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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').
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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"

21952 results found.

  1. EP261030a: EP-FXT follow-up observation
  2. EP261030a: GROWTH-India Telescope Upper Limit
  3. EP261030a: Einstein Probe detection of a fast X-ray transient
  4. GRB 261029A: SVOM/ECLAIRs refined analysis
  5. GRB 261029A / AT 2026ahaw: Optical upper limits from the PKU 60cm Telescope
  6. GRB 261024D: SVOM/GRM observation
  7. GRB 261026A: Mondy, SAO RAS and Terskol optical observations
  8. GRB 261029A : SVOM/GWAC-F60 observations
  9. EP-WXT trigger 01709321980: confirmation of a stellar flare by BOOTES-5
  10. GRB 261029A: WFST optical observations
  11. GRB 261029A: ULL-ASTRO-MASTER observations with LCO 1-m telescope at Siding Spring Observatory
  12. GRB 261029A: Ondrejov D50 optical observations, possible rebrightening
  13. GRB 261029A: Optical detection with 60cm Panzhihua Telescope
  14. GRB261029A: Infrared fading detected with MDM/MIRAGE
  15. GRB 261029A: SVOM/VT optical observation
  16. GRB 261029A / AT2026ahaw: r- and i-band optical follow-up with the PKU 60cm Telescope
  17. GRB 261029A: SVOM/C-GFT optical observations
  18. EP261010a: Xinglong optical follow-up
  19. GRB 261029A: LCO optical observations (correction to GCN 46082)
  20. GRB 261029A: SVOM/COLIBRÍ (FM-GFT) optical observations
  21. GRB 261029A: LCO optical observations
  22. GRB261029A: Early infrared detection with MDM/MIRAGE
  23. GRB 261029A: KAIT optical observations
  24. GRB 261029A: TRT optical observations
  25. EP261006a / AT 2026aetp: Xinglong 2.16-m optical follow-up
  26. GRB 261029A: GOTO optical counterpart candidate
  27. GRB 261024C: GECAM-B observation
  28. GRB261026A: Infrared detection with MDM/MIRAGE
  29. GRB 261026A: SAO RAS optical observations
  30. GRB 261026A: Upper Limit with 60cm Panzhihua Telescope
  31. EP 261025a: J-band upper limit with MIRAGE
  32. GRB 261026A: Ondrejov D50 optical limit
  33. GRB 261026A: ULL-ASTRO-MASTER optical detection with LCO 40-cm telescope at Haleakalā Observatory
  34. GRB 261026A: J-band observations by the SYSU 80cm infrared telescope
  35. GRB 261026A: WINTER J-band observations
  36. GRB 261024D: AstroSat CZTI detection of a long burst
  37. GRB 261019A: SVOM/GRM observation
  38. GRB 261026A: KAIT optical observations
  39. GRB 261026A: SVOM/COLIBRÍ (FM-GFT) optical observations
  40. GRB 261026A: SVOM detection of a burst
  41. EP261025a: J-band upper limit with WINTER
  42. EP261023a: J-band upper limit with WINTER
  43. EP 261025a: COLIBRÍ optical upper limit
  44. EP261025a: Einstein Probe detection of a fast X-ray transient
  45. EP261023a: J band upper limit by SYSU 80cm infrared telescope
  46. EP261015a: VST optical observations
  47. EP261023a: Mondy optical upper limit
  48. EP261015a: MAO/AZT-22 optical observations
  49. EP261015a: VLA non-detection
  50. EP261023a: NOT optical counterpart candidate
  51. EP261023a: Einstein Probe detection of an X-ray transient
  52. EP261015a: GSP multiband optical follow-up observations
  53. GRB 261017A: SVOM/GRM observation
  54. EP261015a: Further optical observations with the 1.3m DFOT
  55. EP261015a: AZT-20 Assy-Turgen optical observations
  56. GRB 261017A: SAO RAS optical upper limit
  57. EP261015a: Follow-up with the 1.3m DFOT
  58. EP261015a: Terskol Zeiss-2000 optical upper limit
  59. EP261007b: Further EP-FXT follow-up observations
  60. GRB 261017A: COLIBRÍ optical upper limit
  61. EP261015a: COLIBRÍ optical observations of a rebrightening
  62. Konus-Wind detection of GRB 261017A
  63. GRB 261017A: Possible Swift/UVOT Detection
  64. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  65. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  66. GRB 261017A: a short minimum variability timescale compatible with a compact object merger origin
  67. EP261015b: NOT Optical Observations
  68. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
  69. EP261015c: refined analysis of the EP-FXT observation favors a stellar flare interpretation
  70. GRB 261017A : MITSuME Akeno optical upper limits
  71. GRB 261017A: Nanshan/NEXT optical upper limit
  72. GRB 261017A: Enhanced Swift-XRT position
  73. GRB 261017A: Swift detection of a burst
  74. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  75. EP261015b: Refined analysis of EP-FXT observations
  76. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  77. EP261015a: refined analysis of EP-FXT observations
  78. EP261015c: J-band upper limit with WINTER
  79. EP261015a: J-band upper limit with WINTER
  80. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  81. GRB 261011A: 1.3m DFOT optical upper limit
  82. GRB 261010A: Pan-STARRS z-band imaging and upper limit
  83. EP261015a: SVOM/VT optical observation
  84. EP261015a: COLIBRÍ optical observations
  85. EP261015c: Einstein Probe detection of a fast X-ray transient
  86. EP261015b: Einstein Probe detection of an X-ray transient
  87. EP261015a: Einstein Probe detection of a fast X-ray transient
  88. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  89. GRB 261010A: LBT tentative near-infrared detection
  90. GRB 261011A: SAO RAS and AbAO optical observations
  91. GRB 261008A: SVOM/GRM observation
  92. EP261006a : MeerKAT radio observations.
  93. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  94. GRB 261011A: Later-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  95. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  96. GRB 261011A: Swift-XRT refined Analysis
  97. GRB 261011A: Enhanced Swift-XRT position
  98. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  99. GRB 261011A: REM optical/NIR observations
  100. Konus-Wind detection of GRB 261010A

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