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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"

12057 results found.

  1. GRB 260307B: SVOM/VT upper limit with X band data analysis
  2. Fermi GRB 260307A: Global MASTER-Net observations report
  3. GRB260307B: GROWTH-India Telescope optical upper limit
  4. GRB 260307B: SVOM/C-GFT upper limit
  5. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  6. EP260302a: Gemini-South redshift z = 1.535
  7. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  8. GRB 260303A: 1.3m DFOT optical upper limit
  9. EP260214b: ATCA 6 GHz observations
  10. Fermi GRB 260305A: Global MASTER-Net observations report
  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. GRB 260228A: CAHA 2.2m telescope optical upper limit
  15. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  16. GRB 260228A: SVOM/VT optical upper limits
  17. GRB 260226A: Asiago r-band upper limit
  18. GRB 260225A: SVOM/VT optical continued observations and upper limit
  19. EP260227a: Global MASTER-Net observations report
  20. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  21. GRB 260225A: WINTER J-band upper limit
  22. GRB 260226A: COLIBRÍ optical upper limits
  23. GRB 260226A: LCOGT Optical Upper Limit
  24. GRB 260226A : GROWTH-India Telescope optical observations
  25. GRB 260226A: LAST optical upper limit
  26. LAT GRB260226.44: Global MASTER-Net observations report
  27. Fermi GRB 260226A: Global MASTER-Net observations report
  28. EP260224a: LCO optical upper limits
  29. GRB 260225A: SVOM/VT optical upper limits
  30. EP260223a: Liverpool Telescope upper limits
  31. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  32. EP260223a: Xinglong optical upper limit
  33. EP260213a: Mephisto optical upper limits
  34. EP260223a: EP-FXT follow-up observation
  35. sb26021801: SVOM/VT optical upper limits
  36. sb26021801: SVOM/C-GFT upper limit
  37. EP260223a: COLIBRÍ optical upper limits
  38. EP260221a: Optical upper limit with Kinder observations
  39. Fermi GRB 260223A: Global MASTER-Net observations report
  40. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  41. EP260221a: Gemini South z-band upper limit
  42. EP260221a: Global MASTER-Net observations report
  43. EP260221a: EP-FXT follow-up observation
  44. Fermi GRB 260221B: Global MASTER-Net observations report
  45. EP-WXT01709258519: Xinglong optical upper limit
  46. EP260221a: Xinglong optical upper limit
  47. Fermi GRB 260221A: Global MASTER-Net observations report
  48. EP260221a: GOTO optical upper limit
  49. EP260221a: COLIBRÍ optical upper limit
  50. SVOM alert sb26021801: LCO optical upper limit
  51. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  52. Fermi GRB 260219A: Global MASTER-Net observations report
  53. SVOM alert sb26021801: LAST optical upper limit
  54. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  55. IceCube Alert 260217A: Global MASTER-Net observations report
  56. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  57. EP-WXT 01709258455: NOT optical upper limits
  58. EP260214b: 1.3m DFOT optical upper limit
  59. EP260210a: Mondy optical upper limits
  60. Konus-Wind detection of GRB 260212A
  61. GRB 260208A: AbAO and Terskol optical upper limits
  62. EP260214b: Optical upper limit with Kinder observations
  63. EP260214a: Optical upper limits with Kinder observations
  64. EP260214b: GROWTH-India Telescope optical upper limit
  65. EP260214a: NOT optical upper limits
  66. EP260214a: COLIBRÍ optical upper limits
  67. EP260214a: SVOM/VT optical upper limits
  68. EP260214a: Global MASTER-Net observations report
  69. EP260213a: Liverpool Telescope optical upper limits
  70. EP260213a: Global MASTER-Net observations report
  71. EP260213a: COLIBRÍ optical upper limits
  72. EP260213a: Optical upper limits with Kinder observations
  73. EP260213a: SVOM/VT optical upper limit
  74. EP260213a: Mondy R-band optical upper limit
  75. EP260213a: NUTTelA-TAO Early Optical Limits
  76. EP260213a: SVOM/C-GFT upper limit
  77. EP/WXT 01709258378: NOT optical upper limits
  78. GRB 260211A: GOTO optical upper limit
  79. Fermi GRB 260212A: Global MASTER-Net observations report
  80. GRB 260211A: LAST optical upper limit
  81. Konus-Wind detection of GRB 260207B
  82. GRB 260211A: LCO optical upper limits
  83. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  84. Fermi trigger No 792537871: Global MASTER-Net observations report
  85. Konus-Wind detection of GRB 260209B
  86. GRB 260208A: Swift UVOT detection
  87. EP260209a: COLIBRÍ optical upper limit
  88. Fermi GRB 260210C: Global MASTER-Net observations report
  89. EP260209a: LCO optical upper limits
  90. EP260210a: Global MASTER-Net observations report
  91. EP260209a: Global MASTER-Net observations report
  92. EP260210a: Optical upper limits with Kinder observations
  93. EP260210a: SVOM/VT optical upper limit
  94. EP260210a: COLIBRÍ optical upper limit
  95. EP260210a: SVOM/C-GFT upper limit
  96. GRB 260204A: Swift-XRT afterglow detection
  97. Fermi GRB 260209A: Global MASTER-Net observations report
  98. GRB 260208B: Swift-XRT observations
  99. GRB 260204A: Swift/UVOT Upper Limits
  100. Fermi GRB 260208C: Global MASTER-Net observations report

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