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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. GRB 261007A / EP261007a: SVOM/GWAC-F60A/B observations
  2. EP261006a / AT 2026aetp: VLT/X-shooter spectroscopic redshift z = 0.1853
  3. GRB 261007A: Glowbug gamma-ray detection
  4. GRB 261008A: Fermi GBM Final Real-time Localization
  5. GRB 261007A: NOT optical observations
  6. EP261007b: NOT optical observations, variable source outside the FXT region
  7. GRB 261007A: SVOM/GRM observation
  8. EP261007b: SVOM/C-GFT optical upper limits
  9. EP261007b: J-band upper limit with WINTER
  10. The EP-WXT trigger 01709321008/EP261007b：Xinglong optical upper limit
  11. GRB 261007A / EP261007a: AstroSat CZTI detection
  12. GRB 261005A: GECAM-B observation
  13. EP261006a: Swift/XRT detection of the fading X-ray counterpart
  14. EP261007a/GRB 261007A：Xinglong optical observation
  15. GRB 261007A/EP261007a: Optical follow-up observations with Kinder
  16. EP261006a: Optical follow-up observations with Kinder
  17. EP261006a: Liverpool Telescope optical observations
  18. EP261006a: Early Optical Observations by WFST
  19. GRB 261007A / EP261007a: SVOM/VT optical observations
  20. GRB 261007A: Swift-XRT afterglow detection
  21. EP261007b: SVOM/VT optical upper limits
  22. GRB 261007A: SVOM/COLIBRÍ (FM-GFT) optical observations
  23. EP261007b: Einstein Probe detection of an X-ray transient
  24. GRB 261007A / EP261007a: NuSTAR detection of prompt emission
  25. EP Alert 261007.63: Global MASTER-Net observations report
  26. GRB 261007A / EP261007a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at McDonald Observatory
  27. GRB 261007A: Autonomous identification and follow-up of the counterpart to GRB 261007A by BTSbot with ZTF and P60/SEDM
  28. SVOM GRB261007.27: Global MASTER-Net observations report
  29. GRB 261007A: GROWTH-India Telescope optical observations
  30. GRB 261007A / EP261007a: TRT optical observations
  31. GRB 261007A: Swift ToO observations
  32. GRB 261007A: SVOM/C-GFT optical observations
  33. GRB 261007A / EP261007a: LCO optical observations
  34. GRB 261007B: Fermi GBM Final Real-time Localization
  35. SVOM GRB261007.23: Global MASTER-Net observations report
  36. GRB 261005B: Swift-BAT refined analysis
  37. EP261006a: NOT spectroscopy of a blue continuum
  38. GRB 261007A: WINTER J-band observations
  39. EP261006a: LT and NOT discovery of an optical counterpart
  40. GRB 261007A: Fermi GBM observation
  41. GRB 261007A / EP261007a: VLT/X-shooter spectroscopic redshift z = 2.101
  42. EP261007a/GRB 261007A: Einstein Probe detection of an X-ray transient
  43. EP261006a: SVOM/VT optical upper limits
  44. EP261006a: Einstein Probe detection of an X-ray transient
  45. GRB 261007A: KAIT optical counterpart candidate
  46. GRB 261007A: SVOM detection of a burst
  47. EP trigger 01709320985: SVOM/C-GFT optical upper limits
  48. GRB 261005B: Swift-XRT refined Analysis
  49. EP trigger 01709320985: Ondrejov D50 optical upper limits
  50. GRB 261005A: Glowbug gamma-ray detection
  51. GRB 261005B: Swift/UVOT Upper Limits
  52. GRB 261005B: J-band upper limit with WINTER
  53. GRB 261001A: GECAM-B observation of a likely long GRB
  54. GRB 261005B: Fermi GBM Observation
  55. GRB 261005B: Enhanced Swift-XRT position
  56. The EP-WXT trigger 01709320908 is likely a flaring star
  57. EP trigger 01709320908: Ondrejov D50 observation, fading star suggests stellar flare
  58. GRB 261005B: Swift detection of a burst
  59. GRB 261005A: Fermi GBM Final Real-time Localization
  60. GRB 261003A: Glowbug gamma-ray detection of a likely short burst
  61. GRB 261002A: Fermi GBM Final Localization
  62. EP#01709320865: Swift-XRT observations
  63. GRB 260930B: SVOM/GRM observation
  64. Konus-Wind detection of GRB 260919A / EP 260920a
  65. GRB 260921B: GECAM-B observation
  66. EP261003a: J-band upper limit with WINTER
  67. EP261003a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  68. GRB 260930B: GECAM-B detection of a burst
  69. EP261003a: COLIBRÍ optical upper limits
  70. Trigger_21915: Swift ToO observations (retracted)
  71. Fermi GRB 261003A: Global MASTER-Net observations report
  72. EP261003a: Einstein Probe detection of an X-ray transient
  73. GRB 261003A: Fermi GBM Final Real-time Localization
  74. EP Alert 261003.01: Global MASTER-Net observations report
  75. Fermi-LAT Gamma-ray Observations of IceCube-260930A
  76. Fermi GBM Detection of GRB 260919A / EP260920a
  77. IceCube-260930A: Upper limits from a search for additional neutrino events in IceCube
  78. IPN triangulation of GRB 260919A / EP260920a
  79. Fermi GRB 260930B: Global MASTER-Net observations report
  80. GRB 260926C: SVOM/GRM observation
  81. GRB 260930B: Fermi GBM Final Real-time Localization
  82. GRB 260930A: Fermi GBM Final Real-time Localization
  83. IceCube-260930A - IceCube observation of a high-energy neutrino candidate track-like event
  84. IceCube Alert 260930A: Global MASTER-Net observations report
  85. The EP-WXT trigger 01709320790 is likely a flaring star
  86. EP260927a: SVOM/ECLAIRs Upper Limit
  87. GRB 260926C: AstroSat CZTI detection
  88. GRB 260926C: GECAM-B observation
  89. GRB 260926A: GECAM-B observation
  90. EP260927a: Global MASTER-Net observations report
  91. EP260927a: Einstein Probe detection of a fast X-ray transient
  92. GRB 260926B: Glowbug gamma-ray detection of a likely short burst
  93. GRB 260926A: Glowbug gamma-ray detection
  94. GRB 260924A: VLA detection
  95. GRB 260924A: Swift/UVOT UV grism spectrum results
  96. GRB 260924A: AbAO optical observations
  97. Fermi GRB 260928A: Global MASTER-Net observations report
  98. GRB 260928A: Fermi GBM Final Real-time Localization
  99. EP260924a: Global MASTER-Net observations report
  100. GRB 260925A: Swift-BAT refined analysis

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