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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"

38654 results found.

  1. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  2. GRB 260101A: COLIBRÍ optical observations
  3. SVOM GRB260103.08: Global MASTER-Net observations report
  4. GRB 260102B: Fermi GBM Final Real-time Localization
  5. SVOM GRB260102A: Global MASTER-Net observations report
  6. Fermi GBM Sub-Threshold Detection of GRB 260102A
  7. GRB 260102A: EP-FXT follow-up observation
  8. GRB 260102A: LCO optical upper limits
  9. GRB 260102A: Swift-XRT observations
  10. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  11. Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
  12. GRB 251230A / EP251230a: GECAM-B detection
  13. GRB 260102A: SVOM/VT optical counterpart
  14. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  15. GRB 260102A: Swift ToO observations
  16. GRB 260101A: Fermi GBM Observation
  17. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  18. GRB 260102A: SVOM detection of a burst
  19. GRB 260101A: GECAM-B detection
  20. GRB 260101A: NOT spectroscopic observations
  21. GRB 260101A: SVOM/GRM observation
  22. GRB 260101A: Swift-XRT refined Analysis
  23. GRB 260101A: Enhanced Swift-XRT position
  24. EP260101a: Einstein Probe detection of an X-ray transient
  25. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  26. GRB 260101A: LCO detection of the optical counterpart
  27. GRB 260101A: Swift detection of a burst with an optical counterpart
  28. GRB 260101A: Fermi GBM Final Real-time Localization
  29. SVOM GRB251231.57: Global MASTER-Net observations report
  30. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  31. GRB 251230A: GRANDMA/TAROT Early Detection
  32. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  33. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  34. EP251229a: Optical upper limit with Kinder observations
  35. GRB 251230A: 1.3m DFOT optical upper limit
  36. Fermi Gamma-ray Burst Monitor trigger 788833547/251231018 is not a GRB
  37. GRB 251230A: Swift-XRT refined Analysis
  38. GRB 251231A: Fermi GBM Final Real-time Localization
  39. GRB 251222A: Mondy Optical Observations
  40. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  41. GRB 251230A: Swift/UVOT detection
  42. GRB251230A: 7DT optical upper limits
  43. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  44. EP251229a: BOOTES-2 early optical upper limit
  45. GRB 251230A: GOTO optical upper limit
  46. EP251229a: NOT optical upper limits
  47. GRB 251230A / EP251230a: SVOM/VT optical observation
  48. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  49. GRB 251230A: Enhanced Swift-XRT position
  50. GRB 251230A: Early optical counterpart detection by LCO.
  51. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  52. GRB 251230A: Optical Observations via Virtual Telescope Project, Italy
  53. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  54. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  55. EP251229a: Einstein Probe detection of an X-ray transient
  56. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  57. GRB 251226A: Glowbug gamma-ray detection
  58. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  59. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  60. The EP-WXT trigger 01709250662 is likely a flaring star
  61. GRB 251228A: Fermi GBM Final Real-time Localization
  62. GRB 251226A: SVOM/GRM observation
  63. GRB 251226A: GECAM-B detection
  64. SVOM GRB251227.07: Global MASTER-Net observations report
  65. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  66. The EP-WXT trigger 01709250617 is likely a flaring star
  67. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  68. Fermi Gamma-ray Burst Monitor trigger 788368008/251225630 is not a GRB
  69. GRB 251222A: NUTTelA-TAO Early Measurements
  70. GRB 251222A/EP251222b: Optical detection with Kinder observations
  71. EP251222a: Optical upper limit with Kinder observations
  72. GRB 251205A: Kilonova-Catcher optical afterglow detection
  73. GRB 251222A: AbAO optical observations
  74. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  75. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  76. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  77. GRB 251222A: ZTSH BVRI optical observations
  78. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  79. GRB 251222A: Continued 1.3m DFOT optical observation
  80. EP251220a: 3.6m DOT optical afterglow detection
  81. GRB 251222A: Fermi GBM Observation
  82. EP251220a: CrAO ZTSh optical observations
  83. EP251221a: PRIME upper limit
  84. GRB 251222A / EP251222b: GECAM-B observation
  85. EP251221a: Liverpool Telescope upper limits
  86. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  87. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  88. Konus-Wind detection of GRB 251222A / EP251222b
  89. GRB 251222A: Swift-XRT afterglow detection
  90. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  91. EP251222a: NTT/ULTRACAM optical observations
  92. EP251222a: GOTO optical upper limit
  93. GRB 251222A / EP251222b: GOTO optical counterpart detection
  94. GRB 251222A / EP251222b: LCO optical observations
  95. GRB 251222A: 1.3m DFOT optical detection
  96. GRB251221A: 7DT optical upper limits
  97. EP251222a: GSP Optical Counterpart Detection
  98. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  99. GRB 251222A / EP251222b: SVOM/VT optical rebrightening
  100. EP251222b/GRB 251222A: SVOM/GRM observation

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