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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"
  1. GRB 240905B: Fermi GBM Final Real-time Localization
  2. GRB 240825A: ATCA Detection of Radio Counterpart
  3. Swift GRB 240904A: Global MASTER-Net observations report
  4. GRB 240905A: Fermi GBM Final Real-time Localization
  5. Fermi Gamma-ray Burst Monitor trigger 747163821/240904729 is not a GRB
  6. Fermi trigger No 747163821: Global MASTER-Net observations report
  7. GRB 240904A: Swift detection of a burst
  8. GRB 240828A: SVOM/GRM observation
  9. LIGO/Virgo/KAGRA S240825ar: Upper limits from Swift/BAT-GUANO
  10. LIGO/Virgo/KAGRA S240807h: Upper limits from Swift/BAT-GUANO
  11. Fermi Gamma-ray Burst Monitor trigger 240831A is not a GRB
  12. LIGO/Virgo/KAGRA S240902bq: Updated Sky localization
  13. GRB 240828A: GECAM detection
  14. GRB 240831B: Fermi GBM Final Localization
  15. Fermi Gamma-ray Burst Monitor trigger 746882332/240901471 is not a GRB
  16. LIGO/Virgo/KAGRA S240902bq: Identification of a GW compact binary merger candidate
  17. GRB 240825A: Magnitude Correction in SVOM/C-GFT Optical Observations
  18. GRB 240825A: MeerLICHT afterglow detection
  19. Fermi trigger No 746923430: Global MASTER-Net observations report
  20. GRB 240828A: SAO RAS AS-500(2) optical observations
  21. GRB 240821A: VLT spectroscopic observations
  22. Fermi trigger No 746882332: Global MASTER-Net observations report
  23. GRB 240825A: TSHAO Optical Upper Limit
  24. GRB 240829B: GRBAlpha detection
  25. GRB240828B: REM optical/NIR upper limits
  26. Fermi trigger No 746816563: Global MASTER-Net observations report
  27. GRB 240828B: AbAO optical upper limit
  28. GRB 240831A: Fermi GBM Final Real-time Localization
  29. GRB 240825A: SOAR observations
  30. GRB 240828B: Mephisto optical upper limit
  31. GRB 240828B: GRANDMA Optical Upper Limit
  32. LIGO/Virgo/KAGRA S240830gn: Coverage and upper limits from MAXI/GSC observations
  33. LIGO/Virgo/KAGRA S240830gn: Updated Sky localization and EM Bright Classification
  34. GRB 240829A: Swift-BAT refined analysis
  35. GRB 240825A: Swift-BAT refined analysis
  36. LIGO/Virgo/KAGRA S240830gn: Identification of a GW compact binary merger candidate
  37. GRB 240825A: MeerKAT detection
  38. GRB 240828B: J-band upper limit from WINTER
  39. Fermi trigger No 746684112: Global MASTER-Net observations report
  40. GRB 240828B: GMG Optical Upper Limit
  41. GRB 240828A: KAIT continued optical observations
  42. GRB 240828B: GWAC-F50A optical upper limit
  43. GRB 240828B: SVOM/C-GFT optical upper limit
  44. GRB 240828B: SAO RAS optical upper limit
  45. GRB 240828B: KAIT optical upper limit
  46. GRB 240828A: SAO RAS optical observations
  47. Fermi trigger No 746587425: Global MASTER-Net observations report
  48. GRB 240829B: Fermi GBM Final Localization
  49. GRB 240828A: Fermi GBM Observation
  50. GRB 240629A: First GRB Detected by BurstCube
  51. GRB 240828A: KAIT Optical Afterglow Candidate
  52. GRB 240825A: SVOM/VT optical detection
  53. GRB 240828A: Swift-XRT afterglow detection
  54. GRB 240825A: further SAO RAS optical observations
  55. GRB 240825A: iTelescope optical observations
  56. GRB 240828B: Swift-XRT afterglow detection
  57. GRB 240829A: Swift detection of a burst
  58. Swift GRB240829.16: Global MASTER-Net observations report
  59. GRB 240828A: Fermi-LAT detection
  60. GRB 240828A: Tiled Swift observations
  61. LAT GRB240828.62: Global MASTER-Net observations report
  62. GRB 240828A: AstroSat CZTI detection of a long burst
  63. Fermi GRB 240828A: Bassano Bresciano Observatory upper limit
  64. GRB 240825A: Upper limits from a neutrino search with IceCube
  65. GRB 240819A as a likely X-Ray Flash
  66. GRB 240828B: Swift ToO observations
  67. GRB 240821A: PRIME near-infrared observations
  68. GRB 240825A: VLA detection
  69. Fermi GRB 240828A: Global MASTER-Net observations report
  70. Fermi trigger No 746438824: Global MASTER-Net observations report
  71. SVOM GRB 240821A: optical afterglow discovery
  72. GRB 240828B : Detection of a possible very soft X-ray transient by SVOM/ECLAIRs
  73. GRB 240828A: Fermi GBM Final Real-time Localization
  74. GRB 240821A: the second and third EP-FXT follow-up observations and afterglow candidates
  75. GRB 240825A: GECAM detection
  76. GRB 240825A: ALMA detection
  77. GRB 240825A: SAO RAS optical observations
  78. GRB 240824A: GIT optical upper limit
  79. GRB 240819A: Swift afterglow confirmation
  80. GRB 240825A: TNG optical photometry and spectroscopy
  81. LIGO/Virgo/KAGRA S240825ar: Updated Sky localization
  82. LIGO/Virgo/KAGRA S240825ar: Updated Sky localization
  83. GRB 240825A: NUTTelA-TAO / BSTI Optical Limits
  84. GRB 240825A: GMG Continued Optical Observation on the Second Night
  85. GRB 240824B: Ondrejov D50 optical limit
  86. GRB 240825A: KAIT optical observations
  87. GRB 240825A: PRIME near-infrared detection
  88. Konus-Wind detection of GRB 240825A (bright/long)
  89. GRB 240825A: Fermi GBM Observation
  90. GRB 240825A : MISTRAL/T193 OHP optical follow-up of the afterglow
  91. GRB 240825A: AKO Optical Follow-Up Observations
  92. GRB 240825A: AstroSat CZTI detection of the long bright burst
  93. SGR 1E 1841-045 / Kes 73: SVOM/GRM observation
  94. GRB 240825A: Swift/UVOT Detection
  95. GRB 240825A: REM detection of the optical/NIR afterglow
  96. GRB 240825A: Swift-XRT refined Analysis
  97. GRB 240825A: VLT/X-shooter redshift
  98. GRB 240825A: SVOM/C-GFT optical observations
  99. GRB 240825A: Montarrenti Observatory optical observations
  100. GRB 240825A: Enhanced Swift-XRT position

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