Skip to main content
End of Swift Science Operations, CHIME Notices Unavailable During Upgrade. See news and announcements

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"

28302 results found.

  1. GRB 250403A: JinShan optical observations
  2. GRB 250403A: Optical counterpart detection by LCO.
  3. EP250402a: EP-FXT follow-up observations
  4. GRB 250403A: Swift-XRT observations
  5. GRB 250322A: 10 GHz VLA radio upper limits
  6. GRB 250403A: GMG Optical Observation
  7. GRB 250403A: 1.6m Mephisto multi-band optical detection
  8. GRB 250402A: Fermi GBM Observation
  9. GRB 250403A: SVOM/C-GFT optical observations
  10. GRB 250402A: Swift-XRT observations
  11. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  12. GRB 250402A: REM optical/NIR upper limits
  13. GRB 250402A: LCO optical counterpart detection
  14. EP250402a: Einstein Probe detection of a fast X-ray transient
  15. GRB 250402B: AstroSat CZTI detection of a short burst
  16. GRB 250402A: SVOM/VT optical counterpart
  17. GRB 250402A: SVOM detection of a burst
  18. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  19. GRB 250329B: Swift/UVOT Upper Limit
  20. GRB 250329A: Swift/UVOT Upper Limit
  21. GRB 250327B: Swift/UVOT Detection
  22. GRB 250327A: Swift/UVOT Upper Limits
  23. GRB 250331E: SVOM/GRM observation
  24. GRB 250327B: Kilonova-Catcher Observations
  25. GRB250331D: AbAO optical observations
  26. GRB 250331D: Fermi GBM observation
  27. GRB 250331C: Swift/UVOT Upper Limits
  28. GRB 250331B: Swift/UVOT Upper Limits
  29. GRB 250328A: AbAO AS-32 Optical Observations
  30. GRB 250219A: NOT candidate host galaxy detection
  31. GRB 250331D: Swift-XRT observations
  32. GRB 250331C: Swift-XRT refined Analysis
  33. GRB 250331B: Swift-XRT refined Analysis
  34. GRB 250331B: Swift-XRT refined Analysis
  35. GRB 250322B possible detection by the AstroSat Satellite
  36. GRB 250330B: SVOM/GRM observation of a short burst
  37. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  38. GRB 250330B: EIRSAT-1 GMOD Detection
  39. GRB 250327A Swift-BAT refined analysis
  40. LIGO/Virgo/KAGRA S250331o: Updated Sky localization
  41. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  42. Swift GRB 250331C: Global MASTER-Net observations report
  43. Swift GRB 250331B: Global MASTER-Net observations report
  44. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  45. GRB 250331C: Enhanced Swift-XRT position
  46. IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube
  47. LIGO/Virgo/KAGRA S250331o: NED Galaxies in the 3-Initial Localization Volume
  48. GRB 250331B: Enhanced Swift-XRT position
  49. GRB 250320C : SVOM detection of a burst through offline search
  50. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  51. GRB 250330A: VLT/FORS2 Afterglow Detection
  52. GRB20250327B: 45th Parallel Observatory upper limit
  53. GRB 250328A: Swift/UVOT Detection
  54. GRB 250328A: Swift-XRT refined Analysis
  55. Fermi-LAT gamma-ray observations of IceCube-250330A
  56. SVOM/sb25033102 is a false trigger
  57. GRB 250330A: Fermi GBM Observation
  58. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  59. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  60. GRB 250331C: Swift detection of a burst
  61. GRB 250331B: Swift detection of a burst
  62. GRB 250331A: MAXI/GSC detection
  63. SVOM/sb25033102: SVOM detection of an X-ray transient
  64. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  65. GRB 250330A: Swift/UVOT Upper Limits
  66. GRB 250330A: Swift-XRT afterglow detection
  67. GRB 250328A: 1.6m Mephisto optical observations
  68. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  69. GRB 250330A: VLT/FORS2 Optical Observations
  70. GRB 250329B: Swift-XRT afterglow detection
  71. GRB 250330A: Swift detection of a burst
  72. GRB 250329B: SVOM/C-GFT optical upper limit
  73. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 1)
  74. GRB 250329B: SVOM/VT optical upper limit
  75. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  76. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  77. LIGO/Virgo/KAGRA S250329fl: 2 counterpart neutrino candidate events from an IceCube neutrino search
  78. GRB250329A: REM optical afterglow detection
  79. GRB 250329A: Swift-XRT afterglow detection
  80. GRB 250328A: SVOM/VT optical observation
  81. GRB 250329A: Fading optical counterpart detection by LCO.
  82. GRB 250328A: SVOM/C-GFT optical upper limit
  83. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  84. GRB 250329A: SVOM/VT optical counterpart confirmation
  85. GRB 250329A: SVOM detection of a burst
  86. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  87. GRB 250327B: J-band observations with WINTER
  88. GRB 250327B: LCO optical counterpart detection
  89. GRB 250328A: SVOM detection of a burst
  90. LIGO/Virgo/KAGRA S250328ae: NED Galaxies in the 4-Update Localization Volume
  91. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  92. GRB 250327B: CrAO and SAO RAS Optical Observations
  93. GRB 250327b: Liverpool Telescope optical observations
  94. GRB 250322A: GRANDMA/TNOT optical upper limits
  95. LIGO/Virgo/KAGRA S250328ae: Updated Sky localization
  96. GRB 250327A: SVOM/VT upper limits on the XRT position
  97. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  98. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  99. GRB 250327B: Las Cumbres optical counterpart detection
  100. GRB 250327B: Swift-XRT detection of the X-ray afterglow

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov