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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"

20358 results found.

  1. GRB 251214B : MASTER optical afterglow detection
  2. GRB 251214B: SVOM/C-GFT optical observations
  3. EP251214a: COLIBRÍ optical upper limit
  4. EP251214.305: COLIBRÍ optical upper limit
  5. GRB 251214B: Swift detection of a burst with an optical counterpart
  6. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  7. EP251212a: KAIT optical upper limit
  8. EP251212a : COLIBRÍ optical upper limit
  9. EP251212a: Einstein Probe detection of an X-ray transient
  10. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  11. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  12. IceCube-251210A: DDOTI Optical Upper Limit
  13. GRB 251209A: Fermi GBM observation
  14. GRB 251205A: 1.3m DFOT optical upper limit
  15. GRB 251209A: AstroSat CZTI detection
  16. EP251124a: Mondy optical upper limit
  17. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  18. EP251130a: Mondy and AbAO optical observations
  19. GRB 251208B: COLIBRÍ optical upper limits
  20. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  21. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  22. GRB 251208B: Swift-XRT afterglow detection
  23. GRB 251208D: LAST optical upper limit
  24. GRB 251208D: LCO analysis of the XRT sources
  25. GRB 251208B: GROWTH-India Telescope optical upper limits
  26. GRB 251205A: J-band detection with WINTER
  27. GRB 251208A: SVOM/GRM observation of a short burst
  28. GRB 251208C: SVOM/GRM observation of a short burst
  29. GRB 251129A: e-MERLIN C-band observations
  30. GRB 251205A: Liverpool Telescope further optical follow-up observations
  31. GRB 251208D: LCO optical upper limits
  32. GRB 251206A: SVOM detection of a burst through offline search
  33. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  34. GRB 251205A: Liverpool Telescope further optical follow-up observations
  35. GRB 251205A: GROWTH-India Telescope optical observations
  36. GRB 251205A: Swift/UVOT Detection
  37. GRB 251205A: Liverpool Telescope optical follow-up observations
  38. GRB 251203C: Swift/UVOT Upper Limit
  39. Konus-Wind detection of GRB 251118A
  40. GRB 251205A: COLIBRÍ optical observations
  41. GRB 251205A: NOT optical observations
  42. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  43. GRB 251205A: Enhanced Swift-XRT position
  44. Swift GRB 251205A : MASTER OT detection with host galaxy
  45. GRB 251205A: Swift detection of a burst with an optical afterglow
  46. GRB 251203C: SVOM/ECLAIRs refined analysis
  47. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  48. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  49. GRB 251202A: SVOM/GRM observation
  50. GRB 251203A: SVOM/GRM observation
  51. GRB 251203C: J-band observations with WINTER
  52. GRB 251203C: SVOM/VT optical counterpart
  53. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  54. GRB 251203B: Swift-XRT observations
  55. GRB 251203C: LCO optical upper limits
  56. GRB 251203B: LCO optical upper limits
  57. GRB 251203B: SVOM/VT optical observation
  58. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  59. GRB 251203B: SVOM detection of a burst
  60. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  61. EP251130a: MAO/AZT-22 optical observations
  62. EP251202a / GRB251202A: AstroSat CZTI detection
  63. GRB 251201B: Fermi GBM Observation
  64. EP251202a/GRB 251202A: KAIT optical observations
  65. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  66. IPN triangulation of GRB 251129B (short/hard)
  67. GRB251129A/EP251129a: Swift UVOT detection
  68. GRB 251202A: Swift/UVOT Detection
  69. GRB 251201B: Kilonova-Catcher optical afterglow detection
  70. GRB 251201B: Swift/UVOT Detection
  71. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  72. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  73. GRB 251126A: SAO RAS optical marginal detection
  74. GRB 251202A: Swift-XRT afterglow detection
  75. EP251129a/GRB 251129A: NOWT Detection
  76. GRB 251126A: SVOM/VT optical observation
  77. EP251130a: SVOM/VT optical observation
  78. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  79. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  80. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  81. GRB 251201A: SVOM/GRM observation of a burst
  82. GRB 251201B: SVOM/VT optical fading
  83. Swift GRB 251201B : MASTER optical counterpart detection
  84. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  85. GRB 251201B: Enhanced Swift-XRT position
  86. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  87. GRB 251130B: AstroSat CZTI detection
  88. GRB 251201B: Swift detection of a burst with an optical counterpart
  89. EP251130a: Mondy optical observations
  90. EP251130a: Optical detections with Kinder observations
  91. EP251130a: SAO RAS optical observations
  92. EP251130A: Optical observation from 1.3m DFOT
  93. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  94. EP251130a: JinShan optical observations
  95. GRB 251127A: SVOM/GRM observation
  96. EP251130a: COLIBRÍ optical counterpart candidate
  97. EP251130a: Einstein Probe detection of an X-ray transient
  98. GRB 251129A / EP251129a: SAO RAS optical observations
  99. GRB 251126A: SAO RAS optical observations
  100. GRB 251128A: GECAM-B detection

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