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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"

21572 results found.

  1. GRB 260225A: SVOM/VT optical continued observations and upper limit
  2. EP260227a: Global MASTER-Net observations report
  3. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  4. Konus-Wind detection of GRB 260226A
  5. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  6. EP260214a: VLT/FORS2 optical observations
  7. GRB 260225A: WINTER J-band upper limit
  8. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  9. GRB 260226A : GROWTH-India Telescope optical observations
  10. GRB 260226A: LAST optical upper limit
  11. LAT GRB260226.44: Global MASTER-Net observations report
  12. Fermi GRB 260226A: Global MASTER-Net observations report
  13. EP260214a: VLA 6 GHz detection
  14. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  15. EP260126a: VLA 6 GHz detection
  16. GRB 260225A: SVOM detection of a burst
  17. EP260224a: Einstein Probe detection of an X-ray transient
  18. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  19. sb26021801: SVOM/C-GFT upper limit
  20. EP260223a: Einstein Probe detection of an X-ray transient
  21. GRB 260223A: COLIBRÍ further optical observations and a brightening
  22. EP260221a: Optical upper limit with Kinder observations
  23. GRB 260223A: COLIBRÍ optical observations
  24. GRB 260223A: DDOTI Optical Candidate
  25. Fermi GRB 260223A: Global MASTER-Net observations report
  26. EP260221a: Global MASTER-Net observations report
  27. Fermi GRB 260221B: Global MASTER-Net observations report
  28. Fermi GRB 260221A: Global MASTER-Net observations report
  29. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  30. EP260221a: GOTO optical upper limit
  31. Fermi GRB 260219A: Global MASTER-Net observations report
  32. SVOM alert sb26021801: LAST optical upper limit
  33. IceCube Alert 260217A: Global MASTER-Net observations report
  34. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  35. EP-WXT 01709258455: NOT optical upper limits
  36. EP260214b: Mondy optical observations
  37. EP260214b: 1.3m DFOT optical upper limit
  38. EP260210a: Mondy optical upper limits
  39. Konus-Wind detection of GRB 260212A
  40. GRB 260208A: continued Mondy optical observations
  41. EP260214b: Liverpool Telescope optical observations
  42. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  43. EP260214b: Optical upper limit with Kinder observations
  44. EP260214a: Optical upper limits with Kinder observations
  45. EP260214b: DDOTI Optical Detection
  46. EP260214b: GROWTH-India Telescope optical upper limit
  47. EP260214a: VLT near-infrared observation
  48. EP260214a: NOT optical upper limits
  49. EP260214b: OHP/T120 optical observations
  50. EP260214a: refined analysis of the EP-FXT observation
  51. EP260214b: LCO optical counterpart detection
  52. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  53. GRB 260211A: SVOM/VT optical counterpart
  54. EP260214b: COLIBRÍ optical observations
  55. EP260214a: Global MASTER-Net observations report
  56. EP260213a: Global MASTER-Net observations report
  57. EP260213a: Optical upper limits with Kinder observations
  58. EP260213a: NUTTelA-TAO Early Optical Limits
  59. EP260213a: SVOM/C-GFT upper limit
  60. EP260213a: refined analysis of the EP-FXT observation
  61. EP/WXT 01709258378: NOT optical upper limits
  62. GRB 260211A - SVOM/ECLAIRs refined analysis
  63. GRB 260204A: SVOM/ECLAIRs refined analysis
  64. GRB 260211A: GOTO optical upper limit
  65. Fermi GRB 260212A: Global MASTER-Net observations report
  66. GRB 260211A: LAST optical upper limit
  67. GRB 260128B: SVOM/ECLAIRs refined analysis
  68. GRB260131A/B: 3.6m DOT Optical Observations
  69. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  70. Fermi trigger No 792537871: Global MASTER-Net observations report
  71. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  72. Konus-Wind detection of GRB 260209B
  73. GRB 260208A: Swift UVOT detection
  74. Fermi GRB 260210C: Global MASTER-Net observations report
  75. EP260209a: LCO optical upper limits
  76. EP260210a: Global MASTER-Net observations report
  77. EP260210a: refined analysis of the EP-FXT observation
  78. EP260209a: Global MASTER-Net observations report
  79. GRB 260208A: LCO detection of the optical counterpart
  80. EP260210a: Optical upper limits with Kinder observations
  81. EP260210a: SVOM/C-GFT upper limit
  82. GRB 260204A: Swift-XRT afterglow detection
  83. GRB260208A: Liverpool Telescope optical follow-up observations
  84. Fermi GRB 260209A: Global MASTER-Net observations report
  85. GRB 260208B: Swift-XRT observations
  86. GRB 260131A/B: continued Mondy optical observations
  87. GRB 260204A: Swift/UVOT Upper Limits
  88. GRB 260208B: COLIBRÍ optical observations
  89. GRB 260208A: Mondy optical observations (duplicate submission)
  90. GRB 260208A: Mondy optical observations
  91. GRB 260208A: 1.3m DFOT optical detection
  92. GRB 260208A: COLIBRÍ optical observations
  93. GRB 260208A: NOT spectroscopic redshift z = 2.36
  94. GRB 260208A: Liverpool Telescope optical detection
  95. Fermi GRB 260208C: Global MASTER-Net observations report
  96. GRB 260208B: SVOM/VT optical candidate
  97. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  98. GRB 260208A: SVOM/VT optical observation
  99. Fermi GRB 260208D: Global MASTER-Net observations report
  100. GRB 260208A: Swift-XRT observations

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