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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"

36009 results found.

  1. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  2. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  3. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  4. GRB 250702F: Kilonova-Catcher optical afterglow detection
  5. GRB 250702F: Monte Agliale Observatory optical observations
  6. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  7. EP250704a / GRB 250704B: VLT/X-shooter spectroscopic redshift z = 0.661
  8. EP250704a / GRB 250704B: JinShan optical observations
  9. GRB 250704A: SVOM/VT optical observation
  10. EP250704a / GRB 250704B: SAO RAS optical observations
  11. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  12. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  13. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  14. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  15. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  16. GRB 250702A: Insight-HXMT detection
  17. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  18. EP250704a / GRB250704B: Swift-XRT counterpart detection
  19. GRB 250704A: Swift-XRT afterglow detection
  20. GRB 250702B / EP2050702a: FTW optical and NIR observations
  21. Konus-Wind detection of GRB 250702F
  22. EP250704a / GRB 250704B - REM observations
  23. GRB 250702F: GROWTH-India Telescope optical observations
  24. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  25. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  26. EP250704a: Einstein Probe detection of an X-ray transient
  27. GRB 250704B: SVOM/GRM observation of a short burst
  28. GRB 250702F: optical photometry from Konkoly
  29. GRB 250704A: REM detection of the optical afterglow
  30. GRB 250702F: SVOM/VT optical observation
  31. GRB 250704A: SVOM detection of a burst
  32. GRB 250702F: Swift/UVOT Detection
  33. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  34. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  35. Fermi GRB 250703A: Global MASTER-Net observations report
  36. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  37. GRB 250702F: Swift-XRT refined Analysis
  38. GRB 250702F: Fermi GBM Observation
  39. GRB 250702F: Leavitt Observatory optical observations
  40. GRB 250702F: AKO Optical Afterglow Detection
  41. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  42. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  43. GRB 250702A: GECAM-B detection
  44. GRB 250702F: Skynet Optical Observations
  45. GRB 250424A: VIRT Optical Upper Limit
  46. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  47. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  48. GRB 250702F: TRT Optical Observation
  49. GRB 250703A: DDOTI Optical Upper Limit
  50. GRB 250702F: REM optical afterglow detection
  51. GRB 250702F: DDOTI Optical Observation
  52. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  53. GRB 250703A: Fermi GBM Final Real-time Localization
  54. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  55. GRB 250702F: COLIBRÍ Observations of the Afterglow
  56. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  57. Fermi GRB 250702E: Global MASTER-Net observations report
  58. Fermi GRB 250702B: Global MASTER-Net observations report
  59. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  60. GRB 250702F: Enhanced Swift-XRT position
  61. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  62. GRB 250702F: NOT observations of the optical afterglow
  63. GRB 250702F: MASTER optical afterglow observation
  64. Fermi GRB 250702F: Global MASTER-Net observations report
  65. Fermi GRB 250702C: Global MASTER-Net observations report
  66. GRB 250702F: GOTO optical counterpart detection
  67. GRB 250702F: Ondrejov D50 optical afterglow detection
  68. GRB 250702F: Swift detection of a burst with an optical counterpart
  69. Swift GRB 250702F: Global MASTER-Net observations report
  70. GRB 250702F: Fermi GBM Final Real-time Localization
  71. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  72. GRB 250702E: Fermi GBM Final Real-time Localization
  73. Konus-Wind detection of GRB 250627A
  74. IPN triangulation of GRB 250627A (short)
  75. GRB 250702A: Fermi GBM Detection
  76. GRB 250702D: Fermi GBM Final Localization Correction
  77. GRB 250702C: Fermi GBM Final Real-time Localization
  78. GRB 250702B: Fermi GBM Final Real-time Localization
  79. GRB 250702A: BALROG localization (Fermi Trigger 773142852 / GRB 250702413)
  80. GRB 250702A: Fermi GBM Final Real-time Localization
  81. Fermi Gamma-ray Burst Monitor trigger 772838080/250628885 is not a GRB
  82. GRB 250628B: Swift-XRT observations
  83. Fermi Gamma-ray Burst Monitor trigger 772981768/250630548 is not a GRB
  84. GRB 250628B: SVOM/VT optical upper limit
  85. GRB 250628B: EP-FXT counterpart detection
  86. GRB 250627A: Insight-HXMT detection
  87. GRB 250627A: SVOM/GRM detection of a short burst
  88. GRB 250628A: REM optical/NIR upper limits
  89. GRB 250628C: Fermi GBM Final Real-time Localization
  90. GRB 250628B: SVOM detection of a long burst
  91. Fermi Gamma-ray Burst Monitor trigger 772811638/250628579 is not a GRB
  92. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  93. GRB 250628A: VLT/X-shooter upper limits
  94. GRB 250628A: Swift/UVOT Upper Limits
  95. GRB 250628A: Swift-XRT refined Analysis
  96. Fermi GRB 250626A: Global MASTER-Net observations report
  97. Swift GRB 250628A: Global MASTER-Net observations report
  98. GRB 250628A: Enhanced Swift-XRT position
  99. GRB 250628A: Swift detection of a burst
  100. GRB 250625A: Swift-BAT refined analysis

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