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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"

20536 results found.

  1. GRB 251214B: Xinglong-2.16m optical observation
  2. GRB 251214B : MASTER optical afterglow detection
  3. Fermi trigger No 787396657: Global MASTER-Net observations report
  4. GRB 251214B: SVOM/C-GFT optical observations
  5. Swift GRB 251214B: Global MASTER-Net observations report
  6. Fermi GRB 251214A: Global MASTER-Net observations report
  7. EP251212a: Global MASTER-Net observations report
  8. EP251212a: KAIT optical upper limit
  9. IceCube-251210A: No Candidate Transients from the Zwicky Transient Facility
  10. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  11. Fermi GRB 251211B: Global MASTER-Net observations report
  12. IceCube-251210A: DDOTI Optical Upper Limit
  13. SVOM GRB251211.12: Global MASTER-Net observations report
  14. GRB 251205A: 1.3m DFOT optical upper limit
  15. IceCube Alert 251210.46: Global MASTER-Net observations report
  16. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  17. EP251130a: Mondy and AbAO optical observations
  18. Fermi GBM Sub-Threshold Detection of GRB 251205A
  19. Fermi GRB 251209A: Global MASTER-Net observations report
  20. Fermi GRB 251208C: Global MASTER-Net observations report
  21. GRB 251208B: Swift-XRT afterglow detection
  22. GRB 251208D: LAST optical upper limit
  23. GRB 251208D: LCO analysis of the XRT sources
  24. GRB 251208B: GROWTH-India Telescope optical upper limits
  25. GRB 251205A: J-band detection with WINTER
  26. GRB 251208D: Swift-XRT observations
  27. GRB 251129A: e-MERLIN C-band observations
  28. LAT GRB251208.43: Global MASTER-Net observations report
  29. GRB 251205A: Liverpool Telescope further optical follow-up observations
  30. SVOM GRB251208D: Global MASTER-Net observations report
  31. GRB 251208B: Swift ToO observations
  32. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  33. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  34. GRB 251205A: FTW optical and NIR observations
  35. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  36. GRB 251205A: Liverpool Telescope further optical follow-up observations
  37. SVOM GRB251206.86: Global MASTER-Net observations report
  38. GRB 251205A: ZTF and ATLAS optical afterglow detections
  39. GRB 251205A: GROWTH-India Telescope optical observations
  40. GRB 251205A: Swift/UVOT Detection
  41. GRB 251205A: Liverpool Telescope optical follow-up observations
  42. GRB 251203C: Swift/UVOT Upper Limit
  43. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  44. GRB 251205A: COLIBRÍ optical observations
  45. GRB 251205A: GOTO optical afterglow detection
  46. GRB 251205A: NOT optical observations
  47. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  48. Swift GRB 251205A : MASTER OT detection with host galaxy
  49. Swift GRB251205A: Global MASTER-Net observations report
  50. GRB 251203C: SVOM/ECLAIRs refined analysis
  51. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  52. GRB 251203C: J-band observations with WINTER
  53. EP251130a: JinShan near-infrared observations
  54. GRB 251203C: SVOM/VT optical counterpart
  55. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  56. GRB 251203B: Swift-XRT observations
  57. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  58. GRB 251203B: LCO optical upper limits
  59. GRB 251203B: SVOM/VT optical observation
  60. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  61. SVOM GRB251203.77: Global MASTER-Net observations report
  62. SVOM GRB251203B: Global MASTER-Net observations report
  63. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  64. EP251130a: MAO/AZT-22 optical observations
  65. GRB 251202A / EP251202a: SVOM/VT optical observation
  66. EP251202a/GRB 251202A: KAIT optical observations
  67. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  68. Fermi GRB 251202B: Global MASTER-Net observations report
  69. GRB251129A/EP251129a: Swift UVOT detection
  70. GRB 251202A: Swift/UVOT Detection
  71. GRB 251201B: Kilonova-Catcher optical afterglow detection
  72. GRB 251201B: Swift/UVOT Detection
  73. EP251130a: continued NOT optical observations indicate steep fading phase
  74. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  75. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  76. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  77. GRB 251202A: GOTO optical afterglow detection
  78. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  79. GRB 251202A: Swift-XRT afterglow detection
  80. Fermi GRB 251202A: Global MASTER-Net observations report
  81. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  82. Swift GRB 251201B: Global MASTER-Net observations report
  83. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  84. EP251130a: Mondy optical observations
  85. EP251130a: Optical detections with Kinder observations
  86. SVOM GRB251201.19: Global MASTER-Net observations report
  87. EP251130a: SAO RAS optical observations
  88. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  89. EP251130a: KAIT optical observations
  90. EP251130A: Optical observation from 1.3m DFOT
  91. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  92. EP251130a: JinShan optical observations
  93. Fermi GRB 251130B: Global MASTER-Net observations report
  94. IceCube Alert 251130.75: Global MASTER-Net observations report
  95. EP251130a: Swift-XRT counterpart detection
  96. EP251130a: Global MASTER-Net observations report
  97. EP251129a/GRB 251129A: EP-FXT follow-up observations
  98. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  99. GRB 251129A / EP251129a: SAO RAS optical observations
  100. GRB 251126A: SAO RAS optical observations

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