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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"

28083 results found.

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

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