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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"

28208 results found.

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

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