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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"

20480 results found.

  1. SVOM GRB251220.98: Global MASTER-Net observations report
  2. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  3. GRB 251215A: Swift-XRT afterglow detection
  4. IceCube-251218A: COLIBRÍ optical upper limits
  5. SVOM GRB251219.11: Global MASTER-Net observations report
  6. IceCube Alert 251218.85: Global MASTER-Net observations report
  7. Fermi trigger No 787736968: Global MASTER-Net observations report
  8. Fermi GRB 251217A: Global MASTER-Net observations report
  9. GRB 251215A: Swift/UVOT Upper LImits
  10. Fermi GRB 251216A: Global MASTER-Net observations report
  11. GRB 251215A: COLIBRÍ optical upper limit
  12. GRB 251215A: Swift-XRT observations
  13. Fermi GRB 251215A: Global MASTER-Net observations report
  14. EP251214a: Optical upper limit with Kinder observations
  15. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  16. GRB 251214B: UAFO optical upper limit
  17. GRB 251214B: VLT/X-shooter observations
  18. GRB 251202A: radio detection with the VLA
  19. EP251214b: Global MASTER-Net observations report
  20. GRB 251214B: AbAO optical observations
  21. GRB 251214B: LCO detection of the optical counterpart
  22. GRB 251215A: Swift ToO observations
  23. EP251214b (EP trigger 01709250023): LCO optical limits
  24. GRB 251203B: AbAO optical observations
  25. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  26. GRB 251214B: Swift/UVOT Detection
  27. GRB 251214B: COLIBRÍ observations of the afterglow
  28. GRB 251214B: 1.3m DFOT optical detection
  29. EP251214a: Global MASTER-Net observations report
  30. GRB 251214B: Xinglong-2.16m optical observation
  31. GRB 251214B : MASTER optical afterglow detection
  32. Fermi trigger No 787396657: Global MASTER-Net observations report
  33. GRB 251214B: SVOM/C-GFT optical observations
  34. Swift GRB 251214B: Global MASTER-Net observations report
  35. Fermi GRB 251214A: Global MASTER-Net observations report
  36. EP251212a: Global MASTER-Net observations report
  37. EP251212a: KAIT optical upper limit
  38. IceCube-251210A: No Candidate Transients from the Zwicky Transient Facility
  39. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  40. Fermi GRB 251211B: Global MASTER-Net observations report
  41. IceCube-251210A: DDOTI Optical Upper Limit
  42. SVOM GRB251211.12: Global MASTER-Net observations report
  43. GRB 251205A: 1.3m DFOT optical upper limit
  44. IceCube Alert 251210.46: Global MASTER-Net observations report
  45. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  46. EP251130a: Mondy and AbAO optical observations
  47. Fermi GRB 251209A: Global MASTER-Net observations report
  48. Fermi GRB 251208C: Global MASTER-Net observations report
  49. GRB 251208B: Swift-XRT afterglow detection
  50. GRB 251208D: LAST optical upper limit
  51. GRB 251208D: LCO analysis of the XRT sources
  52. GRB 251208B: GROWTH-India Telescope optical upper limits
  53. GRB 251205A: J-band detection with WINTER
  54. GRB 251208D: Swift-XRT observations
  55. GRB 251129A: e-MERLIN C-band observations
  56. LAT GRB251208.43: Global MASTER-Net observations report
  57. GRB 251205A: Liverpool Telescope further optical follow-up observations
  58. SVOM GRB251208D: Global MASTER-Net observations report
  59. GRB 251208B: Swift ToO observations
  60. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  61. GRB 251205A: FTW optical and NIR observations
  62. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  63. GRB 251205A: Liverpool Telescope further optical follow-up observations
  64. SVOM GRB251206.86: Global MASTER-Net observations report
  65. GRB 251205A: ZTF and ATLAS optical afterglow detections
  66. GRB 251205A: GROWTH-India Telescope optical observations
  67. GRB 251205A: Swift/UVOT Detection
  68. GRB 251205A: Liverpool Telescope optical follow-up observations
  69. GRB 251203C: Swift/UVOT Upper Limit
  70. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  71. GRB 251205A: COLIBRÍ optical observations
  72. GRB 251205A: GOTO optical afterglow detection
  73. GRB 251205A: NOT optical observations
  74. Swift GRB 251205A : MASTER OT detection with host galaxy
  75. Swift GRB251205A: Global MASTER-Net observations report
  76. GRB 251203C: SVOM/ECLAIRs refined analysis
  77. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  78. GRB 251203C: J-band observations with WINTER
  79. EP251130a: JinShan near-infrared observations
  80. GRB 251203C: SVOM/VT optical counterpart
  81. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  82. GRB 251203B: Swift-XRT observations
  83. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  84. GRB 251203B: LCO optical upper limits
  85. GRB 251203B: SVOM/VT optical observation
  86. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  87. SVOM GRB251203.77: Global MASTER-Net observations report
  88. SVOM GRB251203B: Global MASTER-Net observations report
  89. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  90. EP251130a: MAO/AZT-22 optical observations
  91. GRB 251202A / EP251202a: SVOM/VT optical observation
  92. EP251202a/GRB 251202A: KAIT optical observations
  93. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  94. Fermi GRB 251202B: Global MASTER-Net observations report
  95. GRB251129A/EP251129a: Swift UVOT detection
  96. GRB 251202A: Swift/UVOT Detection
  97. GRB 251201B: Kilonova-Catcher optical afterglow detection
  98. GRB 251201B: Swift/UVOT Detection
  99. EP251130a: continued NOT optical observations indicate steep fading phase
  100. GRB 251122A/EP251122a: CrAO ZTSh optical observations

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