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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

23561 results found.

  1. EP261015a: VST optical observations
  2. EP261023a: Mondy optical upper limit
  3. EP261015a: MAO/AZT-22 optical observations
  4. EP261015a: VLA non-detection
  5. EP261023a: NOT optical counterpart candidate
  6. EP261023a: Einstein Probe detection of an X-ray transient
  7. NuSTAR 261020, a 830s hard X-ray transient
  8. EP261015a: GSP multiband optical follow-up observations
  9. GRB 261017A: SVOM/GRM observation
  10. EP261015a: Further optical observations with the 1.3m DFOT
  11. EP261015a: AZT-20 Assy-Turgen optical observations
  12. GRB 261017A: SAO RAS optical upper limit
  13. GRB 260903A
  14. EP261015a: Follow-up with the 1.3m DFOT
  15. EP261015a: Terskol Zeiss-2000 optical upper limit
  16. EP261007b: Further EP-FXT follow-up observations
  17. GRB 261017A: COLIBRÍ optical upper limit
  18. EP261015a: COLIBRÍ optical observations of a rebrightening
  19. Konus-Wind detection of GRB 261017A
  20. GRB 261017A: Possible Swift/UVOT Detection
  21. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  22. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  23. GRB 261017A: a short minimum variability timescale compatible with a compact object merger origin
  24. EP261015b: NOT Optical Observations
  25. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
  26. EP261015c: refined analysis of the EP-FXT observation favors a stellar flare interpretation
  27. GRB 261017A : MITSuME Akeno optical upper limits
  28. GRB 261017A: Nanshan/NEXT optical upper limit
  29. GRB 261017A: Enhanced Swift-XRT position
  30. GRB261010A: Retraction of Keck/MOSFIRE near-IR source
  31. GRB 261017A: Swift detection of a burst
  32. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  33. EP261015b: Refined analysis of EP-FXT observations
  34. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  35. EP261015a: refined analysis of EP-FXT observations
  36. EP261015c: J-band upper limit with WINTER
  37. EP261015a: J-band upper limit with WINTER
  38. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  39. GRB 261011A: 1.3m DFOT optical upper limit
  40. GRB 261010A: Pan-STARRS z-band imaging and upper limit
  41. EP261015a: SVOM/VT optical observation
  42. EP241111a and EP250125a: Upper limits from SVOM/GRM Observations
  43. GRB 261010A: VLA radio observations
  44. EP261015a: COLIBRÍ optical observations
  45. EP261015c: Einstein Probe detection of a fast X-ray transient
  46. EP261015b: Einstein Probe detection of an X-ray transient
  47. GRB261010A: Keck/MOSFIRE detection of a near-IR source
  48. EP261015a: Einstein Probe detection of a fast X-ray transient
  49. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  50. GRB 261010A: ASKAP non-detection of a radio afterglow
  51. GRB 261010A: LBT tentative near-infrared detection
  52. GRB 261011A: SAO RAS and AbAO optical observations
  53. GRB 261010A: Glowbug gamma-ray detection
  54. GRB 261008A: SVOM/GRM observation
  55. EP261006a : MeerKAT radio observations.
  56. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  57. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  58. GRB 261010A: Swift-XRT refined Analysis
  59. GRB 261011A: Swift-XRT refined Analysis
  60. GRB 261011A: Enhanced Swift-XRT position
  61. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  62. GRB 261011A: REM optical/NIR observations
  63. Konus-Wind detection of GRB 261010A
  64. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  65. EP261006a: 10 GHz VLA observations
  66. GRB 261011A: VLT/X-shooter redshift constraints
  67. GRB 261010A: Swift-BAT refined analysis
  68. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  69. GRB 261011A: Optical followup from Sichuan South Observatory
  70. GRB 261011A: GMG Optical Observation
  71. GRB 261011A: Liverpool Telescope optical observations
  72. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  73. GRB 261011A: GROWTH-India Telescope optical observations
  74. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  75. GRB 261011A: Optical follow-up observations with Kinder
  76. GRB 261011A: SVOM/C-GFT optical observations
  77. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  78. GRB 261011A: LCO optical observations
  79. GRB 261011A: LCO optical observations
  80. GRB 261011A: TRT optical afterglow detection
  81. GRB 261011A: Swift detection of an unusual burst
  82. GRB 261011A: SVOM detection of a long bright burst
  83. GRB 261010A: Enhanced Swift-XRT position
  84. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  85. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  86. GRB 261010A: Swift detection of a burst
  87. EP261006a: Kilonova-Catcher optical follow-up and detection
  88. GRB 261001A: SVOM/GRM observation
  89. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  90. EP261010a: SVOM/VT optical upper limits
  91. EP261006a: Liverpool Telescope optical follow-up
  92. EP261010a: NOT optical upper limits
  93. EP261010a Einstein Probe detection of an X-ray transient
  94. EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
  95. EP261007b: SVOM/ECLAIRs Upper Limit
  96. EP261007b: J-band upper limit by SYSU 80cm infrared telescope
  97. EP261007b: Refined analysis of the EP-WXT and autonomous EP-FXT observations
  98. GRB 261007A / EP261007a: SVOM/GWAC-F60A/B observations
  99. GRB 261007A: Glowbug gamma-ray detection
  100. EP261007b: NOT optical observations, variable source outside the FXT region

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