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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

28086 results found.

  1. GRB 260104A: Swift-XRT refined Analysis
  2. GRB 260104A: Enhanced Swift-XRT position
  3. GRB 260101A: Swift/UVOT Detection
  4. GRB 260103A: GECAM-B observation of a burst
  5. GRB 260104A: Swift detection of a burst
  6. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  7. GRB 260101A: COLIBRÍ optical observations
  8. SVOM GRB260103.08: Global MASTER-Net observations report
  9. SVOM GRB260102A: Global MASTER-Net observations report
  10. Fermi GBM Sub-Threshold Detection of GRB 260102A
  11. GRB 260102A: EP-FXT follow-up observation
  12. EP260101a: Global MASTER-Net observations report
  13. GRB 260102A: LCO optical upper limits
  14. GRB 260102A: Swift-XRT observations
  15. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical 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: NOT spectroscopic observations
  20. GRB 260101A: SVOM/GRM observation
  21. GRB 260101A: Swift-XRT refined Analysis
  22. Swift GRB 260101A: Global MASTER-Net observations report
  23. GRB 260101A: Enhanced Swift-XRT position
  24. EP260101a: Einstein Probe detection of an X-ray transient
  25. GRB 260101A: LCO detection of the optical counterpart
  26. GRB 260101A: Swift detection of a burst with an optical counterpart
  27. GRB 260101A: Fermi GBM Final Real-time Localization
  28. SVOM GRB251231.57: Global MASTER-Net observations report
  29. GRB 251230A: GRANDMA/TAROT Early Detection
  30. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  31. EP251229a: Optical upper limit with Kinder observations
  32. GRB 251230A: 1.3m DFOT optical upper limit
  33. GRB 251230A: Swift-XRT refined Analysis
  34. GRB 251222A: Mondy Optical Observations
  35. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  36. GRB 251230A: Swift/UVOT detection
  37. GRB251230A: 7DT optical upper limits
  38. GRB 251230A: GOTO optical upper limit
  39. EP251229a: NOT optical upper limits
  40. GRB 251230A / EP251230a: SVOM/VT optical observation
  41. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  42. GRB 251230A: Enhanced Swift-XRT position
  43. GRB 251230A: Early optical counterpart detection by LCO.
  44. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  45. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  46. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  47. Swift GRB 251230A: Global MASTER-Net observations report
  48. EP251229a: Global MASTER-Net observations report
  49. EP251229a: Einstein Probe detection of an X-ray transient
  50. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  51. GRB 251226A: Glowbug gamma-ray detection
  52. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  53. Fermi GRB 251228A: Global MASTER-Net observations report
  54. GRB 251226A: SVOM/GRM observation
  55. GRB 251226A: GECAM-B detection
  56. SVOM GRB251227.07: Global MASTER-Net observations report
  57. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  58. IceCube Alert 251225.84: Global MASTER-Net observations report
  59. GRB 251222A/EP251222b: Optical detection with Kinder observations
  60. EP251222a: Optical upper limit with Kinder observations
  61. GRB 251221A: Swift-BAT refined analysis
  62. GRB 251205A: Kilonova-Catcher optical afterglow detection
  63. GRB 251222A: AbAO optical observations
  64. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  65. GRB 251222A: ZTSH BVRI optical observations
  66. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  67. GRB 251222A: Continued 1.3m DFOT optical observation
  68. EP251220a: 3.6m DOT optical afterglow detection
  69. GRB 251222A: Fermi GBM Observation
  70. EP251220a: CrAO ZTSh optical observations
  71. EP251221a: PRIME upper limit
  72. EP251222a: Global MASTER-Net observations report
  73. EP251221a: Liverpool Telescope upper limits
  74. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  75. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  76. GRB 251222A: Swift-XRT afterglow detection
  77. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  78. EP251222a: NTT/ULTRACAM optical observations
  79. GRB 251222A / EP251222b: GOTO optical counterpart detection
  80. GRB 251222A / EP251222b: LCO optical observations
  81. GRB 251222A: 1.3m DFOT optical detection
  82. GRB251221A: 7DT optical upper limits
  83. EP251222a: GSP Optical Counterpart Detection
  84. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  85. EP251222a: Einstein Probe detection of an X-ray transient
  86. EP251221a: Global MASTER-Net observations report
  87. GRB 251222A: PRIME near-infrared detection
  88. EP251221a: NOT optical upper limit
  89. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  90. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  91. IPN triangulation of GRB 251220B (short)
  92. GRB 251222A: BALROG localization (Fermi Trigger / GRB 251222712)
  93. GRB 251222A: SVOM/VT optical candidate
  94. GRB 251222A: SVOM detection of a long burst
  95. SVOM GRB251222A: Global MASTER-Net observations report
  96. EP251220a: PRIME upper limit
  97. GRB 251221A: PRIME near-infrared observation
  98. GRB 251221A: UAFO and Mondy optical upper limit
  99. GRB 251221A: Swift-XRT refined Analysis
  100. EP251221a: Einstein Probe detection of a fast X-ray transient

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