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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"

42945 results found.

  1. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  2. The EP-WXT trigger 01709321333 is likely a flaring star
  3. GRB 261010A: ASKAP non-detection of a radio afterglow
  4. GRB 261010A: LBT tentative near-infrared detection
  5. GRB 261011A: SAO RAS and AbAO optical observations
  6. GRB 261010A: Glowbug gamma-ray detection
  7. GRB 261008A: SVOM/GRM observation
  8. GRB 261009A: GECAM-B detection of a burst
  9. EP261006a : MeerKAT radio observations.
  10. IceCube-261012A: Upper limits from a search for additional neutrino events in IceCube
  11. GRB 261010A: initial pulse rest-frame energetics from Konus-Wind detection
  12. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  13. GRB 261013A: Fermi GBM Final Real-time Localization
  14. GRB 261011A: Later-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  15. Fermi-LAT Gamma-ray Observations of IceCube-261012A
  16. GRID detection of GRB 261010A
  17. GRB 261011A: GECAM-B observation
  18. GRB 261011B: GECAM-B observation
  19. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  20. IceCube-260919A: No transient candidates from the Zwicky Transient Facility
  21. GRB 261010A: Swift-XRT refined Analysis
  22. GRB 261011A: Swift-XRT refined Analysis
  23. GRB 261011A: Enhanced Swift-XRT position
  24. GRB 261010A: a Type I-L (merger-driven) GRB candidate
  25. GRB 261011A: 10.4m GTC spectroscopic redshift (z = 2.407)
  26. GRB 261011A: Swift-BAT refined analysis
  27. IceCube-261012A - IceCube observation of a high-energy neutrino candidate track-like event
  28. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  29. MAXI GRB261012.23: Global MASTER-Net observations report
  30. GRB 261011A: REM optical/NIR observations
  31. Konus-Wind detection of GRB 261010A
  32. Konus-Wind detection of GRB 261011A
  33. Konus-Wind detection of GRB 261007A/EP261007a
  34. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  35. EP261006a: 10 GHz VLA observations
  36. GRB 261011A: VLT/X-shooter redshift constraints
  37. GRB 261012A: MAXI GSC detection
  38. GRB 261010A: Swift-BAT refined analysis
  39. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  40. GRB 261011A: Optical followup from Sichuan South Observatory
  41. GRB 261011A: GMG Optical Observation
  42. GRB 261011A: Liverpool Telescope optical observations
  43. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  44. GRB 261010A: NOT confirmation of the optical afterglow
  45. GRB 261010A: Fermi GBM Observation
  46. GRB 261011B: Fermi GBM Final Localization
  47. GRB 261011A: continued LCO optical observations
  48. EP261007b: Global MASTER-Net observations report
  49. GRB 261011A: GROWTH-India Telescope optical observations
  50. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  51. Swift GRB 261011A: Global MASTER-Net observations report
  52. GRB 261011A: Optical follow-up observations with Kinder
  53. GRB 261011A: SVOM/C-GFT optical observations
  54. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  55. GRB 261011A: LCO optical observations
  56. GRB 261011A: SVOM/VT optical observation from VHF data
  57. GRB 261011A: LCO optical observations
  58. GRB 261011A: TRT optical afterglow detection
  59. GRB 261011A: GOTO optical counterpart detection
  60. GRB 261011A: Swift detection of an unusual burst
  61. GRB 261011A: SVOM detection of a long bright burst
  62. GRB 261010A: Enhanced Swift-XRT position
  63. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  64. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  65. GRB 261010A: possible optical afterglow detected with the 1.5m OSN
  66. GRB 261010A: NOT possible optical counterpart
  67. GRB 261010A: Swift detection of a burst
  68. GRB 261010A: Fermi GBM Final Real-time Localization
  69. EP261006a: Kilonova-Catcher optical follow-up and detection
  70. GRB 261001A: SVOM/GRM observation
  71. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  72. EP261010a: SVOM/VT optical upper limits
  73. EP261006a: Liverpool Telescope optical follow-up
  74. EP261010a: NOT optical upper limits
  75. EP261010a: Global MASTER-Net observations report
  76. EP261010a Einstein Probe detection of an X-ray transient
  77. GRB 261009A: Fermi GBM Final Real-time Localization
  78. GRB261007A: Lesedi optical afterglow detection
  79. EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
  80. EP261007b: SVOM/ECLAIRs Upper Limit
  81. GRB 261008A: GECAM-B observation
  82. EP261006a: Optical follow-up observations with MATCH
  83. EP261007b: J-band upper limit by SYSU 80cm infrared telescope
  84. EP261007b: Refined analysis of the EP-WXT and autonomous EP-FXT observations
  85. GRB 261007A: SVOM/ECLAIRs refined analysis
  86. EP261007b: SVOM/VT optical detection of the NOT transient
  87. GRB 261007A / EP261007a: SVOM/GWAC-F60A/B observations
  88. EP261006a / AT 2026aetp: VLT/X-shooter spectroscopic redshift z = 0.1853
  89. GRB 261007A: Glowbug gamma-ray detection
  90. GRB 261008A: Fermi GBM Final Real-time Localization
  91. GRB 261007A: NOT optical observations
  92. EP261007b: NOT optical observations, variable source outside the FXT region
  93. GRB 261007A: SVOM/GRM observation
  94. EP261007b: SVOM/C-GFT optical upper limits
  95. EP261007b: J-band upper limit with WINTER
  96. The EP-WXT trigger 01709321008/EP261007b：Xinglong optical upper limit
  97. GRB 261007A / EP261007a: AstroSat CZTI detection
  98. GRB 261005A: GECAM-B observation
  99. EP261006a: Swift/XRT detection of the fading X-ray counterpart
  100. EP261007a/GRB 261007A：Xinglong optical observation

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