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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"

42177 results found.

  1. GRB 260920A: Fermi GBM Final Real-time Localization
  2. EP260920a: SVOM/VT optical upper limits
  3. EP260917a: Global MASTER-Net observations report
  4. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  5. EP260920a: COLIBRÍ optical upper limits
  6. EP260920a: Update of the LCO optical counterpart candidate
  7. EP260917b: EP-FXT non-detection and upper limit
  8. IceCube Alert 260919A: Global MASTER-Net observations report
  9. EP260920a: LCO optical counterpart candidate
  10. EP260920a: Einstein Probe detection of an X-ray transient
  11. EP Alert 260919.40: Global MASTER-Net observations report
  12. GRB 260915A: VLT optical and near-infrared upper limits
  13. EP260917a: refined analysis of the EP-FXT observations
  14. IceCube-260919A - IceCube observation of a high-energy neutrino candidate track-like event
  15. The EP-WXT trigger 01709318491 is likely a flaring star
  16. EP260806a: Yamaguchi Interferometer radio detections
  17. EP260917a: SVOM/VT optical upper limits
  18. GRB 260918A: SVOM/C-GFT optical upper limits
  19. EP Alert 260918.62: Global MASTER-Net observations report
  20. Fermi GBM Sub-Threshold Detection of GRB 260918A
  21. EP Alert 260918.24: Global MASTER-Net observations report
  22. SVOM GRB260918.16: Global MASTER-Net observations report
  23. Konus-Wind detection of GRB 260916B (short/hard)
  24. The EP-WXT trigger 01709318279 is likely a flaring star
  25. GRB 260918A: SVOM/VT optical upper limits
  26. GRB 260916B: Glowbug gamma-ray detection of a short burst
  27. GRB 260918A: EP-FXT follow-up observation
  28. GRB 260917B: Mondy optical upper limit
  29. EP260917b: EP-WXT detection of an X-ray transient
  30. EP260917A: J-band upper limit with WINTER
  31. EP Alert 260917.32: Global MASTER-Net observations report
  32. GRB 260917B: EP-FXT follow-up observation
  33. EP260917a: COLIBRÍ optical upper limits
  34. GRB 260915A: Swift-XRT afterglow detection
  35. GRB 260918A: LCO optical upper limits
  36. EP260917a: Einstein Probe detection of an X-ray transient
  37. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  38. GRB 260918A: SVOM detection of a burst
  39. GRB 260917C: Fermi GBM Final Real-time Localization
  40. GRB 260917B: FRAM-Auger optical limits
  41. GRB 260916B: Fermi GBM Detection
  42. IceCube-260916A: Upper limits from a search for additional neutrino events in IceCube
  43. GRB 260916B: Fermi GBM Final Localization
  44. GRB 260917A: Glowbug gamma-ray detection
  45. GRB 260915A: SVOM/ECLAIRs refined analysis
  46. GRB 260917B: WINTER J-band observations
  47. GRB 260917B: SVOM/VT optical observations
  48. SVOM GRB260917.16: Global MASTER-Net observations report
  49. GRB 260917B: LCO optical observation
  50. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  51. GRB 260917B: SVOM detection of a faint burst
  52. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  53. GRB 260917A: BALROG localization (Fermi Trigger 811304653 / GRB 260917100)
  54. GRB 260917A: Fermi GBM Final Real-time Localization
  55. Fermi trigger No 811304653: Global MASTER-Net observations report
  56. The EP-WXT trigger 01709317235 is likely a flaring star
  57. GRB 260915A: J-band upper limit with WINTER
  58. Fermi trigger No 811264269: Global MASTER-Net observations report
  59. IceCube-260916A - IceCube observation of a high-energy neutrino candidate track-like event
  60. GRB 260909A: NOEMA detection
  61. GRB 260914A: SVOM/GRM observation
  62. GRB 260914A: Mondy and TShAO optical observations
  63. GRB 260914A: SVOM/ECLAIRs refined analysis
  64. GRB 260909A: Swift-XRT observations
  65. GRB 260916A: MAXI/GSC detection
  66. MAXI GRB260916.37: Global MASTER-Net observations report
  67. GRB 260915A: Swift ToO observations
  68. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  69. GRB 260915A: SVOM/C-GFT optical upper limits
  70. GRB 260915A: EP-FXT follow-up observation
  71. GRB 260915A: SVOM/VT refined early optical upper limits
  72. GRB 260915A: REM optical/NIR observations
  73. GRB 260914A: REM optical/NIR observations
  74. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  75. GRB 260915A: SVOM/VT optical upper limits
  76. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  77. GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
  78. GRB 260915A: 10.4m GTC deep optical limits
  79. GRB 260915A: NOT optical upper limit
  80. SVOM GRB260915.05: Global MASTER-Net observations report
  81. GRB 260915A: SVOM/VT optical upper limits from VHF data
  82. Fermi GBM Sub-Threshold Detection of GRB 260915A
  83. GRB 260915A: LCO optical upper limits
  84. EP Alert 260914.53: Global MASTER-Net observations report
  85. GRB 260914A: EP-FXT follow-up observation
  86. GRB 260915A: SVOM detection of a burst
  87. Fermi GBM Sub-Threshold Detection of GRB 260914A
  88. GRB 260914A: LCO optical observation
  89. GRB 260914A: SVOM/C-GFT optical observations
  90. GRB 260914A: SVOM/VT optical counterpart confirmation
  91. GRB 260914A: SVOM/VT optical observation from VHF data
  92. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  93. SVOM GRB260914.47: Global MASTER-Net observations report
  94. GRB 260914A: SVOM detection of a burst
  95. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  96. GRB 260818A: Continued ATCA observations
  97. SVOM GRB260913.32: Global MASTER-Net observations report
  98. GRB 260913A: SVOM/C-GFT optical upper limit
  99. GRB 260913A: SVOM detection of a faint burst
  100. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits

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