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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"

42964 results found.

  1. GRB 261017A: Swift detection of a burst
  2. GRB 261017A: Fermi GBM Final Real-time Localization
  3. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  4. EP261015b: Refined analysis of EP-FXT observations
  5. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  6. EP261015a: refined analysis of EP-FXT observations
  7. EP261015c: J-band upper limit with WINTER
  8. EP261015a: J-band upper limit with WINTER
  9. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  10. GRB 261011A: 1.3m DFOT optical upper limit
  11. GRB 261010A: Pan-STARRS z-band imaging and upper limit
  12. EP261015a: SVOM/VT optical observation
  13. EP241111a and EP250125a: Upper limits from SVOM/GRM Observations
  14. GRB 261010A: VLA radio observations
  15. EP261015a: COLIBRÍ optical observations
  16. EP261015c: Einstein Probe detection of a fast X-ray transient
  17. EP261015b: Einstein Probe detection of an X-ray transient
  18. GRB261010A: Keck/MOSFIRE detection of a near-IR source
  19. EP261015a: Einstein Probe detection of a fast X-ray transient
  20. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  21. The EP-WXT trigger 01709321333 is likely a flaring star
  22. GRB 261010A: ASKAP non-detection of a radio afterglow
  23. GRB 261010A: LBT tentative near-infrared detection
  24. GRB 261011A: SAO RAS and AbAO optical observations
  25. GRB 261010A: Glowbug gamma-ray detection
  26. GRB 261008A: SVOM/GRM observation
  27. GRB 261009A: GECAM-B detection of a burst
  28. EP261006a : MeerKAT radio observations.
  29. IceCube-261012A: Upper limits from a search for additional neutrino events in IceCube
  30. GRB 261010A: initial pulse rest-frame energetics from Konus-Wind detection
  31. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  32. GRB 261013A: Fermi GBM Final Real-time Localization
  33. GRB 261011A: Later-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  34. Fermi-LAT Gamma-ray Observations of IceCube-261012A
  35. GRID detection of GRB 261010A
  36. GRB 261011A: GECAM-B observation
  37. GRB 261011B: GECAM-B observation
  38. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  39. IceCube-260919A: No transient candidates from the Zwicky Transient Facility
  40. GRB 261010A: Swift-XRT refined Analysis
  41. GRB 261011A: Swift-XRT refined Analysis
  42. GRB 261011A: Enhanced Swift-XRT position
  43. GRB 261010A: a Type I-L (merger-driven) GRB candidate
  44. GRB 261011A: 10.4m GTC spectroscopic redshift (z = 2.407)
  45. GRB 261011A: Swift-BAT refined analysis
  46. IceCube-261012A - IceCube observation of a high-energy neutrino candidate track-like event
  47. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  48. MAXI GRB261012.23: Global MASTER-Net observations report
  49. GRB 261011A: REM optical/NIR observations
  50. Konus-Wind detection of GRB 261010A
  51. Konus-Wind detection of GRB 261011A
  52. Konus-Wind detection of GRB 261007A/EP261007a
  53. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  54. EP261006a: 10 GHz VLA observations
  55. GRB 261011A: VLT/X-shooter redshift constraints
  56. GRB 261012A: MAXI GSC detection
  57. GRB 261010A: Swift-BAT refined analysis
  58. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  59. GRB 261011A: Optical followup from Sichuan South Observatory
  60. GRB 261011A: GMG Optical Observation
  61. GRB 261011A: Liverpool Telescope optical observations
  62. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  63. GRB 261010A: NOT confirmation of the optical afterglow
  64. GRB 261010A: Fermi GBM Observation
  65. GRB 261011B: Fermi GBM Final Localization
  66. GRB 261011A: continued LCO optical observations
  67. EP261007b: Global MASTER-Net observations report
  68. GRB 261011A: GROWTH-India Telescope optical observations
  69. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  70. Swift GRB 261011A: Global MASTER-Net observations report
  71. GRB 261011A: Optical follow-up observations with Kinder
  72. GRB 261011A: SVOM/C-GFT optical observations
  73. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  74. GRB 261011A: LCO optical observations
  75. GRB 261011A: SVOM/VT optical observation from VHF data
  76. GRB 261011A: LCO optical observations
  77. GRB 261011A: TRT optical afterglow detection
  78. GRB 261011A: GOTO optical counterpart detection
  79. GRB 261011A: Swift detection of an unusual burst
  80. GRB 261011A: SVOM detection of a long bright burst
  81. GRB 261010A: Enhanced Swift-XRT position
  82. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  83. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  84. GRB 261010A: possible optical afterglow detected with the 1.5m OSN
  85. GRB 261010A: NOT possible optical counterpart
  86. GRB 261010A: Swift detection of a burst
  87. GRB 261010A: Fermi GBM Final Real-time Localization
  88. EP261006a: Kilonova-Catcher optical follow-up and detection
  89. GRB 261001A: SVOM/GRM observation
  90. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  91. EP261010a: SVOM/VT optical upper limits
  92. EP261006a: Liverpool Telescope optical follow-up
  93. EP261010a: NOT optical upper limits
  94. EP261010a: Global MASTER-Net observations report
  95. EP261010a Einstein Probe detection of an X-ray transient
  96. GRB 261009A: Fermi GBM Final Real-time Localization
  97. GRB261007A: Lesedi optical afterglow detection
  98. EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
  99. EP261007b: SVOM/ECLAIRs Upper Limit
  100. GRB 261008A: GECAM-B observation

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