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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"

41682 results found.

  1. LAT GRB260708.42: Global MASTER-Net observations report
  2. GRB260708B: MAXI/GSC detection
  3. GRB 260708A: Fermi-LAT detection
  4. GRB 260705B: SVOM/GRM observation
  5. GRB 260706A: Further EP-FXT follow-up observation
  6. GRB 260706A: SVOM/VT optical upper limits
  7. EP260707a (by EP-FXT): NOT optical upper limit
  8. EP260707a is not a real source
  9. EP260707a: LCOGT Optical Upper Limit
  10. EP260707a: TRT optical upper limit
  11. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  12. EP260707a: Einstein Probe detection of an X-ray transient
  13. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  14. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  15. GRB 260705C: Glowbug gamma-ray detection of a short burst
  16. GRB 260706A: SVOM/ECLAIRs refined analysis
  17. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  18. GRB 260706A: SVOM/GRM observation
  19. GRB 260706A: REM optical/NIR observations
  20. IceCube-260704A: No candidates from the Zwicky Transient Facility
  21. GRB 260706A: LCO optical upper limit
  22. GRB 260706A: EP-FXT follow-up observation
  23. The EP-WXT trigger 01709274141 is likely a flaring star
  24. GRB 260706A: Fermi GBM Observation
  25. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  26. IPN triangulation of GRB 260627A
  27. GRB 260705A: SVOM/ECLAIRs refined analysis
  28. GRB 260706A: SVOM detection of a burst
  29. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  30. The EP-WXT trigger 01709274014 is likely a flaring star
  31. IceCube260704A: OHP/T193 optical observations
  32. GRB 260705A: LCO optical upper limits
  33. GRB 260704A: NOT optical upper limits
  34. Fermi GBM Sub-Threshold Detection of GRB 260705A
  35. GRB 260705A: SVOM detection of a burst
  36. GRB 260704A: EP-FXT follow-up observation
  37. GRB 260629A: SVOM/GRM observation of a short burst
  38. GRB 260629A: GECAM-A observation of a short burst
  39. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  40. GRB 260629A: AstroSat CZTI detection
  41. EP260703a: EP-FXT follow-up observation
  42. GRB 260704A: SVOM detection of a possible GRB
  43. EP260703a: EP-WXT detection of a fast X-ray transient
  44. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  45. Fermi trigger No 804738310: Global MASTER-Net observations report
  46. Fermi GRB 260703A: Global MASTER-Net observations report
  47. GRB 260610B: VLA detection
  48. GRB 260623A: Glowbug gamma-ray detection
  49. GRB 260614B: ATCA Radio Upper Limits
  50. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  51. Fermi trigger No 804552016: Global MASTER-Net observations report
  52. Fermi GBM trigger 804552016/260630945 is not a GRB
  53. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  54. EP260628a: EP-FXT follow-up observation
  55. Fermi GRB 260628A: Global MASTER-Net observations report
  56. EP260628a: EP-WXT detection of a fast X-ray transient
  57. The EP-WXT trigger 01709272671 is likely a flaring star
  58. EP260626a: further Liverpool Telescope optical upper limits
  59. EP260626a: EP-FXT follow-up observation
  60. EP260626a: COLIBRÍ optical upper limit
  61. EP260626a: Liverpool Telescope upper limits
  62. EP260626a: EP-WXT detection of a fast X-ray transient
  63. Konus-Wind detection of GRB 260623B / EP260623a
  64. EP260623a: TNG NIR afterglow detection
  65. GRB 260618A: Fermi GBM Observation
  66. MASS-Cube (GRID 2.0) detection of GRB 260616B
  67. EP260623a: FTW optical and NIR observations
  68. GRB 260619A: SVOM/ECLAIRs refined analysis
  69. EP260623a: Liverpool Telescope optical observations
  70. Fermi GBM trigger 804010507/260624677 is not a GRB
  71. Konus-Wind detection of GRB 260618B
  72. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  73. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  74. EP260623a: WINTER J-band observations
  75. GRB 260617A: Glowbug gamma-ray detection of a short burst
  76. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  77. IPN triangulation of GRB 260605A
  78. EP260623a: Optical follow-up observations with Kinder
  79. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  80. EP260623a: SVOM/VT optical observations
  81. EP260623a: TRT optical observations
  82. EP260623a: REM optical/NIR afterglow detection
  83. EP 260623a: COLIBRÍ optical observations
  84. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  85. EP260623a: OSIRIS+/GTC redshift z = 0.703
  86. EP260623a: Las Cumbres discovery of the optical counterpart
  87. EP260623a: Einstein Probe detection of an X-ray transient
  88. GRB 260614B: EP-FXT follow-up observation
  89. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  90. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  91. EP260618a: Liverpool Telescope optical observations
  92. GRB 260619A: NOT optical observations
  93. GRB 260618B: LCO optical observations
  94. The EP-WXT trigger 01709271197 is likely a flaring star
  95. EP260618a: JinShan optical observations
  96. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  97. GRB 260618B: Fermi GBM Observation
  98. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  99. GRB 260619A: TRT optical counterpart confirmation
  100. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection

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