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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"

26670 results found.

  1. EP 261025a: COLIBRÍ optical upper limit
  2. EP261025a: Einstein Probe detection of a fast X-ray transient
  3. EP261023a: J band upper limit by SYSU 80cm infrared telescope
  4. EP261015a: VST optical observations
  5. EP261023a: Mondy optical upper limit
  6. EP261015a: MAO/AZT-22 optical observations
  7. EP261015a: VLA non-detection
  8. EP261023a: NOT optical counterpart candidate
  9. EP261023a: Einstein Probe detection of an X-ray transient
  10. The EP-WXT trigger 01709321472 is likely a flaring star
  11. IceCube-261020A: Upper limits from a search for additional neutrino events in IceCube
  12. NuSTAR 261020, a 830s hard X-ray transient
  13. EP261015a: GSP multiband optical follow-up observations
  14. GRB 261017A: SVOM/GRM observation
  15. EP261015a: Further optical observations with the 1.3m DFOT
  16. Fermi-LAT Gamma-ray Observations of IceCube-261020A
  17. EP261015a: AZT-20 Assy-Turgen optical observations
  18. GRB 261020A: Fermi GBM Observation
  19. GRB 261017A: SAO RAS optical upper limit
  20. EP261015a: Follow-up with the 1.3m DFOT
  21. EP261015a: Terskol Zeiss-2000 optical upper limit
  22. EP261007b: Further EP-FXT follow-up observations
  23. GRB 261017A: COLIBRÍ optical upper limit
  24. EP261015a: COLIBRÍ optical observations of a rebrightening
  25. Konus-Wind detection of GRB 261017A
  26. GRB 261017A: Possible Swift/UVOT Detection
  27. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  28. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  29. GRB 261017A: a short minimum variability timescale compatible with a compact object merger origin
  30. EP261015b: NOT Optical Observations
  31. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
  32. EP261015c: refined analysis of the EP-FXT observation favors a stellar flare interpretation
  33. GRB 261017A : MITSuME Akeno optical upper limits
  34. GRB 261017A: Swift-XRT refined Analysis
  35. GRB 261017A: Nanshan/NEXT optical upper limit
  36. GRB 261017A: Enhanced Swift-XRT position
  37. GRB 261017A: Fermi GBM Observation
  38. GRB 261017A: Swift detection of a burst
  39. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  40. EP261015b: Refined analysis of EP-FXT observations
  41. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  42. EP261015a: refined analysis of EP-FXT observations
  43. EP261015c: J-band upper limit with WINTER
  44. EP261015a: J-band upper limit with WINTER
  45. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  46. GRB 261011A: 1.3m DFOT optical upper limit
  47. GRB 261010A: Pan-STARRS z-band imaging and upper limit
  48. EP261015a: SVOM/VT optical observation
  49. EP241111a and EP250125a: Upper limits from SVOM/GRM Observations
  50. GRB 261010A: VLA radio observations
  51. EP261015a: COLIBRÍ optical observations
  52. EP261015c: Einstein Probe detection of a fast X-ray transient
  53. EP261015b: Einstein Probe detection of an X-ray transient
  54. EP261015a: Einstein Probe detection of a fast X-ray transient
  55. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  56. The EP-WXT trigger 01709321333 is likely a flaring star
  57. GRB 261010A: LBT tentative near-infrared detection
  58. GRB 261011A: SAO RAS and AbAO optical observations
  59. GRB 261010A: Glowbug gamma-ray detection
  60. GRB 261008A: SVOM/GRM observation
  61. EP261006a : MeerKAT radio observations.
  62. IceCube-261012A: Upper limits from a search for additional neutrino events in IceCube
  63. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  64. Fermi-LAT Gamma-ray Observations of IceCube-261012A
  65. GRID detection of GRB 261010A
  66. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  67. GRB 261010A: Swift-XRT refined Analysis
  68. GRB 261011A: Swift-XRT refined Analysis
  69. GRB 261011A: Enhanced Swift-XRT position
  70. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  71. GRB 261011A: REM optical/NIR observations
  72. Konus-Wind detection of GRB 261010A
  73. Konus-Wind detection of GRB 261011A
  74. Konus-Wind detection of GRB 261007A/EP261007a
  75. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  76. EP261006a: 10 GHz VLA observations
  77. GRB 261011A: VLT/X-shooter redshift constraints
  78. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  79. GRB 261011A: Optical followup from Sichuan South Observatory
  80. GRB 261011A: GMG Optical Observation
  81. GRB 261011A: Liverpool Telescope optical observations
  82. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  83. GRB 261010A: NOT confirmation of the optical afterglow
  84. GRB 261010A: Fermi GBM Observation
  85. GRB 261011A: GROWTH-India Telescope optical observations
  86. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  87. GRB 261011A: Optical follow-up observations with Kinder
  88. GRB 261011A: SVOM/C-GFT optical observations
  89. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  90. GRB 261011A: LCO optical observations
  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: NOT possible optical counterpart
  99. GRB 261010A: Swift detection of a burst
  100. EP261006a: Kilonova-Catcher optical follow-up and detection

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