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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"
  1. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  2. Swift GRB 251230A: Global MASTER-Net observations report
  3. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  4. EP251229a: Global MASTER-Net observations report
  5. EP251229a: Einstein Probe detection of an X-ray transient
  6. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  7. GRB 251226A: Glowbug gamma-ray detection
  8. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  9. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  10. Fermi GRB 251228A: Global MASTER-Net observations report
  11. The EP-WXT trigger 01709250662 is likely a flaring star
  12. GRB 251228A: Fermi GBM Final Real-time Localization
  13. GRB 251226A: SVOM/GRM observation
  14. GRB 251226A: GECAM-B detection
  15. SVOM GRB251227.07: Global MASTER-Net observations report
  16. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  17. The EP-WXT trigger 01709250617 is likely a flaring star
  18. IceCube Alert 251225.84: Global MASTER-Net observations report
  19. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  20. Fermi Gamma-ray Burst Monitor trigger 788368008/251225630 is not a GRB
  21. GRB 251222A: NUTTelA-TAO Early Measurements
  22. GRB 251222A/EP251222b: Optical detection with Kinder observations
  23. EP251222a: Optical upper limit with Kinder observations
  24. GRB 251221A: Swift-BAT refined analysis
  25. GRB 251222A/EP251222b: FTW optical and NIR observations
  26. EP251222a: FTW optical and NIR observations
  27. GRB 251205A: Kilonova-Catcher optical afterglow detection
  28. GRB 251222A: AbAO optical observations
  29. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  30. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  31. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  32. GRB 251222A: ZTSH BVRI optical observations
  33. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  34. GRB 251222A: Continued 1.3m DFOT optical observation
  35. EP251220a: 3.6m DOT optical afterglow detection
  36. GRB 251222A: Fermi GBM Observation
  37. EP251220a: CrAO ZTSh optical observations
  38. EP251221a: PRIME upper limit
  39. EP251222a: Global MASTER-Net observations report
  40. GRB 251222A / EP251222b: GECAM-B observation
  41. EP251221a: Liverpool Telescope upper limits
  42. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  43. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  44. Konus-Wind detection of GRB 251222A / EP251222b
  45. GRB 251222A: Swift-XRT afterglow detection
  46. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  47. EP251222a: NTT/ULTRACAM optical observations
  48. EP251222a: GOTO optical upper limit
  49. GRB 251222A / EP251222b: GOTO optical counterpart detection
  50. GRB 251222A / EP251222b: LCO optical observations
  51. GRB 251222A: 1.3m DFOT optical detection
  52. GRB251221A: 7DT optical upper limits
  53. EP251222a: GSP Optical Counterpart Detection
  54. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  55. GRB 251222A / EP251222b: SVOM/VT optical rebrightening
  56. EP251222b/GRB 251222A: SVOM/GRM observation
  57. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  58. EP251222a: Einstein Probe detection of an X-ray transient
  59. The EP-WXT trigger 01709250397 is likely a flaring star
  60. EP251221a: Global MASTER-Net observations report
  61. GRB 251222A: PRIME near-infrared detection
  62. EP251221a: NOT optical upper limit
  63. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  64. GRB 251222A: NOT optical observations
  65. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  66. IPN triangulation of GRB 251220B (short)
  67. GRB 251222A: Swift ToO observations
  68. GRB 251222A: BALROG localization (Fermi Trigger / GRB 251222712)
  69. GRB 251222A: SVOM/VT optical candidate
  70. GRB 251222A: SVOM detection of a long burst
  71. SVOM GRB251222A: Global MASTER-Net observations report
  72. GRB 251222A: Fermi GBM Final Real-time Localization
  73. EP251220a: PRIME upper limit
  74. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  75. GRB 251221A: PRIME near-infrared observation
  76. EP251220a: NOT optical observations
  77. EP251220a: FTW optical and NIR observations
  78. GRB 251221A: UAFO and Mondy optical upper limit
  79. GRB 251221A: Swift-XRT refined Analysis
  80. EP251221a: Einstein Probe detection of a fast X-ray transient
  81. GRB 251221A: Swift/UVOT Upper Limits
  82. Fermi Gamma-ray Burst Monitor trigger 788028118/251221696 is not a GRB
  83. GRB 251221A: Enhanced Swift-XRT position
  84. GRB 251221A: Fermi GBM Observation
  85. GRB 251221B: Fermi GBM Final Real-time Localization
  86. EP251220a: EP-FXT follow-up observation
  87. GRB 251220B: SVOM/GRM observation of a short burst
  88. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  89. EP 251220a: GOTO optical counterpart detection
  90. GRB 251221A: COLIBRÍ detection of the optical counterpart
  91. EP 251220a: COLIBRÍ detection of the optical counterpart
  92. GRB 251221A: Swift detection of a burst
  93. Swift GRB251221A: Global MASTER-Net observations report
  94. GRB 251221A: Fermi GBM Final Real-time Localization
  95. EP251220a: Global MASTER-Net observations report
  96. EP251220a: EP detection of a fast X-ray transient
  97. SVOM GRB251220.98: Global MASTER-Net observations report
  98. GRB 251220B: Fermi GBM Final Real-time Localization
  99. GRB 251219A: SVOM/GRM observation of a short burst
  100. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645

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