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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"

28100 results found.

  1. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  2. IPN triangulation of GRB 251220B (short)
  3. GRB 251222A: BALROG localization (Fermi Trigger / GRB 251222712)
  4. GRB 251222A: SVOM/VT optical candidate
  5. GRB 251222A: SVOM detection of a long burst
  6. SVOM GRB251222A: Global MASTER-Net observations report
  7. EP251220a: PRIME upper limit
  8. GRB 251221A: PRIME near-infrared observation
  9. GRB 251221A: UAFO and Mondy optical upper limit
  10. GRB 251221A: Swift-XRT refined Analysis
  11. EP251221a: Einstein Probe detection of a fast X-ray transient
  12. GRB 251221A: Swift/UVOT Upper Limits
  13. GRB 251221A: Enhanced Swift-XRT position
  14. GRB 251221A: Fermi GBM Observation
  15. GRB 251220B: SVOM/GRM observation of a short burst
  16. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  17. EP 251220a: GOTO optical counterpart detection
  18. GRB 251221A: COLIBRÍ detection of the optical counterpart
  19. EP 251220a: COLIBRÍ detection of the optical counterpart
  20. GRB 251221A: Swift detection of a burst
  21. Swift GRB251221A: Global MASTER-Net observations report
  22. EP251220a: Global MASTER-Net observations report
  23. EP251220a: EP detection of a fast X-ray transient
  24. SVOM GRB251220.98: Global MASTER-Net observations report
  25. GRB 251219A: SVOM/GRM observation of a short burst
  26. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  27. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  28. GRB 251220A: MAXI/GSC detection
  29. GRB 251215A: Swift-XRT afterglow detection
  30. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  31. IceCube-251218A: COLIBRÍ optical upper limits
  32. SVOM GRB251219.11: Global MASTER-Net observations report
  33. IceCube Alert 251218.85: Global MASTER-Net observations report
  34. GRB 251214B: VIRT Optical Upper Limit
  35. Fermi trigger No 787736968: Global MASTER-Net observations report
  36. Fermi GRB 251217A: Global MASTER-Net observations report
  37. GRB 251215A: Swift/UVOT Upper LImits
  38. GRB 251215A: Fermi GBM Observation
  39. Fermi GRB 251216A: Global MASTER-Net observations report
  40. GRB 251202A/EP251202a: Koshka optical upper limit
  41. GRB 251214B: Mondy optical upper limit
  42. GRB 251215A: COLIBRÍ optical upper limit
  43. EP251214b: KAIT optical upper limit
  44. GRB 251215A: Swift-XRT observations
  45. Fermi GRB 251215A: Global MASTER-Net observations report
  46. EP251214a: Optical upper limit with Kinder observations
  47. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  48. GRB 251215A: Glowbug gamma-ray detection
  49. GRB 251214B: UAFO optical upper limit
  50. GRB 251214B: VLT/X-shooter observations
  51. GRB 251214B: Swift-BAT refined analysis
  52. GRB 251202A: radio detection with the VLA
  53. EP251214b: Global MASTER-Net observations report
  54. EP251214b : Einstein Probe detection of a fast X-ray transient
  55. EP251214b : Einstein Probe detection of a fast X-ray transient
  56. GRB 251214B: AbAO optical observations
  57. GRB 251214B: LCO detection of the optical counterpart
  58. GRB 251214B: Fermi GBM Observation
  59. EP251214b (EP trigger 01709250023): LCO optical limits
  60. GRB 251203B: AbAO optical observations
  61. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  62. GRB 251214B: Swift-XRT refined Analysis
  63. GRB 251213A: SVOM/GRM observation
  64. EP251214a: KAIT optical upper limit
  65. GRB 251213A: AstroSat CZTI detection
  66. GRB 251214A: AstroSat CZTI detection
  67. GRB 251213A: GECAM-B detection
  68. GRB 251214B: Swift/UVOT Detection
  69. GRB 251214B: COLIBRÍ observations of the afterglow
  70. EP251214a: EP-FXT non-detection and upper limit
  71. GRB 251214B: 1.3m DFOT optical detection
  72. EP251214a: Global MASTER-Net observations report
  73. GRB 251214B: Enhanced Swift-XRT position
  74. GRB 251214B: Xinglong-2.16m optical observation
  75. GRB 251214B : MASTER optical afterglow detection
  76. Fermi trigger No 787396657: Global MASTER-Net observations report
  77. GRB 251214B: SVOM/C-GFT optical observations
  78. EP251214a: COLIBRÍ optical upper limit
  79. Swift GRB 251214B: Global MASTER-Net observations report
  80. EP251214.305: COLIBRÍ optical upper limit
  81. GRB 251214B: Swift detection of a burst with an optical counterpart
  82. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  83. Fermi GRB 251214A: Global MASTER-Net observations report
  84. EP251212a: Global MASTER-Net observations report
  85. EP251212a: KAIT optical upper limit
  86. GRB 251211B: AstroSat CZTI detection
  87. GRB 251209A: NuSTAR detection of prompt emission
  88. EP251212a : COLIBRÍ optical upper limit
  89. EP251212a: Einstein Probe detection of an X-ray transient
  90. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  91. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  92. Fermi GRB 251211B: Global MASTER-Net observations report
  93. IceCube-251210A: DDOTI Optical Upper Limit
  94. SVOM GRB251211.12: Global MASTER-Net observations report
  95. GRB 251209A: Fermi GBM observation
  96. GRB 251205A: 1.3m DFOT optical upper limit
  97. GRB 251209A: AstroSat CZTI detection
  98. IceCube Alert 251210.46: Global MASTER-Net observations report
  99. EP251124a: Mondy optical upper limit
  100. GRB 251129A/EP251129a: AbAO and Mondy optical observations

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