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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"

28063 results found.

  1. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  2. GRB 260925A: J-band upper limit by SYSU 80cm infrared telescope
  3. GRB 260925A: Swift-XRT refined Analysis
  4. EP260924a: EP-FXT follow-up observation
  5. Swift Trigger 1513439 is probably not a GRB
  6. GRB 260925A: Swift/UVOT Upper Limits
  7. Konus-Wind detection of GRB 260924A
  8. GRB 260923A: Glowbug gamma-ray detection
  9. GRB 260924A: Optical follow-up observations with Kinder
  10. GRB 260922A: Glowbug gamma-ray detection
  11. GRB 260925A: Enhanced Swift-XRT position
  12. GRB 260925A: COLIBRÍ optical upper limits
  13. GRB 260925A: FRAM-Auger optical limit
  14. GRB 260924A: Ondrejov D50 optical afterglow detection
  15. GRB 260924A: SVOM/GRM observation
  16. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  17. GRB 260925A: Swift detection of a burst
  18. GRB 260923A: Insight-HXMT/HE detection
  19. EP260924a: EP-WXT detection of an X-ray transient
  20. GRB 260924A: Swift/UVOT Detection
  21. GRB 260924A: NuSTAR detection of prompt emission
  22. GRB 260924A: Swift/UVOT Upper Limits
  23. GRB 260924A: Swift-XRT refined Analysis
  24. Konus-Wind detection of GRB 260922A
  25. GRB 260922A: NuSTAR detection of prompt emission
  26. GRB 260921A: NuSTAR detection of prompt emission
  27. Konus-Wind detection of GRB 260921A (correction to GCN 45722)
  28. GRB 260924A: Fermi GRB Observation
  29. Konus-Wind detection of GRB 260921A (possible merger-origin)
  30. GRB 260924A: Fermi-LAT detection of a bright burst
  31. GRB 260924A: AstroSat CZTI detection
  32. GRB 260924A: NOT optical counterpart confirmation
  33. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  34. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  35. GRB 260924A: Enhanced Swift-XRT position
  36. GRB 260924A: Swift detection of a burst
  37. GRB 260924A: Fermi GBM Final Real-time Localization
  38. GRB 260923A: Fermi GBM Final Real-time Localization
  39. Trigger_21914: Swift ToO observations
  40. EP260806a: e-MERLIN detection at 5 GHz
  41. GRB 260922A: Ondrejov D50 optical limit
  42. ATCA observations of GRB 260909A
  43. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  44. GRB 260922A: Swift/UVOT Upper Limits
  45. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  46. GRB 260922A: COLIBRÍ optical upper limits
  47. GRB 260922A: Swift-XRT refined Analysis
  48. GRB 260922A: Enhanced Swift-XRT position
  49. Konus-Wind detection of GRB 260810A
  50. GRB 260920A: Glowbug gamma-ray detection
  51. GRB 260922A: SVOM/C-GFT optical upper limit
  52. GRB 260922A: Swift detection of a burst
  53. GRB 260917C: AstroSat CZTI detection
  54. GRB 260920B/EP260920b: GECAM-B detection of a burst
  55. GRB 260921A: AstroSat CZTI detection
  56. GRB 260921B: Fermi GBM Final Localization
  57. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  58. Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
  59. GRB 260921A: Swift detection of a burst
  60. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  61. GRB 260921A: Fermi GBM Final Real-time Localization
  62. GRB 260920A: AstroSat CZTI detection
  63. EP260920b: LCO optical counterpart detection
  64. EP260920b: Einstein Probe detection of an X-ray transient
  65. EP-WXT detected a brightening of HMXB LS V +44 17
  66. EP260920a: NOT early time optical upper limits
  67. GRB 260920A: Fermi GBM Final Real-time Localization
  68. EP260917b: EP-FXT non-detection and upper limit
  69. EP260920a: Einstein Probe detection of an X-ray transient
  70. GRB 260915A: VLT optical and near-infrared upper limits
  71. IceCube-260919A - IceCube observation of a high-energy neutrino candidate track-like event
  72. GRB 260918A: SVOM/C-GFT optical upper limits
  73. Fermi GBM Sub-Threshold Detection of GRB 260918A
  74. Konus-Wind detection of GRB 260916B (short/hard)
  75. GRB 260918A: SVOM/VT optical upper limits
  76. GRB 260916B: Glowbug gamma-ray detection of a short burst
  77. IPN triangulation of GRB 260916B (short)
  78. EP260917b: EP-WXT detection of an X-ray transient
  79. IPN triangulation of GRB 260810A
  80. GRB 260915A: Swift-XRT afterglow detection
  81. EP260917a: Einstein Probe detection of an X-ray transient
  82. GRB 260918A: SVOM detection of a burst
  83. GRB 260917C: Fermi GBM Final Real-time Localization
  84. GRB 260916B: Fermi GBM Detection
  85. GRB 260916B: Fermi GBM Final Localization
  86. GRB 260917A: Glowbug gamma-ray detection
  87. GRB 260917B: SVOM detection of a faint burst
  88. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  89. GRB 260917A: Fermi GBM Final Real-time Localization
  90. IceCube-260916A - IceCube observation of a high-energy neutrino candidate track-like event
  91. GRB 260909A: NOEMA detection
  92. GRB 260909A: Swift-XRT observations
  93. GRB 260916A: MAXI/GSC detection
  94. GRB 260915A: Swift ToO observations
  95. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  96. GRB 260915A: SVOM/C-GFT optical upper limits
  97. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  98. GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
  99. GRB 260915A: 10.4m GTC deep optical limits
  100. GRB 260915A: SVOM/VT optical upper limits from VHF data

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