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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"

21882 results found.

  1. GRB 261017A: Nanshan/NEXT optical upper limit
  2. GRB 261017A: Enhanced Swift-XRT position
  3. GRB 261017A: Swift detection of a burst
  4. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  5. EP261015b: Refined analysis of EP-FXT observations
  6. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  7. EP261015a: refined analysis of EP-FXT observations
  8. EP261015c: J-band upper limit with WINTER
  9. EP261015a: J-band upper limit with WINTER
  10. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  11. GRB 261011A: 1.3m DFOT optical upper limit
  12. GRB 261010A: Pan-STARRS z-band imaging and upper limit
  13. EP261015a: SVOM/VT optical observation
  14. EP261015a: COLIBRÍ optical observations
  15. EP261015c: Einstein Probe detection of a fast X-ray transient
  16. EP261015b: Einstein Probe detection of an X-ray transient
  17. EP261015a: Einstein Probe detection of a fast X-ray transient
  18. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  19. GRB 261010A: LBT tentative near-infrared detection
  20. GRB 261011A: SAO RAS and AbAO optical observations
  21. GRB 261008A: SVOM/GRM observation
  22. EP261006a : MeerKAT radio observations.
  23. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  24. GRB 261011A: Later-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  25. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  26. GRB 261011A: Swift-XRT refined Analysis
  27. GRB 261011A: Enhanced Swift-XRT position
  28. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  29. GRB 261011A: REM optical/NIR observations
  30. Konus-Wind detection of GRB 261010A
  31. Konus-Wind detection of GRB 261011A
  32. Konus-Wind detection of GRB 261007A/EP261007a
  33. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  34. EP261006a: 10 GHz VLA observations
  35. GRB 261011A: VLT/X-shooter redshift constraints
  36. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  37. GRB 261011A: Optical followup from Sichuan South Observatory
  38. GRB 261011A: GMG Optical Observation
  39. GRB 261011A: Liverpool Telescope optical observations
  40. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  41. GRB 261011A: GROWTH-India Telescope optical observations
  42. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  43. GRB 261011A: Optical follow-up observations with Kinder
  44. GRB 261011A: SVOM/C-GFT optical observations
  45. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  46. GRB 261011A: LCO optical observations
  47. GRB 261011A: LCO optical observations
  48. GRB 261011A: TRT optical afterglow detection
  49. GRB 261011A: GOTO optical counterpart detection
  50. GRB 261011A: Swift detection of an unusual burst
  51. GRB 261011A: SVOM detection of a long bright burst
  52. GRB 261010A: Enhanced Swift-XRT position
  53. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  54. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  55. GRB 261010A: Swift detection of a burst
  56. EP261006a: Kilonova-Catcher optical follow-up and detection
  57. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  58. EP261010a: SVOM/VT optical upper limits
  59. EP261006a: Liverpool Telescope optical follow-up
  60. EP261010a: NOT optical upper limits
  61. EP261010a Einstein Probe detection of an X-ray transient
  62. EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
  63. EP261007b: SVOM/ECLAIRs Upper Limit
  64. EP261007b: J-band upper limit by SYSU 80cm infrared telescope
  65. EP261007b: Refined analysis of the EP-WXT and autonomous EP-FXT observations
  66. GRB 261007A: SVOM/ECLAIRs refined analysis
  67. GRB 261007A / EP261007a: SVOM/GWAC-F60A/B observations
  68. EP261007b: NOT optical observations, variable source outside the FXT region
  69. EP261007b: SVOM/C-GFT optical upper limits
  70. EP261007b: J-band upper limit with WINTER
  71. The EP-WXT trigger 01709321008/EP261007b：Xinglong optical upper limit
  72. GRB 261007A / EP261007a: AstroSat CZTI detection
  73. EP261006a: Swift/XRT detection of the fading X-ray counterpart
  74. EP261007a/GRB 261007A：Xinglong optical observation
  75. GRB 261007A/EP261007a: Optical follow-up observations with Kinder
  76. EP261006a: Optical follow-up observations with Kinder
  77. EP261006a: Liverpool Telescope optical observations
  78. EP261006a: Early Optical Observations by WFST
  79. GRB 261007A / EP261007a: SVOM/VT optical observations
  80. GRB 261007A: Swift-XRT afterglow detection
  81. EP261007b: SVOM/VT optical upper limits
  82. GRB 261007A: SVOM/COLIBRÍ (FM-GFT) optical observations
  83. EP261007b: Einstein Probe detection of an X-ray transient
  84. GRB 261007A / EP261007a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at McDonald Observatory
  85. GRB 261007A: GROWTH-India Telescope optical observations
  86. GRB 261007A / EP261007a: TRT optical observations
  87. GRB 261007A: SVOM/C-GFT optical observations
  88. GRB 261007A: WINTER J-band observations
  89. EP261006a: LT and NOT discovery of an optical counterpart
  90. GRB 261007A: Fermi GBM observation
  91. EP261007a/GRB 261007A: Einstein Probe detection of an X-ray transient
  92. EP261006a: SVOM/VT optical upper limits
  93. EP261006a: Einstein Probe detection of an X-ray transient
  94. GRB 261007A: KAIT optical counterpart candidate
  95. GRB 261007A: SVOM detection of a burst
  96. EP trigger 01709320985: SVOM/C-GFT optical upper limits
  97. GRB 261005B: Swift-XRT refined Analysis
  98. EP trigger 01709320985: Ondrejov D50 optical upper limits
  99. GRB 261005B: Swift/UVOT Upper Limits
  100. GRB 261005B: J-band upper limit with WINTER

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