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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"

32161 results found.

  1. GRB 240801A: SVOM/GRM observation
  2. GRB 240905E: GIT optical upper limit
  3. GRB 240905B: Swift-XRT observations
  4. GRB 240905E: Gaoyazi/GOT optical upper limits
  5. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  6. GRB 240905B: Fermi-LAT detection
  7. GRB 240905B: Swift ToO observations
  8. GRB 240905E: J-band observations with WINTER
  9. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  10. GRB 240905E: AKO Optical Upper Limit
  11. GRB 240905E: SVOM/C-GFT optical upper limit
  12. GRB 240905E: OHP/MISTRAL T193 optical upper limit
  13. Fermi GRB 240905D: Global MASTER-Net observations report
  14. Fermi GRB 240905A: Global MASTER-Net observations report
  15. GRB 240905E: NOT optical upper limits
  16. GRB 240905E: REM optical/NIR upper limits
  17. GRB 240902B: AstroSat CZTI detection of a long burst
  18. GRB 240905E: Swift-XRT refined Analysis
  19. GRB 240902A: AstroSat CZTI detection of a long burst
  20. GRB 240905E: SVOM/GRM observation
  21. GRB 240905E: LCOGT Optical Upper Limit
  22. GRB 240905E: Swift/UVOT Upper Limits
  23. GRB 240905E: SAO RAS optical upper limit
  24. GRB 240825A: Montarrenti Observatory optical follow-up observations
  25. GRB 240905E: Nanshan/HMT optical upper limit
  26. Swift GRB 240905E: Global MASTER-Net observations report
  27. GRB 240905E: Swift detection of a burst
  28. GRB 240819A: Optical upper limits from TESS
  29. GRB 240905D: AstroSat CZTI detection
  30. GRB 240905A: SVOM/GRM observation
  31. Fermi GRB 240905B: Global MASTER-Net observations report
  32. GRB 240905D: Fermi GBM Final Real-time Localization
  33. GRB 240905B: AstroSat CZTI detection and localization
  34. GRB 240905C: Fermi GBM Final Real-time Localization
  35. GRB 240905B: Fermi GBM Final Real-time Localization
  36. GRB 240825A: ATCA Detection of Radio Counterpart
  37. Swift GRB 240904A: Global MASTER-Net observations report
  38. GRB 240905A: Fermi GBM Final Real-time Localization
  39. Fermi Gamma-ray Burst Monitor trigger 747163821/240904729 is not a GRB
  40. GRB 240904A: Swift detection of a burst
  41. GRB 240828A: SVOM/GRM observation
  42. LIGO/Virgo/KAGRA S240825ar: Upper limits from Swift/BAT-GUANO
  43. LIGO/Virgo/KAGRA S240807h: Upper limits from Swift/BAT-GUANO
  44. Fermi Gamma-ray Burst Monitor trigger 240831A is not a GRB
  45. GRB 240828A: GECAM detection
  46. GRB 240831B: Fermi GBM Final Localization
  47. Fermi Gamma-ray Burst Monitor trigger 746882332/240901471 is not a GRB
  48. GRB 240825A: Magnitude Correction in SVOM/C-GFT Optical Observations
  49. GRB 240825A: MeerLICHT afterglow detection
  50. GRB 240828A: SAO RAS AS-500(2) optical observations
  51. GRB 240821A: VLT spectroscopic observations
  52. GRB 240825A: TSHAO Optical Upper Limit
  53. GRB 240829B: GRBAlpha detection
  54. GRB240828B: REM optical/NIR upper limits
  55. GRB 240828B: AbAO optical upper limit
  56. GRB 240831A: Fermi GBM Final Real-time Localization
  57. GRB 240825A: SOAR observations
  58. GRB 240828B: Mephisto optical upper limit
  59. GRB 240828B: GRANDMA Optical Upper Limit
  60. GRB 240829A: Swift-BAT refined analysis
  61. GRB 240825A: Swift-BAT refined analysis
  62. GRB 240825A: MeerKAT detection
  63. GRB 240828B: J-band upper limit from WINTER
  64. GRB 240828B: GMG Optical Upper Limit
  65. GRB 240828A: KAIT continued optical observations
  66. GRB 240828B: GWAC-F50A optical upper limit
  67. GRB 240828B: SVOM/C-GFT optical upper limit
  68. GRB 240828B: SAO RAS optical upper limit
  69. GRB 240828B: KAIT optical upper limit
  70. GRB 240828A: SAO RAS optical observations
  71. GRB 240829B: Fermi GBM Final Localization
  72. GRB 240828A: Fermi GBM Observation
  73. GRB 240629A: First GRB Detected by BurstCube
  74. GRB 240828A: KAIT Optical Afterglow Candidate
  75. GRB 240825A: SVOM/VT optical detection
  76. GRB 240828A: Swift-XRT afterglow detection
  77. GRB 240825A: further SAO RAS optical observations
  78. GRB 240825A: iTelescope optical observations
  79. GRB 240828B: Swift-XRT afterglow detection
  80. GRB 240829A: Swift detection of a burst
  81. GRB 240828A: Fermi-LAT detection
  82. GRB 240828A: Tiled Swift observations
  83. GRB 240828A: AstroSat CZTI detection of a long burst
  84. Fermi GRB 240828A: Bassano Bresciano Observatory upper limit
  85. GRB 240825A: Upper limits from a neutrino search with IceCube
  86. GRB 240819A as a likely X-Ray Flash
  87. GRB 240828B: Swift ToO observations
  88. GRB 240821A: PRIME near-infrared observations
  89. GRB 240825A: VLA detection
  90. Fermi GRB 240828A: Global MASTER-Net observations report
  91. SVOM GRB 240821A: optical afterglow discovery
  92. GRB 240828B : Detection of a possible very soft X-ray transient by SVOM/ECLAIRs
  93. GRB 240828A: Fermi GBM Final Real-time Localization
  94. GRB 240821A: the second and third EP-FXT follow-up observations and afterglow candidates
  95. GRB 240825A: GECAM detection
  96. GRB 240825A: ALMA detection
  97. GRB 240825A: SAO RAS optical observations
  98. GRB 240824A: GIT optical upper limit
  99. GRB 240819A: Swift afterglow confirmation
  100. GRB 240825A: TNG optical photometry and spectroscopy

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