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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"

16160 results found.

  1. EP260214b: ATCA 6 GHz observations
  2. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  3. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  4. GRB 260303A: SVOM/VT optical observations
  5. GRB 260303A: J-band observations with WINTER
  6. EP260227a: Gemini-South optical observations
  7. EP260302a: LCO observations
  8. EP260302a: BOOTES-7 optical counterpart detection at early times
  9. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  10. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  11. EP260227a: Mondy optical observations
  12. GRB 260228A: CAHA 2.2m telescope optical upper limit
  13. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  14. EP260227a: Mephisto optical detection
  15. EP260227a: further LCO observations
  16. EP260227a: SVOM/VT optical observation
  17. GRB 260228A: SVOM/VT optical upper limits
  18. GRB 260225D: SVOM/GRM observation
  19. EP260227A: 3.6m DOT optical afterglow detection
  20. GRB 260225B: SVOM/GRM observation
  21. GRB 260228A: SVOM detection of a burst
  22. EP260227a: FTW optical and NIR observations
  23. EP260227a: Liverpool Telescope optical observations
  24. EP260227a: LCOGT Optical Observations
  25. EP260227a: Thai National Telescope observations
  26. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  27. EP260227a: Liverpool Telescope observations
  28. EP260227a: COLIBRÍ optical observations
  29. EP260227a: NOT optical observations
  30. GRB 260225A: SVOM/VT optical continued observations and upper limit
  31. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  32. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  33. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  34. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  35. EP260214a: VLT/FORS2 optical observations
  36. GRB 260225A: WINTER J-band upper limit
  37. GRB 260226A: COLIBRÍ optical upper limits
  38. GRB 260226A: LCOGT Optical Upper Limit
  39. GRB 260226A : GROWTH-India Telescope optical observations
  40. GRB 260226A: LAST optical upper limit
  41. EP260224a: LCO optical upper limits
  42. GRB260225A: SVOM/ECLAIRs refined position
  43. GRB 260225A: EP-FXT follow-up observation
  44. GRB 260225A: SVOM/VT optical observation
  45. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  46. GRB 260225A: SVOM/VT optical upper limits
  47. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  48. EP260223a: Xinglong optical upper limit
  49. EP260213a: Mephisto optical upper limits
  50. sb26021801: SVOM/VT optical upper limits
  51. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  52. EP260223a: COLIBRÍ optical upper limits
  53. GRB 260223A: SVOM/VT optical observation
  54. GRB 260223A: SVOM/GRM observation
  55. GRB 260223A: COLIBRÍ further optical observations and a brightening
  56. EP260221a: Optical upper limit with Kinder observations
  57. GRB 260223A: COLIBRÍ optical observations
  58. GRB 260223A: DDOTI Optical Candidate
  59. EP260221a: COLIBRÍ optical counterpart candidate
  60. EP260221a: EP-FXT follow-up observation
  61. EP-WXT01709258519: Xinglong optical upper limit
  62. EP260221a: Xinglong optical upper limit
  63. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  64. EP260221a: GOTO optical upper limit
  65. EP260221a: COLIBRÍ optical upper limit
  66. SVOM alert sb26021801: LCO optical upper limit
  67. SVOM alert sb26021801: LAST optical upper limit
  68. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  69. sb26021801: SVOM detection of a long faint X-ray transient
  70. EP-WXT 01709258455: NOT optical upper limits
  71. EP260214b: Mondy optical observations
  72. EP260214b: 1.3m DFOT optical upper limit
  73. EP260210a: Mondy optical upper limits
  74. GRB 260208A: AbAO and Terskol optical upper limits
  75. GRB 260208A: continued Mondy optical observations
  76. EP260214b: Liverpool Telescope optical observations
  77. EP260214b: Optical upper limit with Kinder observations
  78. EP260214a: Optical upper limits with Kinder observations
  79. EP260214b: EP-FXT follow-up observation
  80. EP260214b: DDOTI Optical Detection
  81. EP260214b: GROWTH-India Telescope optical upper limit
  82. EP260214b: SVOM/VT optical observation
  83. EP260214a: NOT optical upper limits
  84. EP260214a: COLIBRÍ optical upper limits
  85. EP260214b: OHP/T120 optical observations
  86. EP260214b: LCO optical counterpart detection
  87. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  88. GRB 260211A: SVOM/VT optical counterpart
  89. EP260214b: COLIBRÍ optical observations
  90. EP260214a: SVOM/VT optical upper limits
  91. EP260214b: NOT optical counterpart detection
  92. EP260213a: Liverpool Telescope optical upper limits
  93. EP260213a: COLIBRÍ optical upper limits
  94. EP260213a: Optical upper limits with Kinder observations
  95. EP260213a: SVOM/VT optical upper limit
  96. EP260213a: Mondy R-band optical upper limit
  97. EP260213a: NUTTelA-TAO Early Optical Limits
  98. EP/WXT 01709258378: NOT optical upper limits
  99. GRB 260212A: SVOM/GRM observation of a long burst
  100. GRB 260211A: SVOM/VT optical observation

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