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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"

3300 results found.

  1. EP260707a: LCOGT Optical Upper Limit
  2. EP260707a: TRT optical upper limit
  3. EP260707a: Einstein Probe detection of an X-ray transient
  4. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  5. GRB 260706A: REM optical/NIR observations
  6. GRB 260706A: LCO optical upper limit
  7. GRB 260706A: EP-FXT follow-up observation
  8. The EP-WXT trigger 01709274151 is likely a flaring star
  9. The EP-WXT trigger 01709274141 is likely a flaring star
  10. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  11. The EP-WXT trigger 01709274014 is likely a flaring star
  12. GRB 260704A: NOT optical upper limits
  13. GRB 260704A: EP-FXT follow-up observation
  14. EP260703a: EP-FXT follow-up observation
  15. EP260703a: EP-WXT detection of a fast X-ray transient
  16. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  17. EP260628a: EP-FXT follow-up observation
  18. EP260628a: EP-WXT detection of a fast X-ray transient
  19. The EP-WXT trigger 01709272671 is likely a flaring star
  20. EP260626a: further Liverpool Telescope optical upper limits
  21. EP260626a: EP-FXT follow-up observation
  22. EP260626a: COLIBRÍ optical upper limit
  23. EP260626a: Liverpool Telescope upper limits
  24. EP260626a: EP-WXT detection of a fast X-ray transient
  25. Konus-Wind detection of GRB 260623B / EP260623a
  26. EP260623a: TNG NIR afterglow detection
  27. GRB 260618A: Fermi GBM Observation
  28. MASS-Cube (GRID 2.0) detection of GRB 260616B
  29. EP260623a: Liverpool Telescope optical observations
  30. Konus-Wind detection of GRB 260618B
  31. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  32. EP260623a: WINTER J-band observations
  33. EP260623a: Optical follow-up observations with Kinder
  34. EP260623a: TRT optical observations
  35. EP260623a: REM optical/NIR afterglow detection
  36. EP 260623a: COLIBRÍ optical observations
  37. EP260623a: OSIRIS+/GTC redshift z = 0.703
  38. EP260623a: Las Cumbres discovery of the optical counterpart
  39. EP260623a: Einstein Probe detection of an X-ray transient
  40. GRB 260614B: EP-FXT follow-up observation
  41. EP260618a: Liverpool Telescope optical observations
  42. The EP-WXT trigger 01709271197 is likely a flaring star
  43. EP260618a: JinShan optical observations
  44. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  45. Konus-Wind detection of GRB 260617A
  46. GRB 260616B: AstroSat CZTI detection
  47. EP260618a: EP-FXT follow-up observation
  48. EP260618a: EP-WXT detection of an X-ray transient
  49. EP260616a/GRB 260616B: EP-FXT follow-up observation
  50. Konus-Wind detection of GRB 260616B/EP260616a
  51. Konus-Wind detection of GRB 260616A
  52. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  53. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  54. EP260616a: EP-WXT detection of a fast X-ray transient
  55. The EP-WXT trigger 01709270148 is likely a flaring star
  56. The EP-WXT trigger 01709269893 is likely a flaring star
  57. The EP-WXT trigger 01709269488 is likely a flaring star
  58. EP260605a: COLIBRÍ optical upper limits
  59. IceCube-260610A: EP-FXT follow-up observation
  60. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  61. EP260610b: GTC likely spectroscopic redshift z = 1.10
  62. The EP-WXT trigger 01709269176 is likely a flaring star
  63. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  64. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  65. EP260610b: MAO/AZT-22 optical observations
  66. EP260610b: NOT optical observation
  67. EP260610a: SVOM/VT optical upper limits
  68. EP260610b: Einstein Probe detection of an X-ray transient
  69. Konus-Wind detection of GRB 260601A
  70. EP260610a: COLIBRÍ optical upper limits
  71. EP260610a: Einstein Probe detection of a fast X-ray transient
  72. Konus-Wind detection of GRB 260604C
  73. Konus-Wind detection of GRB 260607B
  74. EP260605a: EP-FXT follow-up observation
  75. EP260605a: Einstein Probe detection of a fast X-ray transient
  76. The EP-WXT trigger 01709267001 is likely a flaring star
  77. EP260602d: EP-FXT follow-up observation
  78. EP260602c: EP-FXT follow-up observation
  79. The EP-WXT trigger 01709266798 is likely a flaring star
  80. EP260602d: J-band upper limit with WINTER
  81. EP260602b: J-band upper limit with WINTER
  82. EP260602a: EP-FXT follow-up observation
  83. EP260603a: Global MASTER-Net observations report
  84. EP260603a: Einstein Probe detection of a fast X-ray transient
  85. EP260602d: Optical Upper limits with kinder observations
  86. Konus-Wind detection of GRB 260601B/EP260601a
  87. GRB 260603A: EP-FXT follow-up observation
  88. EP260601a/GRB 260601B: EP-FXT follow-up observation
  89. EP260602b: EP-FXT follow-up observation
  90. EP260602a: NOT NIR J-band observations
  91. EP260602d: Einstein Probe detection of a fast X-ray transient
  92. EP260602c: Einstein Probe detection of a fast X-ray transient
  93. EP260602b: Einstein Probe detection of a fast X-ray transient
  94. GRB 260601B/EP260601a: Insight-HXMT detection
  95. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  96. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  97. EP260602a: Optical upper limits with Kinder observations
  98. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  99. EP260602a: Einstein Probe detection of a fast X-ray transient
  100. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst

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