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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. Konus-Wind detection of GRB 261017A
  2. GRB 261019A: Fermi GBM Final Localization
  3. GRB 261017A: Possible Swift/UVOT Detection
  4. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  5. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  6. GRB 261017A: Swift-BAT refined analysis
  7. GRB 261017A: a short minimum variability timescale compatible with a compact object merger origin
  8. EP261015b: NOT Optical Observations
  9. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
  10. EP261015c: refined analysis of the EP-FXT observation favors a stellar flare interpretation
  11. GRB 261017A : MITSuME Akeno optical upper limits
  12. GRB 261017A: Swift-XRT refined Analysis
  13. GRB 261017A: Nanshan/NEXT optical upper limit
  14. GRB 261017A: Enhanced Swift-XRT position
  15. GRB 261017A: Fermi GBM Observation
  16. GRB261010A: Retraction of Keck/MOSFIRE near-IR source
  17. GRB 261017A: Swift detection of a burst
  18. GRB 261017A: Fermi GBM Final Real-time Localization
  19. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  20. EP261015b: Refined analysis of EP-FXT observations
  21. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  22. EP261015a: refined analysis of EP-FXT observations
  23. EP261015c: J-band upper limit with WINTER
  24. EP261015a: J-band upper limit with WINTER
  25. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  26. GRB 261011A: 1.3m DFOT optical upper limit
  27. GRB 261010A: Pan-STARRS z-band imaging and upper limit
  28. EP261015a: SVOM/VT optical observation
  29. EP241111a and EP250125a: Upper limits from SVOM/GRM Observations
  30. GRB 261010A: VLA radio observations
  31. EP261015a: COLIBRÍ optical observations
  32. EP261015c: Einstein Probe detection of a fast X-ray transient
  33. EP261015b: Einstein Probe detection of an X-ray transient
  34. GRB261010A: Keck/MOSFIRE detection of a near-IR source
  35. EP261015a: Einstein Probe detection of a fast X-ray transient
  36. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  37. The EP-WXT trigger 01709321333 is likely a flaring star
  38. GRB 261010A: ASKAP non-detection of a radio afterglow
  39. GRB 261010A: LBT tentative near-infrared detection
  40. GRB 261011A: SAO RAS and AbAO optical observations
  41. GRB 261010A: Glowbug gamma-ray detection
  42. GRB 261008A: SVOM/GRM observation
  43. GRB 261009A: GECAM-B detection of a burst
  44. EP261006a : MeerKAT radio observations.
  45. IceCube-261012A: Upper limits from a search for additional neutrino events in IceCube
  46. GRB 261010A: initial pulse rest-frame energetics from Konus-Wind detection
  47. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  48. GRB 261013A: Fermi GBM Final Real-time Localization
  49. GRB 261011A: Later-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  50. Fermi-LAT Gamma-ray Observations of IceCube-261012A
  51. GRID detection of GRB 261010A
  52. GRB 261011A: GECAM-B observation
  53. GRB 261011B: GECAM-B observation
  54. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  55. IceCube-260919A: No transient candidates from the Zwicky Transient Facility
  56. GRB 261010A: Swift-XRT refined Analysis
  57. GRB 261011A: Swift-XRT refined Analysis
  58. GRB 261011A: Enhanced Swift-XRT position
  59. GRB 261010A: a Type I-L (merger-driven) GRB candidate
  60. GRB 261011A: 10.4m GTC spectroscopic redshift (z = 2.407)
  61. GRB 261011A: Swift-BAT refined analysis
  62. IceCube-261012A - IceCube observation of a high-energy neutrino candidate track-like event
  63. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  64. MAXI GRB261012.23: Global MASTER-Net observations report
  65. GRB 261011A: REM optical/NIR observations
  66. Konus-Wind detection of GRB 261010A
  67. Konus-Wind detection of GRB 261011A
  68. Konus-Wind detection of GRB 261007A/EP261007a
  69. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  70. EP261006a: 10 GHz VLA observations
  71. GRB 261011A: VLT/X-shooter redshift constraints
  72. GRB 261012A: MAXI GSC detection
  73. GRB 261010A: Swift-BAT refined analysis
  74. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  75. GRB 261011A: Optical followup from Sichuan South Observatory
  76. GRB 261011A: GMG Optical Observation
  77. GRB 261011A: Liverpool Telescope optical observations
  78. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  79. GRB 261010A: NOT confirmation of the optical afterglow
  80. GRB 261010A: Fermi GBM Observation
  81. GRB 261011B: Fermi GBM Final Localization
  82. GRB 261011A: continued LCO optical observations
  83. EP261007b: Global MASTER-Net observations report
  84. GRB 261011A: GROWTH-India Telescope optical observations
  85. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  86. Swift GRB 261011A: Global MASTER-Net observations report
  87. GRB 261011A: Optical follow-up observations with Kinder
  88. GRB 261011A: SVOM/C-GFT optical observations
  89. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  90. GRB 261011A: LCO optical observations
  91. GRB 261011A: SVOM/VT optical observation from VHF data
  92. GRB 261011A: LCO optical observations
  93. GRB 261011A: TRT optical afterglow detection
  94. GRB 261011A: GOTO optical counterpart detection
  95. GRB 261011A: Swift detection of an unusual burst
  96. GRB 261011A: SVOM detection of a long bright burst
  97. GRB 261010A: Enhanced Swift-XRT position
  98. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  99. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  100. GRB 261010A: possible optical afterglow detected with the 1.5m OSN

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