/T193 optical detection
  88. GRB 250625A: COLIBRÍ optical observations
  89. GRB 250625A: Fermi-LAT detection
  90. GRB 250625A: Swift-XRT refined Analysis
  91. GRB 250625A: JinShan optical observations
  92. GRB250625A: Fermi GBM Observation
  93. Swift GRB 250625A: Global MASTER-Net observations report
  94. GRB 250625A: NOT z-band upper limit
  95. GRB 250625A: SVOM/VT optical confirmation
  96. GRB 250620B: Fermi GBM Observation
  97. Fermi GRB 250625A: Global MASTER-Net observations report
  98. GRB 250625A: Swift detection of a burst
  99. GRB 250625A: Fermi GBM Final Real-time Localization
  100. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580

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