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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 261008A: Fermi GBM Final Real-time Localization
  2. GRB 261007A: NOT optical observations
  3. EP261007b: NOT optical observations, variable source outside the FXT region
  4. GRB 261007A: SVOM/GRM observation
  5. EP261007b: SVOM/C-GFT optical upper limits
  6. EP261007b: J-band upper limit with WINTER
  7. The EP-WXT trigger 01709321008/EP261007b：Xinglong optical upper limit
  8. GRB 261007A / EP261007a: AstroSat CZTI detection
  9. GRB 261005A: GECAM-B observation
  10. EP261006a: Swift/XRT detection of the fading X-ray counterpart
  11. EP261007a/GRB 261007A：Xinglong optical observation
  12. GRB 261007A/EP261007a: Optical follow-up observations with Kinder
  13. EP261006a: Optical follow-up observations with Kinder
  14. EP261006a: Liverpool Telescope optical observations
  15. EP261006a: Early Optical Observations by WFST
  16. GRB 261007A / EP261007a: SVOM/VT optical observations
  17. GRB 261007A: Swift-XRT afterglow detection
  18. EP261007b: SVOM/VT optical upper limits
  19. GRB 261007A: SVOM/COLIBRÍ (FM-GFT) optical observations
  20. EP261007b: Einstein Probe detection of an X-ray transient
  21. GRB 261007A / EP261007a: NuSTAR detection of prompt emission
  22. EP Alert 261007.63: Global MASTER-Net observations report
  23. GRB 261007A / EP261007a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at McDonald Observatory
  24. GRB 261007A: Autonomous identification and follow-up of the counterpart to GRB 261007A by BTSbot with ZTF and P60/SEDM
  25. SVOM GRB261007.27: Global MASTER-Net observations report
  26. GRB 261007A: GROWTH-India Telescope optical observations
  27. GRB 261007A / EP261007a: TRT optical observations
  28. GRB 261007A: Swift ToO observations
  29. GRB 261007A: SVOM/C-GFT optical observations
  30. GRB 261007A / EP261007a: LCO optical observations
  31. GRB 261007B: Fermi GBM Final Real-time Localization
  32. SVOM GRB261007.23: Global MASTER-Net observations report
  33. GRB 261005B: Swift-BAT refined analysis
  34. EP261006a: NOT spectroscopy of a blue continuum
  35. GRB 261007A: WINTER J-band observations
  36. EP261006a: LT and NOT discovery of an optical counterpart
  37. GRB 261007A: Fermi GBM observation
  38. GRB 261007A / EP261007a: VLT/X-shooter spectroscopic redshift z = 2.101
  39. EP261007a/GRB 261007A: Einstein Probe detection of an X-ray transient
  40. EP261006a: SVOM/VT optical upper limits
  41. EP261006a: Einstein Probe detection of an X-ray transient
  42. GRB 261007A: KAIT optical counterpart candidate
  43. GRB 261007A: SVOM detection of a burst
  44. EP trigger 01709320985: SVOM/C-GFT optical upper limits
  45. GRB 261005B: Swift-XRT refined Analysis
  46. EP trigger 01709320985: Ondrejov D50 optical upper limits
  47. GRB 261005A: Glowbug gamma-ray detection
  48. GRB 261005B: Swift/UVOT Upper Limits
  49. GRB 261005B: J-band upper limit with WINTER
  50. GRB 261001A: GECAM-B observation of a likely long GRB
  51. GRB 261005B: Fermi GBM Observation
  52. GRB 261005B: Enhanced Swift-XRT position
  53. The EP-WXT trigger 01709320908 is likely a flaring star
  54. EP trigger 01709320908: Ondrejov D50 observation, fading star suggests stellar flare
  55. GRB 261005B: Swift detection of a burst
  56. GRB 261005A: Fermi GBM Final Real-time Localization
  57. GRB 261003A: Glowbug gamma-ray detection of a likely short burst
  58. GRB 261002A: Fermi GBM Final Localization
  59. EP#01709320865: Swift-XRT observations
  60. GRB 260930B: SVOM/GRM observation
  61. Konus-Wind detection of GRB 260919A / EP 260920a
  62. GRB 260921B: GECAM-B observation
  63. EP261003a: J-band upper limit with WINTER
  64. EP261003a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  65. GRB 260930B: GECAM-B detection of a burst
  66. EP261003a: COLIBRÍ optical upper limits
  67. Trigger_21915: Swift ToO observations (retracted)
  68. Fermi GRB 261003A: Global MASTER-Net observations report
  69. EP261003a: Einstein Probe detection of an X-ray transient
  70. GRB 261003A: Fermi GBM Final Real-time Localization
  71. EP Alert 261003.01: Global MASTER-Net observations report
  72. Fermi-LAT Gamma-ray Observations of IceCube-260930A
  73. Fermi GBM Detection of GRB 260919A / EP260920a
  74. IceCube-260930A: Upper limits from a search for additional neutrino events in IceCube
  75. IPN triangulation of GRB 260919A / EP260920a
  76. Fermi GRB 260930B: Global MASTER-Net observations report
  77. GRB 260926C: SVOM/GRM observation
  78. GRB 260930B: Fermi GBM Final Real-time Localization
  79. GRB 260930A: Fermi GBM Final Real-time Localization
  80. IceCube-260930A - IceCube observation of a high-energy neutrino candidate track-like event
  81. IceCube Alert 260930A: Global MASTER-Net observations report
  82. The EP-WXT trigger 01709320790 is likely a flaring star
  83. EP260927a: SVOM/ECLAIRs Upper Limit
  84. GRB 260926C: AstroSat CZTI detection
  85. GRB 260926C: GECAM-B observation
  86. GRB 260926A: GECAM-B observation
  87. EP260927a: Global MASTER-Net observations report
  88. EP260927a: Einstein Probe detection of a fast X-ray transient
  89. GRB 260926B: Glowbug gamma-ray detection of a likely short burst
  90. GRB 260926A: Glowbug gamma-ray detection
  91. GRB 260924A: VLA detection
  92. GRB 260924A: Swift/UVOT UV grism spectrum results
  93. GRB 260924A: AbAO optical observations
  94. Fermi GRB 260928A: Global MASTER-Net observations report
  95. GRB 260928A: Fermi GBM Final Real-time Localization
  96. EP260924a: Global MASTER-Net observations report
  97. GRB 260925A: Swift-BAT refined analysis
  98. Swift Trigger 1513439: consistent with noise and not astrophysical
  99. GRB 260924A: Upper limits from a neutrino search with IceCube
  100. Fermi GRB 260926C: Global MASTER-Net observations report

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