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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"

14822 results found.

  1. GRB 260924A: Near-infrared detection with MDM/MIRAGE
  2. GRB 260926A: Fermi GBM Final Real-time Localization
  3. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  4. EP260924a: EP-FXT follow-up observation
  5. Konus-Wind detection of GRB 260924A
  6. GRB 260923A: Glowbug gamma-ray detection
  7. GRB 260924A: Optical follow-up observations with Kinder
  8. GRB 260922A: Glowbug gamma-ray detection
  9. GRB 260924A: Ondrejov D50 optical afterglow detection
  10. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  11. GRB 260925A: Swift detection of a burst
  12. GRB 260923A: Insight-HXMT/HE detection
  13. EP260924a: EP-WXT detection of an X-ray transient
  14. GRB 260924A: Swift/UVOT Detection
  15. GRB 260924A: NuSTAR detection of prompt emission
  16. GRB 260924A: Swift/UVOT Upper Limits
  17. Konus-Wind detection of GRB 260922A
  18. GRB 260922A: NuSTAR detection of prompt emission
  19. GRB 260921A: NuSTAR detection of prompt emission
  20. Konus-Wind detection of GRB 260921A (correction to GCN 45722)
  21. Konus-Wind detection of GRB 260921A (possible merger-origin)
  22. GRB 260924A: Fermi-LAT detection of a bright burst
  23. GRB 260924A: AstroSat CZTI detection
  24. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  25. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  26. GRB 260924A: Swift detection of a burst
  27. GRB 260924A: Fermi GBM Final Real-time Localization
  28. GRB 260923A: Fermi GBM Final Real-time Localization
  29. EP260806a: e-MERLIN detection at 5 GHz
  30. GRB 260922A: Ondrejov D50 optical limit
  31. ATCA observations of GRB 260909A
  32. Konus-Wind detection of GRB 260810A
  33. GRB 260920A: Glowbug gamma-ray detection
  34. GRB 260922A: Swift detection of a burst
  35. GRB 260917C: AstroSat CZTI detection
  36. GRB 260920B/EP260920b: GECAM-B detection of a burst
  37. GRB 260921A: AstroSat CZTI detection
  38. GRB 260921B: Fermi GBM Final Localization
  39. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  40. Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
  41. GRB 260921A: Swift detection of a burst
  42. GRB 260921A: Fermi GBM Final Real-time Localization
  43. GRB 260920A: AstroSat CZTI detection
  44. EP260920b: LCO optical counterpart detection
  45. EP260920b: Einstein Probe detection of an X-ray transient
  46. EP-WXT detected a brightening of HMXB LS V +44 17
  47. EP260920a: NOT early time optical upper limits
  48. EP260920a: NOT optical upper limits
  49. GRB 260920A: Fermi GBM Final Real-time Localization
  50. EP260917b: EP-FXT non-detection and upper limit
  51. EP260920a: LCO optical counterpart candidate
  52. EP260920a: Einstein Probe detection of an X-ray transient
  53. GRB 260915A: VLT optical and near-infrared upper limits
  54. IceCube-260919A - IceCube observation of a high-energy neutrino candidate track-like event
  55. GRB 260918A: SVOM/C-GFT optical upper limits
  56. Fermi GBM Sub-Threshold Detection of GRB 260918A
  57. Konus-Wind detection of GRB 260916B (short/hard)
  58. GRB 260918A: SVOM/VT optical upper limits
  59. GRB 260916B: Glowbug gamma-ray detection of a short burst
  60. GRB 260917B: Mondy optical upper limit
  61. IPN triangulation of GRB 260916B (short)
  62. EP260917b: EP-WXT detection of an X-ray transient
  63. IPN triangulation of GRB 260810A
  64. GRB 260917B: EP-FXT follow-up observation
  65. GRB 260915A: Swift-XRT afterglow detection
  66. EP260917a: Einstein Probe detection of an X-ray transient
  67. GRB 260918A: SVOM detection of a burst
  68. GRB 260917C: Fermi GBM Final Real-time Localization
  69. GRB 260917B: FRAM-Auger optical limits
  70. GRB 260916B: Fermi GBM Detection
  71. GRB 260916B: Fermi GBM Final Localization
  72. GRB 260917A: Glowbug gamma-ray detection
  73. GRB 260917B: WINTER J-band observations
  74. GRB 260917B: SVOM/VT optical observations
  75. GRB 260917B: LCO optical observation
  76. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  77. GRB 260917B: SVOM detection of a faint burst
  78. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  79. GRB 260917A: Fermi GBM Final Real-time Localization
  80. IceCube-260916A - IceCube observation of a high-energy neutrino candidate track-like event
  81. GRB 260909A: NOEMA detection
  82. GRB 260916A: MAXI/GSC detection
  83. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  84. GRB 260915A: SVOM/C-GFT optical upper limits
  85. GRB 260915A: 10.4m GTC deep optical limits
  86. GRB 260915A: SVOM/VT optical upper limits from VHF data
  87. Fermi GBM Sub-Threshold Detection of GRB 260915A
  88. GRB 260915A: SVOM detection of a burst
  89. Fermi GBM Sub-Threshold Detection of GRB 260914A
  90. GRB 260914A: SVOM detection of a burst
  91. GRB 260818A: Continued ATCA observations
  92. GRB 260913A: SVOM detection of a faint burst
  93. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  94. GRB 260910B: GOTO tentative optical counterpart candidates
  95. GRB 260910B: Fermi GBM Final Real-time Localization
  96. EP260806a: VLA+ALMA radio detections
  97. GRB 260910A: Fermi GBM Final Real-time Localization
  98. EP260806a: NOEMA detection
  99. EP260623a: NOEMA detections
  100. GRB 260909A: SVOM detection of a burst

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