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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"

19805 results found.

  1. EP260314a: SVOM/VT optical candidate
  2. EP260314a: Einstein Probe detection of an X-ray transient
  3. GRB 260310A / AT2026fgk: SAO RAS optical observations
  4. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  5. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  6. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  7. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  8. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  9. GRB 260312B: AstroSat CZTI detection
  10. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  11. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  12. GRB 260310A: potential optical counterpart
  13. Fermi GRB 260311B: Global MASTER-Net observations report
  14. GRB 260131A/B: radio detection with the VLA
  15. EP260302a: MeerKAT radio counterpart
  16. GRB 260308A: SVOM/GRM observation of a short GRB
  17. EP260306a: Mondy optical upper limit
  18. GRB 260307B: SVOM/ECLAIRs refined analysis
  19. GRB 260208A: radio detection with the VLA
  20. GRB 260307B: Mephisto optical upper limits
  21. GRB 260307B: possible NOT optical counterpart
  22. GRB 260307B: SVOM/VT upper limit with X band data analysis
  23. GRB260307B: GROWTH-India Telescope optical upper limit
  24. GRB 260307B: SVOM/VT optical candidate
  25. GRB 260307B: SVOM/C-GFT upper limit
  26. GRB 260307B: SVOM detection of a burst
  27. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  28. GRB 260207A: TESS Detection and Possible VLA Counterpart
  29. EP260302a: SVOM/VT optical observation
  30. EP260306a: SVOM/VT optical observation
  31. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  32. EP260306a: Einstein Probe detection of an X-ray transient
  33. GRB 260303A: 1.3m DFOT optical upper limit
  34. EP260214b: ATCA 6 GHz observations
  35. GRB 260303A: SVOM/ECLAIRs refined analysis
  36. GRB 260304A: AstroSat CZTI detection of a long burst
  37. GRB 260303A: SVOM/VT optical observations
  38. GRB 260303A: J-band observations with WINTER
  39. GRB 260228A: SVOM/ECLAIRs refined analysis
  40. GRB 260225A: SVOM/ECLAIRs refined analysis
  41. EP260302a: analysis of the follow-up EP-FXT observation
  42. EP260302a: LCO observations
  43. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  44. GRB 260303A: SVOM detection of a burst
  45. EP260302a: Einstein Probe detection of an X-ray transient
  46. EP260227a: Mondy optical observations
  47. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  48. EP260227a: Mephisto optical detection
  49. GRID detection of GRB 260225D
  50. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  51. EP260227a: SVOM/VT optical observation
  52. GRB 260228A: SVOM/VT optical upper limits
  53. GRB 260225D: SVOM/GRM observation
  54. EP260227A: 3.6m DOT optical afterglow detection
  55. GRB 260225B: SVOM/GRM observation
  56. EP260227a: Liverpool Telescope optical observations
  57. EP260227a: LCOGT Optical Observations
  58. GRB 260226A: Asiago r-band upper limit
  59. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  60. EP260227a: Liverpool Telescope observations
  61. EP260227a: COLIBRÍ optical observations
  62. EP260227a: NOT optical observations
  63. GRID detection of GRB 260223A
  64. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  65. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  66. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  67. Konus-Wind detection of GRB 260226A
  68. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  69. EP260214a: VLT/FORS2 optical observations
  70. GRB 260225A: WINTER J-band upper limit
  71. GRB 260226A: COLIBRÍ optical upper limits
  72. GRB 260226A: LCOGT Optical Upper Limit
  73. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  74. GRB 260226A : GROWTH-India Telescope optical observations
  75. GRB 260226A: LAST optical upper limit
  76. GRB 260226A: Fermi-LAT refined analysis
  77. GRB 260226A: AstroSat CZTI detection of bright long burst
  78. EP260214a: VLA 6 GHz detection
  79. EP260224a: LCO optical upper limits
  80. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  81. GRB 260225A: SVOM/VT optical upper limits
  82. EP260126a: VLA 6 GHz detection
  83. EP260223a: Liverpool Telescope upper limits
  84. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  85. EP260224a: Einstein Probe detection of an X-ray transient
  86. EP 260225.148: COLIBRÍ Confirmation of flaring star
  87. EP260223a: Xinglong optical upper limit
  88. EP260213a: Mephisto optical upper limits
  89. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  90. sb26021801: SVOM/C-GFT upper limit
  91. EP260223a: COLIBRÍ optical upper limits
  92. EP260223a: Einstein Probe detection of an X-ray transient
  93. GRB 260223A: SVOM/GRM observation
  94. GRB 260223A: COLIBRÍ further optical observations and a brightening
  95. EP260221a: Optical upper limit with Kinder observations
  96. GRB 260223A: COLIBRÍ optical observations
  97. GRB 260223A: DDOTI Optical Candidate
  98. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  99. EP260221a: COLIBRÍ optical counterpart candidate
  100. EP260221a: Gemini South z-band upper limit

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