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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"

11099 results found.

  1. Fermi GRB 250814B: Global MASTER-Net observations report
  2. GRB 250816A: Fermi GBM Final Real-time Localization
  3. GRB 250815A: Fermi GBM Final Localization
  4. GRB 250813B: Liverpool Telescope optical upper limits
  5. GRB 250814A: Further COLIBRÍ optical upper limit
  6. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  7. GRB 250814A: GRAWITA TNG NIR observations
  8. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  9. GRB250814A: TRT optical upper limits
  10. GRB 250814B: SVOM/GRM observation
  11. GRB 250813B: SVOM/GRM observation
  12. GRB 250814A: P200/WIRC observations of the afterglow candidate
  13. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  14. GRB 250814A: KAIT optical upper limit
  15. GRB 240814A: Fermi GBM Observation
  16. GRB 250814A: Possible afterglow candidate from P200/WIRC
  17. GRB 250813B: Fermi GBM Observation
  18. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  19. Fermi trigger No 776818276: Global MASTER-Net observations report
  20. GRB 250814A: J-band upper limit from WINTER
  21. GRB 250814A: COLIBRÍ optical upper limit
  22. GRB 250814B: Fermi GBM Final Real-time Localization
  23. GRB 250813A: AstroSat CZTI detection
  24. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  25. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  26. GRB 250814A: Fermi GBM Final Real-time Localization
  27. GRB 250813A: Fermi GBM Final Localization
  28. IceCube-250813A - IceCube observation of a high-energy neutrino candidate track-like event
  29. Fermi Gamma-ray Burst Monitor trigger 776705265/250812644 is not a GRB
  30. Fermi Gamma-ray Burst Monitor trigger 776620220/250811660 is not a GRB
  31. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  32. GRB 250702B: Chandra X-ray Detection
  33. Fermi GRB 250808A: Global MASTER-Net observations report
  34. Fermi Gamma-ray Burst Monitor trigger 776449964/250809689 is not a GRB
  35. GRB 250808A: Fermi GBM Observation
  36. GRB 250808A: SVOM detection of a long burst
  37. GRB 250808A: Fermi GBM Final Real-time Localization
  38. EP250806a: Upper limit from Fermi-GBM Observations
  39. GRB 250804C: AstroSat CZTI detection of a long burst
  40. IceCube-250804A - IceCube observation of a high-energy neutrino candidate track-like event
  41. Fermi trigger No 776041355: Global MASTER-Net observations report
  42. GRB 250804A: Fermi GBM Final Localization
  43. Fermi Gamma-ray Burst Monitor trigger 775945985/250803856 is not a GRB
  44. GRB 250725A: AstroSat CZTI detection
  45. GRB 250725A: PRIME near-infrared observations
  46. GRB 250728A: Swift-XRT observations
  47. GRB 250728A: COLIBRÍ optical upper limit
  48. GRB 250728A: Fermi GBM Observation
  49. Fermi trigger No 775387550: Global MASTER-Net observations report
  50. GRB 250728A: Swift ToO observations
  51. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  52. GRB 250725A: Fermi GBM Observation
  53. Konus-Wind detection of GRB 250725A
  54. GRB 250725A: SVOM/GRM observation
  55. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  56. GRB 250725A: Fermi-LAT detection
  57. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  58. GRB 250725A: SVOM/VT optical candidate
  59. GRB 250725A: Fermi GBM Final Real-time Localization
  60. Fermi GRB 250725A: Global MASTER-Net observations report
  61. GRB 250723B: Fermi GBM Final Real-time Localization
  62. GRB 250721A: Fermi GBM Observation
  63. GRB 250723A: Fermi GBM Final Real-time Localization
  64. GRB 250722A: Fermi GBM Final Real-time Localization
  65. GRB 250717B: SVOM/GRM observation
  66. GRB 250721A: MAXI/GSC detection
  67. GRB 250721A: Fermi GBM Final Localization
  68. GRB 250720B: Fermi GBM Final Localization Correction
  69. GRB 250720A: Fermi GBM Final Localization
  70. Fermi trigger No 774730635: Global MASTER-Net observations report
  71. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  72. Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB
  73. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  74. GRB 250717B: COLIBRÍ optical upper limit
  75. GRB 250717B: Swift-XRT observations
  76. GRB 250718B: Fermi GBM Final Localization Correction
  77. GRB 250718B: Fermi GBM Final Real-time Localization
  78. GRB 250717B: Swift ToO observations
  79. GRB 250717B: Fermi GBM Observation
  80. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  81. Konus-Wind detection of GRB 250716A
  82. GRB 250716A: Swift-XRT afterglow detection
  83. GRB 250717B: Fermi GBM Final Real-time Localization
  84. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  85. GRB 250717A: Fermi GBM Final Real-time Localization
  86. GRB 250716A: Swift ToO observations
  87. GRB 250716A: GOTO tentative optical counterpart candidate
  88. GRB 250716A: Fermi GBM Observation
  89. GRB 250714A: SVOM/GRM observation
  90. Fermi GRB 250716A: Global MASTER-Net observations report
  91. GRB 250716A: Fermi GBM Final Real-time Localization
  92. Fermi GRB 250715A: Global MASTER-Net observations report
  93. GRB 250715A: Fermi GBM Final Real-time Localization
  94. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  95. Fermi GRB 250714A: Global MASTER-Net observations report
  96. GRB 250714A: Fermi GBM Final Real-time Localization
  97. GRB 250711A: DDOTI Optical Upper Limit
  98. GRB 250711A: SVOM/GRM observation
  99. Fermi GRB 250711A: Global MASTER-Net observations report
  100. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)

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