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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"

35259 results found.

  1. GRB 251209A: Insight-HXMT/HE detection
  2. GRB 251215A: Swift ToO observations
  3. GRID detection of GRB 251213A
  4. GRB 251203B: AbAO optical observations
  5. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  6. GRB 251214B: GECAM-B observation of a long burst
  7. GRB 251214B: Swift-XRT refined Analysis
  8. GRB 251213A: SVOM/GRM observation
  9. EP251214a: KAIT optical upper limit
  10. GRB 251214D: AstroSat CZTI detection of a long burst
  11. GRB 251213A: AstroSat CZTI detection
  12. GRB 251214A: AstroSat CZTI detection
  13. GRB 251213A: GECAM-B detection
  14. GRB 251214B: Swift/UVOT Detection
  15. GRB 251215A: Fermi GBM Final Real-time Localization
  16. GRB 251214B: COLIBRÍ observations of the afterglow
  17. GRB 251214A: GECAM-B observation of a likely long burst
  18. GRB 251214B: 1.3m DFOT optical detection
  19. GRB 251214B: Enhanced Swift-XRT position
  20. GRB 251214B: Xinglong-2.16m optical observation
  21. GRB 251214C: Fermi GBM Final Localization
  22. GRB 251214B : MASTER optical afterglow detection
  23. GRB 251214B: SVOM/C-GFT optical observations
  24. EP251214a: COLIBRÍ optical upper limit
  25. Swift GRB 251214B: Global MASTER-Net observations report
  26. GRB 251214B: Swift detection of a burst with an optical counterpart
  27. GRB 251214B: Fermi GBM Final Real-time Localization
  28. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  29. Fermi GRB 251214A: Global MASTER-Net observations report
  30. GRB 251214A: Fermi GBM Final Real-time Localization
  31. EP251212a: KAIT optical upper limit
  32. EP251212a / GRB 251212A: AstroSat CZTI detection
  33. GRB 251211B: AstroSat CZTI detection
  34. GRB 251209A: NuSTAR detection of prompt emission
  35. Fermi GRB 251211B: Global MASTER-Net observations report
  36. GRB 251211B: Fermi GBM Final Real-time Localization
  37. GRB 251211A: Fermi GBM Final Real-time Localization
  38. GRB 251209A: Fermi GBM observation
  39. GRB 251205A: 1.3m DFOT optical upper limit
  40. GRB 251209A: AstroSat CZTI detection
  41. EP251124a: Mondy optical upper limit
  42. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  43. EP251130a: Mondy and AbAO optical observations
  44. GRB 251208A: AstroSat CZTI detection
  45. Fermi GBM Sub-Threshold Detection of GRB 251205A
  46. GRB 251208A: Glowbug gamma-ray detection
  47. GRB 251208B: COLIBRÍ optical upper limits
  48. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  49. GRB 251208C: GECAM-B observation of a short burst
  50. GRB 251208A: GECAM-B observation of a short burst
  51. Fermi GRB 251209A: Global MASTER-Net observations report
  52. Fermi GRB 251208C: Global MASTER-Net observations report
  53. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  54. GRB 251208B: Swift-XRT afterglow detection
  55. GRB 251208D: LAST optical upper limit
  56. GRB 251209A: Fermi GBM Final Real-time Localization
  57. GRB 251208D: LCO analysis of the XRT sources
  58. GRB 251208B: Fermi GBM Observation
  59. GRB 251208B: GROWTH-India Telescope optical upper limits
  60. GRB 251205A: J-band detection with WINTER
  61. GRB 251208D: Swift-XRT observations
  62. GRB 251208A: SVOM/GRM observation of a short burst
  63. GRB 251208C: SVOM/GRM observation of a short burst
  64. GRB 251129A: e-MERLIN C-band observations
  65. GRB 251205A: Liverpool Telescope further optical follow-up observations
  66. GRB 251208D: LCO optical upper limits
  67. GRB 251208B: Swift ToO observations
  68. GRB 251208B: Fermi-LAT detection
  69. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  70. GRB 251208D: SVOM possible detection of a faint burst
  71. GRB 251206A: SVOM detection of a burst through offline search
  72. GRB 251208C: Fermi GBM Final Real-time Localization
  73. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  74. GRB 251208B: Fermi GBM Final Real-time Localization
  75. GRB 251208A: Fermi GBM Final Real-time Localization
  76. GRB 251205A: FTW optical and NIR observations
  77. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  78. GRB 251205A: Liverpool Telescope further optical follow-up observations
  79. GRB 251205A: ZTF and ATLAS optical afterglow detections
  80. GRB 251205A: GROWTH-India Telescope optical observations
  81. GRB 251205A: Swift-BAT refined analysis
  82. GRB 251205A: Swift-XRT refined Analysis
  83. GRB 251205A: Swift/UVOT Detection
  84. GRB 251205A: Liverpool Telescope optical follow-up observations
  85. GRB 251203C: Swift/UVOT Upper Limit
  86. Konus-Wind detection of GRB 251118A
  87. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  88. GRB 251205A: COLIBRÍ optical observations
  89. GRB 251205A: GOTO optical afterglow detection
  90. GRB 251205A: NOT optical observations
  91. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  92. GRB 251205A: Enhanced Swift-XRT position
  93. Swift GRB 251205A : MASTER OT detection with host galaxy
  94. GRB 251205A: Swift detection of a burst with an optical afterglow
  95. GRB 251126B: Fermi GBM Final Localization
  96. GRB 251203A: Insight-HXMT/HE detection
  97. GRB 251203C: SVOM/ECLAIRs refined analysis
  98. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  99. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  100. GRB 251202A: SVOM/GRM observation

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