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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.

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

28226 results found.

  1. NuSTAR 261020, a 830s hard X-ray transient
  2. EP261015a: GSP multiband optical follow-up observations
  3. GRB 261017A: SVOM/GRM observation
  4. EP261015a: Further optical observations with the 1.3m DFOT
  5. GRB 261020B: AstroSat CZTI detection of a short burst
  6. Fermi-LAT Gamma-ray Observations of IceCube-261020A
  7. EP261015a: AZT-20 Assy-Turgen optical observations
  8. GRB 261020A: Fermi GBM Observation
  9. GRB 261017A: SAO RAS optical upper limit
  10. GRB 260903A
  11. EP261015a: Follow-up with the 1.3m DFOT
  12. EP261015a: Terskol Zeiss-2000 optical upper limit
  13. EP261007b: Further EP-FXT follow-up observations
  14. GRB 261017A: COLIBRÍ optical upper limit
  15. GRB 261020A: MAXI GSC detection
  16. EP261015a: COLIBRÍ optical observations of a rebrightening
  17. GRB 261017A: Possible Swift/UVOT Detection
  18. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  19. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  20. GRB 261017A: Swift-BAT refined analysis
  21. EP261015b: NOT Optical Observations
  22. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
  23. EP261015c: refined analysis of the EP-FXT observation favors a stellar flare interpretation
  24. GRB 261017A : MITSuME Akeno optical upper limits
  25. GRB 261017A: Swift-XRT refined Analysis
  26. GRB 261017A: Nanshan/NEXT optical upper limit
  27. GRB 261017A: Enhanced Swift-XRT position
  28. GRB 261017A: Fermi GBM Observation
  29. GRB 261017A: Swift detection of a burst
  30. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  31. EP261015b: Refined analysis of EP-FXT observations
  32. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  33. EP261015a: refined analysis of EP-FXT observations
  34. EP261015c: J-band upper limit with WINTER
  35. EP261015a: J-band upper limit with WINTER
  36. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  37. GRB 261011A: 1.3m DFOT optical upper limit
  38. GRB 261010A: Pan-STARRS z-band imaging and upper limit
  39. EP261015a: SVOM/VT optical observation
  40. GRB 261010A: VLA radio observations
  41. EP261015a: COLIBRÍ optical observations
  42. EP261015c: Einstein Probe detection of a fast X-ray transient
  43. EP261015b: Einstein Probe detection of an X-ray transient
  44. EP261015a: Einstein Probe detection of a fast X-ray transient
  45. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  46. GRB 261010A: LBT tentative near-infrared detection
  47. GRB 261011A: SAO RAS and AbAO optical observations
  48. GRB 261010A: Glowbug gamma-ray detection
  49. GRB 261008A: SVOM/GRM observation
  50. GRB 261009A: GECAM-B detection of a burst
  51. EP261006a : MeerKAT radio observations.
  52. IceCube-261012A: Upper limits from a search for additional neutrino events in IceCube
  53. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  54. Fermi-LAT Gamma-ray Observations of IceCube-261012A
  55. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  56. GRB 261010A: Swift-XRT refined Analysis
  57. GRB 261011A: Swift-XRT refined Analysis
  58. GRB 261011A: Enhanced Swift-XRT position
  59. GRB 261010A: a Type I-L (merger-driven) GRB candidate
  60. GRB 261011A: Swift-BAT refined analysis
  61. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  62. MAXI GRB261012.23: Global MASTER-Net observations report
  63. GRB 261011A: REM optical/NIR observations
  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 261012A: MAXI GSC detection
  68. GRB 261010A: Swift-BAT refined analysis
  69. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  70. GRB 261011A: Optical followup from Sichuan South Observatory
  71. GRB 261011A: GMG Optical Observation
  72. GRB 261011A: Liverpool Telescope optical observations
  73. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  74. GRB 261010A: NOT confirmation of the optical afterglow
  75. GRB 261010A: Fermi GBM Observation
  76. GRB 261011A: continued LCO optical observations
  77. EP261007b: Global MASTER-Net observations report
  78. GRB 261011A: GROWTH-India Telescope optical observations
  79. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  80. Swift GRB 261011A: Global MASTER-Net observations report
  81. GRB 261011A: Optical follow-up observations with Kinder
  82. GRB 261011A: SVOM/C-GFT optical observations
  83. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  84. GRB 261011A: LCO optical observations
  85. GRB 261011A: SVOM/VT optical observation from VHF data
  86. GRB 261011A: LCO optical observations
  87. GRB 261011A: TRT optical afterglow detection
  88. GRB 261011A: Swift detection of an unusual burst
  89. GRB 261011A: SVOM detection of a long bright burst
  90. GRB 261010A: Enhanced Swift-XRT position
  91. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  92. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  93. GRB 261010A: Swift detection of a burst
  94. EP261006a: Kilonova-Catcher optical follow-up and detection
  95. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  96. EP261010a: SVOM/VT optical upper limits
  97. EP261006a: Liverpool Telescope optical follow-up
  98. EP261010a: NOT optical upper limits
  99. EP261010a: Global MASTER-Net observations report
  100. EP261010a Einstein Probe detection of an X-ray transient

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