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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"

36947 results found.

  1. GRB 251214B: Swift-BAT refined analysis
  2. GRB 251202A: radio detection with the VLA
  3. GRB 251214B: AbAO optical observations
  4. GRB 251214B: LCO detection of the optical counterpart
  5. GRB 251209A: GECAM-B observation of a long burst
  6. GRB 251214D: GECAM-B observation of a long burst
  7. GRB 251214B: Fermi GBM Observation
  8. GRB 251209A: Insight-HXMT/HE detection
  9. GRB 251215A: Swift ToO observations
  10. EP251214b (EP trigger 01709250023): LCO optical limits
  11. GRID detection of GRB 251213A
  12. GRB 251203B: AbAO optical observations
  13. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  14. GRB 251214B: GECAM-B observation of a long burst
  15. GRB 251214B: Swift-XRT refined Analysis
  16. GRB 251213A: SVOM/GRM observation
  17. EP251214a: KAIT optical upper limit
  18. GRB 251214D: AstroSat CZTI detection of a long burst
  19. GRB 251213A: AstroSat CZTI detection
  20. GRB 251214A: AstroSat CZTI detection
  21. GRB 251213A: GECAM-B detection
  22. GRB 251214B: Swift/UVOT Detection
  23. GRB 251215A: Fermi GBM Final Real-time Localization
  24. GRB 251214B: COLIBRÍ observations of the afterglow
  25. GRB 251214A: GECAM-B observation of a likely long burst
  26. GRB 251214B: 1.3m DFOT optical detection
  27. GRB 251214B: Enhanced Swift-XRT position
  28. GRB 251214B: Xinglong-2.16m optical observation
  29. GRB 251214C: Fermi GBM Final Localization
  30. GRB 251214B : MASTER optical afterglow detection
  31. GRB 251214B: SVOM/C-GFT optical observations
  32. EP251214a: COLIBRÍ optical upper limit
  33. Swift GRB 251214B: Global MASTER-Net observations report
  34. GRB 251214B: Swift detection of a burst with an optical counterpart
  35. GRB 251214B: Fermi GBM Final Real-time Localization
  36. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  37. Fermi GRB 251214A: Global MASTER-Net observations report
  38. GRB 251214A: Fermi GBM Final Real-time Localization
  39. EP251212a: KAIT optical upper limit
  40. EP251212a / GRB 251212A: AstroSat CZTI detection
  41. GRB 251211B: AstroSat CZTI detection
  42. GRB 251209A: NuSTAR detection of prompt emission
  43. Fermi GRB 251211B: Global MASTER-Net observations report
  44. GRB 251211B: Fermi GBM Final Real-time Localization
  45. GRB 251211A: Fermi GBM Final Real-time Localization
  46. GRB 251209A: Fermi GBM observation
  47. GRB 251205A: 1.3m DFOT optical upper limit
  48. GRB 251209A: AstroSat CZTI detection
  49. EP251124a: Mondy optical upper limit
  50. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  51. EP251130a: Mondy and AbAO optical observations
  52. GRB 251208A: AstroSat CZTI detection
  53. Fermi GBM Sub-Threshold Detection of GRB 251205A
  54. GRB 251208A: Glowbug gamma-ray detection
  55. GRB 251208B: COLIBRÍ optical upper limits
  56. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  57. GRB 251208C: GECAM-B observation of a short burst
  58. GRB 251208A: GECAM-B observation of a short burst
  59. Fermi GRB 251209A: Global MASTER-Net observations report
  60. Fermi GRB 251208C: Global MASTER-Net observations report
  61. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  62. GRB 251208B: Swift-XRT afterglow detection
  63. GRB 251208D: LAST optical upper limit
  64. GRB 251209A: Fermi GBM Final Real-time Localization
  65. GRB 251208D: LCO analysis of the XRT sources
  66. GRB 251208B: Fermi GBM Observation
  67. GRB 251208B: GROWTH-India Telescope optical upper limits
  68. GRB 251205A: J-band detection with WINTER
  69. GRB 251208D: Swift-XRT observations
  70. GRB 251208A: SVOM/GRM observation of a short burst
  71. GRB 251208C: SVOM/GRM observation of a short burst
  72. GRB 251129A: e-MERLIN C-band observations
  73. GRB 251205A: Liverpool Telescope further optical follow-up observations
  74. GRB 251208D: LCO optical upper limits
  75. GRB 251208B: Swift ToO observations
  76. GRB 251208B: Fermi-LAT detection
  77. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  78. GRB 251208D: SVOM possible detection of a faint burst
  79. GRB 251206A: SVOM detection of a burst through offline search
  80. GRB 251208C: Fermi GBM Final Real-time Localization
  81. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  82. GRB 251208B: Fermi GBM Final Real-time Localization
  83. GRB 251208A: Fermi GBM Final Real-time Localization
  84. GRB 251205A: FTW optical and NIR observations
  85. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  86. GRB 251205A: Liverpool Telescope further optical follow-up observations
  87. GRB 251205A: ZTF and ATLAS optical afterglow detections
  88. GRB 251205A: GROWTH-India Telescope optical observations
  89. GRB 251205A: Swift-BAT refined analysis
  90. GRB 251205A: Swift-XRT refined Analysis
  91. GRB 251205A: Swift/UVOT Detection
  92. GRB 251205A: Liverpool Telescope optical follow-up observations
  93. GRB 251203C: Swift/UVOT Upper Limit
  94. Konus-Wind detection of GRB 251118A
  95. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  96. GRB 251205A: COLIBRÍ optical observations
  97. GRB 251205A: GOTO optical afterglow detection
  98. GRB 251205A: NOT optical observations
  99. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  100. GRB 251205A: Enhanced Swift-XRT position

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