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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"

20558 results found.

  1. Fermi GRB 251217A: Global MASTER-Net observations report
  2. GRB 251215A: Swift/UVOT Upper LImits
  3. Fermi GRB 251216A: Global MASTER-Net observations report
  4. GRB 251215A: COLIBRÍ optical upper limit
  5. GRB 251215A: Swift-XRT observations
  6. Fermi GRB 251215A: Global MASTER-Net observations report
  7. EP251214a: Optical upper limit with Kinder observations
  8. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  9. GRB 251214B: UAFO optical upper limit
  10. GRB 251214B: VLT/X-shooter observations
  11. GRB 251202A: radio detection with the VLA
  12. EP251214b: Global MASTER-Net observations report
  13. GRB 251214B: AbAO optical observations
  14. GRB 251214B: LCO detection of the optical counterpart
  15. GRB 251215A: Swift ToO observations
  16. EP251214b (EP trigger 01709250023): LCO optical limits
  17. GRB 251203B: AbAO optical observations
  18. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  19. GRB 251214B: Swift/UVOT Detection
  20. GRB 251214B: COLIBRÍ observations of the afterglow
  21. GRB 251214B: 1.3m DFOT optical detection
  22. EP251214a: Global MASTER-Net observations report
  23. GRB 251214B: Xinglong-2.16m optical observation
  24. GRB 251214B : MASTER optical afterglow detection
  25. Fermi trigger No 787396657: Global MASTER-Net observations report
  26. GRB 251214B: SVOM/C-GFT optical observations
  27. Swift GRB 251214B: Global MASTER-Net observations report
  28. Fermi GRB 251214A: Global MASTER-Net observations report
  29. EP251212a: Global MASTER-Net observations report
  30. EP251212a: KAIT optical upper limit
  31. IceCube-251210A: No Candidate Transients from the Zwicky Transient Facility
  32. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  33. Fermi GRB 251211B: Global MASTER-Net observations report
  34. IceCube-251210A: DDOTI Optical Upper Limit
  35. SVOM GRB251211.12: Global MASTER-Net observations report
  36. GRB 251205A: 1.3m DFOT optical upper limit
  37. IceCube Alert 251210.46: Global MASTER-Net observations report
  38. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  39. EP251130a: Mondy and AbAO optical observations
  40. Fermi GBM Sub-Threshold Detection of GRB 251205A
  41. Fermi GRB 251209A: Global MASTER-Net observations report
  42. Fermi GRB 251208C: Global MASTER-Net observations report
  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 251208D: Swift-XRT observations
  49. GRB 251129A: e-MERLIN C-band observations
  50. LAT GRB251208.43: Global MASTER-Net observations report
  51. GRB 251205A: Liverpool Telescope further optical follow-up observations
  52. SVOM GRB251208D: Global MASTER-Net observations report
  53. GRB 251208B: Swift ToO observations
  54. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  55. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  56. GRB 251205A: FTW optical and NIR observations
  57. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  58. GRB 251205A: Liverpool Telescope further optical follow-up observations
  59. SVOM GRB251206.86: Global MASTER-Net observations report
  60. GRB 251205A: ZTF and ATLAS optical afterglow detections
  61. GRB 251205A: GROWTH-India Telescope optical observations
  62. GRB 251205A: Swift/UVOT Detection
  63. GRB 251205A: Liverpool Telescope optical follow-up observations
  64. GRB 251203C: Swift/UVOT Upper Limit
  65. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  66. GRB 251205A: COLIBRÍ optical observations
  67. GRB 251205A: GOTO optical afterglow detection
  68. GRB 251205A: NOT optical observations
  69. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  70. Swift GRB 251205A : MASTER OT detection with host galaxy
  71. Swift GRB251205A: Global MASTER-Net observations report
  72. GRB 251203C: SVOM/ECLAIRs refined analysis
  73. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  74. GRB 251203C: J-band observations with WINTER
  75. EP251130a: JinShan near-infrared observations
  76. GRB 251203C: SVOM/VT optical counterpart
  77. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  78. GRB 251203B: Swift-XRT observations
  79. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  80. GRB 251203B: LCO optical upper limits
  81. GRB 251203B: SVOM/VT optical observation
  82. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  83. SVOM GRB251203.77: Global MASTER-Net observations report
  84. SVOM GRB251203B: Global MASTER-Net observations report
  85. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  86. EP251130a: MAO/AZT-22 optical observations
  87. GRB 251202A / EP251202a: SVOM/VT optical observation
  88. EP251202a/GRB 251202A: KAIT optical observations
  89. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  90. Fermi GRB 251202B: Global MASTER-Net observations report
  91. GRB251129A/EP251129a: Swift UVOT detection
  92. GRB 251202A: Swift/UVOT Detection
  93. GRB 251201B: Kilonova-Catcher optical afterglow detection
  94. GRB 251201B: Swift/UVOT Detection
  95. EP251130a: continued NOT optical observations indicate steep fading phase
  96. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  97. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  98. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  99. GRB 251202A: GOTO optical afterglow detection
  100. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations

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