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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"

27041 results found.

  1. GRB 250920B: Swift-XRT refined Analysis
  2. GRB 250920B: SVOM/C-GFT optical observations
  3. GRB 250920C: GOTO optical counterpart candidate
  4. GRB 250919A / EP250919a: LCO optical observation
  5. GRB 250920C: Swift detection of a burst
  6. GRB 250920C: Fermi GBM Final Real-time Localization
  7. LIGO/Virgo/KAGRA S250920bq: Coverage and upper limits from MAXI/GSC observations
  8. Swift GRB 250920B: Global MASTER-Net observations report
  9. GRB 250920B: Swift detection of a burst with a bright optical counterpart.
  10. GRB 250920B: Fermi GBM Final Real-time Localization
  11. GRB 250920A: BALROG localization (Fermi Trigger 780029651 / GRB 250920121)
  12. GRB 250920A: Fermi GBM Final Localization
  13. GRB 250919A/EP250919a: SVOM/VT optical observation
  14. GRB 250919A: Fermi GBM Observation
  15. Fermi GRB 250918A: Global MASTER-Net observations report
  16. GRB 250918A: SVOM/GRM observation
  17. GRB 250919A: Swift-XRT afterglow detection
  18. GRB 250919A: Fermi-LAT detection
  19. GRB 250919A: SVOM/GRM observation of a very bright GRB
  20. GRB 250919A: BALROG localization (Fermi Trigger 779934537 / GRB 250919020)
  21. EP250919a: Global MASTER-Net observations report
  22. EP250919a: Einstein Probe detection of an X-ray transient
  23. Correction for GCN 41877: EP-WXT ID is 01709243841
  24. The EP-WXT trigger 01709243841: Las Cumbres discovery of the optical counterpart
  25. GRB 250916A: Fermi GBM Observation
  26. Fermi GRB 250919A: Global MASTER-Net observations report
  27. GRB 250919A: Fermi GBM Final Real-time Localization
  28. GRB 250917B: VLT/HAWK-I near-infrared observations
  29. GRB 250912A: SVOM/ECLAIRs refined analysis
  30. GRB 250917B: Swift-BAT refined analysis
  31. LIGO/Virgo/KAGRA S250918aw: 1 counterpart neutrino candidate event from an IceCube neutrino search
  32. GRB 250918A: BALROG localization (Fermi Trigger 779891543 / GRB 250918522)
  33. GRB 250918A: Fermi GBM Final Real-time Localization
  34. GRB 250917B: Swift/UVOT Upper Limits
  35. EP250916a: EP-FXT follow-up observation
  36. GRB 250916A : GIT optical observations
  37. LIGO/Virgo/KAGRA S250917aq: Three counterpart neutrino candidates from IceCube neutrino searches
  38. GRB 250916A: Glowbug gamma-ray detection
  39. GRB 250917B: Fermi GBM Observation
  40. Fermi GRB 250917B: Global MASTER-Net observations report
  41. GRB 250917B: Swift detection of a short burst
  42. GRB 250916A: GOTO optical counterpart candidate
  43. GRB 250917B: Fermi GBM Final Real-time Localization
  44. GRB 250917A: Fermi GBM Final Real-time Localization
  45. The EP-WXT trigger 01709241037 is likely a flaring star
  46. GRB 250910A: SVOM/ECLAIRs refined analysis
  47. EP250916a: Einstein Probe detection of an X-ray transient
  48. Fermi GRB 250916A: Global MASTER-Net observations report
  49. GRB 250916A: Fermi GBM Final Real-time Localization
  50. LIGO/Virgo/KAGRA S250818k: HCT optical follow-up
  51. SVOM/sb25091517: Confirmation of a stellar flare by SVOM/VT
  52. SVOM/sb25091517: FRAM-ORM stellar flare - transient observation
  53. SVOM/sb25091517: SVOM detection of an X-ray transient
  54. GRB 250912A: Swift/BAT-GUANO localization skymap of a possibly short burst
  55. GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
  56. GRB 250912A: Swift-XRT observations
  57. GRB250912A: VLT/HAWK-I follow-up observations
  58. GRB 250912A: VLT observations
  59. GRB 250912A: Fermi GBM Observation
  60. GRB 250912A: SVOM/GRM analysis suggests a possible short GRB with extended emission
  61. GRB 250912A:SVOM/VT optical upper limit
  62. GRB 250912A: LCO optical upper limit
  63. The EP-WXT trigger 01709240768 is likely a flaring star
  64. Fermi GRB 250912A: Global MASTER-Net observations report
  65. EP250911a: Global MASTER-Net observations report
  66. GRB 250912A: SVOM detection of a burst
  67. GRB 250912A: Fermi GBM Final Real-time Localization
  68. LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search
  69. EP250908c: tentative VLT/FORS2 redshift z = 2.87
  70. EP250911a: Upper limit from Fermi-GBM Observations
  71. GRB 250911A: GECAM-B detection
  72. GRB 250911A: Swift-BAT refined analysis
  73. EP250911a: GTC/OSIRIS+ spectroscopic redshift z = 3.84
  74. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  75. GRB 250910B: SVOM/GRM observation
  76. EP250911a: SVOM/VT optical observation
  77. GRB 250911A: Swift-XRT refined Analysis
  78. GRB 250910C: Fermi GBM Final Localization Correction
  79. EP250911a: Swift-XRT observations
  80. EP250911a: Optical detection with Kinder observations
  81. GRB 250911A: Swift/UVOT Detection
  82. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  83. GRB 250909B: SVOM/GRM observation
  84. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  85. EP250911a: COLIBRÍ optical observations
  86. Fermi GRB 250910B: Global MASTER-Net observations report
  87. EP250911a: LCO optical counterpart discovery
  88. EP250910a: Global MASTER-Net observations report
  89. EP250911a: Einstein Probe detection of an X-ray transient
  90. GRB 250903A: SVOM/ECLAIRs refined analysis
  91. GRB 250911A: Swift-XRT observations
  92. GRB 250911A: COLIBRÍ optical counterpart candidate
  93. GRB 250911A: Swift detection of a burst
  94. GRB 250910B: BALROG localization (Fermi Trigger 779223130 / GRB 250910786)
  95. GRB 250910B: Fermi GBM Final Real-time Localization
  96. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  97. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  98. GRB 250910A: SVOM/VT optical upper limit
  99. EP250908C: GROND observation of the fading optical counterpart
  100. GRB 250910A: LCO optical upper limit

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