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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"

27196 results found.

  1. GRB 250330A: Swift/UVOT Upper Limits
  2. GRB 250328A: 1.6m Mephisto optical observations
  3. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  4. GRB 250330A: Fermi GBM Final Localization
  5. IceCube Alert 250330.35: Global MASTER-Net observations report
  6. GRB 250330A: VLT/FORS2 Optical Observations
  7. GRB 250330A: Prompt Swift-XRT position
  8. GRB 250329B: Swift-XRT afterglow detection
  9. GRB 250330A: Swift detection of a burst
  10. Swift GRB250330.26: Global MASTER-Net observations report
  11. GRB 250328A: A fading optical afterglow confirmed by SVOM/VT
  12. GRB 250329B: SVOM/C-GFT optical upper limit
  13. GRB 250329B: SVOM/VT optical upper limit
  14. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  15. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  16. LIGO/Virgo/KAGRA S250329fl: 2 counterpart neutrino candidate events from an IceCube neutrino search
  17. GRB250329A: REM optical afterglow detection
  18. GRB 250329B: SVOM detection of a faint transient
  19. GRB 250329A: Swift-XRT afterglow detection
  20. GRB 250328A: SVOM/VT optical observation
  21. GRB 250329A: Fading optical counterpart detection by LCO.
  22. GRB 250328A: SVOM/C-GFT optical upper limit
  23. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  24. GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate
  25. GRB 250329A: VLT/X-shooter redshift z = 2.921
  26. GRB 250329A: SVOM/VT optical counterpart confirmation
  27. GRB 250329A: SVOM detection of a burst
  28. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  29. GRB 250327B: MASTER detection of OT rebrightening
  30. GRB 250327B: LCO optical counterpart detection
  31. GRB 250328A: SVOM detection of a burst
  32. GRB 250327B: CrAO and SAO RAS Optical Observations
  33. GRB 250327B: OHP/T193 spectroscopic observations and redshift confirmation
  34. GRB 250327b: Liverpool Telescope optical observations
  35. GRB 250322A: GRANDMA/TNOT optical upper limits
  36. GRB 250327A: SVOM/VT upper limits on the XRT position
  37. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  38. GRB 250327B: Las Cumbres optical counterpart detection
  39. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  40. GRB 250327B: 1.6m Mephisto optical observations
  41. GRB 250327B: NOT spectroscopic redshift z = 3.035
  42. GRB 250327A: Swift-XRT refined Analysis
  43. GRB 250327B: GOTO optical counterpart detection
  44. GRB 250327B: SVOM/VT optically bright counterpart
  45. GRB 250327B: SAO RAS optical candidate
  46. GRB 250327B: SVOM detection of a burst
  47. GRB 250327A: SVOM/VT optical candidate
  48. GRB 250327A: Fermi GBM observation
  49. Fermi GRB 250327A: Global MASTER-Net observations report
  50. Swift GRB 250327A: Global MASTER-Net observations report
  51. GRB 250327A: DDOTI Optical Observations
  52. GRB 250327A: COLIBRÍ optical upper limit
  53. GRB 250327A: Swift detection of a burst
  54. GRB 250327A: Fermi GBM Final Real-time Localization
  55. Fermi trigger No 764700395: Global MASTER-Net observations report
  56. Konus-Wind detection of GRB 250322A (short)
  57. EP250321a: Mondy AZT-33IK Continued Optical Observations
  58. GRB 250322A: Swift-BAT refined analysis
  59. The EP-WXT trigger 01709133021 (designated as EP250324a) is not a real source
  60. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  61. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  62. GRB 250322A: Swift/UVOT Upper Limits
  63. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  64. GRB 250322A: Swift-XRT refined Analysis
  65. EP250304a: VLT/MUSE spectroscopic observation of its associated supernova SN 2025fhm
  66. SVOM/sb25032302: SVOM detection of a long X-ray transient
  67. GRB250322A: STEP/T80S optical limits
  68. GRB 250322A: Gemini-South optical observations
  69. GRB 250322A: VLT optical observations
  70. GRB 250322A: NOT optical upper limits
  71. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  72. GRB 250322A: MASTER optical observation
  73. EP250321a: Liverpool Telescope optical follow-up
  74. EP250321a: Mondy AZT-33IK Optical Observations
  75. GRB 250322A: Swift detection of a short burst
  76. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  77. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  78. EP250321a: KAIT optical observations
  79. EP250321A: COLIBRÍ Continuing Optical Observations
  80. GRB 250225B: GECAM-A detection
  81. GRB 250312A: GECAM-A detection
  82. GRB 250321C: Fermi GBM Final Real-time Localization
  83. GRB 250320B: Fermi GBM Observation
  84. GRB 250321A: Swift-BAT refined analysis
  85. GRB 250321A: Swift-XRT refined Analysis
  86. GRB 250320B: Fermi-LAT detection
  87. GRB 250321B: SVOM detection of a sub-threshold transient event
  88. EP250321a: SVOM/VT optical observation
  89. EP 250321A: Optical counterpart detection by LCO.
  90. EP250321a: Kinder optical follow-up observations
  91. GRB 250321A: Swift/UVOT Upper Limits
  92. GRB 250320B: SVOM/GRM observation of a long burst
  93. EP250321a: LCO optical counterpart detection
  94. EP250321a: Swift-XRT detection of an X-ray source
  95. EP250321A: COLIBRÍ Optical Observations
  96. EP250321a: VLT/X-shooter redshift z = 4.368
  97. EP250321a: REM optical/NIR afterglow detection
  98. Fermi GRB 250320B: Global MASTER-Net observations report
  99. EP250321a: TRT optical counterpart detection
  100. EP250321a: Global MASTER-Net observations report

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