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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"

28215 results found.

  1. GRB 260903A
  2. EP261015a: Follow-up with the 1.3m DFOT
  3. EP261015a: Terskol Zeiss-2000 optical upper limit
  4. EP261007b: Further EP-FXT follow-up observations
  5. GRB 261017A: COLIBRÍ optical upper limit
  6. GRB 261020A: MAXI GSC detection
  7. EP261015a: COLIBRÍ optical observations of a rebrightening
  8. GRB 261017A: Possible Swift/UVOT Detection
  9. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  10. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  11. GRB 261017A: Swift-BAT refined analysis
  12. EP261015b: NOT Optical Observations
  13. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
  14. EP261015c: refined analysis of the EP-FXT observation favors a stellar flare interpretation
  15. GRB 261017A : MITSuME Akeno optical upper limits
  16. GRB 261017A: Swift-XRT refined Analysis
  17. GRB 261017A: Nanshan/NEXT optical upper limit
  18. GRB 261017A: Enhanced Swift-XRT position
  19. GRB 261017A: Fermi GBM Observation
  20. GRB 261017A: Swift detection of a burst
  21. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  22. EP261015b: Refined analysis of EP-FXT observations
  23. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  24. EP261015a: refined analysis of EP-FXT observations
  25. EP261015c: J-band upper limit with WINTER
  26. EP261015a: J-band upper limit with WINTER
  27. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  28. GRB 261011A: 1.3m DFOT optical upper limit
  29. GRB 261010A: Pan-STARRS z-band imaging and upper limit
  30. EP261015a: SVOM/VT optical observation
  31. GRB 261010A: VLA radio observations
  32. EP261015a: COLIBRÍ optical observations
  33. EP261015c: Einstein Probe detection of a fast X-ray transient
  34. EP261015b: Einstein Probe detection of an X-ray transient
  35. EP261015a: Einstein Probe detection of a fast X-ray transient
  36. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  37. GRB 261010A: LBT tentative near-infrared detection
  38. GRB 261011A: SAO RAS and AbAO optical observations
  39. GRB 261010A: Glowbug gamma-ray detection
  40. GRB 261008A: SVOM/GRM observation
  41. GRB 261009A: GECAM-B detection of a burst
  42. EP261006a : MeerKAT radio observations.
  43. IceCube-261012A: Upper limits from a search for additional neutrino events in IceCube
  44. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  45. Fermi-LAT Gamma-ray Observations of IceCube-261012A
  46. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  47. GRB 261010A: Swift-XRT refined Analysis
  48. GRB 261011A: Swift-XRT refined Analysis
  49. GRB 261011A: Enhanced Swift-XRT position
  50. GRB 261010A: a Type I-L (merger-driven) GRB candidate
  51. GRB 261011A: Swift-BAT refined analysis
  52. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  53. MAXI GRB261012.23: Global MASTER-Net observations report
  54. GRB 261011A: REM optical/NIR observations
  55. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  56. EP261006a: 10 GHz VLA observations
  57. GRB 261011A: VLT/X-shooter redshift constraints
  58. GRB 261012A: MAXI GSC detection
  59. GRB 261010A: Swift-BAT refined analysis
  60. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  61. GRB 261011A: Optical followup from Sichuan South Observatory
  62. GRB 261011A: GMG Optical Observation
  63. GRB 261011A: Liverpool Telescope optical observations
  64. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  65. GRB 261010A: NOT confirmation of the optical afterglow
  66. GRB 261010A: Fermi GBM Observation
  67. GRB 261011A: continued LCO optical observations
  68. EP261007b: Global MASTER-Net observations report
  69. GRB 261011A: GROWTH-India Telescope optical observations
  70. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  71. Swift GRB 261011A: Global MASTER-Net observations report
  72. GRB 261011A: Optical follow-up observations with Kinder
  73. GRB 261011A: SVOM/C-GFT optical observations
  74. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  75. GRB 261011A: LCO optical observations
  76. GRB 261011A: SVOM/VT optical observation from VHF data
  77. GRB 261011A: LCO optical observations
  78. GRB 261011A: TRT optical afterglow detection
  79. GRB 261011A: Swift detection of an unusual burst
  80. GRB 261011A: SVOM detection of a long bright burst
  81. GRB 261010A: Enhanced Swift-XRT position
  82. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  83. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  84. GRB 261010A: Swift detection of a burst
  85. EP261006a: Kilonova-Catcher optical follow-up and detection
  86. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  87. EP261010a: SVOM/VT optical upper limits
  88. EP261006a: Liverpool Telescope optical follow-up
  89. EP261010a: NOT optical upper limits
  90. EP261010a: Global MASTER-Net observations report
  91. EP261010a Einstein Probe detection of an X-ray transient
  92. GRB261007A: Lesedi optical afterglow detection
  93. EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
  94. EP261007b: SVOM/ECLAIRs Upper Limit
  95. EP261006a: Optical follow-up observations with MATCH
  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: SVOM/ECLAIRs refined analysis
  99. GRB 261007A / EP261007a: SVOM/GWAC-F60A/B observations
  100. GRB 261007A: Glowbug gamma-ray detection

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