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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"

28097 results found.

  1. GRB 251222A: SVOM/VT optical candidate
  2. GRB 251222A: SVOM detection of a long burst
  3. SVOM GRB251222A: Global MASTER-Net observations report
  4. EP251220a: PRIME upper limit
  5. GRB 251221A: PRIME near-infrared observation
  6. GRB 251221A: UAFO and Mondy optical upper limit
  7. GRB 251221A: Swift-XRT refined Analysis
  8. EP251221a: Einstein Probe detection of a fast X-ray transient
  9. GRB 251221A: Swift/UVOT Upper Limits
  10. GRB 251221A: Enhanced Swift-XRT position
  11. GRB 251221A: Fermi GBM Observation
  12. GRB 251220B: SVOM/GRM observation of a short burst
  13. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  14. EP 251220a: GOTO optical counterpart detection
  15. GRB 251221A: COLIBRÍ detection of the optical counterpart
  16. EP 251220a: COLIBRÍ detection of the optical counterpart
  17. GRB 251221A: Swift detection of a burst
  18. Swift GRB251221A: Global MASTER-Net observations report
  19. EP251220a: Global MASTER-Net observations report
  20. EP251220a: EP detection of a fast X-ray transient
  21. SVOM GRB251220.98: Global MASTER-Net observations report
  22. GRB 251219A: SVOM/GRM observation of a short burst
  23. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  24. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  25. GRB 251220A: MAXI/GSC detection
  26. GRB 251215A: Swift-XRT afterglow detection
  27. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  28. IceCube-251218A: COLIBRÍ optical upper limits
  29. SVOM GRB251219.11: Global MASTER-Net observations report
  30. IceCube Alert 251218.85: Global MASTER-Net observations report
  31. GRB 251214B: VIRT Optical Upper Limit
  32. Fermi trigger No 787736968: Global MASTER-Net observations report
  33. Fermi GRB 251217A: Global MASTER-Net observations report
  34. GRB 251215A: Swift/UVOT Upper LImits
  35. GRB 251215A: Fermi GBM Observation
  36. Fermi GRB 251216A: Global MASTER-Net observations report
  37. GRB 251202A/EP251202a: Koshka optical upper limit
  38. GRB 251214B: Mondy optical upper limit
  39. GRB 251215A: COLIBRÍ optical upper limit
  40. EP251214b: KAIT optical upper limit
  41. GRB 251215A: Swift-XRT observations
  42. Fermi GRB 251215A: Global MASTER-Net observations report
  43. EP251214a: Optical upper limit with Kinder observations
  44. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  45. GRB 251215A: Glowbug gamma-ray detection
  46. GRB 251214B: UAFO optical upper limit
  47. GRB 251214B: VLT/X-shooter observations
  48. GRB 251214B: Swift-BAT refined analysis
  49. GRB 251202A: radio detection with the VLA
  50. EP251214b: Global MASTER-Net observations report
  51. EP251214b : Einstein Probe detection of a fast X-ray transient
  52. EP251214b : Einstein Probe detection of a fast X-ray transient
  53. GRB 251214B: AbAO optical observations
  54. GRB 251214B: LCO detection of the optical counterpart
  55. GRB 251214B: Fermi GBM Observation
  56. EP251214b (EP trigger 01709250023): LCO optical limits
  57. GRB 251203B: AbAO optical observations
  58. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  59. GRB 251214B: Swift-XRT refined Analysis
  60. GRB 251213A: SVOM/GRM observation
  61. EP251214a: KAIT optical upper limit
  62. GRB 251213A: AstroSat CZTI detection
  63. GRB 251214A: AstroSat CZTI detection
  64. GRB 251213A: GECAM-B detection
  65. GRB 251214B: Swift/UVOT Detection
  66. GRB 251214B: COLIBRÍ observations of the afterglow
  67. EP251214a: EP-FXT non-detection and upper limit
  68. GRB 251214B: 1.3m DFOT optical detection
  69. EP251214a: Global MASTER-Net observations report
  70. GRB 251214B: Enhanced Swift-XRT position
  71. GRB 251214B: Xinglong-2.16m optical observation
  72. GRB 251214B : MASTER optical afterglow detection
  73. Fermi trigger No 787396657: Global MASTER-Net observations report
  74. GRB 251214B: SVOM/C-GFT optical observations
  75. EP251214a: COLIBRÍ optical upper limit
  76. Swift GRB 251214B: Global MASTER-Net observations report
  77. EP251214.305: COLIBRÍ optical upper limit
  78. GRB 251214B: Swift detection of a burst with an optical counterpart
  79. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  80. Fermi GRB 251214A: Global MASTER-Net observations report
  81. EP251212a: Global MASTER-Net observations report
  82. EP251212a: KAIT optical upper limit
  83. GRB 251211B: AstroSat CZTI detection
  84. GRB 251209A: NuSTAR detection of prompt emission
  85. EP251212a : COLIBRÍ optical upper limit
  86. EP251212a: Einstein Probe detection of an X-ray transient
  87. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  88. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  89. Fermi GRB 251211B: Global MASTER-Net observations report
  90. IceCube-251210A: DDOTI Optical Upper Limit
  91. SVOM GRB251211.12: Global MASTER-Net observations report
  92. GRB 251209A: Fermi GBM observation
  93. GRB 251205A: 1.3m DFOT optical upper limit
  94. GRB 251209A: AstroSat CZTI detection
  95. IceCube Alert 251210.46: Global MASTER-Net observations report
  96. EP251124a: Mondy optical upper limit
  97. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  98. EP251130a: Mondy and AbAO optical observations
  99. GRB 251208A: AstroSat CZTI detection
  100. Fermi GBM Sub-Threshold Detection of GRB 251205A

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