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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"

41734 results found.

  1. EP251220a: NOT optical observations
  2. EP251220a: FTW optical and NIR observations
  3. GRB 251221A: UAFO and Mondy optical upper limit
  4. GRB 251221A: Swift-XRT refined Analysis
  5. EP251221a: Einstein Probe detection of a fast X-ray transient
  6. GRB 251221A: Swift/UVOT Upper Limits
  7. GRB 251221A: Enhanced Swift-XRT position
  8. GRB 251221A: Fermi GBM Observation
  9. GRB 251221B: Fermi GBM Final Real-time Localization
  10. EP251220a: EP-FXT follow-up observation
  11. GRB 251220B: SVOM/GRM observation of a short burst
  12. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  13. EP 251220a: GOTO optical counterpart detection
  14. GRB 251221A: COLIBRÍ detection of the optical counterpart
  15. EP 251220a: COLIBRÍ detection of the optical counterpart
  16. GRB 251221A: Swift detection of a burst
  17. Swift GRB251221A: Global MASTER-Net observations report
  18. GRB 251221A: Fermi GBM Final Real-time Localization
  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 251220B: Fermi GBM Final Real-time Localization
  23. GRB 251219A: SVOM/GRM observation of a short burst
  24. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  25. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  26. GRB 251220A: MAXI/GSC detection
  27. GRB 251215A: Swift-XRT afterglow detection
  28. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  29. IceCube-251218A: COLIBRÍ optical upper limits
  30. SVOM GRB251219.11: Global MASTER-Net observations report
  31. IceCube-251218A - IceCube observation of a high-energy neutrino candidate track-like event
  32. IceCube Alert 251218.85: Global MASTER-Net observations report
  33. GRB 251214B: VIRT Optical Upper Limit
  34. Fermi trigger No 787736968: Global MASTER-Net observations report
  35. Fermi GRB 251217A: Global MASTER-Net observations report
  36. GRB 251217A: Fermi GBM Final Real-time Localization
  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. GRB 251216A: Fermi GBM Final Real-time Localization
  44. EP251214b: KAIT optical upper limit
  45. GRB 251215A: Swift-XRT observations
  46. Fermi GRB 251215A: Global MASTER-Net observations report
  47. EP251214a: Optical upper limit with Kinder observations
  48. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  49. GRB 251215A: Glowbug gamma-ray detection
  50. GRB 251214B: UAFO optical upper limit
  51. GRB 251214B: VLT/X-shooter observations
  52. GRB 251213A: GRID-10B observation
  53. GRB 251214B: Swift-BAT refined analysis
  54. GRB 251202A: radio detection with the VLA
  55. EP251214b: Global MASTER-Net observations report
  56. EP251214b : Einstein Probe detection of a fast X-ray transient
  57. EP251214b : Einstein Probe detection of a fast X-ray transient
  58. GRB 251214B: AbAO optical observations
  59. GRB 251214B: LCO detection of the optical counterpart
  60. GRB 251209A: GECAM-B observation of a long burst
  61. GRB 251214D: GECAM-B observation of a long burst
  62. GRB 251214B: Fermi GBM Observation
  63. GRB 251209A: Insight-HXMT/HE detection
  64. GRB 251215A: Swift ToO observations
  65. EP251214b (EP trigger 01709250023): LCO optical limits
  66. GRID detection of GRB 251213A
  67. GRB 251203B: AbAO optical observations
  68. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  69. GRB 251214B: GECAM-B observation of a long burst
  70. GRB 251214B: Swift-XRT refined Analysis
  71. GRB 251213A: SVOM/GRM observation
  72. EP251214a: KAIT optical upper limit
  73. GRB 251214D: AstroSat CZTI detection of a long burst
  74. GRB 251213A: AstroSat CZTI detection
  75. GRB 251214A: AstroSat CZTI detection
  76. GRB 251213A: GECAM-B detection
  77. GRB 251214B: Swift/UVOT Detection
  78. GRB 251215A: Fermi GBM Final Real-time Localization
  79. GRB 251214B: COLIBRÍ observations of the afterglow
  80. EP251214a: EP-FXT non-detection and upper limit
  81. GRB 251214A: GECAM-B observation of a likely long burst
  82. GRB 251214B: 1.3m DFOT optical detection
  83. EP251214a: Global MASTER-Net observations report
  84. GRB 251214B: Enhanced Swift-XRT position
  85. GRB 251214B: Xinglong-2.16m optical observation
  86. GRB 251214C: Fermi GBM Final Localization
  87. GRB 251214B : MASTER optical afterglow detection
  88. Fermi trigger No 787396657: Global MASTER-Net observations report
  89. GRB 251214B: SVOM/C-GFT optical observations
  90. EP251214a: COLIBRÍ optical upper limit
  91. Swift GRB 251214B: Global MASTER-Net observations report
  92. EP251214.305: COLIBRÍ optical upper limit
  93. GRB 251214B: Swift detection of a burst with an optical counterpart
  94. GRB 251214B: Fermi GBM Final Real-time Localization
  95. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  96. Fermi GRB 251214A: Global MASTER-Net observations report
  97. GRB 251214A: Fermi GBM Final Real-time Localization
  98. EP251212a: Global MASTER-Net observations report
  99. EP251212a: KAIT optical upper limit
  100. EP251212a / GRB 251212A: AstroSat CZTI detection

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