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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"

15985 results found.

  1. EP260306a: SVOM/VT optical observation
  2. EP260302a: Gemini-South redshift z = 1.535
  3. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  4. EP260306a: Einstein Probe detection of an X-ray transient
  5. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  6. EP260302a: Optical afterglow rebrightening
  7. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  8. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  9. GRB 260303A: 1.3m DFOT optical upper limit
  10. EP260214b: ATCA 6 GHz observations
  11. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  12. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  13. GRB 260303A: SVOM/VT optical observations
  14. GRB 260303A: J-band observations with WINTER
  15. EP260227a: Gemini-South optical observations
  16. EP260302a: LCO observations
  17. EP260302a: BOOTES-7 optical counterpart detection at early times
  18. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  19. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  20. EP260227a: Mondy optical observations
  21. GRB 260228A: CAHA 2.2m telescope optical upper limit
  22. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  23. EP260227a: Mephisto optical detection
  24. EP260227a: further LCO observations
  25. EP260227a: SVOM/VT optical observation
  26. GRB 260228A: SVOM/VT optical upper limits
  27. GRB 260225D: SVOM/GRM observation
  28. EP260227A: 3.6m DOT optical afterglow detection
  29. GRB 260225B: SVOM/GRM observation
  30. GRB 260228A: SVOM detection of a burst
  31. EP260227a: FTW optical and NIR observations
  32. EP260227a: Liverpool Telescope optical observations
  33. EP260227a: LCOGT Optical Observations
  34. EP260227a: Thai National Telescope observations
  35. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  36. EP260227a: Liverpool Telescope observations
  37. EP260227a: COLIBRÍ optical observations
  38. EP260227a: NOT optical observations
  39. GRB 260225A: SVOM/VT optical continued observations and upper limit
  40. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  41. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  42. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  43. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  44. EP260214a: VLT/FORS2 optical observations
  45. GRB 260225A: WINTER J-band upper limit
  46. GRB 260226A: COLIBRÍ optical upper limits
  47. GRB 260226A: LCOGT Optical Upper Limit
  48. GRB 260226A : GROWTH-India Telescope optical observations
  49. GRB 260226A: LAST optical upper limit
  50. EP260224a: LCO optical upper limits
  51. GRB260225A: SVOM/ECLAIRs refined position
  52. GRB 260225A: EP-FXT follow-up observation
  53. GRB 260225A: SVOM/VT optical observation
  54. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  55. GRB 260225A: SVOM/VT optical upper limits
  56. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  57. EP260223a: Xinglong optical upper limit
  58. EP260213a: Mephisto optical upper limits
  59. sb26021801: SVOM/VT optical upper limits
  60. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  61. EP260223a: COLIBRÍ optical upper limits
  62. GRB 260223A: SVOM/VT optical observation
  63. GRB 260223A: SVOM/GRM observation
  64. GRB 260223A: COLIBRÍ further optical observations and a brightening
  65. EP260221a: Optical upper limit with Kinder observations
  66. GRB 260223A: COLIBRÍ optical observations
  67. GRB 260223A: DDOTI Optical Candidate
  68. EP260221a: COLIBRÍ optical counterpart candidate
  69. EP260221a: EP-FXT follow-up observation
  70. EP-WXT01709258519: Xinglong optical upper limit
  71. EP260221a: Xinglong optical upper limit
  72. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  73. EP260221a: GOTO optical upper limit
  74. EP260221a: COLIBRÍ optical upper limit
  75. SVOM alert sb26021801: LCO optical upper limit
  76. SVOM alert sb26021801: LAST optical upper limit
  77. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  78. sb26021801: SVOM detection of a long faint X-ray transient
  79. EP-WXT 01709258455: NOT optical upper limits
  80. EP260214b: Mondy optical observations
  81. EP260214b: 1.3m DFOT optical upper limit
  82. EP260210a: Mondy optical upper limits
  83. GRB 260208A: AbAO and Terskol optical upper limits
  84. GRB 260208A: continued Mondy optical observations
  85. EP260214b: Liverpool Telescope optical observations
  86. EP260214b: Optical upper limit with Kinder observations
  87. EP260214a: Optical upper limits with Kinder observations
  88. EP260214b: EP-FXT follow-up observation
  89. EP260214b: DDOTI Optical Detection
  90. EP260214b: GROWTH-India Telescope optical upper limit
  91. EP260214b: SVOM/VT optical observation
  92. EP260214a: NOT optical upper limits
  93. EP260214a: COLIBRÍ optical upper limits
  94. EP260214b: OHP/T120 optical observations
  95. EP260214b: LCO optical counterpart detection
  96. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  97. GRB 260211A: SVOM/VT optical counterpart
  98. EP260214b: COLIBRÍ optical observations
  99. EP260214a: SVOM/VT optical upper limits
  100. EP260214b: NOT optical counterpart detection

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