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"

28284 results found.

  1. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  2. GRB 250728A: Swift-XRT observations
  3. GRB 250728A: COLIBRÍ optical upper limit
  4. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  5. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  6. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  7. GRB 250727A: EP-FXT counterpart detection
  8. GRB 250727A: Swift-XRT observations
  9. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  10. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  11. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  12. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  13. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  14. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  15. GRB 250725A: Swift-XRT refined Analysis
  16. GRB 250725A: Fermi GBM Observation
  17. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  18. GRB 250725A: Swift-BAT refined analysis
  19. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  20. GRB 250725A: SVOM/GRM observation
  21. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  22. GRB 250725A: Swift/UVOT Upper Limits
  23. GRB 250725A: Fermi-LAT detection
  24. GRB 250725A: BOOTES-7 early optical detection
  25. GRB 250725A: SVOM/VT optical candidate
  26. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  27. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  28. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  29. GRB 250725A: Enhanced Swift-XRT position
  30. GRB 250725A: Swift detection of a burst
  31. Swift GRB 250725A: Global MASTER-Net OT detection
  32. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  33. SVOM J195836+32283 is not a real source
  34. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  35. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  36. GRB 250721A: Fermi GBM Observation
  37. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  38. GRB 250721A: Swift-XRT observations
  39. GRB 250717B: SVOM/GRM observation
  40. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  41. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  42. GRB 250721A: MAXI/GSC detection
  43. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  44. GRB 250717B: COLIBRÍ optical upper limit
  45. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  46. GRB 250717B: Swift-XRT observations
  47. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  48. Swift GRB250718.01: Global MASTER-Net observations report
  49. GRB 270713A: Kitab and AbAO Optical Observations
  50. GRB 250717B: Fermi GBM Observation
  51. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  52. GRB 250716A: Swift-XRT afterglow detection
  53. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  54. GRB 250716A: Fermi GBM Observation
  55. GRB 250714A: SVOM/GRM observation
  56. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  57. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  58. GRB 250713A: Mephisto optical upper limits
  59. GRB 250713A: SVOM/VT optical upper limit
  60. GRB 250713A: NOT optical upper limits
  61. GRB 250713A: OHP/T193 upper limit
  62. GRB 250713A: SVOM/C-GFT upper limit
  63. GRB 250706B/C: 7DT Follow-up Observations
  64. GRB 250713A: Swift-XRT observations
  65. GRB 250713A: EP-FXT counterpart detection
  66. EP250711a: COLIBRÍ continuous optical observations
  67. GRB 250706A: Swift-BAT refined analysis
  68. GRB 250702F: Swift-BAT refined analysis
  69. GRB 250628A: Swift-BAT refined analysis
  70. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  71. GRB 250713A: JinShan optical upper limits
  72. GRB 250713A: SVOM detection of a long burst
  73. EP250711a: Global MASTER-Net observations report
  74. GRB 250711A: DDOTI Optical Upper Limit
  75. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  76. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  77. GRB 250711A: SVOM/GRM observation
  78. EP250711a: NOT optical counterpart candidate
  79. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  80. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  81. GRB 250704A: GRANDMA observations
  82. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  83. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  84. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  85. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  86. IceCube-250708A: No Candidates from WINTER
  87. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  88. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  89. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  90. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  91. EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6
  92. EP250704a/GRB 250704B: 10 GHz VLA detection
  93. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
  94. IceCube-250706A: No Candidates from WINTER
  95. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  96. IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
  97. LIGO/Virgo/KAGRA S250705cb: Updated Sky localization
  98. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  99. LIGO/Virgo/KAGRA S250702n: Updated Sky localization
  100. LIGO/Virgo/KAGRA S250701bq: Updated Sky localization

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