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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"

28264 results found.

  1. GRB 250327A Swift-BAT refined analysis
  2. LIGO/Virgo/KAGRA S250331o: Updated Sky localization
  3. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  4. Swift GRB 250331C: Global MASTER-Net observations report
  5. Swift GRB 250331B: Global MASTER-Net observations report
  6. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  7. GRB 250331C: Enhanced Swift-XRT position
  8. IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube
  9. LIGO/Virgo/KAGRA S250331o: NED Galaxies in the 3-Initial Localization Volume
  10. GRB 250331B: Enhanced Swift-XRT position
  11. GRB 250320C : SVOM detection of a burst through offline search
  12. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  13. GRB 250330A: VLT/FORS2 Afterglow Detection
  14. GRB20250327B: 45th Parallel Observatory upper limit
  15. GRB 250328A: Swift/UVOT Detection
  16. GRB 250328A: Swift-XRT refined Analysis
  17. Fermi-LAT gamma-ray observations of IceCube-250330A
  18. SVOM/sb25033102 is a false trigger
  19. GRB 250330A: Fermi GBM Observation
  20. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  21. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  22. GRB 250331C: Swift detection of a burst
  23. GRB 250331B: Swift detection of a burst
  24. GRB 250331A: MAXI/GSC detection
  25. SVOM/sb25033102: SVOM detection of an X-ray transient
  26. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  27. GRB 250330A: Swift/UVOT Upper Limits
  28. GRB 250330A: Swift-XRT afterglow detection
  29. GRB 250328A: 1.6m Mephisto optical observations
  30. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  31. GRB 250330A: VLT/FORS2 Optical Observations
  32. GRB 250329B: Swift-XRT afterglow detection
  33. GRB 250330A: Swift detection of a burst
  34. GRB 250329B: SVOM/C-GFT optical upper limit
  35. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 1)
  36. GRB 250329B: SVOM/VT optical upper limit
  37. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  38. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  39. LIGO/Virgo/KAGRA S250329fl: 2 counterpart neutrino candidate events from an IceCube neutrino search
  40. GRB250329A: REM optical afterglow detection
  41. GRB 250329A: Swift-XRT afterglow detection
  42. GRB 250328A: SVOM/VT optical observation
  43. GRB 250329A: Fading optical counterpart detection by LCO.
  44. GRB 250328A: SVOM/C-GFT optical upper limit
  45. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  46. GRB 250329A: SVOM/VT optical counterpart confirmation
  47. GRB 250329A: SVOM detection of a burst
  48. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  49. GRB 250327B: J-band observations with WINTER
  50. GRB 250327B: LCO optical counterpart detection
  51. GRB 250328A: SVOM detection of a burst
  52. LIGO/Virgo/KAGRA S250328ae: NED Galaxies in the 4-Update Localization Volume
  53. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  54. GRB 250327B: CrAO and SAO RAS Optical Observations
  55. GRB 250327b: Liverpool Telescope optical observations
  56. GRB 250322A: GRANDMA/TNOT optical upper limits
  57. LIGO/Virgo/KAGRA S250328ae: Updated Sky localization
  58. GRB 250327A: SVOM/VT upper limits on the XRT position
  59. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  60. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  61. GRB 250327B: Las Cumbres optical counterpart detection
  62. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  63. GRB 250327B: 1.6m Mephisto optical observations
  64. GRB 250327A: Swift-XRT refined Analysis
  65. GRB 250327B: SVOM/VT optically bright counterpart
  66. GRB 250327B: SAO RAS optical candidate
  67. GRB 250327B: SVOM detection of a burst
  68. FRB 20250316A: Gemini Imaging and Spectroscopy of the Sub-arcsecond Localization Region of FRB 20250316A
  69. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  70. GRB 250327A: J-band observations with WINTER
  71. GRB 250327A: SVOM/VT optical candidate
  72. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  73. GRB 250327A: DDOTI Optical Observations
  74. GRB 250327A: COLIBRÍ optical upper limit
  75. LIGO/Virgo/KAGRA S250326y: Updated Sky localization
  76. IPN triangulation of GRB 250322B
  77. LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
  78. EP250321a: Mondy AZT-33IK Continued Optical Observations
  79. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  80. GRB 250322A: third epoch of NOT optical observations
  81. GRB 250322A: Swift-BAT refined analysis
  82. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  83. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  84. GRB 250322A: further NOT optical observations
  85. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  86. GRB 250322A: Swift/UVOT Upper Limits
  87. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  88. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  89. GRB 250322B: NuSTAR detection of the prompt emission and regular dips during the burst
  90. GRB 250321B: Swift-XRT observations
  91. GRB 250322A: Swift-XRT refined Analysis
  92. EP250321a: TNOT Observation of Optical Counterpart
  93. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  94. SVOM/sb25032302: SVOM detection of a long X-ray transient
  95. GRB 250322B: AstroSat CZTI detection of a bright long burst
  96. GRB 250322A: VLT optical observations
  97. GRB 250322A: VLT near-infrared observations
  98. FRB 250316A: DDOTI Continued Optical Observations
  99. GRB 250322A: NOT optical upper limits
  100. GRB 250322A: Enhanced Swift-XRT position

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