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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"

45749 results found.

  1. GRB 250329B: Swift-XRT confirmation of fading
  2. GRB 250330A: VLT/FORS2 Afterglow Detection
  3. GRB20250327B: 45th Parallel Observatory upper limit
  4. GRB 250328A: Swift/UVOT Detection
  5. GRB 250328A: Swift-XRT refined Analysis
  6. Fermi-LAT gamma-ray observations of IceCube-250330A
  7. SVOM/sb25033102 is a false trigger
  8. GRB 250330A: Fermi GBM Observation
  9. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  10. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  11. GRB 250331D: Fermi GBM Final Real-time Localization
  12. GRB 250331C: Prompt enhanced Swift-XRT position
  13. GRB 250331C: Swift detection of a burst
  14. GRB 250331B: Swift detection of a burst
  15. GRB 250330A: SVOM/VT optical upper limit
  16. GRB 250331A: MAXI/GSC detection
  17. SVOM/sb25033102: SVOM detection of an X-ray transient
  18. GRB 250314A: VLA detection
  19. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  20. Fermi GRB 250330B: Global MASTER-Net observations report
  21. GRB 250330B: Fermi GBM Final Real-time Localization
  22. Fermi GRB 250330A: Global MASTER-Net observations report
  23. GRB 250330A: BOOTES-7 early optical upper limit
  24. GRB 250330A: Swift/UVOT Upper Limits
  25. GRB 250330A: Swift-XRT afterglow detection
  26. GRB 250328A: 1.6m Mephisto optical observations
  27. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  28. GRB 250330A: Fermi GBM Final Localization
  29. IceCube-250330A - IceCube observation of a high-energy neutrino candidate track-like event
  30. IceCube Alert 250330.35: Global MASTER-Net observations report
  31. GRB 250330A: VLT/FORS2 Optical Observations
  32. GRB 250330A: Prompt Swift-XRT position
  33. GRB 250329B: Swift-XRT afterglow detection
  34. GRB 250330A: Swift detection of a burst
  35. Swift GRB250330.26: Global MASTER-Net observations report
  36. GRB 250328A: A fading optical afterglow confirmed by SVOM/VT
  37. GRB 250329B: SVOM/C-GFT optical upper limit
  38. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 1)
  39. GRB 250327B: ALMA detection
  40. GRB 250327B: VLA detection
  41. GRB 250329B: SVOM/VT optical upper limit
  42. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  43. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  44. LIGO/Virgo/KAGRA S250329fl: 2 counterpart neutrino candidate events from an IceCube neutrino search
  45. GRB250329A: REM optical afterglow detection
  46. GRB 250329B: GWAC-F50A optical upper limit
  47. GRB 250329B: SVOM detection of a faint transient
  48. GRB 250329A: Swift-XRT afterglow detection
  49. GRB 250328A: SVOM/VT optical observation
  50. GRB 250329A: Fading optical counterpart detection by LCO.
  51. GRB 250328A: SVOM/C-GFT optical upper limit
  52. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  53. GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate
  54. GRB 250329A: VLT/X-shooter redshift z = 2.921
  55. GRB 250329A: SVOM/VT optical counterpart confirmation
  56. GRB 250329A: SVOM detection of a burst
  57. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  58. GRB 250327B: J-band observations with WINTER
  59. GRB 250327B: MASTER detection of OT rebrightening
  60. GRB 250327B: LCO optical counterpart detection
  61. GRB 250328A: GWAC-F50A optical upper limit
  62. GRB 250328A: SVOM detection of a burst
  63. FRB 20250316A: FTW optical observations
  64. LIGO/Virgo/KAGRA S250328ae: NED Galaxies in the 4-Update Localization Volume
  65. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  66. GRB 250327B: CrAO and SAO RAS Optical Observations
  67. GRB 250327B: OHP/T193 spectroscopic observations and redshift confirmation
  68. GRB 250327B: further optical observations by LCOGT
  69. EP250315a: Pan-STARRS r and i-band imaging and photometry
  70. GRB 250327b: Liverpool Telescope optical observations
  71. GRB 250322A: GRANDMA/TNOT optical upper limits
  72. LIGO/Virgo/KAGRA S250328ae: Updated Sky localization
  73. GRB 250327A: SVOM/VT upper limits on the XRT position
  74. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  75. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  76. GRB 250327B: Las Cumbres optical counterpart detection
  77. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  78. GRB 250327B: 1.6m Mephisto optical observations
  79. GRB 250327B: NOT spectroscopic redshift z = 3.035
  80. GRB 250327A: Swift-XRT refined Analysis
  81. GRB 250327B: GOTO optical counterpart detection
  82. GRB 250327B: SVOM/VT optically bright counterpart
  83. GRB 250327B: SAO RAS optical candidate
  84. GRB 250327B: SVOM detection of a burst
  85. FRB 20250316A: Gemini Imaging and Spectroscopy of the Sub-arcsecond Localization Region of FRB 20250316A
  86. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  87. GRB 250327A: J-band observations with WINTER
  88. GRB 250327A: SVOM/VT optical candidate
  89. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  90. GRB 250327A: Fermi GBM observation
  91. Fermi GRB 250327A: Global MASTER-Net observations report
  92. Swift GRB 250327A: Global MASTER-Net observations report
  93. GRB 250327A: DDOTI Optical Observations
  94. GRB 250327A: COLIBRÍ optical upper limit
  95. GRB 250327A: Swift detection of a burst
  96. GRB 250327A: Fermi GBM Final Real-time Localization
  97. Fermi trigger No 764700395: Global MASTER-Net observations report
  98. LIGO/Virgo/KAGRA S250326y: Updated Sky localization
  99. Konus-Wind detection of GRB 250322A (short)
  100. IPN triangulation of GRB 250322B

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