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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"

28207 results found.

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

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