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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

3136 results found.

  1. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  2. Fermi GRB 251023A: Global MASTER-Net observations report
  3. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  4. GRB 251016A: Fermi GBM Observation
  5. GRB 251018A: Fermi GBM Observation
  6. IceCube-251018A: Global MASTER-Net observations report
  7. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  8. GRB 251016A: AstroSat CZTI detection of a short burst
  9. GRB 251016B: AstroSat CZTI detection
  10. GRB 251017A: Swift detection of a burst with an optical counterpart
  11. Fermi GRB 251016A: Global MASTER-Net observations report
  12. GRB 251013C: SVOM/ECLAIRs refined analysis
  13. GRB 251013D: Fermi GBM Observation
  14. GRB 251013C: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an bright optical counterpart
  15. LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
  16. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  17. GRB 251013C: AstroSat CZTI detection
  18. Fermi trigger No 782044789: Global MASTER-Net observations report
  19. Fermi GRB 251013C: Global MASTER-Net observations report
  20. GRB 251013C: BOOTES-6 early optical detection
  21. GRB 251013C: SVOM/VT optical observation
  22. GRB 251013C: SVOM detection of a burst
  23. LIGO/Virgo/KAGRA S251013x: Identification of a GW compact binary merger candidate
  24. GRB 251010A: AstroSat CZTI detection
  25. GRB 251011A: AstroSat CZTI detection
  26. EP251006a: Global MASTER-Net observations report
  27. IceCube Alert 251008A: Global MASTER-Net observations report
  28. GRB 251007A: AstroSat CZTI detection
  29. GRB 251007B: SVOM detection of a faint burst
  30. GRB 251006B/EP251006a: SVOM/VT optical candidate
  31. LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate
  32. Fermi GRB 251006A: Global MASTER-Net observations report
  33. GRB 251005C: AstroSat CZTI detection
  34. GRB 251001A: AstroSat CZTI detection
  35. Fermi/SVOM GRB 251002A : MASTER OT earlier detection in 2 polarization filters
  36. GRB 251002A: SVOM detection of a burst
  37. Fermi GRB 251002A: Global MASTER-Net observations report
  38. Fermi GRB 250929A: Global MASTER-Net observations report
  39. LIGO/Virgo/KAGRA S250929c: Identification of a GW compact binary merger candidate
  40. LIGO/Virgo/KAGRA S250927cy: Identification of a GW compact binary merger candidate
  41. GRB 250926A: AstroSat CZTI detection
  42. GRB 250925A: Leavitt Observatory optical upper limit
  43. GRB 250924A: SAO RAS optical observations
  44. GRB 250924A: AstroSat CZTI detection
  45. GRB 250914A: AstroSat CZTI detection
  46. GRB 250920B: AstroSat CZTI detection
  47. GRB 250922C: AstroSat CZTI detection of a short burst
  48. Fermi trigger No 780156732: Global MASTER-Net observations report
  49. Swift GRB 250920C: Global MASTER-Net observations report
  50. Konus-Wind detection of GRB 250919A
  51. GRB 250920A: AstroSat CZTI detection
  52. EP250919a: Global MASTER-Net observations report
  53. Fermi GRB 250919A: Global MASTER-Net observations report
  54. GRB 250916A: SAO RAS optical observations
  55. GRB250917B: WFST optical observations
  56. GRB 250916A: AstroSat CZTI detection of a bright long burst
  57. Fermi GRB 250916A: Global MASTER-Net observations report
  58. Fermi GRB 250912A: Global MASTER-Net observations report
  59. EP250911a: Global MASTER-Net observations report
  60. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  61. Fermi GRB 250910B: Global MASTER-Net observations report
  62. EP250910a: Global MASTER-Net observations report
  63. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  64. GRB 250909B: AstroSat CZTI detection of a long burst
  65. GRB 250909A: AstroSat CZTI detection
  66. The EP-WXT trigger EP250908a/01709240652 is not a real source
  67. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  68. IceCube Alert 250905.84: Global MASTER-Net observations report
  69. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  70. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  71. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  72. EP250901a: Mondy, Assy and SAO RAS optical limits
  73. GRB 250902B: AstroSat CZTI detection
  74. Fermi GRB 250902B: Global MASTER-Net observations report
  75. EP250901a: Swift-XRT observations
  76. GRB 250901A: LCO optical upper limit
  77. EP250827b: Swift observations of AT 2025wkm
  78. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  79. EP250901a: Global MASTER-Net observations report
  80. GRB 250830C: AstroSat CZTI detection of a long burst
  81. EP250831a: Global MASTER-Net observations report
  82. EP250830a: Global MASTER-Net observations report
  83. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  84. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  86. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  87. GRB 250826A: Fermi GBM Final Real-time Localization
  88. Fermi GRB 250824B: Global MASTER-Net observations report
  89. GRB 250821B: AstroSat CZTI detection
  90. GRB 250819A: AstroSat CZTI detection
  91. LIGO/Virgo/KAGRA S250818k: GRAWITA TNG NIR observations of AT2025ulz
  92. GRB 250821C: Fermi GBM Final Real-time Localization
  93. LIGO/Virgo/KAGRA S250818k: Swift observations of AT 2025ulz
  94. LIGO/Virgo/KAGRA S250818k: AstroSat CZTI non-detection and upper limits
  95. GRB 250818A: AstroSat CZTI detection
  96. LIGO/Virgo/KAGRA S250818k: Keck I LRIS spectroscopy of ZTF25abjmnps (AT2025ulz)
  97. GRB 250818C: Fermi GBM Final Real-time Localization
  98. Fermi trigger No 776849714: Global MASTER-Net observations report
  99. LIGO/Virgo/KAGRA S250818t: Identification of a GW compact binary merger candidate
  100. GRB 250813B: Liverpool Telescope optical upper limits

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