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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"

35360 results found.

  1. Fermi GRB 260105B: Global MASTER-Net observations report
  2. GRB 260105B: Fermi GBM Final Real-time Localization
  3. GRB 260105A: Fermi GBM Final Real-time Localization
  4. GRB 260101A: COLIBRÍ optical upper limits
  5. GRB 260103A: Insight-HXMT/HE detection
  6. GRB 260104A: COLIBRÍ optical upper limits
  7. GRB 260104C: Fermi GBM Final Real-time Localization
  8. Fermi GRB 260104B: Global MASTER-Net observations report
  9. Swift GRB 260104A: Global MASTER-Net observations report
  10. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  11. GRB 260104A: Swift-XRT refined Analysis
  12. GRB 260104A: Enhanced Swift-XRT position
  13. GRB 260101A: Swift/UVOT Detection
  14. GRB 260103A: GECAM-B observation of a burst
  15. GRB 260104B: Fermi GBM Final Localization
  16. GRB 260104A: Swift detection of a burst
  17. GRB 260103A: SVOM/GRM observation of a possible GRB
  18. GRB 260101A: COLIBRÍ optical observations
  19. GRB 260102B: Fermi GBM Final Real-time Localization
  20. Fermi GBM Sub-Threshold Detection of GRB 260102A
  21. GRB 260102A: EP-FXT follow-up observation
  22. GRB 260102A: LCO optical upper limits
  23. GRB 260102A: Swift-XRT observations
  24. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  25. Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
  26. GRB 251230A / EP251230a: GECAM-B detection
  27. GRB 260102A: SVOM/VT optical counterpart
  28. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  29. GRB 260102A: Swift ToO observations
  30. GRB 260101A: Fermi GBM Observation
  31. GRB 260102A: SVOM detection of a burst
  32. GRB 260101A: GECAM-B detection
  33. GRB 260101A: NOT spectroscopic observations
  34. GRB 260101A: SVOM/GRM observation
  35. GRB 260101A: Swift-XRT refined Analysis
  36. Swift GRB 260101A: Global MASTER-Net observations report
  37. GRB 260101A: Enhanced Swift-XRT position
  38. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  39. GRB 260101A: LCO detection of the optical counterpart
  40. GRB 260101A: Swift detection of a burst with an optical counterpart
  41. GRB 260101A: Fermi GBM Final Real-time Localization
  42. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  43. GRB 251230A: GRANDMA/TAROT Early Detection
  44. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  45. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  46. GRB 251230A: 1.3m DFOT optical upper limit
  47. Fermi Gamma-ray Burst Monitor trigger 788833547/251231018 is not a GRB
  48. GRB 251230A: Swift-XRT refined Analysis
  49. GRB 251231A: Fermi GBM Final Real-time Localization
  50. GRB 251222A: Mondy Optical Observations
  51. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  52. GRB 251230A: Swift/UVOT detection
  53. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  54. GRB 251230A: GOTO optical upper limit
  55. GRB 251230A / EP251230a: SVOM/VT optical observation
  56. GRB 251230A: Enhanced Swift-XRT position
  57. GRB 251230A: Early optical counterpart detection by LCO.
  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. Swift GRB 251230A: Global MASTER-Net observations report
  62. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  63. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  64. GRB 251226A: Glowbug gamma-ray detection
  65. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  66. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  67. Fermi GRB 251228A: Global MASTER-Net observations report
  68. GRB 251228A: Fermi GBM Final Real-time Localization
  69. GRB 251226A: SVOM/GRM observation
  70. GRB 251226A: GECAM-B detection
  71. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  72. Fermi Gamma-ray Burst Monitor trigger 788368008/251225630 is not a GRB
  73. GRB 251222A: NUTTelA-TAO Early Measurements
  74. GRB 251222A/EP251222b: Optical detection with Kinder observations
  75. GRB 251221A: Swift-BAT refined analysis
  76. GRB 251222A/EP251222b: 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. GRB 251222A: ZTSH BVRI optical observations
  82. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  83. GRB 251222A: Continued 1.3m DFOT optical observation
  84. GRB 251222A: Fermi GBM Observation
  85. EP251220a: CrAO ZTSh optical observations
  86. GRB 251222A / EP251222b: GECAM-B observation
  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. GRB 251222A / EP251222b: GOTO optical counterpart detection
  92. GRB 251222A / EP251222b: LCO optical observations
  93. GRB 251222A: 1.3m DFOT optical detection
  94. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  95. GRB 251222A / EP251222b: SVOM/VT optical rebrightening
  96. EP251222b/GRB 251222A: SVOM/GRM observation
  97. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  98. GRB 251222A: PRIME near-infrared detection
  99. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  100. GRB 251222A: NOT optical observations

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