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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"

28206 results found.

  1. GRB 261017A: Swift-BAT refined analysis
  2. EP261015b: NOT Optical Observations
  3. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
  4. EP261015c: refined analysis of the EP-FXT observation favors a stellar flare interpretation
  5. GRB 261017A : MITSuME Akeno optical upper limits
  6. GRB 261017A: Swift-XRT refined Analysis
  7. GRB 261017A: Nanshan/NEXT optical upper limit
  8. GRB 261017A: Enhanced Swift-XRT position
  9. GRB 261017A: Fermi GBM Observation
  10. GRB 261017A: Swift detection of a burst
  11. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  12. EP261015b: Refined analysis of EP-FXT observations
  13. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  14. EP261015a: refined analysis of EP-FXT observations
  15. EP261015c: J-band upper limit with WINTER
  16. EP261015a: J-band upper limit with WINTER
  17. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  18. GRB 261011A: 1.3m DFOT optical upper limit
  19. GRB 261010A: Pan-STARRS z-band imaging and upper limit
  20. EP261015a: SVOM/VT optical observation
  21. GRB 261010A: VLA radio observations
  22. EP261015a: COLIBRÍ optical observations
  23. EP261015c: Einstein Probe detection of a fast X-ray transient
  24. EP261015b: Einstein Probe detection of an X-ray transient
  25. EP261015a: Einstein Probe detection of a fast X-ray transient
  26. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  27. GRB 261010A: LBT tentative near-infrared detection
  28. GRB 261011A: SAO RAS and AbAO optical observations
  29. GRB 261010A: Glowbug gamma-ray detection
  30. GRB 261008A: SVOM/GRM observation
  31. GRB 261009A: GECAM-B detection of a burst
  32. EP261006a : MeerKAT radio observations.
  33. IceCube-261012A: Upper limits from a search for additional neutrino events in IceCube
  34. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  35. Fermi-LAT Gamma-ray Observations of IceCube-261012A
  36. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  37. GRB 261010A: Swift-XRT refined Analysis
  38. GRB 261011A: Swift-XRT refined Analysis
  39. GRB 261011A: Enhanced Swift-XRT position
  40. GRB 261010A: a Type I-L (merger-driven) GRB candidate
  41. GRB 261011A: Swift-BAT refined analysis
  42. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  43. MAXI GRB261012.23: Global MASTER-Net observations report
  44. GRB 261011A: REM optical/NIR observations
  45. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  46. EP261006a: 10 GHz VLA observations
  47. GRB 261011A: VLT/X-shooter redshift constraints
  48. GRB 261012A: MAXI GSC detection
  49. GRB 261010A: Swift-BAT refined analysis
  50. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  51. GRB 261011A: Optical followup from Sichuan South Observatory
  52. GRB 261011A: GMG Optical Observation
  53. GRB 261011A: Liverpool Telescope optical observations
  54. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  55. GRB 261010A: NOT confirmation of the optical afterglow
  56. GRB 261010A: Fermi GBM Observation
  57. GRB 261011A: continued LCO optical observations
  58. EP261007b: Global MASTER-Net observations report
  59. GRB 261011A: GROWTH-India Telescope optical observations
  60. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  61. Swift GRB 261011A: Global MASTER-Net observations report
  62. GRB 261011A: Optical follow-up observations with Kinder
  63. GRB 261011A: SVOM/C-GFT optical observations
  64. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  65. GRB 261011A: LCO optical observations
  66. GRB 261011A: SVOM/VT optical observation from VHF data
  67. GRB 261011A: LCO optical observations
  68. GRB 261011A: TRT optical afterglow detection
  69. GRB 261011A: Swift detection of an unusual burst
  70. GRB 261011A: SVOM detection of a long bright burst
  71. GRB 261010A: Enhanced Swift-XRT position
  72. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  73. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  74. GRB 261010A: Swift detection of a burst
  75. EP261006a: Kilonova-Catcher optical follow-up and detection
  76. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  77. EP261010a: SVOM/VT optical upper limits
  78. EP261006a: Liverpool Telescope optical follow-up
  79. EP261010a: NOT optical upper limits
  80. EP261010a: Global MASTER-Net observations report
  81. EP261010a Einstein Probe detection of an X-ray transient
  82. GRB261007A: Lesedi optical afterglow detection
  83. EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
  84. EP261007b: SVOM/ECLAIRs Upper Limit
  85. EP261006a: Optical follow-up observations with MATCH
  86. EP261007b: J-band upper limit by SYSU 80cm infrared telescope
  87. EP261007b: Refined analysis of the EP-WXT and autonomous EP-FXT observations
  88. GRB 261007A: SVOM/ECLAIRs refined analysis
  89. GRB 261007A / EP261007a: SVOM/GWAC-F60A/B observations
  90. GRB 261007A: Glowbug gamma-ray detection
  91. EP261007b: NOT optical observations, variable source outside the FXT region
  92. EP261007b: SVOM/C-GFT optical upper limits
  93. EP261007b: J-band upper limit with WINTER
  94. The EP-WXT trigger 01709321008/EP261007b：Xinglong optical upper limit
  95. EP261006a: Swift/XRT detection of the fading X-ray counterpart
  96. EP261007a/GRB 261007A：Xinglong optical observation
  97. GRB 261007A/EP261007a: Optical follow-up observations with Kinder
  98. EP261006a: Optical follow-up observations with Kinder
  99. EP261006a: Liverpool Telescope optical observations
  100. EP261006a: Early Optical Observations by WFST

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