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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"

28229 results found.

  1. EP261015a: VLA non-detection
  2. EP261023a: NOT optical counterpart candidate
  3. EP261023a: Einstein Probe detection of an X-ray transient
  4. The EP-WXT trigger 01709321472 is likely a flaring star
  5. IceCube-261020A: Upper limits from a search for additional neutrino events in IceCube
  6. NuSTAR 261020, a 830s hard X-ray transient
  7. EP261015a: GSP multiband optical follow-up observations
  8. GRB 261017A: SVOM/GRM observation
  9. EP261015a: Further optical observations with the 1.3m DFOT
  10. GRB 261020B: AstroSat CZTI detection of a short burst
  11. Fermi-LAT Gamma-ray Observations of IceCube-261020A
  12. EP261015a: AZT-20 Assy-Turgen optical observations
  13. GRB 261020A: Fermi GBM Observation
  14. GRB 261017A: SAO RAS optical upper limit
  15. GRB 260903A
  16. EP261015a: Follow-up with the 1.3m DFOT
  17. EP261015a: Terskol Zeiss-2000 optical upper limit
  18. EP261007b: Further EP-FXT follow-up observations
  19. GRB 261017A: COLIBRÍ optical upper limit
  20. GRB 261020A: MAXI GSC detection
  21. EP261015a: COLIBRÍ optical observations of a rebrightening
  22. GRB 261017A: Possible Swift/UVOT Detection
  23. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  24. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  25. GRB 261017A: Swift-BAT refined analysis
  26. EP261015b: NOT Optical Observations
  27. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
  28. EP261015c: refined analysis of the EP-FXT observation favors a stellar flare interpretation
  29. GRB 261017A : MITSuME Akeno optical upper limits
  30. GRB 261017A: Swift-XRT refined Analysis
  31. GRB 261017A: Nanshan/NEXT optical upper limit
  32. GRB 261017A: Enhanced Swift-XRT position
  33. GRB 261017A: Fermi GBM Observation
  34. GRB 261017A: Swift detection of a burst
  35. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  36. EP261015b: Refined analysis of EP-FXT observations
  37. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  38. EP261015a: refined analysis of EP-FXT observations
  39. EP261015c: J-band upper limit with WINTER
  40. EP261015a: J-band upper limit with WINTER
  41. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  42. GRB 261011A: 1.3m DFOT optical upper limit
  43. GRB 261010A: Pan-STARRS z-band imaging and upper limit
  44. EP261015a: SVOM/VT optical observation
  45. GRB 261010A: VLA radio observations
  46. EP261015a: COLIBRÍ optical observations
  47. EP261015c: Einstein Probe detection of a fast X-ray transient
  48. EP261015b: Einstein Probe detection of an X-ray transient
  49. EP261015a: Einstein Probe detection of a fast X-ray transient
  50. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  51. GRB 261010A: LBT tentative near-infrared detection
  52. GRB 261011A: SAO RAS and AbAO optical observations
  53. GRB 261010A: Glowbug gamma-ray detection
  54. GRB 261008A: SVOM/GRM observation
  55. GRB 261009A: GECAM-B detection of a burst
  56. EP261006a : MeerKAT radio observations.
  57. IceCube-261012A: Upper limits from a search for additional neutrino events in IceCube
  58. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  59. Fermi-LAT Gamma-ray Observations of IceCube-261012A
  60. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  61. GRB 261010A: Swift-XRT refined Analysis
  62. GRB 261011A: Swift-XRT refined Analysis
  63. GRB 261011A: Enhanced Swift-XRT position
  64. GRB 261010A: a Type I-L (merger-driven) GRB candidate
  65. GRB 261011A: Swift-BAT refined analysis
  66. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  67. MAXI GRB261012.23: Global MASTER-Net observations report
  68. GRB 261011A: REM optical/NIR observations
  69. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  70. EP261006a: 10 GHz VLA observations
  71. GRB 261011A: VLT/X-shooter redshift constraints
  72. GRB 261012A: MAXI GSC detection
  73. GRB 261010A: Swift-BAT refined analysis
  74. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  75. GRB 261011A: Optical followup from Sichuan South Observatory
  76. GRB 261011A: GMG Optical Observation
  77. GRB 261011A: Liverpool Telescope optical observations
  78. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  79. GRB 261010A: NOT confirmation of the optical afterglow
  80. GRB 261010A: Fermi GBM Observation
  81. GRB 261011A: continued LCO optical observations
  82. EP261007b: Global MASTER-Net observations report
  83. GRB 261011A: GROWTH-India Telescope optical observations
  84. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  85. Swift GRB 261011A: Global MASTER-Net observations report
  86. GRB 261011A: Optical follow-up observations with Kinder
  87. GRB 261011A: SVOM/C-GFT optical observations
  88. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  89. GRB 261011A: LCO optical observations
  90. GRB 261011A: SVOM/VT optical observation from VHF data
  91. GRB 261011A: LCO optical observations
  92. GRB 261011A: TRT optical afterglow detection
  93. GRB 261011A: Swift detection of an unusual burst
  94. GRB 261011A: SVOM detection of a long bright burst
  95. GRB 261010A: Enhanced Swift-XRT position
  96. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  97. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  98. GRB 261010A: Swift detection of a burst
  99. EP261006a: Kilonova-Catcher optical follow-up and detection
  100. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope

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