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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. EP261025a: Einstein Probe detection of a fast X-ray transient
  2. GRB 261025A: Fermi GBM Final Localization Correction
  3. EP261023a: J band upper limit by SYSU 80cm infrared telescope
  4. GRB 261024B: Fermi GBM Final Real-time Localization
  5. EP261015a: VST optical observations
  6. GRB 261024A: BALROG localization (Fermi Trigger 814551785 / GRB 261024683)
  7. GRB 261024A: Fermi GBM Final Real-time Localization
  8. EP261023a: Mondy optical upper limit
  9. EP261015a: MAO/AZT-22 optical observations
  10. EP261015a: VLA non-detection
  11. EP261023a: NOT optical counterpart candidate
  12. EP261023a: Einstein Probe detection of an X-ray transient
  13. GRB 261019A: Insight-HXMT/HE detection
  14. The EP-WXT trigger 01709321472 is likely a flaring star
  15. IceCube-261020A: Upper limits from a search for additional neutrino events in IceCube
  16. NuSTAR 261020, a 830s hard X-ray transient
  17. EP261015a: GSP multiband optical follow-up observations
  18. GRB 261017A: SVOM/GRM observation
  19. GRB 261021A: Fermi GBM Final Real-time Localization
  20. EP261015a: Further optical observations with the 1.3m DFOT
  21. GRB 261020B: AstroSat CZTI detection of a short burst
  22. Fermi-LAT Gamma-ray Observations of IceCube-261020A
  23. EP261015a: AZT-20 Assy-Turgen optical observations
  24. GRB 261020A: Fermi GBM Observation
  25. GRB 261017A: SAO RAS optical upper limit
  26. EP261015a: Wendelstein 43 cm optical observations
  27. GRB 260903A
  28. EP261015a: Follow-up with the 1.3m DFOT
  29. EP261015a: Terskol Zeiss-2000 optical upper limit
  30. EP261007b: Further EP-FXT follow-up observations
  31. GRB 261017A: COLIBRÍ optical upper limit
  32. IceCube-261020A - IceCube observation of a high-energy neutrino candidate track-like event
  33. GRB 261020A: MAXI GSC detection
  34. GRB 261020A: Fermi GBM Final Real-time Localization
  35. EP261015a: COLIBRÍ optical observations of a rebrightening
  36. Konus-Wind detection of GRB 261017A
  37. GRB 261019A: Fermi GBM Final Localization
  38. GRB 261017A: Possible Swift/UVOT Detection
  39. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  40. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  41. GRB 261017A: Swift-BAT refined analysis
  42. GRB 261017A: a short minimum variability timescale compatible with a compact object merger origin
  43. EP261015b: NOT Optical Observations
  44. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
  45. EP261015c: refined analysis of the EP-FXT observation favors a stellar flare interpretation
  46. GRB 261017A : MITSuME Akeno optical upper limits
  47. GRB 261017A: Swift-XRT refined Analysis
  48. GRB 261017A: Nanshan/NEXT optical upper limit
  49. GRB 261017A: Enhanced Swift-XRT position
  50. GRB 261017A: Fermi GBM Observation
  51. GRB261010A: Retraction of Keck/MOSFIRE near-IR source
  52. GRB 261017A: Swift detection of a burst
  53. GRB 261017A: Fermi GBM Final Real-time Localization
  54. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  55. EP261015b: Refined analysis of EP-FXT observations
  56. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  57. EP261015a: refined analysis of EP-FXT observations
  58. EP261015c: J-band upper limit with WINTER
  59. EP261015a: J-band upper limit with WINTER
  60. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  61. GRB 261011A: 1.3m DFOT optical upper limit
  62. GRB 261010A: Pan-STARRS z-band imaging and upper limit
  63. EP261015a: SVOM/VT optical observation
  64. EP241111a and EP250125a: Upper limits from SVOM/GRM Observations
  65. GRB 261010A: VLA radio observations
  66. EP261015a: COLIBRÍ optical observations
  67. EP261015c: Einstein Probe detection of a fast X-ray transient
  68. EP261015b: Einstein Probe detection of an X-ray transient
  69. GRB261010A: Keck/MOSFIRE detection of a near-IR source
  70. EP261015a: Einstein Probe detection of a fast X-ray transient
  71. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  72. The EP-WXT trigger 01709321333 is likely a flaring star
  73. GRB 261010A: ASKAP non-detection of a radio afterglow
  74. GRB 261010A: LBT tentative near-infrared detection
  75. GRB 261011A: SAO RAS and AbAO optical observations
  76. GRB 261010A: Glowbug gamma-ray detection
  77. GRB 261008A: SVOM/GRM observation
  78. GRB 261009A: GECAM-B detection of a burst
  79. EP261006a : MeerKAT radio observations.
  80. IceCube-261012A: Upper limits from a search for additional neutrino events in IceCube
  81. GRB 261010A: initial pulse rest-frame energetics from Konus-Wind detection
  82. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  83. GRB 261013A: Fermi GBM Final Real-time Localization
  84. GRB 261011A: Later-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  85. Fermi-LAT Gamma-ray Observations of IceCube-261012A
  86. GRID detection of GRB 261010A
  87. GRB 261011A: GECAM-B observation
  88. GRB 261011B: GECAM-B observation
  89. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  90. IceCube-260919A: No transient candidates from the Zwicky Transient Facility
  91. GRB 261010A: Swift-XRT refined Analysis
  92. GRB 261011A: Swift-XRT refined Analysis
  93. GRB 261011A: Enhanced Swift-XRT position
  94. GRB 261010A: a Type I-L (merger-driven) GRB candidate
  95. GRB 261011A: 10.4m GTC spectroscopic redshift (z = 2.407)
  96. GRB 261011A: Swift-BAT refined analysis
  97. IceCube-261012A - IceCube observation of a high-energy neutrino candidate track-like event
  98. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  99. MAXI GRB261012.23: Global MASTER-Net observations report
  100. GRB 261011A: REM optical/NIR observations

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