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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

20501 results found.

  1. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  2. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  3. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  4. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  5. GRB 260312B: AstroSat CZTI detection
  6. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  7. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  8. GRB 260310A: potential optical counterpart
  9. Fermi GRB 260311B: Global MASTER-Net observations report
  10. GRB 260131A/B: radio detection with the VLA
  11. EP260302a: MeerKAT radio counterpart
  12. GRB 260308A: SVOM/GRM observation of a short GRB
  13. EP260306a: Mondy optical upper limit
  14. GRB 260307B: SVOM/ECLAIRs refined analysis
  15. GRB 260208A: radio detection with the VLA
  16. GRB 260307B: Mephisto optical upper limits
  17. GRB 260307B: possible NOT optical counterpart
  18. GRB 260307B: SVOM/VT upper limit with X band data analysis
  19. GRB260307B: GROWTH-India Telescope optical upper limit
  20. GRB 260307B: SVOM/VT optical candidate
  21. GRB 260307B: SVOM/C-GFT upper limit
  22. GRB 260307B: SVOM detection of a burst
  23. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  24. GRB 260207A: TESS Detection and Possible VLA Counterpart
  25. EP260302a: SVOM/VT optical observation
  26. EP260306a: SVOM/VT optical observation
  27. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  28. EP260306a: Einstein Probe detection of an X-ray transient
  29. GRB 260303A: 1.3m DFOT optical upper limit
  30. EP260214b: ATCA 6 GHz observations
  31. GRB 260303A: SVOM/ECLAIRs refined analysis
  32. GRB 260304A: AstroSat CZTI detection of a long burst
  33. GRB 260303A: SVOM/VT optical observations
  34. GRB 260303A: J-band observations with WINTER
  35. GRB 260228A: SVOM/ECLAIRs refined analysis
  36. GRB 260225A: SVOM/ECLAIRs refined analysis
  37. EP260302a: analysis of the follow-up EP-FXT observation
  38. EP260302a: LCO observations
  39. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  40. GRB 260303A: SVOM detection of a burst
  41. EP260302a: Einstein Probe detection of an X-ray transient
  42. EP260227a: Mondy optical observations
  43. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  44. EP260227a: Mephisto optical detection
  45. GRID detection of GRB 260225D
  46. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  47. EP260227a: SVOM/VT optical observation
  48. GRB 260228A: SVOM/VT optical upper limits
  49. GRB 260225D: SVOM/GRM observation
  50. EP260227A: 3.6m DOT optical afterglow detection
  51. GRB 260225B: SVOM/GRM observation
  52. EP260227a: Liverpool Telescope optical observations
  53. EP260227a: LCOGT Optical Observations
  54. GRB 260226A: Asiago r-band upper limit
  55. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  56. EP260227a: Liverpool Telescope observations
  57. EP260227a: COLIBRÍ optical observations
  58. EP260227a: NOT optical observations
  59. GRID detection of GRB 260223A
  60. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  61. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  62. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  63. Konus-Wind detection of GRB 260226A
  64. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  65. EP260214a: VLT/FORS2 optical observations
  66. GRB 260225A: WINTER J-band upper limit
  67. GRB 260226A: COLIBRÍ optical upper limits
  68. GRB 260226A: LCOGT Optical Upper Limit
  69. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  70. GRB 260226A : GROWTH-India Telescope optical observations
  71. GRB 260226A: LAST optical upper limit
  72. GRB 260226A: Fermi-LAT refined analysis
  73. GRB 260226A: AstroSat CZTI detection of bright long burst
  74. EP260214a: VLA 6 GHz detection
  75. EP260224a: LCO optical upper limits
  76. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  77. GRB 260225A: SVOM/VT optical upper limits
  78. EP260126a: VLA 6 GHz detection
  79. EP260223a: Liverpool Telescope upper limits
  80. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  81. EP260224a: Einstein Probe detection of an X-ray transient
  82. EP 260225.148: COLIBRÍ Confirmation of flaring star
  83. EP260223a: Xinglong optical upper limit
  84. EP260213a: Mephisto optical upper limits
  85. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  86. sb26021801: SVOM/C-GFT upper limit
  87. EP260223a: COLIBRÍ optical upper limits
  88. EP260223a: Einstein Probe detection of an X-ray transient
  89. GRB 260223A: SVOM/GRM observation
  90. GRB 260223A: COLIBRÍ further optical observations and a brightening
  91. EP260221a: Optical upper limit with Kinder observations
  92. GRB 260223A: COLIBRÍ optical observations
  93. GRB 260223A: DDOTI Optical Candidate
  94. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  95. EP260221a: COLIBRÍ optical counterpart candidate
  96. EP260221a: Gemini South z-band upper limit
  97. EP260221a: EP-FXT follow-up observation
  98. EP-WXT01709258519: Xinglong optical upper limit
  99. EP260221a: Xinglong optical upper limit
  100. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations

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