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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"

11113 results found.

  1. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  2. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  3. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  4. IceCube-241006A - IceCube observation of a high-energy neutrino candidate track-like event
  5. GRB 240930B: SVOM/C-GFT optical upper limit
  6. Fermi trigger No 749721670: Global MASTER-Net observations report
  7. GRB 240930B / EP 240930a: SVOM/GRM observation
  8. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  9. GRB 241002B: Fermi GBM Observation
  10. Fermi trigger No 749735279: Global MASTER-Net observations report
  11. Fermi trigger No 749630753: Global MASTER-Net observations report
  12. Fermi trigger No 749693019: Global MASTER-Net observations report
  13. GRB 241002B: Swift-XRT observations
  14. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  15. GRB 241002B: Swift ToO observations
  16. GRB 241002B: PRIME near-infrared detection
  17. Fermi-GBM Sub-Threshold Detection of GRB 241002D
  18. IPN triangulation of GRB 240930B / EP 240930a
  19. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  20. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  21. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  22. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  23. EP240930a: Liverpool Telescope observations
  24. GRB 241002B: GOTO optical counterpart candidate
  25. GRB 240929A: Liverpool Telescope prompt followup observations
  26. Fermi GRB 241002B: Global MASTER-Net observations report
  27. GRB 241002B: Fermi GBM Final Real-time Localization
  28. GRB 240930B: Fermi GBM Observation
  29. GRB 240930B: GRBAlpha detection
  30. GRB 240929A: GRBAlpha detection
  31. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  32. EP240930a: EP-FXT follow-up observation update
  33. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  34. EP240930a: GOTO optical upper limits
  35. GRB 240929A: SVOM/GRM observation
  36. EP240930a: EP-WXT detection of a fast X-ray transient
  37. GRB 240929A : Leavitt Observatory optical upper limit
  38. Fermi GRB 240930B: Global MASTER-Net observations report
  39. GRB 240930B: Fermi GBM Final Real-time Localization
  40. GRB 240825A: LBT optical observations
  41. Fermi GRB 240930A: Global MASTER-Net observations report
  42. Fermi Gamma-ray Burst Monitor trigger 749362078/240930172 (GRB 240930A) is not a GRB
  43. GRB 240930A: Fermi GBM Final Real-time Localization
  44. Fermi trigger No 749339671: Global MASTER-Net observations report
  45. Fermi Gamma-ray Burst Monitor trigger 749339671/240929913 is not a GRB
  46. GRB 240929A long GRB detected by INTEGRAL
  47. GRB 240929A: BALROG localization (Fermi Trigger 749332209 / GRB 240929826)
  48. Fermi GRB 240929A: Global MASTER-Net observations report
  49. GRB 240929A: Fermi GBM Final Real-time Localization
  50. IceCube-240929A - IceCube observation of a high-energy neutrino candidate track-like event
  51. Konus-Wind detection of GRB 240912A
  52. Fermi Gamma-ray Burst Monitor trigger 749191601/240928199 is not a GRB
  53. Konus-Wind detection of GRB 240905B
  54. Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
  55. Konus-Wind detection of GRB 240918B
  56. IPN triangulation of GRB 240918B
  57. GRB 240905B: VZLUSAT-2 detection
  58. GRB 240918B: AstroSat CZTI detection
  59. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  60. GRB 240414A: further radio observations with the VLA
  61. GRB 240919A / EP240919a: SVOM/GRM observation
  62. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  63. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  64. GRB 240910A: radio detection with the VLA
  65. EP240919a: JinShan optical upper limits
  66. EP240919a is likely a GRB event
  67. GRB 240918A and GRB 240918B : INTEGRAL SPI ACS LIGHT CURVE
  68. GRB 240918B: Fermi GBM Detection
  69. Fermi GRB 240918A: Global MASTER-Net observations report
  70. GRB 240918A: Fermi GBM Final Real-time Localization
  71. GRB 240916A: GRBAlpha detection
  72. GRB 240914B: GRBAlpha detection
  73. GRB 240916A: NOT optical observation
  74. IPN triangulation of GRB 240913C / EP 240913a
  75. GRB 240825A: INTEGRAL SPI ACS LIGHT CURVE
  76. GRB 240916A: Fermi GBM Observation
  77. GRB 240821A: radio observation with the VLA
  78. GRB 240916A (AT 2024vlp / GOTO24fzn): VLT/X-shooter redshift
  79. GRB 240916A: Swift-XRT afterglow detection
  80. GRB 240916A: Swift ToO observations
  81. GRB 240916A: JinShan optical decay in one of the two GOTO candidates
  82. GRB 240916B: Fermi GBM Final Real-time Localization
  83. GRB 240914B: Fermi GBM Final Localization
  84. GRB 240916A: GOTO identification of two new optical sources within the GBM localisation region
  85. GRB 240916A INTEGRAL SPI ACS LIGHT CURVE
  86. GRB 240916A: Fermi GBM Final Real-time Localization
  87. Fermi Gamma-ray Burst Monitor trigger 748124309/240915846 is not a GRB
  88. EP240913a / GRB 240913C INTEGRAL SPI ACS LIGHT CURVE
  89. GRB 240913C: Fermi GBM detection
  90. GRB 240913C: Joint location by ETJASMIN
  91. GRB 240914B: AstroSat CZTI detection
  92. EP240913A / GRB 240913C: AstroSat CZTI detection
  93. GRB 240910A: SVOM/VT optical observations
  94. GRB 240914B: BALROG localization (Fermi Trigger 747990592 / GRB 240914298)
  95. EP240913a: A GRB Event
  96. GRB 240913B: Fermi GBM Final Real-time Localization
  97. Fermi Gamma-ray Burst Monitor trigger 747837485/240912526 is not a GRB
  98. Fermi trigger No 747920561: Global MASTER-Net observations report
  99. GRB 240912A: SVOM/GRM observation
  100. Fermi GRB 240913A: Global MASTER-Net observations report

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