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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"

20958 results found.

  1. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  2. GRB 260207A: TESS Detection and Possible VLA Counterpart
  3. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  4. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  5. GRB 260303A: 1.3m DFOT optical upper limit
  6. EP260214b: ATCA 6 GHz observations
  7. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  8. GRB 260303A: SVOM/ECLAIRs refined analysis
  9. Fermi GRB 260305A: Global MASTER-Net observations report
  10. GRB 260303A: SVOM/VT optical observations
  11. GRB 260303A: J-band observations with WINTER
  12. EP260302a: Global MASTER-Net observations report
  13. Fermi GRB 260303B: Global MASTER-Net observations report
  14. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  15. GRB 260228A: SVOM/ECLAIRs refined analysis
  16. GRB 260225A: SVOM/ECLAIRs refined analysis
  17. EP260227a: Gemini-South optical observations
  18. EP260302a: LCO observations
  19. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  20. EP260227a: Mondy optical observations
  21. EP260227a: Mephisto optical detection
  22. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  23. EP260227a: further LCO observations
  24. EP260227A: 3.6m DOT optical afterglow detection
  25. EP260227a: FTW optical and NIR observations
  26. EP260227a: Liverpool Telescope optical observations
  27. EP260227a: LCOGT Optical Observations
  28. GRB 260226A: Asiago r-band upper limit
  29. EP260227a: Thai National Telescope observations
  30. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  31. EP260227a: Liverpool Telescope observations
  32. EP260227a: COLIBRÍ optical observations
  33. EP260227a: NOT optical observations
  34. GRB 260225A: SVOM/VT optical continued observations and upper limit
  35. EP260227a: Global MASTER-Net observations report
  36. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  37. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  38. EP260214a: VLT/FORS2 optical observations
  39. GRB 260225A: WINTER J-band upper limit
  40. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  41. GRB 260226A : GROWTH-India Telescope optical observations
  42. GRB 260226A: LAST optical upper limit
  43. LAT GRB260226.44: Global MASTER-Net observations report
  44. Fermi GRB 260226A: Global MASTER-Net observations report
  45. EP260214a: VLA 6 GHz detection
  46. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  47. EP260126a: VLA 6 GHz detection
  48. GRB 260225A: SVOM detection of a burst
  49. EP260224a: Einstein Probe detection of an X-ray transient
  50. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  51. sb26021801: SVOM/C-GFT upper limit
  52. EP260223a: Einstein Probe detection of an X-ray transient
  53. GRB 260223A: COLIBRÍ further optical observations and a brightening
  54. EP260221a: Optical upper limit with Kinder observations
  55. GRB 260223A: COLIBRÍ optical observations
  56. GRB 260223A: DDOTI Optical Candidate
  57. Fermi GRB 260223A: Global MASTER-Net observations report
  58. EP260221a: Global MASTER-Net observations report
  59. Fermi GRB 260221B: Global MASTER-Net observations report
  60. Fermi GRB 260221A: Global MASTER-Net observations report
  61. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  62. EP260221a: GOTO optical upper limit
  63. Fermi GRB 260219A: Global MASTER-Net observations report
  64. SVOM alert sb26021801: LAST optical upper limit
  65. IceCube Alert 260217A: Global MASTER-Net observations report
  66. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  67. EP-WXT 01709258455: NOT optical upper limits
  68. EP260214b: Mondy optical observations
  69. EP260214b: 1.3m DFOT optical upper limit
  70. EP260210a: Mondy optical upper limits
  71. GRB 260208A: continued Mondy optical observations
  72. EP260214b: Liverpool Telescope optical observations
  73. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  74. EP260214b: Optical upper limit with Kinder observations
  75. EP260214a: Optical upper limits with Kinder observations
  76. EP260214b: DDOTI Optical Detection
  77. EP260214b: GROWTH-India Telescope optical upper limit
  78. EP260214a: VLT near-infrared observation
  79. EP260214a: NOT optical upper limits
  80. EP260214b: OHP/T120 optical observations
  81. EP260214a: refined analysis of the EP-FXT observation
  82. EP260214b: LCO optical counterpart detection
  83. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  84. GRB 260211A: SVOM/VT optical counterpart
  85. EP260214b: COLIBRÍ optical observations
  86. EP260214a: Global MASTER-Net observations report
  87. EP260213a: Global MASTER-Net observations report
  88. EP260213a: Optical upper limits with Kinder observations
  89. EP260213a: NUTTelA-TAO Early Optical Limits
  90. EP260213a: SVOM/C-GFT upper limit
  91. EP260213a: refined analysis of the EP-FXT observation
  92. EP/WXT 01709258378: NOT optical upper limits
  93. GRB 260211A - SVOM/ECLAIRs refined analysis
  94. GRB 260204A: SVOM/ECLAIRs refined analysis
  95. GRB 260211A: GOTO optical upper limit
  96. Fermi GRB 260212A: Global MASTER-Net observations report
  97. GRB 260211A: LAST optical upper limit
  98. GRB 260128B: SVOM/ECLAIRs refined analysis
  99. GRB260131A/B: 3.6m DOT Optical Observations
  100. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits

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