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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"

21770 results found.

  1. EP260227a: Mondy optical observations
  2. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  3. EP260227a: Mephisto optical detection
  4. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  5. EP260227a: SVOM/VT optical observation
  6. GRB 260228A: SVOM/VT optical upper limits
  7. GRB 260225D: SVOM/GRM observation
  8. EP260227A: 3.6m DOT optical afterglow detection
  9. GRB 260225B: SVOM/GRM observation
  10. GRB 260228A: SVOM detection of a burst
  11. EP260227a: Liverpool Telescope optical observations
  12. EP260227a: LCOGT Optical Observations
  13. GRB 260226A: Asiago r-band upper limit
  14. EP260227a: Liverpool Telescope observations
  15. EP260227a: COLIBRÍ optical observations
  16. EP260227a: NOT optical observations
  17. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  18. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  19. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  20. EP260214a: VLT/FORS2 optical observations
  21. GRB 260225A: WINTER J-band upper limit
  22. GRB 260226A: COLIBRÍ optical upper limits
  23. GRB 260226A: LCOGT Optical Upper Limit
  24. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  25. GRB 260226A : GROWTH-India Telescope optical observations
  26. GRB 260226A: LAST optical upper limit
  27. GRB 260226A: AstroSat CZTI detection of bright long burst
  28. EP260224a: LCO optical upper limits
  29. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  30. GRB 260225A: SVOM/VT optical upper limits
  31. EP260223a: Liverpool Telescope upper limits
  32. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  33. EP260224a: Einstein Probe detection of an X-ray transient
  34. EP 260225.148: COLIBRÍ Confirmation of flaring star
  35. EP260223a: Xinglong optical upper limit
  36. EP260213a: Mephisto optical upper limits
  37. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  38. sb26021801: SVOM/C-GFT upper limit
  39. EP260223a: COLIBRÍ optical upper limits
  40. EP260223a: Einstein Probe detection of an X-ray transient
  41. GRB 260223A: SVOM/GRM observation
  42. GRB 260223A: COLIBRÍ further optical observations and a brightening
  43. EP260221a: Optical upper limit with Kinder observations
  44. GRB 260223A: COLIBRÍ optical observations
  45. GRB 260223A: DDOTI Optical Candidate
  46. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  47. EP260221a: COLIBRÍ optical counterpart candidate
  48. EP260221a: Gemini South z-band upper limit
  49. EP260221a: EP-FXT follow-up observation
  50. EP-WXT01709258519: Xinglong optical upper limit
  51. EP260221a: Xinglong optical upper limit
  52. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  53. EP260221a: GOTO optical upper limit
  54. EP260221a: COLIBRÍ optical upper limit
  55. SVOM alert sb26021801: LCO optical upper limit
  56. EP260221a: Einstein Probe detection of an X-ray transient
  57. SVOM alert sb26021801: LAST optical upper limit
  58. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  59. sb26021801: SVOM detection of a long faint X-ray transient
  60. EP-WXT 01709258455: NOT optical upper limits
  61. EP260214b: Mondy optical observations
  62. EP260214b: 1.3m DFOT optical upper limit
  63. EP260210a: Mondy optical upper limits
  64. GRB 260208A: AbAO and Terskol optical upper limits
  65. GRB 260208A: continued Mondy optical observations
  66. IPN triangulation of GRB 260212A
  67. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  68. EP260214b: Liverpool Telescope optical observations
  69. EP260214b: Optical upper limit with Kinder observations
  70. EP260214a: Optical upper limits with Kinder observations
  71. EP260214b: EP-FXT follow-up observation
  72. EP260214b: DDOTI Optical Detection
  73. EP260214b: GROWTH-India Telescope optical upper limit
  74. EP260214a: VLT near-infrared observation
  75. EP260214a: NOT optical upper limits
  76. EP260214a: COLIBRÍ optical upper limits
  77. EP260214b: OHP/T120 optical observations
  78. EP260214a: refined analysis of the EP-FXT observation
  79. EP260214b: LCO optical counterpart detection
  80. EP260214b: COLIBRÍ optical observations
  81. EP260214b: NOT optical counterpart detection
  82. EP260214b: Einstein Probe detection of a fast X-ray transient
  83. EP260214a: Einstein Probe detection of an X-ray transient
  84. GRB 260212A: AstroSat CZTI detection
  85. EP260213a: Liverpool Telescope optical upper limits
  86. EP260213a: COLIBRÍ optical upper limits
  87. EP260213a: Optical upper limits with Kinder observations
  88. EP260213a: Mondy R-band optical upper limit
  89. EP260213a: NUTTelA-TAO Early Optical Limits
  90. EP260213a: SVOM/C-GFT upper limit
  91. EP260213a: refined analysis of the EP-FXT observation
  92. EP260213a: Einstein Probe detection of a fast X-ray transient
  93. EP/WXT 01709258378: NOT optical upper limits
  94. GRB 260212A: SVOM/GRM observation of a long burst
  95. GRB 260211A - SVOM/ECLAIRs refined analysis
  96. GRB 260211A: GOTO optical upper limit
  97. GRB 260211A: LAST optical upper limit
  98. GRB 260210A: SVOM/GRM observation
  99. Konus-Wind detection of GRB 260207B
  100. GRB 260211A: LCO optical upper limits

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