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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"

3757 results found.

  1. Fermi GRB 240824C: Global MASTER-Net observations report
  2. GRB 240824A: Retraction of GCN 37255
  3. GRB 240821A: Fermi GBM Observation
  4. Fermi trigger No 745866488: Global MASTER-Net observations report
  5. Trigger 1249878: Swift detection of another burst from SGR 1E 1841-045 / Kes 73
  6. GRB GRB 240809A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  7. GRB 240805B: Osservatorio Astronomico Nastro Verde upper limit
  8. Fermi trigger No 745501396: Global MASTER-Net observations report
  9. EP240816a: EP detection of a fast X-ray transient and follow-up observation
  10. GRB 240809A: ALMA detection
  11. GRB 240809B: MAXI/GSC detection
  12. LIGO/Virgo/KAGRA S240807h: Updated Sky localization and EM Bright Classification
  13. GRB 240809A: SVOM/GRM observation
  14. EP EP240807a: Global MASTER-Net observations report
  15. EP EP240806a: Global MASTER-Net observations report
  16. Fermi trigger No 744761058: Global MASTER-Net observations report
  17. Fermi trigger No 744629911: Global MASTER-Net observations report
  18. Fermi trigger No 744544656: Global MASTER-Net observations report
  19. EP240801a: BTA BVRI photometry
  20. GRB 240805B: Swift detection of a burst
  21. Fermi GRB 240804A: Global MASTER-Net observations report
  22. EP240801a: optical observations at CrAO and AbAO
  23. Fermi trigger No 744083370: Global MASTER-Net observations report
  24. Fermi trigger No 743953682: Global MASTER-Net observations report
  25. Fermi trigger No 743868421: Global MASTER-Net observations report
  26. Fermi Gamma-ray Burst Monitor trigger 743868421/240728588 is not a GRB
  27. Fermi GRB 240726A: Global MASTER-Net observations report
  28. GRB 240726A: AstroSat CZTI detection of a short burst
  29. Fermi trigger No 743219692: Global MASTER-Net observations report
  30. Fermi GRB 240718A: Global MASTER-Net observations report
  31. LAT GRB240718.27: Global MASTER-Net observations report
  32. GRB 240713A: J-band upper limit from WINTER
  33. GRB240713A: X-ray follow-up observation with EP-FXT
  34. Fermi trigger No 742317942: Global MASTER-Net observations report
  35. EP240708a: EP-WXT detection of a fast X-ray transient
  36. LIGO/Virgo S240615dg: Swift XRT observations, 28 futher X-ray sources
  37. EP240703a: BOOTES-3 optical upper limit
  38. EP240702a: Swift/XRT upper limit
  39. Fermi Gamma-ray Burst Monitor trigger 741288821/240628732 is not a GRB
  40. LIGO/Virgo/KAGRA S240629by: Identification of a GW compact binary merger candidate
  41. Fermi trigger No 741296200: Global MASTER-Net observations report
  42. Fermi trigger No 741251380: Global MASTER-Net observations report
  43. IPN triangulation of GRB 240619C
  44. IceCube-Cascade 240626A: Upper limits from a search for additional neutrino events in IceCube
  45. GRB 240628A: BALROG localization (Fermi Trigger 741288821 / GRB 240628732)
  46. Fermi trigger No 741211696: Global MASTER-Net observations report
  47. EP240626a: Montarrenti Observatory optical upper limit
  48. LIGO/Virgo/KAGRA S240627by: Identification of a GW compact binary merger candidate
  49. EP240626a: EP-WXT detection of a fast X-ray transient
  50. Fermi GRB 240625B: Global MASTER-Net observations report
  51. EP240618a: NOT optical counterpart candidate
  52. LIGO/Virgo/KAGRA S240621em: Identification of a GW compact binary merger candidate
  53. LIGO/Virgo S240615dg: Swift XRT observations, 39 X-ray sources
  54. Fermi trigger No 740430582: Global MASTER-Net observations report
  55. Konus-Wind detection of GRB 240615A (short/hard)
  56. Fermi trigger No 740166710: Global MASTER-Net observations report
  57. GRB 240612A: Fermi GBM Final Real-time Localization
  58. Fermi GRB 240607A: Global MASTER-Net observations report
  59. Fermi GRB 240604A: Global MASTER-Net observations report
  60. Fermi GRB 240605A: Global MASTER-Net observations report
  61. IPN triangulation of GRB 240603A
  62. GRB 240604A: Fermi GBM Final Localization
  63. GRB 240604A: GECAM detection of a long burst
  64. Fermi GRB 240602A: Global MASTER-Net observations report
  65. LIGO/Virgo S240527fv: GRANDMA/FRAM-Auger Optical Observations
  66. LIGO/Virgo/KAGRA S240527fv: Identification of a GW compact binary merger candidate
  67. LAT GRB240527.59: Global MASTER-Net observations report
  68. Fermi trigger No 738348224: Global MASTER-Net observations report
  69. Fermi trigger No 738330463: Global MASTER-Net observations report
  70. Fermi trigger No 737996942: Global MASTER-Net observations report
  71. GRB 240502A: VZLUSAT-2 detection
  72. Fermi GRB 240517A: Global MASTER-Net observations report
  73. Fermi trigger No 737523389: Global MASTER-Net observations report
  74. GRB 240516A: Swift detection of a burst
  75. LIGO/Virgo/KAGRA S240514c: Identification of a GW compact binary merger candidate
  76. LAT GRB240513.31: Global MASTER-Net observations report
  77. Fermi GRB 240513B: Global MASTER-Net observations report
  78. LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
  79. Fermi trigger No 737258655: Global MASTER-Net observations report
  80. Fermi trigger No 737247400: Global MASTER-Net observations report
  81. Fermi trigger No 737152719: Global MASTER-Net observations report
  82. Fermi trigger No 736967879: Global MASTER-Net observations report
  83. Fermi trigger No 736733320: Global MASTER-Net observations report
  84. Fermi trigger No 736564880: Global MASTER-Net observations report
  85. GRB 240502A: Fermi GBM Observation
  86. GRB 240430A: GRBAlpha detection
  87. GRB 240502A long GRB detected by INTEGRAL
  88. GRB 240502A: Fermi GBM Final Real-time Localization
  89. Fermi trigger No 736197684: Global MASTER-Net observations report
  90. GRB 240501B: AstroSat CZTI detection
  91. GRB 240429A: Fermi GBM Final Real-time Localization
  92. LIGO/Virgo/KAGRA S240422ed: ENGRAVE VLT/XShooter spectroscopy of the host galaxy of J-GEM24a
  93. LIGO/Virgo/KAGRA S240428dr: Identification of a GW compact binary merger candidate
  94. Fermi GRB 240428A: Global MASTER-Net observations report
  95. GRB 240428A: Fermi GBM Final Real-time Localization
  96. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  97. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  98. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  99. S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4
  100. LIGO/Virgo/KAGRA S240422ed: Second night Pan-STARRS observations of the skymap

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