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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"

32532 results found.

  1. GRB 260921A: Swift-BAT refined analysis
  2. GRB 260921A: Fermi GBM Observation
  3. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  4. GRB 260917B:: SVOM/ECLAIRs refined analysis
  5. EP260920a: VLT/HAWK-I near-infrared candidate
  6. Swift GRB 260921A: Global MASTER-Net observations report
  7. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  8. EP260920b: LCO observations
  9. GRB 260920A: AstroSat CZTI detection
  10. EP260920b: SVOM/VT optical observation
  11. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  12. EP260920b: COLIBRÍ optical observations
  13. EP260920b: LCO optical counterpart detection
  14. EP260920b: Global MASTER-Net observations report
  15. IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
  16. EP260920a: NOT early time optical upper limits
  17. EP260920a: NOT optical upper limits
  18. EP260920a: SVOM/VT optical upper limits
  19. EP260917a: Global MASTER-Net observations report
  20. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  21. EP260920a: COLIBRÍ optical upper limits
  22. EP260920a: Update of the LCO optical counterpart candidate
  23. EP260917b: EP-FXT non-detection and upper limit
  24. EP260920a: LCO optical counterpart candidate
  25. GRB 260915A: VLT optical and near-infrared upper limits
  26. EP260917a: refined analysis of the EP-FXT observations
  27. IceCube-260919A - IceCube observation of a high-energy neutrino candidate track-like event
  28. EP260806a: Yamaguchi Interferometer radio detections
  29. EP260917a: SVOM/VT optical upper limits
  30. GRB 260918A: SVOM/C-GFT optical upper limits
  31. Fermi GBM Sub-Threshold Detection of GRB 260918A
  32. Konus-Wind detection of GRB 260916B (short/hard)
  33. GRB 260918A: SVOM/VT optical upper limits
  34. GRB 260916B: Glowbug gamma-ray detection of a short burst
  35. GRB 260918A: EP-FXT follow-up observation
  36. GRB 260917B: Mondy optical upper limit
  37. IPN triangulation of GRB 260916B (short)
  38. EP260917A: J-band upper limit with WINTER
  39. IPN triangulation of GRB 260810A
  40. GRB 260917B: EP-FXT follow-up observation
  41. EP260917a: COLIBRÍ optical upper limits
  42. GRB 260915A: Swift-XRT afterglow detection
  43. GRB 260918A: LCO optical upper limits
  44. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  45. GRB 260918A: SVOM detection of a burst
  46. GRB 260917B: FRAM-Auger optical limits
  47. IceCube-260916A: Upper limits from a search for additional neutrino events in IceCube
  48. GRB 260917A: Glowbug gamma-ray detection
  49. GRB 260915A: SVOM/ECLAIRs refined analysis
  50. GRB 260917B: WINTER J-band observations
  51. GRB 260917B: SVOM/VT optical observations
  52. GRB 260917B: LCO optical observation
  53. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  54. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  55. GRB 260915A: J-band upper limit with WINTER
  56. IceCube-260916A - IceCube observation of a high-energy neutrino candidate track-like event
  57. GRB 260909A: NOEMA detection
  58. GRB 260914A: SVOM/GRM observation
  59. GRB 260914A: Mondy and TShAO optical observations
  60. GRB 260914A: SVOM/ECLAIRs refined analysis
  61. GRB 260909A: Swift-XRT observations
  62. GRB 260915A: Swift ToO observations
  63. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  64. GRB 260915A: SVOM/C-GFT optical upper limits
  65. GRB 260915A: EP-FXT follow-up observation
  66. GRB 260915A: SVOM/VT refined early optical upper limits
  67. GRB 260915A: EP-FXT follow-up observation
  68. GRB 260915A: REM optical/NIR observations
  69. GRB 260914A: REM optical/NIR observations
  70. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  71. GRB 260915A: SVOM/VT optical upper limits
  72. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  73. GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
  74. GRB 260915A: 10.4m GTC deep optical limits
  75. GRB 260915A: NOT optical upper limit
  76. GRB 260915A: SVOM/VT optical upper limits from VHF data
  77. Fermi GBM Sub-Threshold Detection of GRB 260915A
  78. GRB 260915A: LCO optical upper limits
  79. GRB 260914A: EP-FXT follow-up observation
  80. Fermi GBM Sub-Threshold Detection of GRB 260914A
  81. GRB 260914A: LCO optical observation
  82. GRB 260914A: SVOM/C-GFT optical observations
  83. GRB 260914A: SVOM/VT optical counterpart confirmation
  84. GRB 260914A: SVOM/VT optical observation from VHF data
  85. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  86. GRB 260914A: SVOM detection of a burst
  87. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  88. GRB 260818A: Continued ATCA observations
  89. GRB 260913A: SVOM/C-GFT optical upper limit
  90. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  91. GRB 260907A: SVOM/GRM observation
  92. GRB 260909A: CrAO and AbAO optical upper limits
  93. GRB 260909A: SVOM/ECLAIRs refined analysis
  94. GRB 260910B: GOTO tentative optical counterpart candidates
  95. GRB 260909A: Swift ToO observations
  96. GRB 260909A: KAIT optical upper limit
  97. GRB 260903A: Swift-XRT observations
  98. EP260806a: VLA+ALMA radio detections
  99. GRB 260909A: OHP/T193 z-band upper limit
  100. GRB 260909A: VLT optical and near-infrared upper limits

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