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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 261025A: Fermi GBM Final Localization Correction
  2. EP261023a: J band upper limit by SYSU 80cm infrared telescope
  3. GRB 261024B: Fermi GBM Final Real-time Localization
  4. EP261015a: VST optical observations
  5. GRB 261024A: BALROG localization (Fermi Trigger 814551785 / GRB 261024683)
  6. GRB 261024A: Fermi GBM Final Real-time Localization
  7. EP261023a: Mondy optical upper limit
  8. EP261015a: MAO/AZT-22 optical observations
  9. EP261015a: VLA non-detection
  10. EP261023a: NOT optical counterpart candidate
  11. EP261023a: Einstein Probe detection of an X-ray transient
  12. GRB 261019A: Insight-HXMT/HE detection
  13. The EP-WXT trigger 01709321472 is likely a flaring star
  14. IceCube-261020A: Upper limits from a search for additional neutrino events in IceCube
  15. NuSTAR 261020, a 830s hard X-ray transient
  16. EP261015a: GSP multiband optical follow-up observations
  17. GRB 261017A: SVOM/GRM observation
  18. GRB 261021A: Fermi GBM Final Real-time Localization
  19. EP261015a: Further optical observations with the 1.3m DFOT
  20. GRB 261020B: AstroSat CZTI detection of a short burst
  21. Fermi-LAT Gamma-ray Observations of IceCube-261020A
  22. EP261015a: AZT-20 Assy-Turgen optical observations
  23. GRB 261020A: Fermi GBM Observation
  24. GRB 261017A: SAO RAS optical upper limit
  25. EP261015a: Wendelstein 43 cm optical observations
  26. GRB 260903A
  27. EP261015a: Follow-up with the 1.3m DFOT
  28. EP261015a: Terskol Zeiss-2000 optical upper limit
  29. EP261007b: Further EP-FXT follow-up observations
  30. GRB 261017A: COLIBRÍ optical upper limit
  31. IceCube-261020A - IceCube observation of a high-energy neutrino candidate track-like event
  32. GRB 261020A: MAXI GSC detection
  33. GRB 261020A: Fermi GBM Final Real-time Localization
  34. EP261015a: COLIBRÍ optical observations of a rebrightening
  35. Konus-Wind detection of GRB 261017A
  36. GRB 261019A: Fermi GBM Final Localization
  37. GRB 261017A: Possible Swift/UVOT Detection
  38. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  39. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  40. GRB 261017A: Swift-BAT refined analysis
  41. GRB 261017A: a short minimum variability timescale compatible with a compact object merger origin
  42. EP261015b: NOT Optical Observations
  43. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
  44. EP261015c: refined analysis of the EP-FXT observation favors a stellar flare interpretation
  45. GRB 261017A : MITSuME Akeno optical upper limits
  46. GRB 261017A: Swift-XRT refined Analysis
  47. GRB 261017A: Nanshan/NEXT optical upper limit
  48. GRB 261017A: Enhanced Swift-XRT position
  49. GRB 261017A: Fermi GBM Observation
  50. GRB261010A: Retraction of Keck/MOSFIRE near-IR source
  51. GRB 261017A: Swift detection of a burst
  52. GRB 261017A: Fermi GBM Final Real-time Localization
  53. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  54. EP261015b: Refined analysis of EP-FXT observations
  55. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  56. EP261015a: refined analysis of EP-FXT observations
  57. EP261015c: J-band upper limit with WINTER
  58. EP261015a: J-band upper limit with WINTER
  59. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  60. GRB 261011A: 1.3m DFOT optical upper limit
  61. GRB 261010A: Pan-STARRS z-band imaging and upper limit
  62. EP261015a: SVOM/VT optical observation
  63. EP241111a and EP250125a: Upper limits from SVOM/GRM Observations
  64. GRB 261010A: VLA radio observations
  65. EP261015a: COLIBRÍ optical observations
  66. EP261015c: Einstein Probe detection of a fast X-ray transient
  67. EP261015b: Einstein Probe detection of an X-ray transient
  68. GRB261010A: Keck/MOSFIRE detection of a near-IR source
  69. EP261015a: Einstein Probe detection of a fast X-ray transient
  70. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  71. The EP-WXT trigger 01709321333 is likely a flaring star
  72. GRB 261010A: ASKAP non-detection of a radio afterglow
  73. GRB 261010A: LBT tentative near-infrared detection
  74. GRB 261011A: SAO RAS and AbAO optical observations
  75. GRB 261010A: Glowbug gamma-ray detection
  76. GRB 261008A: SVOM/GRM observation
  77. GRB 261009A: GECAM-B detection of a burst
  78. EP261006a : MeerKAT radio observations.
  79. IceCube-261012A: Upper limits from a search for additional neutrino events in IceCube
  80. GRB 261010A: initial pulse rest-frame energetics from Konus-Wind detection
  81. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  82. GRB 261013A: Fermi GBM Final Real-time Localization
  83. GRB 261011A: Later-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  84. Fermi-LAT Gamma-ray Observations of IceCube-261012A
  85. GRID detection of GRB 261010A
  86. GRB 261011A: GECAM-B observation
  87. GRB 261011B: GECAM-B observation
  88. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  89. IceCube-260919A: No transient candidates from the Zwicky Transient Facility
  90. GRB 261010A: Swift-XRT refined Analysis
  91. GRB 261011A: Swift-XRT refined Analysis
  92. GRB 261011A: Enhanced Swift-XRT position
  93. GRB 261010A: a Type I-L (merger-driven) GRB candidate
  94. GRB 261011A: 10.4m GTC spectroscopic redshift (z = 2.407)
  95. GRB 261011A: Swift-BAT refined analysis
  96. IceCube-261012A - IceCube observation of a high-energy neutrino candidate track-like event
  97. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  98. MAXI GRB261012.23: Global MASTER-Net observations report
  99. GRB 261011A: REM optical/NIR observations
  100. Konus-Wind detection of GRB 261010A

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