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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"

28033 results found.

  1. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  2. EP260713a: Einstein Probe detection of an X-ray transient
  3. GRB 260619A: SVOM/VT continuous optical observations
  4. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  5. EP260623a: KAIT optical observations
  6. GRB 260708A: GRANDMA Optical Observations
  7. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  8. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  9. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  10. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  11. GRB 260708A: LCO optical observations
  12. EP260711a: Einstein Probe detection of an X-ray transient
  13. GRB 260709A: SVOM/GRM detection
  14. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  15. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  16. GRB 260708A: Glowbug gamma-ray detection
  17. GRB 260706A : GRANDMA Upper limits
  18. GRB 260708A: Kilonova-Catcher optical afterglow detection
  19. IceCube-260708A: One candidate from the Zwicky Transient Facility
  20. GRB 260708A: Fermi-GBM observation
  21. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  22. IceCube Alert 260709A: Global MASTER-Net observations report
  23. LAT GRB260708.42: Global MASTER-Net observations report
  24. GRB260708B: MAXI/GSC detection
  25. GRB 260705B: SVOM/GRM observation
  26. GRB 260706A: Further EP-FXT follow-up 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 260705C: Glowbug gamma-ray detection of a short burst
  34. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  35. GRB 260706A: REM optical/NIR observations
  36. GRB 260706A: LCO optical upper limit
  37. GRB 260706A: EP-FXT follow-up observation
  38. The EP-WXT trigger 01709274151 is likely a flaring star
  39. GRB 260706A: Fermi GBM Observation
  40. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  41. GRB 260706A: SVOM detection of a burst
  42. GRB 260705A: LCO optical upper limits
  43. GRB 260704A: NOT optical upper limits
  44. Fermi GBM Sub-Threshold Detection of GRB 260705A
  45. GRB 260704A: EP-FXT follow-up observation
  46. GRB 260629A: SVOM/GRM observation of a short burst
  47. GRB 260629A: AstroSat CZTI detection
  48. EP260703a: EP-FXT follow-up observation
  49. GRB 260704A: SVOM detection of a possible GRB
  50. EP260703a: EP-WXT detection of a fast X-ray transient
  51. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  52. Fermi trigger No 804738310: Global MASTER-Net observations report
  53. Fermi GRB 260703A: Global MASTER-Net observations report
  54. GRB 260623A: Glowbug gamma-ray detection
  55. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  56. Fermi trigger No 804552016: Global MASTER-Net observations report
  57. GRB 260701A: Fermi GBM Final Real-time Localization
  58. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  59. EP260628a: EP-FXT follow-up observation
  60. Fermi GRB 260628A: Global MASTER-Net observations report
  61. EP260628a: EP-WXT detection of a fast X-ray transient
  62. EP260626a: further Liverpool Telescope optical upper limits
  63. EP260626a: COLIBRÍ optical upper limit
  64. EP260626a: Liverpool Telescope upper limits
  65. EP260626a: EP-WXT detection of a fast X-ray transient
  66. EP260623a: TNG NIR afterglow detection
  67. GRB 260618A: Fermi GBM Observation
  68. GRB 260619A: SVOM/ECLAIRs refined analysis
  69. EP260623a: Liverpool Telescope optical observations
  70. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  71. EP260623a: WINTER J-band observations
  72. GRB 260617A: Glowbug gamma-ray detection of a short burst
  73. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  74. EP260623a: Optical follow-up observations with Kinder
  75. EP260623a: SVOM/VT optical observations
  76. EP260623a: TRT optical observations
  77. EP260623a: REM optical/NIR afterglow detection
  78. EP 260623a: COLIBRÍ optical observations
  79. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  80. EP260623a: Las Cumbres discovery of the optical counterpart
  81. EP260623a: Einstein Probe detection of an X-ray transient
  82. GRB 260614B: EP-FXT follow-up observation
  83. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  84. EP260618a: Liverpool Telescope optical observations
  85. GRB 260618B: LCO optical observations
  86. EP260618a: JinShan optical observations
  87. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  88. GRB 260618B: Fermi GBM Observation
  89. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  90. GRB 260619A: TRT optical counterpart confirmation
  91. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  92. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  93. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  94. GRB 260616B: AstroSat CZTI detection
  95. GRB 260616A: AstroSat CZTI detection
  96. GRB 260616A: SVOM/GRM observation
  97. EP260618a: OHP/T193 optical observations
  98. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  99. GRB 260619A: Kilonova-Catcher optical upper limit
  100. EP260618a: LCO optical counterpart confirmation

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