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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

42482 results found.

  1. GRB 251001B: LCOGT Optical Observations
  2. GRB 250930A: SVOM/GRM observation
  3. GRB 251001B: TRT optical afterglow detection and potential host galaxy
  4. GRB 251001B: GOTO optical counterpart detection
  5. GRB 251001B: Swift detection of a burst
  6. GRB 251001B: Fermi GBM Final Real-time Localization
  7. GRB 251001A: Fermi GBM Detection
  8. GRB 250910A / EP250910a: VLT limits on the possible associated supernova
  9. GRB 251001A: BALROG localization (Fermi Trigger 780979261 / GRB 251001112)
  10. GRB 251001A: Fermi GBM Final Real-time Localization
  11. LIGO/Virgo/KAGRA S250830bp: SOAR spectroscopy of two DESGW candidates
  12. LIGO/Virgo/KAGRA S250818k: further MeerKAT monitoring
  13. GRB 250910A / EP250910a: VLT/X-shooter host galaxy redshift z = 0.592
  14. GRB 250925A: MAO/AZT-22 optical observations
  15. Fermi GRB 250929A: Global MASTER-Net observations report
  16. GRB 250929A: Fermi GBM Final Real-time Localization
  17. GRB 250926A: CALET Gamma-Ray Burst Monitor detection
  18. GRB 250925A: Mondy I-band optical observations
  19. GRB 250916A: SVOM/VT optical observation
  20. LIGO/Virgo/KAGRA S250929c: Identification of a GW compact binary merger candidate
  21. LIGO/Virgo/KAGRA S250927ck: Updated Sky localization
  22. Fermi-LAT Gamma-ray Observations of IceCube-250926A
  23. GRB 250926A: triangulation location with Insight-HXMT/HE and Fermi/GBM
  24. GRB 250924A: SVOM/GRM observation
  25. GRB 250925A: Swift-XRT refined Analysis
  26. LIGO/Virgo/KAGRA S250927cy: Identification of a GW compact binary merger candidate
  27. LIGO/Virgo/KAGRA S250927ck: Identification of a GW compact binary merger candidate
  28. IceCube-250926A: Upper limits from a search for additional neutrino events in IceCube
  29. GRB 250926A: Insight-HXMT detection
  30. GRB 250926B: Fermi GBM Final Localization
  31. Fermi trigger No 780609036: Global MASTER-Net observations report
  32. IceCube Alert 250926.52: Global MASTER-Net observations report
  33. GRB 250920C: ULL-ASTRO-MASTER early detection of the optical afterglow with LCO 40-cm telescope at Siding Spring Observatory
  34. GRB 250926A: AstroSat CZTI detection
  35. GRB 250925A: Swift/UVOT Upper Limits
  36. GRB 250925A: Swift-BAT refined analysis
  37. GRB 250925A: Mondy and AbAO optical observations
  38. GRB 250925A: COLIBRÍ photometric redshift
  39. IceCube-250926A - IceCube observation of a high-energy neutrino candidate track-like event
  40. GRB 250925A: SVOM/GWAC-F60A upper limit
  41. GRB 250925A/EP250925a: EP-WXT detection
  42. GRB 250926A: DDOTI Optical Observations and Spatial Coincidence with the Orion Nebula
  43. GRB 250925A : MITSuME Akeno optical upper limits
  44. GRB 250925A: JinShan optical observations
  45. GRB 250925A: 1.5m OSN optical detection and redshift with the 10.4m GTC/OSIRIS+
  46. GRB 250919A / EP250919a: Global MASTER Net before, during and after trigger optical observations
  47. GRB 250925A: COLIBRÍ optical photometry of the afterglow
  48. Fermi GRB 250926A: Global MASTER-Net observations report
  49. GRB 250926A: Fermi GBM Final Real-time Localization
  50. GRB 250925A: Optical Observations via Virtual Telescope Project, Italy
  51. GRB250925A: Liverpool Telescope optical observations
  52. GRB 250925A: NOT optical afterglow candidate
  53. GRB 250925A: Leavitt Observatory optical upper limit
  54. GRB 250925A: Enhanced Swift-XRT position
  55. GRB 250924A: Swift-BAT refined analysis
  56. GRB 250925A: GROWTH-India Telescope Upper Limits
  57. GRB 250925A: Swift detection of a burst
  58. Swift GRB 250925A: Global MASTER-Net observations report
  59. GRB 250922A: SVOM/GRM observation
  60. GRB 250924A: 1.6m Mephisto optical upper limits
  61. GRB 250924A: SAO RAS optical observations
  62. GRB 250924A: NOT optical observations
  63. GRB 250924A: AstroSat CZTI detection
  64. GRB 250914A: AstroSat CZTI detection
  65. GRB 250920B: AstroSat CZTI detection
  66. GRB 250924A: SVOM/VT optical observation
  67. GRB 250924A: Swift/UVOT Detection
  68. GRB 250924A: Swift-XRT refined Analysis
  69. GRB 250924A: Enhanced Swift-XRT position
  70. GRB 250924A: J-band detection with WINTER
  71. GRB 250924A: GROWTH-India Telescope Upper Limits
  72. GRB 250924A: KAIT optical observations
  73. GRB 250924A: Mondy optical observations, afterglow fading
  74. GRB 250924A: Kilonova-Catcher optical afterglow detection
  75. GRB 250920C: Kilonova-Catcher optical afterglow detection
  76. GRB 250922B: SVOM/GRM observation
  77. GRB 250920C: TRT optical observation
  78. GRB 250924B: Fermi GBM Final Localization
  79. GRB 250924A: COLIBRÍ optical observations
  80. Swift GRB 250924A: Global MASTER-Net observations report
  81. GRB 250919A / EP250919a: further LCO optical observation
  82. GRB 250924A: DDOTI Detection of the Optical Counterpart
  83. GRB 250924A: Swift detection of a burst with an optical counterpart
  84. GRB 250920B: AbAO optical upper limits
  85. Konus-Wind detection of GRB 250920C
  86. GRB 250920C: KAIT optical observations
  87. GRB 250920C: VLT redshift confirmation z = 1.399
  88. EP250911a: e-MERLIN radio observations
  89. GRB 250920B: CrAO ZTSH optical observations
  90. GRB 250920C: SALT redshift confirmation
  91. GRB 250920C: COLIBRÍ optical observations
  92. GRB 250922C: AstroSat CZTI detection of a short burst
  93. Fermi GRB 250922B: Global MASTER-Net observations report
  94. GRB 250920B: SAO RAS optical observations
  95. GRB 250920C: NIR observations with WINTER
  96. GRB 250920B: NIR observations with WINTER
  97. Fermi trigger No 780156732: Global MASTER-Net observations report
  98. GRB 250922B: Fermi GBM Final Real-time Localization
  99. GRB 250920C: PRIME near-infrared detection
  100. Konus-Wind detection of GRB 250920B

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