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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"

22060 results found.

  1. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  2. EP260527a: SVOM/VT optical observation
  3. EP260527a: COLIBRÍ optical detection
  4. Fermi trigger No 801580882: Global MASTER-Net observations report
  5. EP260526a: Einstein Probe detection of a fast X-ray transient
  6. Fermi GRB 260526A: Global MASTER-Net observations report
  7. EP-WXT 01709266106: NOT optical upper limits
  8. Fermi GRB 260525A: Global MASTER-Net observations report
  9. Fermi GRB 260523A: Global MASTER-Net observations report
  10. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  11. GRB 260522A: GOTO optical upper limit
  12. Fermi trigger No 801135305: Global MASTER-Net observations report
  13. Fermi GRB 260522A: Global MASTER-Net observations report
  14. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  15. Konus-Wind detection of GRB 260519C
  16. GRB 260509A: SVOM/ECLAIRs refined analysis
  17. GRB 260516D: SVOM/ECLAIRs refined analysis
  18. GRB 260515A: SVOM/ECLAIRs refined analysis
  19. GRB 260421B: radio detection with the VLA
  20. GRB 260516D: GOTO optical counterpart detection
  21. GRB 260516D: LCO optical observations
  22. GRB 260515A: further Liverpool Telescope observations
  23. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  24. GRB 260516D: GROWTH-India Telescope optical detection
  25. GRB 260515A: CrAO ZTSh BVRI optical observations
  26. Fermi GRB 260516C: Global MASTER-Net observations report
  27. SVOM GRB260516D: Global MASTER-Net observations report
  28. GRB 260515A: Liverpool Telescope optical detection
  29. GRB 260515A: LCO optical counterpart detection
  30. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  31. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  32. EP260514a: SVOM/VT optical candidate
  33. Fermi GRB 260516B: Global MASTER-Net observations report
  34. GRB 260515A: SVOM/VT optical observations
  35. GRB 260515A: OHP/T193 optical observations
  36. GRB 260515A: LCO optical observations
  37. SVOM GRB 260515A: Global MASTER-Net observations report
  38. GRB 260515A: NOT optical observations.
  39. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  40. GRB 260515A: JinShan optical counterpart candidate
  41. IceCube-260504A: No Candidate Transients from the Zwicky Transient Facility
  42. GRB 260511B: NOT optical observations
  43. Konus-Wind detection of GRB 260512A
  44. EP260514a: Global MASTER-Net observations report
  45. GRB 260511B: Mephisto multi-band optical followup
  46. Fermi GRB 260514A: Global MASTER-Net observations report
  47. EP260512a: EP-FXT follow-up observation
  48. EP260507a: Xinglong Schmidt optical counterpart detection
  49. EP260512a: Global MASTER-Net observations report
  50. Fermi GRB 260513A: Global MASTER-Net observations report
  51. Fermi GRB 260512A: Global MASTER-Net observations report
  52. GRB 260511B: further SAO RAS optical observations
  53. GRB 260509A: SVOM/VT optical observations
  54. Konus-Wind detection of GRB 260511B
  55. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  56. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  57. GRB 260512A: NuSTAR detection of prompt emission
  58. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  59. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  60. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  61. Konus-Wind detection of GRB 260511A
  62. GRB 260511B: SAO RAS optical observations
  63. GRB 260511B: FRAM-ORM optical detection
  64. GRB 260511A: EP-FXT follow-up observation
  65. GRB 260511B: EP-FXT follow-up observation
  66. GRB 260511B: LCO optical counterpart detection
  67. GRB260511B: MAO/AZT-22 optical observations
  68. GRB 260511A: SVOM/VT optical observations
  69. GRB 260511B: LCO optical observations
  70. GRB 260511B: OHP/T193 spectroscopic observations
  71. GRB 260511B: GOTO optical counterpart detection
  72. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  73. GRB 260511B: SVOM/VT optical observations
  74. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  75. GRB 260509A: SAO RAS optical observations
  76. GRB 260511A: REM near-infrared detection
  77. GRB 260511B: GROWTH-India Telescope optical observations
  78. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  79. GRB 260510B: SVOM/ECLAIRs refined analysis
  80. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  81. GRB 260511B SVOM/C-GFT optical counterpart detection
  82. GRB 260511A: UTGO H50 optical afterglow observation
  83. GRB 260510C: SVOM/VT optical counterpart confirmation
  84. EP260509a: EP-FXT non-detection and upper limit
  85. GRB 260511A: SVOM/VT optical observation with VHF data
  86. Fermi GRB 260511A: Global MASTER-Net observations report
  87. GRB 260511A: KAIT optical afterglow observations
  88. GRB 260511A: TRT optical counterpart detection
  89. GRB 260510B: SVOM/VT optical upper limits
  90. GRB 260510C: SVOM/VT optical upper limits
  91. EP260509a: Global MASTER-Net observations report
  92. GRB 260510B: GOTO early upper limit
  93. GRB 260509A: Liverpool Telescope optical observations
  94. GRB 260509A: LCO optical observations
  95. SVOM GRB 260509A: MASTER-OAFA optical observation
  96. Fermi GRB 260510A: Global MASTER-Net observations report
  97. GRB 260509A: KAIT optical observations
  98. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  99. GRB 260509A: SVOM/VT optical candidate with VHF data
  100. GRB 260509A: GOTO optical counterpart candidate

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