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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 251221A: Swift/UVOT Upper Limits
  2. GRB 251221A: Enhanced Swift-XRT position
  3. GRB 251221A: Fermi GBM Observation
  4. GRB 251220B: SVOM/GRM observation of a short burst
  5. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  6. EP 251220a: GOTO optical counterpart detection
  7. GRB 251221A: COLIBRÍ detection of the optical counterpart
  8. EP 251220a: COLIBRÍ detection of the optical counterpart
  9. GRB 251221A: Swift detection of a burst
  10. Swift GRB251221A: Global MASTER-Net observations report
  11. EP251220a: Global MASTER-Net observations report
  12. EP251220a: EP detection of a fast X-ray transient
  13. SVOM GRB251220.98: Global MASTER-Net observations report
  14. GRB 251219A: SVOM/GRM observation of a short burst
  15. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  16. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  17. GRB 251220A: MAXI/GSC detection
  18. GRB 251215A: Swift-XRT afterglow detection
  19. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  20. IceCube-251218A: COLIBRÍ optical upper limits
  21. SVOM GRB251219.11: Global MASTER-Net observations report
  22. IceCube Alert 251218.85: Global MASTER-Net observations report
  23. GRB 251214B: VIRT Optical Upper Limit
  24. Fermi trigger No 787736968: Global MASTER-Net observations report
  25. Fermi GRB 251217A: Global MASTER-Net observations report
  26. GRB 251215A: Swift/UVOT Upper LImits
  27. GRB 251215A: Fermi GBM Observation
  28. Fermi GRB 251216A: Global MASTER-Net observations report
  29. GRB 251202A/EP251202a: Koshka optical upper limit
  30. GRB 251214B: Mondy optical upper limit
  31. GRB 251215A: COLIBRÍ optical upper limit
  32. EP251214b: KAIT optical upper limit
  33. GRB 251215A: Swift-XRT observations
  34. Fermi GRB 251215A: Global MASTER-Net observations report
  35. EP251214a: Optical upper limit with Kinder observations
  36. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  37. GRB 251215A: Glowbug gamma-ray detection
  38. GRB 251214B: UAFO optical upper limit
  39. GRB 251214B: VLT/X-shooter observations
  40. GRB 251214B: Swift-BAT refined analysis
  41. GRB 251202A: radio detection with the VLA
  42. EP251214b: Global MASTER-Net observations report
  43. EP251214b : Einstein Probe detection of a fast X-ray transient
  44. EP251214b : Einstein Probe detection of a fast X-ray transient
  45. GRB 251214B: AbAO optical observations
  46. GRB 251214B: LCO detection of the optical counterpart
  47. GRB 251214B: Fermi GBM Observation
  48. EP251214b (EP trigger 01709250023): LCO optical limits
  49. GRB 251203B: AbAO optical observations
  50. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  51. GRB 251214B: Swift-XRT refined Analysis
  52. GRB 251213A: SVOM/GRM observation
  53. EP251214a: KAIT optical upper limit
  54. GRB 251213A: AstroSat CZTI detection
  55. GRB 251214A: AstroSat CZTI detection
  56. GRB 251213A: GECAM-B detection
  57. GRB 251214B: Swift/UVOT Detection
  58. GRB 251214B: COLIBRÍ observations of the afterglow
  59. EP251214a: EP-FXT non-detection and upper limit
  60. GRB 251214B: 1.3m DFOT optical detection
  61. EP251214a: Global MASTER-Net observations report
  62. GRB 251214B: Enhanced Swift-XRT position
  63. GRB 251214B: Xinglong-2.16m optical observation
  64. GRB 251214B : MASTER optical afterglow detection
  65. Fermi trigger No 787396657: Global MASTER-Net observations report
  66. GRB 251214B: SVOM/C-GFT optical observations
  67. EP251214a: COLIBRÍ optical upper limit
  68. Swift GRB 251214B: Global MASTER-Net observations report
  69. EP251214.305: COLIBRÍ optical upper limit
  70. GRB 251214B: Swift detection of a burst with an optical counterpart
  71. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  72. Fermi GRB 251214A: Global MASTER-Net observations report
  73. EP251212a: Global MASTER-Net observations report
  74. EP251212a: KAIT optical upper limit
  75. GRB 251211B: AstroSat CZTI detection
  76. GRB 251209A: NuSTAR detection of prompt emission
  77. EP251212a : COLIBRÍ optical upper limit
  78. EP251212a: Einstein Probe detection of an X-ray transient
  79. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  80. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  81. Fermi GRB 251211B: Global MASTER-Net observations report
  82. IceCube-251210A: DDOTI Optical Upper Limit
  83. SVOM GRB251211.12: Global MASTER-Net observations report
  84. GRB 251209A: Fermi GBM observation
  85. GRB 251205A: 1.3m DFOT optical upper limit
  86. GRB 251209A: AstroSat CZTI detection
  87. IceCube Alert 251210.46: Global MASTER-Net observations report
  88. EP251124a: Mondy optical upper limit
  89. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  90. EP251130a: Mondy and AbAO optical observations
  91. GRB 251208A: AstroSat CZTI detection
  92. Fermi GBM Sub-Threshold Detection of GRB 251205A
  93. GRB 251208A: Glowbug gamma-ray detection
  94. GRB 251208B: COLIBRÍ optical upper limits
  95. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  96. Fermi GRB 251209A: Global MASTER-Net observations report
  97. Fermi GRB 251208C: Global MASTER-Net observations report
  98. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  99. GRB 251208B: Swift-XRT afterglow detection
  100. GRB 251208D: LAST optical upper limit

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