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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

19477 results found.

  1. GRB 260718A : GRANDMA and KNC upper limits
  2. GRB 260718A: SVOM/VT optical upper limits
  3. GRB 260718A: SVOM/VT optical upper limits from VHF data
  4. GRB 260714B: SVOM/GRM observation
  5. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  6. GRB 260714B: COLIBRÍ optical counterpart candidate
  7. sb26071506: SVOM detection of a X-ray transient
  8. EP260703a: SVOM/ECLAIRs Upper Limit
  9. GRB 260709A: AstroSat CZTI detection
  10. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  11. GRB 260706A: ATCA detection of possible radio counterpart
  12. GRB 260705A: ATCA radio observations
  13. EP260713a: Einstein Probe detection of an X-ray transient
  14. EP260623a: KAIT optical observations
  15. GRB 260708A: GRANDMA Optical Observations
  16. GRB 260708A: LCO optical observations
  17. EP260711a: Einstein Probe detection of an X-ray transient
  18. GRB 260709A: SVOM/GRM detection
  19. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  20. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  21. GRB 260706A : GRANDMA Upper limits
  22. GRB 260708A: Kilonova-Catcher optical afterglow detection
  23. IceCube-260708A: One candidate from the Zwicky Transient Facility
  24. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  25. GRB260708B: MAXI/GSC detection
  26. GRB 260705B: SVOM/GRM observation
  27. EP260707a (by EP-FXT): NOT optical upper limit
  28. EP260707a is not a real source
  29. EP260707a: LCOGT Optical Upper Limit
  30. EP260707a: TRT optical upper limit
  31. EP260707a: Einstein Probe detection of an X-ray transient
  32. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  33. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  34. GRB 260706A: SVOM/GRM observation
  35. GRB 260706A: REM optical/NIR observations
  36. GRB 260706A: LCO optical upper limit
  37. GRB 260706A: SVOM detection of a burst
  38. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  39. GRB 260705A: LCO optical upper limits
  40. GRB 260704A: NOT optical upper limits
  41. Fermi GBM Sub-Threshold Detection of GRB 260705A
  42. GRB 260705A: SVOM detection of a burst
  43. GRB 260629A: SVOM/GRM observation of a short burst
  44. GRB 260629A: AstroSat CZTI detection
  45. GRB 260704A: SVOM detection of a possible GRB
  46. EP260703a: EP-WXT detection of a fast X-ray transient
  47. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  48. GRB 260614B: ATCA Radio Upper Limits
  49. EP260628a: EP-WXT detection of a fast X-ray transient
  50. EP260626a: further Liverpool Telescope optical upper limits
  51. EP260626a: COLIBRÍ optical upper limit
  52. EP260626a: Liverpool Telescope upper limits
  53. EP260626a: EP-WXT detection of a fast X-ray transient
  54. Konus-Wind detection of GRB 260623B / EP260623a
  55. EP260623a: TNG NIR afterglow detection
  56. GRB 260619A: SVOM/ECLAIRs refined analysis
  57. EP260623a: Liverpool Telescope optical observations
  58. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  59. EP260623a: WINTER J-band observations
  60. EP260623a: Optical follow-up observations with Kinder
  61. EP260623a: SVOM/VT optical observations
  62. EP260623a: TRT optical observations
  63. EP260623a: REM optical/NIR afterglow detection
  64. EP 260623a: COLIBRÍ optical observations
  65. EP260623a: Las Cumbres discovery of the optical counterpart
  66. EP260623a: Einstein Probe detection of an X-ray transient
  67. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  68. EP260618a: Liverpool Telescope optical observations
  69. GRB 260618B: LCO optical observations
  70. EP260618a: JinShan optical observations
  71. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  72. GRB 260619A: TRT optical counterpart confirmation
  73. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  74. GRB 260604B: 239Alferov CubeSat detection
  75. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  76. GRB 260616A: SVOM/GRM observation
  77. EP260618a: OHP/T193 optical observations
  78. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  79. GRB 260619A: Kilonova-Catcher optical upper limit
  80. EP260618a: LCO optical counterpart confirmation
  81. EP260618a: COLIBRÍ optical counterpart candidate
  82. GRB 260619A: SVOM possible detection of a faint burst
  83. EP260618a: EP-WXT detection of an X-ray transient
  84. GRB 260610B: AbAO optical observations
  85. GRB 260506B: cubesat Avion detection
  86. GRB 260616C: GECAM-B observation of a burst
  87. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  88. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  89. GRB 260429A: cubesat Avion detection
  90. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  91. EP260616a: EP-WXT detection of a fast X-ray transient
  92. GRB 260610B: Terskol optical observations
  93. GRB 260610B: SVOM/GRM observation
  94. GRB 260614B: SVOM/VT optical candidate from VHF data
  95. GRB 260614B: SVOM detection of a burst
  96. GRB 260611B: SVOM/GRM detection
  97. GRB 260603C: AstroSat CZTI detection
  98. GRB 260610B: further Liverpool Telescope optical observations
  99. GRB 260610B / AT2026owq: GRANDMA optical observations
  100. GRB 260610B / AT2026owq: further SAO RAS optical observations

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