Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. 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"

28246 results found.

  1. EP250807a: NTT z-band optical upper limit
  2. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  3. GRB 250807A: SVOM/GRM observation
  4. GRB 250807A: AstroSat CZTI detection of bright long burst
  5. GRB 250807B: Swift-XRT refined Analysis
  6. EP250807a: EP-WXT detection of a fast X-ray transient
  7. EP 250807.979: GOTO optical upper limit
  8. EP250807a: COLIBRÍ optical upper limit
  9. EP250806a: Upper limit from Fermi-GBM Observations
  10. GRB 250807B: Enhanced Swift-XRT position
  11. GRB 250807A: Enhanced Swift-XRT position
  12. IceCube-Cascade 250804A: Upper limits from a search for additional neutrino events in IceCube
  13. GRB 250807B: Swift detection of a burst with an optical counterpart.
  14. GRB 250805A: Kilonova-Catcher optical upper limits
  15. GRB 250805A: Swift/UVOT Upper Limits
  16. GRB 250806A: Swift/UVOT U-band detection
  17. EP250806a: Liverpool telescope optical upper limit
  18. GRB 250807A: Swift detection of a burst with an optical counterpart
  19. EP250802a: EP-FXT follow-up observation
  20. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  21. EP250806a: SVOM /VT optical candidate
  22. GRB 250806A: J-band upper limit from WINTER
  23. GRB 250805A: Swift-BAT refined analysis
  24. GRB 250806A: KAIT optical upper limit
  25. GRB 250806A: Swift-XRT counterpart detection
  26. EP250806a: COLIBRÍ optical upper limit
  27. GRB 250806A: Kilonova-Catcher optical upper limits
  28. EP250806a: Einstein Probe detection of an X-ray transient
  29. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  30. GRB 250806A: SVOM/VT optical upper limit
  31. GRB 250806A: SVOM detection of a soft burst
  32. GRB 250805A: SVOM/VT optical counterpart
  33. GRB 250805A: Swift-XRT refined Analysis
  34. GRB 250804B: Swift-XRT observations
  35. GRB 250805A: Enhanced Swift-XRT position
  36. GRB 250805A: TRT optical upper limits
  37. GRB 250805A: Swift-XRT observations
  38. GRB 250804B: SVOM/GRM observation of a short burst
  39. GRB 250804A: Fermi GBM Final Localization
  40. EP250802a: additional Liverpool Telescope upper limits
  41. EP250730a: SVOM/VT optical upper limit
  42. EP250802a: Liverpool Telescope optical upper limits
  43. EP250802a: Global MASTER-Net observations report
  44. EP250802a: GROWTH-India Telescope optical upper limit
  45. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  46. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  47. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  48. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  49. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  50. EP250711a: CrAO and Assy optical observations
  51. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  52. EP250730a: COLIBRÍ optical upper limit
  53. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  54. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  55. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  56. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  57. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  58. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  59. GRB 250727A: EP-FXT follow-up observation
  60. GRB 250725A: PRIME near-infrared observations
  61. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  62. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  63. GRB 250728A: Swift-XRT observations
  64. GRB 250728A: COLIBRÍ optical upper limit
  65. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  66. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  67. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  68. GRB 250727A: EP-FXT counterpart detection
  69. GRB 250727A: Swift-XRT observations
  70. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  71. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  72. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  73. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  74. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  75. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  76. GRB 250725A: Swift-XRT refined Analysis
  77. GRB 250725A: Fermi GBM Observation
  78. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  79. GRB 250725A: Swift-BAT refined analysis
  80. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  81. GRB 250725A: SVOM/GRM observation
  82. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  83. GRB 250725A: Swift/UVOT Upper Limits
  84. GRB 250725A: Fermi-LAT detection
  85. GRB 250725A: BOOTES-7 early optical detection
  86. GRB 250725A: SVOM/VT optical candidate
  87. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  88. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  89. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  90. GRB 250725A: Enhanced Swift-XRT position
  91. GRB 250725A: Swift detection of a burst
  92. Swift GRB 250725A: Global MASTER-Net OT detection
  93. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  94. SVOM J195836+32283 is not a real source
  95. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  96. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  97. GRB 250721A: Fermi GBM Observation
  98. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  99. GRB 250721A: Swift-XRT observations
  100. GRB 250717B: SVOM/GRM observation

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov