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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"

32556 results found.

  1. Swift GRB 251230A: Global MASTER-Net OT detection
  2. Fermi GRB 260107A: Global MASTER-Net observations report
  3. GRB 260102A: AbAO optical observations
  4. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  5. Fermi GRB 260105A: Global MASTER-Net observations report
  6. EP260105a: FTW optical observations
  7. EP260104a: FTW optical observations
  8. GRB 260105A: SVOM/GRM observation
  9. GRB 260105B: SVOM/GRM observation
  10. FRB 20251229A: COLIBRÍ optical upper limits
  11. Fermi GRB 260105B: Global MASTER-Net observations report
  12. EP260105a: SVOM/VT optical upperlimit
  13. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  14. EP260105a: LCO Optical Upper limit
  15. EP260104a: Global MASTER-Net observations report
  16. GRB 260101A: COLIBRÍ optical upper limits
  17. EP260105a: Global MASTER-Net observations report
  18. GRB 260103A: Insight-HXMT/HE detection
  19. GRB 260104A: COLIBRÍ optical upper limits
  20. Fermi GRB 260104B: Global MASTER-Net observations report
  21. Swift GRB 260104A: Global MASTER-Net observations report
  22. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  23. GRB 260101A: Swift/UVOT Detection
  24. GRB 260103A: GECAM-B observation of a burst
  25. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  26. GRB 260101A: COLIBRÍ optical observations
  27. Fermi GBM Sub-Threshold Detection of GRB 260102A
  28. GRB 260102A: EP-FXT follow-up observation
  29. EP260101a: Global MASTER-Net observations report
  30. GRB 260102A: LCO optical upper limits
  31. GRB 260102A: Swift-XRT observations
  32. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  33. GRB 251230A / EP251230a: GECAM-B detection
  34. GRB 260102A: SVOM/VT optical counterpart
  35. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  36. GRB 260102A: Swift ToO observations
  37. GRB 260101A: Fermi GBM Observation
  38. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  39. GRB 260101A: GECAM-B detection
  40. GRB 260101A: NOT spectroscopic observations
  41. GRB 260101A: SVOM/GRM observation
  42. Swift GRB 260101A: Global MASTER-Net observations report
  43. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  44. GRB 260101A: LCO detection of the optical counterpart
  45. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  46. GRB 251230A: GRANDMA/TAROT Early Detection
  47. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  48. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  49. EP251229a: Optical upper limit with Kinder observations
  50. GRB 251230A: 1.3m DFOT optical upper limit
  51. GRB 251222A: Mondy Optical Observations
  52. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  53. GRB 251230A: Swift/UVOT detection
  54. GRB251230A: 7DT optical upper limits
  55. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  56. EP251229a: BOOTES-2 early optical upper limit
  57. GRB 251230A: GOTO optical upper limit
  58. EP251229a: NOT optical upper limits
  59. GRB 251230A / EP251230a: SVOM/VT optical observation
  60. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  61. GRB 251230A: Early optical counterpart detection by LCO.
  62. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  63. GRB 251230A: Optical Observations via Virtual Telescope Project, Italy
  64. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  65. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  66. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  67. Swift GRB 251230A: Global MASTER-Net observations report
  68. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  69. EP251229a: Global MASTER-Net observations report
  70. GRB 251226A: Glowbug gamma-ray detection
  71. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  72. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  73. Fermi GRB 251228A: Global MASTER-Net observations report
  74. GRB 251226A: SVOM/GRM observation
  75. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  76. GRB 251222A: NUTTelA-TAO Early Measurements
  77. GRB 251222A/EP251222b: Optical detection with Kinder observations
  78. EP251222a: Optical upper limit with Kinder observations
  79. GRB 251221A: Swift-BAT refined analysis
  80. GRB 251222A/EP251222b: FTW optical and NIR observations
  81. EP251222a: FTW optical and NIR observations
  82. GRB 251205A: Kilonova-Catcher optical afterglow detection
  83. GRB 251222A: AbAO optical observations
  84. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  85. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  86. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  87. GRB 251222A: ZTSH BVRI optical observations
  88. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  89. GRB 251222A: Continued 1.3m DFOT optical observation
  90. EP251220a: 3.6m DOT optical afterglow detection
  91. GRB 251222A: Fermi GBM Observation
  92. EP251220a: CrAO ZTSh optical observations
  93. EP251221a: PRIME upper limit
  94. EP251222a: Global MASTER-Net observations report
  95. GRB 251222A / EP251222b: GECAM-B observation
  96. EP251221a: Liverpool Telescope upper limits
  97. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  98. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  99. Konus-Wind detection of GRB 251222A / EP251222b
  100. GRB 251222A / EP251222b: LCO detection of the optical counterpart

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