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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"

32502 results found.

  1. Fermi GBM Sub-Threshold Detection of GRB 260918A
  2. Konus-Wind detection of GRB 260916B (short/hard)
  3. GRB 260918A: SVOM/VT optical upper limits
  4. GRB 260916B: Glowbug gamma-ray detection of a short burst
  5. GRB 260918A: EP-FXT follow-up observation
  6. GRB 260917B: Mondy optical upper limit
  7. IPN triangulation of GRB 260916B (short)
  8. EP260917A: J-band upper limit with WINTER
  9. IPN triangulation of GRB 260810A
  10. GRB 260917B: EP-FXT follow-up observation
  11. EP260917a: COLIBRÍ optical upper limits
  12. GRB 260915A: Swift-XRT afterglow detection
  13. GRB 260918A: LCO optical upper limits
  14. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  15. GRB 260918A: SVOM detection of a burst
  16. GRB 260917B: FRAM-Auger optical limits
  17. IceCube-260916A: Upper limits from a search for additional neutrino events in IceCube
  18. GRB 260917A: Glowbug gamma-ray detection
  19. GRB 260915A: SVOM/ECLAIRs refined analysis
  20. GRB 260917B: WINTER J-band observations
  21. GRB 260917B: SVOM/VT optical observations
  22. GRB 260917B: LCO optical observation
  23. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  24. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  25. GRB 260915A: J-band upper limit with WINTER
  26. IceCube-260916A - IceCube observation of a high-energy neutrino candidate track-like event
  27. GRB 260909A: NOEMA detection
  28. GRB 260914A: SVOM/GRM observation
  29. GRB 260914A: Mondy and TShAO optical observations
  30. GRB 260914A: SVOM/ECLAIRs refined analysis
  31. GRB 260909A: Swift-XRT observations
  32. GRB 260915A: Swift ToO observations
  33. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  34. GRB 260915A: SVOM/C-GFT optical upper limits
  35. GRB 260915A: EP-FXT follow-up observation
  36. GRB 260915A: SVOM/VT refined early optical upper limits
  37. GRB 260915A: EP-FXT follow-up observation
  38. GRB 260915A: REM optical/NIR observations
  39. GRB 260914A: REM optical/NIR observations
  40. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  41. GRB 260915A: SVOM/VT optical upper limits
  42. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  43. GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
  44. GRB 260915A: 10.4m GTC deep optical limits
  45. GRB 260915A: NOT optical upper limit
  46. GRB 260915A: SVOM/VT optical upper limits from VHF data
  47. Fermi GBM Sub-Threshold Detection of GRB 260915A
  48. GRB 260915A: LCO optical upper limits
  49. GRB 260914A: EP-FXT follow-up observation
  50. Fermi GBM Sub-Threshold Detection of GRB 260914A
  51. GRB 260914A: LCO optical observation
  52. GRB 260914A: SVOM/C-GFT optical observations
  53. GRB 260914A: SVOM/VT optical counterpart confirmation
  54. GRB 260914A: SVOM/VT optical observation from VHF data
  55. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  56. GRB 260914A: SVOM detection of a burst
  57. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  58. GRB 260818A: Continued ATCA observations
  59. GRB 260913A: SVOM/C-GFT optical upper limit
  60. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  61. GRB 260907A: SVOM/GRM observation
  62. GRB 260909A: CrAO and AbAO optical upper limits
  63. GRB 260909A: SVOM/ECLAIRs refined analysis
  64. GRB 260910B: GOTO tentative optical counterpart candidates
  65. GRB 260909A: Swift ToO observations
  66. GRB 260909A: KAIT optical upper limit
  67. GRB 260903A: Swift-XRT observations
  68. EP260806a: VLA+ALMA radio detections
  69. GRB 260909A: OHP/T193 z-band upper limit
  70. GRB 260909A: VLT optical and near-infrared upper limits
  71. GRB 260909A: EP-FXT follow-up observation
  72. EP260806a: NOEMA detection
  73. EP260623a: NOEMA detections
  74. GRB 260909A: SVOM/VT optical upper limits
  75. GRB 260909A: SVOM/GRM observation
  76. GRB 260909A: Mondy optical observations and afterglow candidate
  77. GRB 260909A: Xinglong 2.16m optical upper limit
  78. GRB 260909A: SVOM/C-GFT optical upper limit
  79. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  80. GRB 260903A: Swift ToO observations
  81. Fermi GRB 260907B: Global MASTER-Net observations report
  82. GRB 260903A: SAO RAS optical upper limit
  83. Fermi GRB 260907A: Global MASTER-Net observations report
  84. EP260903a: EP-FXT follow-up observation
  85. GRB 260903A: J-band upper limit with WINTER
  86. GRB 260903A: SVOM/ECLAIRs refined analysis
  87. GRB260903A: Liverpool Telescope optical observations
  88. GRB 260903A: SAO RAS optical observations
  89. GRB 260830A: GECAM-B detection of a burst
  90. EP260903a: EP-WXT detection of a fast X-ray transient
  91. GRB 260830A: Insight-HXMT/HE detection
  92. GRB 260903A: EP-FXT follow-up observation
  93. GRB 260903A: OHP/T193 optical afterglow detection
  94. GRB 260903A: NOT optical observations and afterglow fading
  95. NuSTAR Transient 260828: SOAR Optical Upper Limits
  96. GRB 260903A: LCO optical observations
  97. GRB 260903A: SVOM/VT optical candidate
  98. GRB 260903A: Retraction of optical counterpart of GCN 45501
  99. GRB 260831A: GECAM-B observation
  100. GRB 260903A: LCO optical counterpart detection

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