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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"
  1. GRB261007A: Lesedi optical afterglow detection
  2. EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
  3. EP261007b: SVOM/ECLAIRs Upper Limit
  4. GRB 261008A: GECAM-B observation
  5. EP261006a: Optical follow-up observations with MATCH
  6. EP261007b: J-band upper limit by SYSU 80cm infrared telescope
  7. EP261007b: Refined analysis of the EP-WXT and autonomous EP-FXT observations
  8. GRB 261007A: SVOM/ECLAIRs refined analysis
  9. EP261007b: SVOM/VT optical detection of the NOT transient
  10. GRB 261007A / EP261007a: SVOM/GWAC-F60A/B observations
  11. EP261006a / AT 2026aetp: VLT/X-shooter spectroscopic redshift z = 0.1853
  12. GRB 261007A: Glowbug gamma-ray detection
  13. GRB 261008A: Fermi GBM Final Real-time Localization
  14. GRB 261007A: NOT optical observations
  15. EP261007b: NOT optical observations, variable source outside the FXT region
  16. GRB 261007A: SVOM/GRM observation
  17. EP261007b: SVOM/C-GFT optical upper limits
  18. EP261007b: J-band upper limit with WINTER
  19. The EP-WXT trigger 01709321008/EP261007b：Xinglong optical upper limit
  20. GRB 261007A / EP261007a: AstroSat CZTI detection
  21. GRB 261005A: GECAM-B observation
  22. EP261006a: Swift/XRT detection of the fading X-ray counterpart
  23. EP261007a/GRB 261007A：Xinglong optical observation
  24. GRB 261007A/EP261007a: Optical follow-up observations with Kinder
  25. EP261006a: Optical follow-up observations with Kinder
  26. EP261006a: Liverpool Telescope optical observations
  27. EP261006a: Early Optical Observations by WFST
  28. GRB 261007A / EP261007a: SVOM/VT optical observations
  29. GRB 261007A: Swift-XRT afterglow detection
  30. EP261007b: SVOM/VT optical upper limits
  31. GRB 261007A: SVOM/COLIBRÍ (FM-GFT) optical observations
  32. EP261007b: Einstein Probe detection of an X-ray transient
  33. GRB 261007A / EP261007a: NuSTAR detection of prompt emission
  34. EP Alert 261007.63: Global MASTER-Net observations report
  35. GRB 261007A / EP261007a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at McDonald Observatory
  36. GRB 261007A: Autonomous identification and follow-up of the counterpart to GRB 261007A by BTSbot with ZTF and P60/SEDM
  37. SVOM GRB261007.27: Global MASTER-Net observations report
  38. GRB 261007A: GROWTH-India Telescope optical observations
  39. GRB 261007A / EP261007a: TRT optical observations
  40. GRB 261007A: Swift ToO observations
  41. GRB 261007A: SVOM/C-GFT optical observations
  42. GRB 261007A / EP261007a: LCO optical observations
  43. GRB 261007B: Fermi GBM Final Real-time Localization
  44. SVOM GRB261007.23: Global MASTER-Net observations report
  45. GRB 261005B: Swift-BAT refined analysis
  46. EP261006a: NOT spectroscopy of a blue continuum
  47. GRB 261007A: WINTER J-band observations
  48. EP261006a: LT and NOT discovery of an optical counterpart
  49. GRB 261007A: Fermi GBM observation
  50. GRB 261007A / EP261007a: VLT/X-shooter spectroscopic redshift z = 2.101
  51. EP261007a/GRB 261007A: Einstein Probe detection of an X-ray transient
  52. EP261006a: SVOM/VT optical upper limits
  53. EP261006a: Einstein Probe detection of an X-ray transient
  54. GRB 261007A: KAIT optical counterpart candidate
  55. GRB 261007A: SVOM detection of a burst
  56. EP trigger 01709320985: SVOM/C-GFT optical upper limits
  57. GRB 261005B: Swift-XRT refined Analysis
  58. EP trigger 01709320985: Ondrejov D50 optical upper limits
  59. GRB 261005A: Glowbug gamma-ray detection
  60. GRB 261005B: Swift/UVOT Upper Limits
  61. GRB 261005B: J-band upper limit with WINTER
  62. GRB 261001A: GECAM-B observation of a likely long GRB
  63. GRB 261005B: Fermi GBM Observation
  64. GRB 261005B: Enhanced Swift-XRT position
  65. The EP-WXT trigger 01709320908 is likely a flaring star
  66. EP trigger 01709320908: Ondrejov D50 observation, fading star suggests stellar flare
  67. GRB 261005B: Swift detection of a burst
  68. GRB 261005A: Fermi GBM Final Real-time Localization
  69. GRB 261003A: Glowbug gamma-ray detection of a likely short burst
  70. GRB 261002A: Fermi GBM Final Localization
  71. EP#01709320865: Swift-XRT observations
  72. GRB 260930B: SVOM/GRM observation
  73. Konus-Wind detection of GRB 260919A / EP 260920a
  74. GRB 260921B: GECAM-B observation
  75. EP261003a: J-band upper limit with WINTER
  76. EP261003a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  77. GRB 260930B: GECAM-B detection of a burst
  78. EP261003a: COLIBRÍ optical upper limits
  79. Trigger_21915: Swift ToO observations (retracted)
  80. Fermi GRB 261003A: Global MASTER-Net observations report
  81. EP261003a: Einstein Probe detection of an X-ray transient
  82. GRB 261003A: Fermi GBM Final Real-time Localization
  83. EP Alert 261003.01: Global MASTER-Net observations report
  84. Fermi-LAT Gamma-ray Observations of IceCube-260930A
  85. Fermi GBM Detection of GRB 260919A / EP260920a
  86. IceCube-260930A: Upper limits from a search for additional neutrino events in IceCube
  87. IPN triangulation of GRB 260919A / EP260920a
  88. Fermi GRB 260930B: Global MASTER-Net observations report
  89. GRB 260926C: SVOM/GRM observation
  90. GRB 260930B: Fermi GBM Final Real-time Localization
  91. GRB 260930A: Fermi GBM Final Real-time Localization
  92. IceCube-260930A - IceCube observation of a high-energy neutrino candidate track-like event
  93. IceCube Alert 260930A: Global MASTER-Net observations report
  94. The EP-WXT trigger 01709320790 is likely a flaring star
  95. EP260927a: SVOM/ECLAIRs Upper Limit
  96. GRB 260926C: AstroSat CZTI detection
  97. GRB 260926C: GECAM-B observation
  98. GRB 260926A: GECAM-B observation
  99. EP260927a: Global MASTER-Net observations report
  100. EP260927a: Einstein Probe detection of a fast X-ray transient

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