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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"

32552 results found.

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

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