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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"

19206 results found.

  1. GRB 261011A: GOTO optical counterpart detection
  2. GRB 261011A: SVOM detection of a long bright burst
  3. GRB 261010A: Enhanced Swift-XRT position
  4. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  5. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  6. GRB 261010A: NOT possible optical counterpart
  7. GRB 261010A: Fermi GBM Final Real-time Localization
  8. GRB 261001A: SVOM/GRM observation
  9. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  10. EP261010a: SVOM/VT optical upper limits
  11. EP261006a: Liverpool Telescope optical follow-up
  12. EP261010a: NOT optical upper limits
  13. EP261010a: Global MASTER-Net observations report
  14. EP261010a Einstein Probe detection of an X-ray transient
  15. GRB 261009A: Fermi GBM Final Real-time Localization
  16. GRB261007A: Lesedi optical afterglow detection
  17. EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
  18. EP261007b: SVOM/ECLAIRs Upper Limit
  19. GRB 261008A: GECAM-B observation
  20. EP261006a: Optical follow-up observations with MATCH
  21. EP261007b: J-band upper limit by SYSU 80cm infrared telescope
  22. EP261007b: Refined analysis of the EP-WXT and autonomous EP-FXT observations
  23. GRB 261007A: SVOM/ECLAIRs refined analysis
  24. GRB 261007A / EP261007a: SVOM/GWAC-F60A/B observations
  25. EP261006a / AT 2026aetp: VLT/X-shooter spectroscopic redshift z = 0.1853
  26. GRB 261007A: Glowbug gamma-ray detection
  27. GRB 261008A: Fermi GBM Final Real-time Localization
  28. GRB 261007A: NOT optical observations
  29. EP261007b: NOT optical observations, variable source outside the FXT region
  30. GRB 261007A: SVOM/GRM observation
  31. EP261007b: SVOM/C-GFT optical upper limits
  32. EP261007b: J-band upper limit with WINTER
  33. The EP-WXT trigger 01709321008/EP261007b：Xinglong optical upper limit
  34. GRB 261007A / EP261007a: AstroSat CZTI detection
  35. GRB 261005A: GECAM-B observation
  36. EP261006a: Swift/XRT detection of the fading X-ray counterpart
  37. EP261007a/GRB 261007A：Xinglong optical observation
  38. GRB 261007A/EP261007a: Optical follow-up observations with Kinder
  39. EP261006a: Optical follow-up observations with Kinder
  40. EP261006a: Liverpool Telescope optical observations
  41. EP261006a: Early Optical Observations by WFST
  42. GRB 261007A / EP261007a: SVOM/VT optical observations
  43. GRB 261007A: Swift-XRT afterglow detection
  44. EP261007b: SVOM/VT optical upper limits
  45. GRB 261007A: SVOM/COLIBRÍ (FM-GFT) optical observations
  46. EP261007b: Einstein Probe detection of an X-ray transient
  47. GRB 261007A / EP261007a: NuSTAR detection of prompt emission
  48. EP Alert 261007.63: Global MASTER-Net observations report
  49. GRB 261007A / EP261007a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at McDonald Observatory
  50. GRB 261007A: Autonomous identification and follow-up of the counterpart to GRB 261007A by BTSbot with ZTF and P60/SEDM
  51. SVOM GRB261007.27: Global MASTER-Net observations report
  52. GRB 261007A: GROWTH-India Telescope optical observations
  53. GRB 261007A / EP261007a: TRT optical observations
  54. GRB 261007A: SVOM/C-GFT optical observations
  55. GRB 261007A / EP261007a: LCO optical observations
  56. GRB 261007B: Fermi GBM Final Real-time Localization
  57. SVOM GRB261007.23: Global MASTER-Net observations report
  58. GRB 261005B: Swift-BAT refined analysis
  59. EP261006a: NOT spectroscopy of a blue continuum
  60. GRB 261007A: WINTER J-band observations
  61. EP261006a: LT and NOT discovery of an optical counterpart
  62. GRB 261007A: Fermi GBM observation
  63. GRB 261007A / EP261007a: VLT/X-shooter spectroscopic redshift z = 2.101
  64. EP261007a/GRB 261007A: Einstein Probe detection of an X-ray transient
  65. EP261006a: SVOM/VT optical upper limits
  66. EP261006a: Einstein Probe detection of an X-ray transient
  67. GRB 261007A: SVOM detection of a burst
  68. EP trigger 01709320985: SVOM/C-GFT optical upper limits
  69. GRB 261005B: Swift-XRT refined Analysis
  70. EP trigger 01709320985: Ondrejov D50 optical upper limits
  71. GRB 261005A: Glowbug gamma-ray detection
  72. GRB 261005B: J-band upper limit with WINTER
  73. GRB 261001A: GECAM-B observation of a likely long GRB
  74. GRB 261005B: Fermi GBM Observation
  75. The EP-WXT trigger 01709320908 is likely a flaring star
  76. EP trigger 01709320908: Ondrejov D50 observation, fading star suggests stellar flare
  77. GRB 261005A: Fermi GBM Final Real-time Localization
  78. GRB 261003A: Glowbug gamma-ray detection of a likely short burst
  79. GRB 261002A: Fermi GBM Final Localization
  80. EP#01709320865: Swift-XRT observations
  81. GRB 260930B: SVOM/GRM observation
  82. Konus-Wind detection of GRB 260919A / EP 260920a
  83. GRB 260921B: GECAM-B observation
  84. EP261003a: J-band upper limit with WINTER
  85. EP261003a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  86. GRB 260930B: GECAM-B detection of a burst
  87. EP261003a: COLIBRÍ optical upper limits
  88. Fermi GRB 261003A: Global MASTER-Net observations report
  89. EP261003a: Einstein Probe detection of an X-ray transient
  90. GRB 261003A: Fermi GBM Final Real-time Localization
  91. EP Alert 261003.01: Global MASTER-Net observations report
  92. Fermi-LAT Gamma-ray Observations of IceCube-260930A
  93. Fermi GBM Detection of GRB 260919A / EP260920a
  94. IceCube-260930A: Upper limits from a search for additional neutrino events in IceCube
  95. Fermi GRB 260930B: Global MASTER-Net observations report
  96. GRB 260926C: SVOM/GRM observation
  97. GRB 260930B: Fermi GBM Final Real-time Localization
  98. GRB 260930A: Fermi GBM Final Real-time Localization
  99. IceCube Alert 260930A: Global MASTER-Net observations report
  100. The EP-WXT trigger 01709320790 is likely a flaring star

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