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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

28103 results found.

  1. GRB 260601A: Glowbug gamma-ray detection of a short burst
  2. GRB 260531B: Glowbug gamma-ray detection
  3. GRB 260601A: Fermi GBM Observation
  4. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  5. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  6. Fermi GRB 260601A: Global MASTER-Net observations report
  7. GRB 260601A: Fermi GBM Final Real-time Localization
  8. The EP-WXT trigger 01709266272 is likely a flaring star
  9. AT2026nik: EP-FXT X-ray counterpart
  10. Fermi trigger No 801900520: Global MASTER-Net observations report
  11. GRB 260531A: MAXI/GSC detection
  12. AT 2026nuz: COLIBRÍ optical observations
  13. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  14. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  15. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  16. Fermi GRB 260529A: Global MASTER-Net observations report
  17. EP260526a: SVOM/VT optical upper limits
  18. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  19. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  20. EP260527a/GRB 260527A: EP-FXT follow-up observation
  21. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  22. EP260527a: SVOM/VT optical observation
  23. EP260527a: COLIBRÍ optical detection
  24. EP260527a: Einstein Probe detection of a fast X-ray transient
  25. Fermi trigger No 801580882: Global MASTER-Net observations report
  26. EP260526a: LCO optical upper limits
  27. EP260526a: Einstein Probe detection of a fast X-ray transient
  28. EP260526.405: COLIBRÍ optical upper limits
  29. The EP-WXT trigger 01709266106 is not a real source
  30. Fermi GRB 260526A: Global MASTER-Net observations report
  31. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  32. EP-WXT 01709266106: NOT optical upper limits
  33. Fermi GRB 260525A: Global MASTER-Net observations report
  34. GRB 260523B: AstroSat CZTI detection
  35. Fermi GRB 260523A: Global MASTER-Net observations report
  36. GRB 260522A: Fermi GBM Observation
  37. GRB 260522B: NuSTAR detection of prompt emission
  38. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  39. Fermi trigger No 801135305: Global MASTER-Net observations report
  40. Fermi GRB 260522A: Global MASTER-Net observations report
  41. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  42. GRB 260511A: iTelescope T-75 optical detection
  43. GRB 260520B: SVOM/GRM observation
  44. GRB 260411B: TERI Gamma-ray detection
  45. GRB 260407A: TERI Gamma-ray detection
  46. GRB 260307A: TERI Gamma-ray detection
  47. GRB 260225D: TERI Gamma-ray detection
  48. GRB 251118A: TERI Gamma-ray detection
  49. GRB 251113A: TERI Gamma-ray detection
  50. GRB 260428A: TERI Gamma-ray detection
  51. GRB 260519C: NuSTAR detection of prompt emission
  52. Konus-Wind detection of GRB 260518A
  53. GRB 260516D: SVOM/ECLAIRs refined analysis
  54. GRB 260421B: radio detection with the VLA
  55. GRB 260509A: CrAO ZTSh optical upper limit
  56. GRB 260516D: GOTO optical counterpart detection
  57. GRB 260516D: LCO optical observations
  58. GRB 260515A: further Liverpool Telescope observations
  59. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  60. GRB 260516D: GROWTH-India Telescope optical detection
  61. GRB 260516D: SVOM/VT optical bright candidate
  62. GRB 260515A: CrAO ZTSh BVRI optical observations
  63. Fermi GRB 260516C: Global MASTER-Net observations report
  64. SVOM GRB260516D: Global MASTER-Net observations report
  65. GRB 260516D: SVOM possible detection of a burst
  66. GRB 260515A: LCO optical counterpart detection
  67. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  68. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  69. EP260514a: NOT optical counterpart confirmation
  70. EP260514a: TRT optical counterpart candidate
  71. EP260514a: SVOM/VT optical candidate
  72. Fermi GRB 260516B: Global MASTER-Net observations report
  73. GRB 260515A: OHP/T193 optical observations
  74. EP260514a: COLIBRÍ optical upper limits
  75. GRB 260515A: LCO optical observations
  76. SVOM GRB 260515A: Global MASTER-Net observations report
  77. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  78. GRB 260515A: SVOM/VT optical candidate from VHF data
  79. GRB 260515A: JinShan optical counterpart candidate
  80. GRB 260515A: SVOM detection of a burst
  81. GRB 260510C: Glowbug gamma-ray detection
  82. EP260514a: GROWTH-India Telescope optical upper limit
  83. GRB 260511B: GMG Optical Upper Limit
  84. EP260514a: Global MASTER-Net observations report
  85. EP260514a: Einstein Probe detection of a fast X-ray transient
  86. EP260512a: LCO optical upper limits
  87. GRB 260511B: Mephisto multi-band optical followup
  88. Fermi GRB 260514A: Global MASTER-Net observations report
  89. GRB 260512A: AstroSat CZTI detection
  90. EP260512a: EP-FXT follow-up observation
  91. EP260507a: Xinglong Schmidt optical counterpart detection
  92. EP260512a: Global MASTER-Net observations report
  93. Fermi GRB 260513A: Global MASTER-Net observations report
  94. Fermi GRB 260512A: Global MASTER-Net observations report
  95. GRB 260511B: further SAO RAS optical observations
  96. GRB 260509A: SVOM/VT optical observations
  97. The EP-WXT trigger 01709262036 is likely a flaring star
  98. EP260512a: COLIBRÍ optical upper limits
  99. EP260512a: Einstein Probe detection of an X-ray transient
  100. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope

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