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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"

22215 results found.

  1. Fermi GRB 260105B: Global MASTER-Net observations report
  2. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  3. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  4. EP260105a: LCO Optical Upper limit
  5. EP260104a: Global MASTER-Net observations report
  6. EP260104a: Einstein Probe detection of a fast X-ray transient
  7. EP260105a: Global MASTER-Net observations report
  8. Fermi GRB 260104B: Global MASTER-Net observations report
  9. Swift GRB 260104A: Global MASTER-Net observations report
  10. GRB 260101A: Swift/UVOT Detection
  11. GRB 260103A: SVOM/GRM observation of a possible GRB
  12. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  13. GRB 260101A: COLIBRÍ optical observations
  14. SVOM GRB260103.08: Global MASTER-Net observations report
  15. SVOM GRB260102A: Global MASTER-Net observations report
  16. EP260101a: Global MASTER-Net observations report
  17. GRB 260102A: Swift-XRT observations
  18. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  19. GRB 260102A: Swift ToO observations
  20. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  21. GRB 260101A: NOT spectroscopic observations
  22. Swift GRB 260101A: Global MASTER-Net observations report
  23. GRB 260101A: LCO detection of the optical counterpart
  24. SVOM GRB251231.57: Global MASTER-Net observations report
  25. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  26. GRB 251230A: GRANDMA/TAROT Early Detection
  27. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  28. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  29. EP251229a: Optical upper limit with Kinder observations
  30. GRB 251230A: 1.3m DFOT optical upper limit
  31. GRB 251222A: Mondy Optical Observations
  32. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  33. GRB 251230A: Swift/UVOT detection
  34. GRB251230A: 7DT optical upper limits
  35. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  36. EP251229a: BOOTES-2 early optical upper limit
  37. GRB 251230A: GOTO optical upper limit
  38. EP251229a: NOT optical upper limits
  39. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  40. GRB 251230A: Early optical counterpart detection by LCO.
  41. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  42. GRB 251230A: Optical Observations via Virtual Telescope Project, Italy
  43. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  44. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  45. Swift GRB 251230A: Global MASTER-Net observations report
  46. EP251229a: Global MASTER-Net observations report
  47. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  48. Fermi GRB 251228A: Global MASTER-Net observations report
  49. SVOM GRB251227.07: Global MASTER-Net observations report
  50. IceCube Alert 251225.84: Global MASTER-Net observations report
  51. GRB 251222A: NUTTelA-TAO Early Measurements
  52. GRB 251222A/EP251222b: Optical detection with Kinder observations
  53. EP251222a: Optical upper limit with Kinder observations
  54. GRB 251222A/EP251222b: FTW optical and NIR observations
  55. EP251222a: FTW optical and NIR observations
  56. GRB 251205A: Kilonova-Catcher optical afterglow detection
  57. GRB 251222A: AbAO optical observations
  58. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  59. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  60. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  61. GRB 251222A: ZTSH BVRI optical observations
  62. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  63. GRB 251222A: Continued 1.3m DFOT optical observation
  64. EP251220a: 3.6m DOT optical afterglow detection
  65. EP251220a: CrAO ZTSh optical observations
  66. EP251221a: PRIME upper limit
  67. EP251222a: Global MASTER-Net observations report
  68. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  69. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  70. Konus-Wind detection of GRB 251222A / EP251222b
  71. GRB 251222A: Swift-XRT afterglow detection
  72. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  73. EP251222a: NTT/ULTRACAM optical observations
  74. EP251222a: GOTO optical upper limit
  75. GRB 251222A / EP251222b: GOTO optical counterpart detection
  76. GRB 251222A / EP251222b: LCO optical observations
  77. GRB 251222A: 1.3m DFOT optical detection
  78. GRB251221A: 7DT optical upper limits
  79. EP251222a: GSP Optical Counterpart Detection
  80. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  81. EP251221a: Global MASTER-Net observations report
  82. GRB 251222A: PRIME near-infrared detection
  83. EP251221a: NOT optical upper limit
  84. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  85. GRB 251222A: NOT optical observations
  86. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  87. GRB 251222A: Swift ToO observations
  88. SVOM GRB251222A: Global MASTER-Net observations report
  89. EP251220a: PRIME upper limit
  90. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  91. GRB 251221A: PRIME near-infrared observation
  92. EP251220a: NOT optical observations
  93. EP251220a: FTW optical and NIR observations
  94. GRB 251221A: UAFO and Mondy optical upper limit
  95. GRB 251221A: Swift/UVOT Upper Limits
  96. EP251220a: EP-FXT follow-up observation
  97. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  98. EP 251220a: GOTO optical counterpart detection
  99. EP 251220a: COLIBRÍ detection of the optical counterpart
  100. Swift GRB251221A: Global MASTER-Net observations report

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