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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"

19575 results found.

  1. GRB 251215A: Swift-XRT observations
  2. EP251214a: Optical upper limit with Kinder observations
  3. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  4. GRB 251214B: UAFO optical upper limit
  5. GRB 251214B: VLT/X-shooter observations
  6. GRB 251202A: radio detection with the VLA
  7. EP251214b : Einstein Probe detection of a fast X-ray transient
  8. EP251214b : Einstein Probe detection of a fast X-ray transient
  9. GRB 251214B: AbAO optical observations
  10. GRB 251214B: LCO detection of the optical counterpart
  11. GRB 251215A: Swift ToO observations
  12. EP251214b (EP trigger 01709250023): LCO optical limits
  13. GRB 251203B: AbAO optical observations
  14. GRB 251214B: Swift-XRT refined Analysis
  15. GRB 251213A: SVOM/GRM observation
  16. EP251214a: KAIT optical upper limit
  17. GRB 251214D: AstroSat CZTI detection of a long burst
  18. GRB 251214B: Swift/UVOT Detection
  19. GRB 251214B: COLIBRÍ observations of the afterglow
  20. EP251214a: EP-FXT non-detection and upper limit
  21. GRB 251214B: 1.3m DFOT optical detection
  22. GRB 251214B: Enhanced Swift-XRT position
  23. GRB 251214B: Xinglong-2.16m optical observation
  24. GRB 251214B : MASTER optical afterglow detection
  25. GRB 251214B: SVOM/C-GFT optical observations
  26. EP251214a: COLIBRÍ optical upper limit
  27. EP251214.305: COLIBRÍ optical upper limit
  28. GRB 251214B: Swift detection of a burst with an optical counterpart
  29. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  30. EP251212a: KAIT optical upper limit
  31. GRB 251211B: AstroSat CZTI detection
  32. EP251212a : COLIBRÍ optical upper limit
  33. EP251212a: Einstein Probe detection of an X-ray transient
  34. IceCube-251210A: DDOTI Optical Upper Limit
  35. GRB 251205A: 1.3m DFOT optical upper limit
  36. EP251124a: Mondy optical upper limit
  37. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  38. EP251130a: Mondy and AbAO optical observations
  39. Fermi GBM Sub-Threshold Detection of GRB 251205A
  40. GRB 251208B: COLIBRÍ optical upper limits
  41. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  42. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  43. GRB 251208B: Swift-XRT afterglow detection
  44. GRB 251208D: LAST optical upper limit
  45. GRB 251208D: LCO analysis of the XRT sources
  46. GRB 251208B: GROWTH-India Telescope optical upper limits
  47. GRB 251205A: J-band detection with WINTER
  48. GRB 251208A: SVOM/GRM observation of a short burst
  49. GRB 251208C: SVOM/GRM observation of a short burst
  50. GRB 251205A: Liverpool Telescope further optical follow-up observations
  51. GRB 251208D: LCO optical upper limits
  52. GRB 251208B: Swift ToO observations
  53. GRB 251208D: SVOM possible detection of a faint burst
  54. GRB 251208C: Fermi GBM Final Real-time Localization
  55. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  56. GRB 251208B: Fermi GBM Final Real-time Localization
  57. GRB 251208A: Fermi GBM Final Real-time Localization
  58. GRB 251205A: Liverpool Telescope further optical follow-up observations
  59. GRB 251205A: GROWTH-India Telescope optical observations
  60. GRB 251205A: Swift/UVOT Detection
  61. GRB 251205A: Liverpool Telescope optical follow-up observations
  62. GRB 251203C: Swift/UVOT Upper Limit
  63. GRB 251205A: COLIBRÍ optical observations
  64. GRB 251205A: NOT optical observations
  65. GRB 251205A: Enhanced Swift-XRT position
  66. Swift GRB 251205A : MASTER OT detection with host galaxy
  67. GRB 251205A: Swift detection of a burst with an optical afterglow
  68. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  69. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  70. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  71. GRB 251202A: SVOM/GRM observation
  72. GRB 251203A: SVOM/GRM observation
  73. GRB 251203C: J-band observations with WINTER
  74. GRB 251203A: AstroSat CZTI detection
  75. GRB 251203C: SVOM/VT optical counterpart
  76. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  77. GRB 251203C: LCO optical upper limits
  78. GRB 251203B: LCO optical upper limits
  79. GRB 251203B: SVOM/VT optical observation
  80. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  81. GRB 251203C: SVOM detection of a burst
  82. GRB 251203B: SVOM detection of a burst
  83. GRB 251201B: Insight-HXMT/HE detection
  84. EP251130a: MAO/AZT-22 optical observations
  85. EP251202a/GRB 251202A: KAIT optical observations
  86. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  87. IPN triangulation of GRB 251129B (short/hard)
  88. GRB251129A/EP251129a: Swift UVOT detection
  89. GRB 251202A: Swift/UVOT Detection
  90. GRB 251201B: Kilonova-Catcher optical afterglow detection
  91. GRB 251201B: Swift/UVOT Detection
  92. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  93. GRB 251126A: SAO RAS optical marginal detection
  94. GRB 251202A: Swift-XRT afterglow detection
  95. EP251129a/GRB 251129A: NOWT Detection
  96. GRB 251126A: SVOM/VT optical observation
  97. EP251130a: SVOM/VT optical observation
  98. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  99. GRB 251201A: SVOM/GRM observation of a burst
  100. GRB 251201B: SVOM/VT optical fading

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