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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"

32534 results found.

  1. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  2. Fermi GRB 260601A: Global MASTER-Net observations report
  3. GRB 260531B: GECAM-B observation
  4. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  5. AT 2026nuz: COLIBRÍ optical observations
  6. IPN triangulation of GRB 260527A / EP260527a
  7. EP260527a/GRB 260527A: further FTW optical and NIR observations
  8. GRB 260527A / EP260527a: VLA radio detection
  9. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  10. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  11. GRB 260529A: GOTO tentative optical afterglow candidate
  12. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  13. GRB 260527A/EP260527a: Insight-HXMT detection
  14. Fermi GRB 260529A: Global MASTER-Net observations report
  15. EP260526a: SVOM/VT optical upper limits
  16. GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
  17. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  18. EP260527a / GRB 260527A: NOT optical observations
  19. GRB 260527A/EP260527a: FTW optical and NIR observations
  20. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  21. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  22. EP260527a/GRB 260527A: EP-FXT follow-up observation
  23. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  24. GRB 260526A: GECAM-B observation
  25. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  26. EP260526a: EP-FXT follow-up observation
  27. EP260527a: SVOM/VT optical observation
  28. EP260527a: COLIBRÍ optical detection
  29. EP260526a: LCO optical upper limits
  30. EP260526a: Einstein Probe detection of a fast X-ray transient
  31. GRB 260525A: AstroSat CZTI detection
  32. The EP-WXT trigger 01709266106 is not a real source
  33. Fermi GRB 260526A: Global MASTER-Net observations report
  34. Fermi GRB 260525A: Global MASTER-Net observations report
  35. GRB 260523B: AstroSat CZTI detection
  36. GRB 260523B: GECAM-B observation
  37. Fermi GRB 260523A: Global MASTER-Net observations report
  38. GRB 260522A: Fermi GBM Observation
  39. GRB 260522B: NuSTAR detection of prompt emission
  40. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  41. GRB 260522A: GOTO optical upper limit
  42. Fermi GRB 260522A: Global MASTER-Net observations report
  43. GRB 260522A: Fermi-LAT detection
  44. GRB 260519C: SVOM/GRM observation
  45. GRB 260511A: iTelescope T-75 optical detection
  46. GRB 260520B: SVOM/GRM observation
  47. GRB 260411B: TERI Gamma-ray detection
  48. GRB 260407A: TERI Gamma-ray detection
  49. GRB 260307A: TERI Gamma-ray detection
  50. GRB 260225D: TERI Gamma-ray detection
  51. GRB 251118A: TERI Gamma-ray detection
  52. GRB 251113A: TERI Gamma-ray detection
  53. GRB 260428A: TERI Gamma-ray detection
  54. Konus-Wind detection of GRB 260519C
  55. GRB 260509A: SVOM/ECLAIRs refined analysis
  56. GRB 260519C: NuSTAR detection of prompt emission
  57. Konus-Wind detection of GRB 260518A
  58. GRB 260516D: SVOM/ECLAIRs refined analysis
  59. GRB 260515A: SVOM/ECLAIRs refined analysis
  60. GRB 260421B: radio detection with the VLA
  61. GRID detection of GRB 260511A
  62. GRB 260509A: CrAO ZTSh optical upper limit (Duplicate Submission)
  63. GRB 260509A: CrAO ZTSh optical upper limit
  64. GRB 260516D: EP-FXT follow-up observation
  65. GRB 260516D: GOTO optical counterpart detection
  66. GRB 260516D: LCO optical observations
  67. GRB 260515A: further Liverpool Telescope observations
  68. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  69. GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
  70. GRB 260516D: GROWTH-India Telescope optical detection
  71. GRB 260516D: SVOM/VT optical bright candidate
  72. GRB 260515A: CrAO ZTSh BVRI optical observations
  73. Fermi GRB 260516C: Global MASTER-Net observations report
  74. Konus-Wind detection of GRB 260515A
  75. GRB 260515A: Liverpool Telescope optical detection
  76. GRB 260515A: LCO optical counterpart detection
  77. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  78. GRB 260515A: EP-FXT follow-up observation
  79. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  80. EP260514a: NOT optical counterpart confirmation
  81. EP260514a: TRT optical counterpart candidate
  82. EP260514a: SVOM/VT optical candidate
  83. Fermi GRB 260516B: Global MASTER-Net observations report
  84. GRB 260515A: SVOM/VT optical observations
  85. GRB 260515A: OHP/T193 optical observations
  86. EP260514a: COLIBRÍ optical upper limits
  87. GRID detection of GRB 260507A
  88. GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
  89. GRB 260515A: LCO optical observations
  90. SVOM GRB 260515A: Global MASTER-Net observations report
  91. GRB 260515A: NOT optical observations.
  92. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  93. GRB 260515A: SVOM/VT optical candidate from VHF data
  94. GRB 260515A: JinShan optical counterpart candidate
  95. GRB 260510C: Glowbug gamma-ray detection
  96. IceCube-260504A: No Candidate Transients from the Zwicky Transient Facility
  97. EP260514a: GROWTH-India Telescope optical upper limit
  98. GRB 260511B: NOT optical observations
  99. Konus-Wind detection of GRB 260512A
  100. GRB 260510C: CALET Gamma-Ray Burst Monitor detection

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