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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"

11528 results found.

  1. GRB 250824A: Fermi GBM Final Real-time Localization
  2. GRB 250823A: NOT optical observations
  3. GRB 250823A: Fermi GBM Observation
  4. GRB 250823A: BOOTES6/DPRT early optical detection
  5. GRB 250823A: Liverpool Telescope optical detection
  6. GRB 250823A: Fermi GBM Final Real-time Localization
  7. Konus-Wind detection of GRB 250821B
  8. IPN triangulation of GRB 250821B (long/bright)
  9. GRB 250821B: SVOM/GRM observation
  10. Fermi GRB 250821B: Global MASTER-Net observations report
  11. GRB 250821C: Fermi GBM Final Real-time Localization
  12. GRB 250821B: Fermi GBM Detection
  13. GRB 250821B: BALROG localization (Fermi Trigger / GRB 250821672)
  14. GRB 250821B: Fermi GBM Final Localization of a Bright Burst
  15. GRB 250814A: CMO SAI and SAO RAS izJ observations.
  16. IPN triangulation of GRB 250816A (short)
  17. LIGO/Virgo/KAGRA S250818k: Upper limits from Fermi-GBM Observations
  18. GRB 250818A: AstroSat CZTI detection
  19. Fermi Gamma-ray Burst Monitor trigger 777342746/250820022 is not a GRB
  20. GRB 250820A: Fermi GBM Final Real-time Localization
  21. Fermi GRB 250816A: Global MASTER-Net observations report
  22. Fermi Gamma-ray Burst Monitor trigger 777251788/250818970 is not a GRB
  23. GRB 250818C: Fermi GBM Final Real-time Localization
  24. Fermi trigger No 776849714: Global MASTER-Net observations report
  25. GRB 250813B: SVOM/ECLAIRs refined analysis
  26. GRB 250818A: Fermi GBM Observation
  27. GRB 250814A: Further GRAWITA TNG NIR observations
  28. GRB 250818A: Fermi GBM Final Real-time Localization
  29. GRB 250816A: SVOM/GRM observation of a short burst
  30. Fermi GRB 250814B: Global MASTER-Net observations report
  31. GRB 250816A: Fermi GBM Final Real-time Localization
  32. GRB 250815A: Fermi GBM Final Localization
  33. GRB 250813B: Liverpool Telescope optical upper limits
  34. GRB 250814A: Further COLIBRÍ optical upper limit
  35. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  36. GRB 250814A: GRAWITA TNG NIR observations
  37. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  38. GRB250814A: TRT optical upper limits
  39. GRB 250814B: SVOM/GRM observation
  40. GRB 250813B: SVOM/GRM observation
  41. GRB 250814A: P200/WIRC observations of the afterglow candidate
  42. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  43. GRB 250814A: KAIT optical upper limit
  44. GRB 240814A: Fermi GBM Observation
  45. GRB 250814A: Possible afterglow candidate from P200/WIRC
  46. GRB 250813B: Fermi GBM Observation
  47. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  48. Fermi trigger No 776818276: Global MASTER-Net observations report
  49. GRB 250814A: J-band upper limit from WINTER
  50. GRB 250814A: COLIBRÍ optical upper limit
  51. GRB 250814B: Fermi GBM Final Real-time Localization
  52. GRB 250813A: AstroSat CZTI detection
  53. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  54. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  55. GRB 250814A: Fermi GBM Final Real-time Localization
  56. GRB 250813A: Fermi GBM Final Localization
  57. IceCube-250813A - IceCube observation of a high-energy neutrino candidate track-like event
  58. Fermi Gamma-ray Burst Monitor trigger 776705265/250812644 is not a GRB
  59. Fermi Gamma-ray Burst Monitor trigger 776620220/250811660 is not a GRB
  60. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  61. GRB 250702B: Chandra X-ray Detection
  62. Fermi GRB 250808A: Global MASTER-Net observations report
  63. Fermi Gamma-ray Burst Monitor trigger 776449964/250809689 is not a GRB
  64. GRB 250808A: Fermi GBM Observation
  65. GRB 250808A: SVOM detection of a long burst
  66. GRB 250808A: Fermi GBM Final Real-time Localization
  67. EP250806a: Upper limit from Fermi-GBM Observations
  68. GRB 250804C: AstroSat CZTI detection of a long burst
  69. IceCube-250804A - IceCube observation of a high-energy neutrino candidate track-like event
  70. Fermi trigger No 776041355: Global MASTER-Net observations report
  71. GRB 250804A: Fermi GBM Final Localization
  72. Fermi Gamma-ray Burst Monitor trigger 775945985/250803856 is not a GRB
  73. GRB 250725A: AstroSat CZTI detection
  74. GRB 250725A: PRIME near-infrared observations
  75. GRB 250728A: Swift-XRT observations
  76. GRB 250728A: COLIBRÍ optical upper limit
  77. GRB 250728A: Fermi GBM Observation
  78. Fermi trigger No 775387550: Global MASTER-Net observations report
  79. GRB 250728A: Swift ToO observations
  80. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  81. GRB 250725A: Fermi GBM Observation
  82. Konus-Wind detection of GRB 250725A
  83. GRB 250725A: SVOM/GRM observation
  84. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  85. GRB 250725A: Fermi-LAT detection
  86. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  87. GRB 250725A: SVOM/VT optical candidate
  88. GRB 250725A: Fermi GBM Final Real-time Localization
  89. Fermi GRB 250725A: Global MASTER-Net observations report
  90. GRB 250723B: Fermi GBM Final Real-time Localization
  91. GRB 250721A: Fermi GBM Observation
  92. GRB 250723A: Fermi GBM Final Real-time Localization
  93. GRB 250722A: Fermi GBM Final Real-time Localization
  94. GRB 250717B: SVOM/GRM observation
  95. GRB 250721A: MAXI/GSC detection
  96. GRB 250721A: Fermi GBM Final Localization
  97. GRB 250720B: Fermi GBM Final Localization Correction
  98. GRB 250720A: Fermi GBM Final Localization
  99. Fermi trigger No 774730635: Global MASTER-Net observations report
  100. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate

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