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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 240825A: Swift-BAT refined analysis
  2. LIGO/Virgo/KAGRA S240830gn: Identification of a GW compact binary merger candidate
  3. GRB 240825A: MeerKAT detection
  4. GRB 240828B: J-band upper limit from WINTER
  5. Fermi trigger No 746684112: Global MASTER-Net observations report
  6. GRB 240828B: GMG Optical Upper Limit
  7. GRB 240828A: KAIT continued optical observations
  8. GRB 240828B: GWAC-F50A optical upper limit
  9. GRB 240828B: SVOM/C-GFT optical upper limit
  10. GRB 240828B: SAO RAS optical upper limit
  11. GRB 240828B: KAIT optical upper limit
  12. GRB 240828A: SAO RAS optical observations
  13. Fermi trigger No 746587425: Global MASTER-Net observations report
  14. GRB 240829B: Fermi GBM Final Localization
  15. GRB 240828A: Fermi GBM Observation
  16. GRB 240629A: First GRB Detected by BurstCube
  17. GRB 240828A: KAIT Optical Afterglow Candidate
  18. GRB 240825A: SVOM/VT optical detection
  19. GRB 240828A: Swift-XRT afterglow detection
  20. GRB 240825A: further SAO RAS optical observations
  21. GRB 240825A: iTelescope optical observations
  22. GRB 240828B: Swift-XRT afterglow detection
  23. GRB 240829A: Swift detection of a burst
  24. Swift GRB240829.16: Global MASTER-Net observations report
  25. GRB 240828A: Fermi-LAT detection
  26. GRB 240828A: Tiled Swift observations
  27. LAT GRB240828.62: Global MASTER-Net observations report
  28. GRB 240828A: AstroSat CZTI detection of a long burst
  29. Fermi GRB 240828A: Bassano Bresciano Observatory upper limit
  30. GRB 240825A: Upper limits from a neutrino search with IceCube
  31. GRB 240819A as a likely X-Ray Flash
  32. GRB 240828B: Swift ToO observations
  33. GRB 240821A: PRIME near-infrared observations
  34. GRB 240825A: VLA detection
  35. Fermi GRB 240828A: Global MASTER-Net observations report
  36. Fermi trigger No 746438824: Global MASTER-Net observations report
  37. SVOM GRB 240821A: optical afterglow discovery
  38. GRB 240828B : Detection of a possible very soft X-ray transient by SVOM/ECLAIRs
  39. GRB 240828A: Fermi GBM Final Real-time Localization
  40. GRB 240821A: the second and third EP-FXT follow-up observations and afterglow candidates
  41. GRB 240825A: GECAM detection
  42. GRB 240825A: ALMA detection
  43. GRB 240825A: SAO RAS optical observations
  44. GRB 240824A: GIT optical upper limit
  45. GRB 240819A: Swift afterglow confirmation
  46. GRB 240825A: TNG optical photometry and spectroscopy
  47. LIGO/Virgo/KAGRA S240825ar: Updated Sky localization
  48. LIGO/Virgo/KAGRA S240825ar: Updated Sky localization
  49. GRB 240825A: NUTTelA-TAO / BSTI Optical Limits
  50. GRB 240825A: GMG Continued Optical Observation on the Second Night
  51. GRB 240824B: Ondrejov D50 optical limit
  52. GRB 240825A: KAIT optical observations
  53. GRB 240825A: PRIME near-infrared detection
  54. Konus-Wind detection of GRB 240825A (bright/long)
  55. GRB 240825A: Fermi GBM Observation
  56. GRB 240825A : MISTRAL/T193 OHP optical follow-up of the afterglow
  57. GRB 240825A: AKO Optical Follow-Up Observations
  58. GRB 240825A: AstroSat CZTI detection of the long bright burst
  59. SGR 1E 1841-045 / Kes 73: SVOM/GRM observation
  60. GRB 240825A: Swift/UVOT Detection
  61. GRB 240825A: REM detection of the optical/NIR afterglow
  62. GRB 240825A: Swift-XRT refined Analysis
  63. GRB 240825A: VLT/X-shooter redshift
  64. GRB 240825A: SVOM/C-GFT optical observations
  65. GRB 240825A: Montarrenti Observatory optical observations
  66. GRB 240825A: Enhanced Swift-XRT position
  67. GRB 240825A: MASTER optical counterpart observation
  68. GRB 240825A: Fermi-LAT detection
  69. GRB 240825A: LCO optical observations
  70. GRB 240824B: KAIT optical upper limit
  71. SGR 1E 1841-045 / Kes 73 (Trigger 1249878): Osservatorio Atronomico Nastro Verde optical upper limit
  72. GRB 240824B: Fermi GBM Observation
  73. Fermi GRB 240825A: Global MASTER-Net observations report
  74. SGR 1E 1841-045 / Kes 73 (Trigger 1249653) - Osservatorio Astronomico Nastro Verde upper limit
  75. GRB 240824B: NOT optical upper limit
  76. GRB 240825A: GMG Optical Observation
  77. Swift GRB 240825A: Global MASTER-Net observations report
  78. GRB 240825A: 1.6m Mephisto multi-band detection
  79. GRB 240825A: AKO Optical Afterglow Detection
  80. GRB 240825A: Skynet Optical Afterglow observations
  81. GRB 240825A: Nanshan/HMT optical afterglow observations
  82. GRB 240825A: Swift detection of a burst with a bright optical counterpart
  83. GRB 240825A: Fermi GBM Final Real-time Localization
  84. GRB 240824A: Swift-BAT refined analysis
  85. GRB 240824A: SVOM/C-GFT optical upper limit
  86. GRB 240824B: Swift-XRT afterglow detection
  87. GRB 240824A: Swift-XRT observations
  88. LIGO/Virgo/KAGRA S240825ar: Identification of a GW compact binary merger candidate
  89. GRB 240824B: Swift/BAT arcminute localization of a burst
  90. GRB 240824B: Swift ToO observations
  91. Fermi GRB 240824C: Global MASTER-Net observations report
  92. GRB 240824C: Fermi GBM Final Localization
  93. GRB 240824A: Swift/UVOT Upper Limits
  94. GRB 240821A: Swift/UVOT observations of the XRT sources.
  95. GRB 240824B: MAXI/GSC detection
  96. GRB 240824B: Fermi GBM Final Real-time Localization
  97. GRB 240824A: Retraction of GCN 37255
  98. GRB240824A: GRANDMA/TAROT-TCA Upper Limit
  99. SGR 1E 1841-045 / Kes 73: Leavitt Observatory optical upper limit
  100. GRB 240824A: KAIT optical upper limit

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