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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"

43661 results found.

  1. EP260527a: Einstein Probe detection of a fast X-ray transient
  2. The EP-WXT trigger 01709266172 is likely a flaring star
  3. The EP-WXT trigger 01709266147 is likely a flaring star
  4. Fermi trigger No 801580882: Global MASTER-Net observations report
  5. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  6. EP260526a: LCO optical upper limits
  7. EP260526a: Einstein Probe detection of a fast X-ray transient
  8. GRB 260525A: AstroSat CZTI detection
  9. EP260526.405: COLIBRÍ optical upper limits
  10. The EP-WXT trigger 01709266106 is not a real source
  11. Fermi GRB 260526A: Global MASTER-Net observations report
  12. GRB 260526A: Fermi GBM Final Real-time Localization
  13. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  14. EP-WXT 01709266106: NOT optical upper limits
  15. Fermi GRB 260525A: Global MASTER-Net observations report
  16. GRB 260525A: Fermi GBM Final Real-time Localization
  17. GRB 260523B: AstroSat CZTI detection
  18. GRB 260523B: GECAM-B observation
  19. Fermi GRB 260523A: Global MASTER-Net observations report
  20. GRB 260523B: Fermi GBM Final Real-time Localization
  21. GRB 260523A: Fermi GBM Final Real-time Localization
  22. GRB 260522A: Fermi GBM Observation
  23. GRB 260522B: NuSTAR detection of prompt emission
  24. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  25. GRB 260522B: Fermi GBM Final Real-time Localization
  26. GRB 260522A: GOTO optical upper limit
  27. Fermi trigger No 801135305: Global MASTER-Net observations report
  28. Fermi GRB 260522A: Global MASTER-Net observations report
  29. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  30. GRB 260522A: Fermi-LAT detection
  31. GRB 260519C: SVOM/GRM observation
  32. GRB 260522A: Fermi GBM Final Real-time Localization
  33. GRB 260511A: iTelescope T-75 optical detection
  34. GRB 260520B: SVOM/GRM observation
  35. GRB 260411B: TERI Gamma-ray detection
  36. GRB 260407A: TERI Gamma-ray detection
  37. GRB 260307A: TERI Gamma-ray detection
  38. GRB 260225D: TERI Gamma-ray detection
  39. GRB 251118A: TERI Gamma-ray detection
  40. GRB 251113A: TERI Gamma-ray detection
  41. GRB 260428A: TERI Gamma-ray detection
  42. Konus-Wind detection of GRB 260519C
  43. GRB 260520B: Fermi GBM Final Localization
  44. GRB 260509A: SVOM/ECLAIRs refined analysis
  45. GRB 260520A: Fermi GBM Final Localization
  46. GRB 260519D: Fermi GBM Final Localization Correction
  47. GRB 260519C: NuSTAR detection of prompt emission
  48. Konus-Wind detection of GRB 260518A
  49. GRB 260519B: Fermi GBM Final Localization
  50. GRB 260519A: Fermi GBM Final Localization
  51. GRB 260518A: AstroSat CZTI detection of a long burst
  52. GRB 260516D: SVOM/ECLAIRs refined analysis
  53. GRB 260515A: SVOM/ECLAIRs refined analysis
  54. GRB 260421B: radio detection with the VLA
  55. GRID detection of GRB 260511A
  56. GRB 260509A: CrAO ZTSh optical upper limit (Duplicate Submission)
  57. GRB 260509A: CrAO ZTSh optical upper limit
  58. GRB 260516D: EP-FXT follow-up observation
  59. GRB 260516D: GOTO optical counterpart detection
  60. GRB 260516D: LCO optical observations
  61. GRB 260515A: further Liverpool Telescope observations
  62. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  63. GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
  64. GRB 260516D: GROWTH-India Telescope optical detection
  65. GRB 260516D: SVOM/VT optical bright candidate
  66. GRB 260516D: FRAM-ORM optical limit
  67. GRB 260515A: CrAO ZTSh BVRI optical observations
  68. Fermi GRB 260516C: Global MASTER-Net observations report
  69. SVOM GRB260516D: Global MASTER-Net observations report
  70. GRB 260516D: SVOM possible detection of a burst
  71. GRB 260516C: Fermi GBM Final Real-time Localization
  72. Konus-Wind detection of GRB 260515A
  73. GRB 260515A: Liverpool Telescope optical detection
  74. GRB 260515A: LCO optical counterpart detection
  75. Fermi Gamma-ray Burst Monitor trigger 800627191/260516518 is not a GRB
  76. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  77. GRB 260515A: EP-FXT follow-up observation
  78. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  79. EP260514a: NOT optical counterpart confirmation
  80. EP260514a: TRT optical counterpart candidate
  81. EP260514a: SVOM/VT optical candidate
  82. Fermi GRB 260516B: Global MASTER-Net observations report
  83. GRB 260516B: Fermi GBM Final Real-time Localization
  84. Fermi Gamma-ray Burst Monitor trigger 800592653/260516119 is not a GRB
  85. GRB 260515A: SVOM/VT optical observations
  86. GRB 260515A: OHP/T193 optical observations
  87. EP260514a: COLIBRÍ optical upper limits
  88. GRB 260516A: Fermi GBM Final Real-time Localization
  89. GRID detection of GRB 260507A
  90. GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
  91. GRB 260515A: LCO optical observations
  92. SVOM GRB 260515A: Global MASTER-Net observations report
  93. GRB 260515A: NOT optical observations.
  94. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  95. GRB 260515A: SVOM/VT optical candidate from VHF data
  96. GRB 260515A: JinShan optical counterpart candidate
  97. GRB 260515A: SVOM detection of a burst
  98. GRB 260510C: Glowbug gamma-ray detection
  99. IceCube-260504A: No Candidate Transients from the Zwicky Transient Facility
  100. EP260514a: GROWTH-India Telescope optical upper limit

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