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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"

27920 results found.

  1. GRB 250704A: SVOM/VT optical observation
  2. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  3. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  4. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  5. EP 250704a: BOOTES-5 optical detection
  6. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  7. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  8. GRB 250702A: Insight-HXMT detection
  9. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  10. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  11. EP250704a / GRB250704B: Swift-XRT counterpart detection
  12. GRB 250704A: Swift-XRT afterglow detection
  13. GRB 250702B / EP2050702a: FTW optical and NIR observations
  14. Konus-Wind detection of GRB 250702F
  15. GRB 250702F: GROWTH-India Telescope optical observations
  16. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  17. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  18. EP250702a: WFST optical observations
  19. EP250704a: Einstein Probe detection of an X-ray transient
  20. GRB 250702F: optical photometry from Konkoly
  21. GRB 250704A: REM detection of the optical afterglow
  22. GRB 250702F: SVOM/VT optical observation
  23. GRB 250704A: SVOM detection of a burst
  24. GRB 250702F: Swift/UVOT Detection
  25. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  26. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  27. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  28. GRB 250702F: Swift-XRT refined Analysis
  29. GRB 250702F: Fermi GBM Observation
  30. GRB 250702F: Leavitt Observatory optical observations
  31. GRB 250702F: AKO Optical Afterglow Detection
  32. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  33. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  34. GRB 250702A: GECAM-B detection
  35. GRB 250702F: Skynet Optical Observations
  36. GRB 250424A: VIRT Optical Upper Limit
  37. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  38. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  39. GRB 250702F: TRT Optical Observation
  40. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  41. GRB 250702F: REM optical afterglow detection
  42. GRB 250702F: DDOTI Optical Observation
  43. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  44. GRB 250703A: Fermi GBM Final Real-time Localization
  45. GRB 250702F: COLIBRÍ Observations of the Afterglow
  46. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  47. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  48. GRB 250702F: Enhanced Swift-XRT position
  49. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  50. GRB 250702F: NOT observations of the optical afterglow
  51. GRB 250702F: MASTER optical afterglow observation
  52. GRB 250702F: GOTO optical counterpart detection
  53. GRB 250702F: Ondrejov D50 optical afterglow detection
  54. GRB 250702F: Swift detection of a burst with an optical counterpart
  55. Swift GRB 250702F: Global MASTER-Net observations report
  56. GRB 250702F: Fermi GBM Final Real-time Localization
  57. GRB 250702E: Fermi GBM Final Real-time Localization
  58. Konus-Wind detection of GRB 250627A
  59. IPN triangulation of GRB 250627A (short)
  60. GRB 250702A: Fermi GBM Detection
  61. GRB 250702D: Fermi GBM Final Localization Correction
  62. GRB 250702C: Fermi GBM Final Real-time Localization
  63. GRB 250702B: Fermi GBM Final Real-time Localization
  64. GRB 250702A: Fermi GBM Final Real-time Localization
  65. GRB 250628B: Swift-XRT observations
  66. GRB 250628B: SVOM/VT optical upper limit
  67. GRB 250628B: EP-FXT counterpart detection
  68. GRB 250627A: Insight-HXMT detection
  69. GRB 250627A: SVOM/GRM detection of a short burst
  70. GRB 250628A: REM optical/NIR upper limits
  71. GRB 250628C: Fermi GBM Final Real-time Localization
  72. GRB 250628B: SVOM detection of a long burst
  73. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  74. GRB 250628A: VLT/X-shooter upper limits
  75. GRB 250628A: Swift/UVOT Upper Limits
  76. GRB 250628A: Swift-XRT refined Analysis
  77. Swift GRB 250628A: Global MASTER-Net observations report
  78. GRB 250628A: Enhanced Swift-XRT position
  79. GRB 250628A: Swift detection of a burst
  80. GRB 250625A: Swift-BAT refined analysis
  81. GRB 250625A: Leavitt Observatory afterglow detection
  82. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  83. GRB 250626A: Fermi GBM Final Real-time Localization
  84. GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  85. GRB 250625A: SVOM/C-GFT upper limit in early phase
  86. GRB 250625A: GECAM-B detection
  87. GRB 250625A: Swift/UVOT Upper Limits
  88. GRB 250625A: ABObservatory afterglow detection
  89. GRB 250625A: OHP/T193 optical detection
  90. GRB 250625A: COLIBRÍ optical observations
  91. GRB 250625A: Fermi-LAT detection
  92. GRB 250625A: Swift-XRT refined Analysis
  93. GRB 250625A: JinShan optical observations
  94. GRB250625A: Fermi GBM Observation
  95. Swift GRB 250625A: Global MASTER-Net observations report
  96. GRB 250625A: SVOM/VT optical confirmation
  97. GRB 250620B: Fermi GBM Observation
  98. GRB 250625A: Enhanced Swift-XRT position
  99. GRB 250625A: Swift detection of a burst
  100. GRB 250625A: Fermi GBM Final Real-time Localization

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