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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"

28048 results found.

  1. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  2. EP260526a: Einstein Probe detection of a fast X-ray transient
  3. GRB 260525A: AstroSat CZTI detection
  4. EP260526.405: COLIBRÍ optical upper limits
  5. The EP-WXT trigger 01709266106 is not a real source
  6. Fermi GRB 260526A: Global MASTER-Net observations report
  7. GRB 260526A: Fermi GBM Final Real-time Localization
  8. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  9. EP-WXT 01709266106: NOT optical upper limits
  10. Fermi GRB 260525A: Global MASTER-Net observations report
  11. GRB 260525A: Fermi GBM Final Real-time Localization
  12. GRB 260523B: AstroSat CZTI detection
  13. GRB 260523B: GECAM-B observation
  14. Fermi GRB 260523A: Global MASTER-Net observations report
  15. GRB 260523B: Fermi GBM Final Real-time Localization
  16. GRB 260523A: Fermi GBM Final Real-time Localization
  17. GRB 260522A: Fermi GBM Observation
  18. GRB 260522B: NuSTAR detection of prompt emission
  19. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  20. GRB 260522B: Fermi GBM Final Real-time Localization
  21. GRB 260522A: GOTO optical upper limit
  22. Fermi trigger No 801135305: Global MASTER-Net observations report
  23. Fermi GRB 260522A: Global MASTER-Net observations report
  24. GRB 260522A: Fermi-LAT detection
  25. GRB 260519C: SVOM/GRM observation
  26. GRB 260522A: Fermi GBM Final Real-time Localization
  27. GRB 260511A: iTelescope T-75 optical detection
  28. GRB 260520B: SVOM/GRM observation
  29. GRB 260411B: TERI Gamma-ray detection
  30. GRB 260407A: TERI Gamma-ray detection
  31. GRB 260307A: TERI Gamma-ray detection
  32. GRB 251118A: TERI Gamma-ray detection
  33. GRB 251113A: TERI Gamma-ray detection
  34. GRB 260428A: TERI Gamma-ray detection
  35. GRB 260520B: Fermi GBM Final Localization
  36. GRB 260520A: Fermi GBM Final Localization
  37. GRB 260519D: Fermi GBM Final Localization Correction
  38. GRB 260519B: Fermi GBM Final Localization
  39. GRB 260519A: Fermi GBM Final Localization
  40. GRB 260516D: SVOM/ECLAIRs refined analysis
  41. GRB 260515A: SVOM/ECLAIRs refined analysis
  42. GRB 260421B: radio detection with the VLA
  43. GRID detection of GRB 260511A
  44. GRB 260509A: CrAO ZTSh optical upper limit
  45. GRB 260516D: EP-FXT follow-up observation
  46. GRB 260516D: LCO optical observations
  47. GRB 260515A: further Liverpool Telescope observations
  48. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  49. GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
  50. GRB 260516D: GROWTH-India Telescope optical detection
  51. GRB 260516D: SVOM/VT optical bright candidate
  52. GRB 260516D: FRAM-ORM optical limit
  53. GRB 260515A: CrAO ZTSh BVRI optical observations
  54. Fermi GRB 260516C: Global MASTER-Net observations report
  55. SVOM GRB260516D: Global MASTER-Net observations report
  56. GRB 260516D: SVOM possible detection of a burst
  57. GRB 260516C: Fermi GBM Final Real-time Localization
  58. GRB 260515A: LCO optical counterpart detection
  59. Fermi Gamma-ray Burst Monitor trigger 800627191/260516518 is not a GRB
  60. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  61. GRB 260515A: EP-FXT follow-up observation
  62. EP260514a: NOT optical counterpart confirmation
  63. EP260514a: TRT optical counterpart candidate
  64. EP260514a: SVOM/VT optical candidate
  65. Fermi GRB 260516B: Global MASTER-Net observations report
  66. GRB 260516B: Fermi GBM Final Real-time Localization
  67. Fermi Gamma-ray Burst Monitor trigger 800592653/260516119 is not a GRB
  68. GRB 260515A: SVOM/VT optical observations
  69. GRB 260515A: OHP/T193 optical observations
  70. EP260514a: COLIBRÍ optical upper limits
  71. GRB 260516A: Fermi GBM Final Real-time Localization
  72. GRID detection of GRB 260507A
  73. GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
  74. GRB 260515A: LCO optical observations
  75. SVOM GRB 260515A: Global MASTER-Net observations report
  76. GRB 260515A: NOT optical observations.
  77. GRB 260515A: SVOM/VT optical candidate from VHF data
  78. GRB 260515A: JinShan optical counterpart candidate
  79. GRB 260515A: SVOM detection of a burst
  80. GRB 260510C: Glowbug gamma-ray detection
  81. EP260514a: GROWTH-India Telescope optical upper limit
  82. GRB 260511B: NOT optical observations
  83. Konus-Wind detection of GRB 260512A
  84. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  85. GRB 260511B: GMG Optical Upper Limit
  86. EP260514a: Global MASTER-Net observations report
  87. IPN triangulation of GRB 260512A
  88. GRB 260511B: Mephisto multi-band optical followup
  89. Fermi GRB 260514A: Global MASTER-Net observations report
  90. GRB 260512A: AstroSat CZTI detection
  91. The EP-WXT trigger 01709262077 is likely a flaring star
  92. EP260507a: Xinglong Schmidt optical counterpart detection
  93. GRB 260514A: Fermi GBM Final Real-time Localization
  94. EP260512a: Global MASTER-Net observations report
  95. Fermi GRB 260513A: Global MASTER-Net observations report
  96. Fermi GRB 260512A: Global MASTER-Net observations report
  97. GRB 260511B: further SAO RAS optical observations
  98. GRB 260513A: Fermi GBM Final Real-time Localization
  99. GRB 260509A: SVOM/VT optical observations
  100. Konus-Wind detection of GRB 260511B

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