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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"

32735 results found.

  1. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  2. GRB 260101A: Swift/UVOT Detection
  3. GRB 260103A: GECAM-B observation of a burst
  4. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  5. GRB 260101A: COLIBRÍ optical observations
  6. Fermi GBM Sub-Threshold Detection of GRB 260102A
  7. GRB 260102A: EP-FXT follow-up observation
  8. EP260101a: Global MASTER-Net observations report
  9. GRB 260102A: LCO optical upper limits
  10. GRB 260102A: Swift-XRT observations
  11. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  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 260101A: GECAM-B detection
  19. GRB 260101A: NOT spectroscopic observations
  20. GRB 260101A: SVOM/GRM observation
  21. Swift GRB 260101A: Global MASTER-Net observations report
  22. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  23. GRB 260101A: LCO detection of the optical counterpart
  24. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  25. GRB 251230A: GRANDMA/TAROT Early Detection
  26. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  27. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  28. EP251229a: Optical upper limit with Kinder observations
  29. GRB 251230A: 1.3m DFOT optical upper limit
  30. GRB 251222A: Mondy Optical Observations
  31. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  32. GRB 251230A: Swift/UVOT detection
  33. GRB251230A: 7DT optical upper limits
  34. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  35. EP251229a: BOOTES-2 early optical upper limit
  36. GRB 251230A: GOTO optical upper limit
  37. EP251229a: NOT optical upper limits
  38. GRB 251230A / EP251230a: SVOM/VT optical observation
  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. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  44. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  45. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  46. Swift GRB 251230A: Global MASTER-Net observations report
  47. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  48. EP251229a: Global MASTER-Net observations report
  49. GRB 251226A: Glowbug gamma-ray detection
  50. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  51. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  52. Fermi GRB 251228A: Global MASTER-Net observations report
  53. GRB 251226A: SVOM/GRM observation
  54. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  55. GRB 251222A: NUTTelA-TAO Early Measurements
  56. GRB 251222A/EP251222b: Optical detection with Kinder observations
  57. EP251222a: Optical upper limit with Kinder observations
  58. GRB 251221A: Swift-BAT refined analysis
  59. GRB 251222A/EP251222b: FTW optical and NIR observations
  60. EP251222a: FTW optical and NIR observations
  61. GRB 251205A: Kilonova-Catcher optical afterglow detection
  62. GRB 251222A: AbAO optical observations
  63. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  64. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  65. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  66. GRB 251222A: ZTSH BVRI optical observations
  67. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  68. GRB 251222A: Continued 1.3m DFOT optical observation
  69. EP251220a: 3.6m DOT optical afterglow detection
  70. GRB 251222A: Fermi GBM Observation
  71. EP251220a: CrAO ZTSh optical observations
  72. EP251221a: PRIME upper limit
  73. EP251222a: Global MASTER-Net observations report
  74. GRB 251222A / EP251222b: GECAM-B observation
  75. EP251221a: Liverpool Telescope upper limits
  76. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  77. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  78. Konus-Wind detection of GRB 251222A / EP251222b
  79. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  80. EP251222a: NTT/ULTRACAM optical observations
  81. EP251222a: GOTO optical upper limit
  82. GRB 251222A / EP251222b: GOTO optical counterpart detection
  83. GRB 251222A / EP251222b: LCO optical observations
  84. GRB 251222A: 1.3m DFOT optical detection
  85. GRB251221A: 7DT optical upper limits
  86. EP251222a: GSP Optical Counterpart Detection
  87. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  88. GRB 251222A / EP251222b: SVOM/VT optical rebrightening
  89. EP251222b/GRB 251222A: SVOM/GRM observation
  90. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  91. EP251221a: Global MASTER-Net observations report
  92. GRB 251222A: PRIME near-infrared detection
  93. EP251221a: NOT optical upper limit
  94. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  95. GRB 251222A: NOT optical observations
  96. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  97. IPN triangulation of GRB 251220B (short)
  98. GRB 251222A: Swift ToO observations
  99. GRB 251222A: SVOM/VT optical candidate
  100. GRB 251222A: SVOM detection of a long burst

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