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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"

20966 results found.

  1. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  2. GRB 251214B: UAFO optical upper limit
  3. GRB 251214B: VLT/X-shooter observations
  4. GRB 251202A: radio detection with the VLA
  5. EP251214b: Global MASTER-Net observations report
  6. GRB 251214B: AbAO optical observations
  7. GRB 251214B: LCO detection of the optical counterpart
  8. GRB 251215A: Swift ToO observations
  9. EP251214b (EP trigger 01709250023): LCO optical limits
  10. GRB 251203B: AbAO optical observations
  11. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  12. GRB 251214B: Swift/UVOT Detection
  13. GRB 251214B: COLIBRÍ observations of the afterglow
  14. GRB 251214B: 1.3m DFOT optical detection
  15. EP251214a: Global MASTER-Net observations report
  16. GRB 251214B: Xinglong-2.16m optical observation
  17. GRB 251214B : MASTER optical afterglow detection
  18. Fermi trigger No 787396657: Global MASTER-Net observations report
  19. GRB 251214B: SVOM/C-GFT optical observations
  20. Swift GRB 251214B: Global MASTER-Net observations report
  21. Fermi GRB 251214A: Global MASTER-Net observations report
  22. EP251212a: Global MASTER-Net observations report
  23. EP251212a: KAIT optical upper limit
  24. IceCube-251210A: No Candidate Transients from the Zwicky Transient Facility
  25. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  26. Fermi GRB 251211B: Global MASTER-Net observations report
  27. IceCube-251210A: DDOTI Optical Upper Limit
  28. SVOM GRB251211.12: Global MASTER-Net observations report
  29. GRB 251205A: 1.3m DFOT optical upper limit
  30. IceCube Alert 251210.46: Global MASTER-Net observations report
  31. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  32. EP251130a: Mondy and AbAO optical observations
  33. Fermi GRB 251209A: Global MASTER-Net observations report
  34. Fermi GRB 251208C: Global MASTER-Net observations report
  35. GRB 251208B: Swift-XRT afterglow detection
  36. GRB 251208D: LAST optical upper limit
  37. GRB 251208D: LCO analysis of the XRT sources
  38. GRB 251208B: GROWTH-India Telescope optical upper limits
  39. GRB 251205A: J-band detection with WINTER
  40. GRB 251208D: Swift-XRT observations
  41. GRB 251129A: e-MERLIN C-band observations
  42. LAT GRB251208.43: Global MASTER-Net observations report
  43. GRB 251205A: Liverpool Telescope further optical follow-up observations
  44. SVOM GRB251208D: Global MASTER-Net observations report
  45. GRB 251208B: Swift ToO observations
  46. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  47. GRB 251205A: FTW optical and NIR observations
  48. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  49. GRB 251205A: Liverpool Telescope further optical follow-up observations
  50. SVOM GRB251206.86: Global MASTER-Net observations report
  51. GRB 251205A: ZTF and ATLAS optical afterglow detections
  52. GRB 251205A: GROWTH-India Telescope optical observations
  53. GRB 251205A: Swift/UVOT Detection
  54. GRB 251205A: Liverpool Telescope optical follow-up observations
  55. GRB 251203C: Swift/UVOT Upper Limit
  56. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  57. GRB 251205A: COLIBRÍ optical observations
  58. GRB 251205A: GOTO optical afterglow detection
  59. GRB 251205A: NOT optical observations
  60. Swift GRB 251205A : MASTER OT detection with host galaxy
  61. Swift GRB251205A: Global MASTER-Net observations report
  62. GRB 251203C: SVOM/ECLAIRs refined analysis
  63. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  64. GRB 251203C: J-band observations with WINTER
  65. EP251130a: JinShan near-infrared observations
  66. GRB 251203C: SVOM/VT optical counterpart
  67. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  68. GRB 251203B: Swift-XRT observations
  69. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  70. GRB 251203B: LCO optical upper limits
  71. GRB 251203B: SVOM/VT optical observation
  72. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  73. SVOM GRB251203.77: Global MASTER-Net observations report
  74. SVOM GRB251203B: Global MASTER-Net observations report
  75. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  76. EP251130a: MAO/AZT-22 optical observations
  77. GRB 251202A / EP251202a: SVOM/VT optical observation
  78. EP251202a/GRB 251202A: KAIT optical observations
  79. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  80. Fermi GRB 251202B: Global MASTER-Net observations report
  81. GRB251129A/EP251129a: Swift UVOT detection
  82. GRB 251202A: Swift/UVOT Detection
  83. GRB 251201B: Kilonova-Catcher optical afterglow detection
  84. GRB 251201B: Swift/UVOT Detection
  85. EP251130a: continued NOT optical observations indicate steep fading phase
  86. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  87. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  88. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  89. GRB 251202A: GOTO optical afterglow detection
  90. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  91. GRB 251202A: Swift-XRT afterglow detection
  92. Fermi GRB 251202A: Global MASTER-Net observations report
  93. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  94. Swift GRB 251201B: Global MASTER-Net observations report
  95. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  96. EP251130a: Mondy optical observations
  97. EP251130a: Optical detections with Kinder observations
  98. SVOM GRB251201.19: Global MASTER-Net observations report
  99. EP251130a: SAO RAS optical observations
  100. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening

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