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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"

15684 results found.

  1. GRB 260310A: Fermi GBM Observation
  2. GRB 260310A: potential optical counterpart
  3. GRB 260131A/B: radio detection with the VLA
  4. GRB 260308A: SVOM/GRM observation of a short GRB
  5. EP260306a: Mondy optical upper limit
  6. GRB 260208A: radio detection with the VLA
  7. GRB 260307B: Mephisto optical upper limits
  8. GRB 260307B: possible NOT optical counterpart
  9. GRB260307B: GROWTH-India Telescope optical upper limit
  10. GRB 260307B: SVOM/VT optical candidate
  11. GRB 260307B: SVOM detection of a burst
  12. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  13. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  14. EP260302a: SVOM/VT optical observation
  15. EP260306a: Gemini-North redshift z = 4.773
  16. EP260306a: SVOM/VT optical observation
  17. EP260302a: Gemini-South redshift z = 1.535
  18. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  19. EP260306a: Einstein Probe detection of an X-ray transient
  20. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  21. EP260302a: Optical afterglow rebrightening
  22. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  23. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  24. GRB 260303A: 1.3m DFOT optical upper limit
  25. EP260214b: ATCA 6 GHz observations
  26. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  27. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  28. GRB 260303A: SVOM/VT optical observations
  29. GRB 260303A: J-band observations with WINTER
  30. EP260227a: Gemini-South optical observations
  31. EP260302a: LCO observations
  32. EP260302a: BOOTES-7 optical counterpart detection at early times
  33. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  34. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  35. EP260227a: Mondy optical observations
  36. GRB 260228A: CAHA 2.2m telescope optical upper limit
  37. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  38. EP260227a: Mephisto optical detection
  39. EP260227a: further LCO observations
  40. EP260227a: SVOM/VT optical observation
  41. GRB 260228A: SVOM/VT optical upper limits
  42. GRB 260225D: SVOM/GRM observation
  43. EP260227A: 3.6m DOT optical afterglow detection
  44. GRB 260225B: SVOM/GRM observation
  45. GRB 260228A: SVOM detection of a burst
  46. EP260227a: FTW optical and NIR observations
  47. EP260227a: Liverpool Telescope optical observations
  48. EP260227a: LCOGT Optical Observations
  49. EP260227a: Thai National Telescope observations
  50. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  51. EP260227a: Liverpool Telescope observations
  52. EP260227a: COLIBRÍ optical observations
  53. EP260227a: NOT optical observations
  54. GRB 260225A: SVOM/VT optical continued observations and upper limit
  55. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  56. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  57. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  58. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  59. EP260214a: VLT/FORS2 optical observations
  60. GRB 260225A: WINTER J-band upper limit
  61. GRB 260226A: COLIBRÍ optical upper limits
  62. GRB 260226A: LCOGT Optical Upper Limit
  63. GRB 260226A : GROWTH-India Telescope optical observations
  64. GRB 260226A: LAST optical upper limit
  65. EP260224a: LCO optical upper limits
  66. GRB260225A: SVOM/ECLAIRs refined position
  67. GRB 260225A: EP-FXT follow-up observation
  68. GRB 260225A: SVOM/VT optical observation
  69. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  70. GRB 260225A: SVOM/VT optical upper limits
  71. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  72. EP260223a: Xinglong optical upper limit
  73. EP260213a: Mephisto optical upper limits
  74. sb26021801: SVOM/VT optical upper limits
  75. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  76. EP260223a: COLIBRÍ optical upper limits
  77. GRB 260223A: SVOM/VT optical observation
  78. GRB 260223A: SVOM/GRM observation
  79. GRB 260223A: COLIBRÍ further optical observations and a brightening
  80. EP260221a: Optical upper limit with Kinder observations
  81. GRB 260223A: COLIBRÍ optical observations
  82. GRB 260223A: DDOTI Optical Candidate
  83. EP260221a: COLIBRÍ optical counterpart candidate
  84. EP260221a: EP-FXT follow-up observation
  85. EP-WXT01709258519: Xinglong optical upper limit
  86. EP260221a: Xinglong optical upper limit
  87. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  88. EP260221a: GOTO optical upper limit
  89. EP260221a: COLIBRÍ optical upper limit
  90. SVOM alert sb26021801: LCO optical upper limit
  91. SVOM alert sb26021801: LAST optical upper limit
  92. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  93. sb26021801: SVOM detection of a long faint X-ray transient
  94. EP-WXT 01709258455: NOT optical upper limits
  95. EP260214b: Mondy optical observations
  96. EP260214b: 1.3m DFOT optical upper limit
  97. EP260210a: Mondy optical upper limits
  98. GRB 260208A: AbAO and Terskol optical upper limits
  99. GRB 260208A: continued Mondy optical observations
  100. EP260214b: Liverpool Telescope optical observations

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