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"

43897 results found.

  1. Fermi Gamma-ray Burst Monitor trigger 776449964/250809689 is not a GRB
  2. GRB 250808A: VLT X-shooter candidate counterpart
  3. GRB 250809A: Prompt enhanced Swift-XRT position
  4. GRB 250809A: Swift detection of a gamma ray burst
  5. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  6. GRB 250808A: Fermi GBM Observation
  7. GRB 250808A: Swift-XRT candidate counterpart detection
  8. GRB 250807A: SVOM/VT optical continued observation
  9. EP-WXT trigger 01709195487: KAIT confirmation of the stellar flare
  10. GRB 250808A: SVOM detection of a long burst
  11. GRB 250808A: Fermi GBM Final Real-time Localization
  12. Konus-Wind detection of GRB 250807A
  13. GRB 250807B: Swift/UVOT Detection
  14. GRB 250807B: Kilonova-Catcher optical afterglow detection
  15. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  16. GRB 250807A: Swift/UVOT Detection
  17. GRB 250807A: Swift-XRT refined Analysis
  18. GRB 250807B: VLT/X-Shooter spectroscopic redshift z = 1.522
  19. GRB 250806A: SVOM/MXT refined analysis
  20. GRB 250806A: SVOM/ECLAIRs refined analysis
  21. EP250807a: NTT z-band optical upper limit
  22. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  23. GRB 250804B: Insight-HXMT detection
  24. GRB 250807A: SVOM/GRM observation
  25. Swift GRB250807.45: Global MASTER-Net observations report
  26. GRB 250807A: AstroSat CZTI detection of bright long burst
  27. GRB 250807B: Swift-XRT refined Analysis
  28. GRB 250806A: NOT z-band upper limit and host galaxy candidate
  29. GRB 250807B: NTT optical observations
  30. EP250807a: EP-WXT detection of a fast X-ray transient
  31. EP 250807.979: GOTO optical upper limit
  32. EP250807a: COLIBRÍ optical upper limit
  33. GRB 250807A: SVOM/VT optical observation
  34. EP250806a: Upper limit from Fermi-GBM Observations
  35. GRB 250807B: Enhanced Swift-XRT position
  36. Swift GRB250807.65: Global MASTER-Net observations report
  37. GRB 250807A: Enhanced Swift-XRT position
  38. IceCube-Cascade 250804A: Upper limits from a search for additional neutrino events in IceCube
  39. GRB 250807B: Swift detection of a burst with an optical counterpart.
  40. GRB 250805A: Kilonova-Catcher optical upper limits
  41. EP250806a:SVOM/VT refined analysis
  42. EP250806a: Liverpool telescope optical upper limit
  43. GRB 250807A: Swift detection of a burst with an optical counterpart
  44. IceCube Alert 250804.84: Global MASTER-Net observations report
  45. GRB 250806A: EP-FXT observation
  46. EP#01709198415/EP250806a: Swift-XRT observations
  47. EP250806a: Global MASTER-Net observations report
  48. EP250802a: EP-FXT follow-up observation
  49. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  50. EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS
  51. EP250806a: SVOM /VT optical candidate
  52. GRB 250806A: J-band upper limit from WINTER
  53. GRB 250805A: Swift-BAT refined analysis
  54. GRB 250806A: KAIT optical upper limit
  55. GRB 250806A: SVOM/VT refined analysis
  56. GRB 250806A: Swift-XRT counterpart detection
  57. EP250806a: COLIBRÍ optical upper limit
  58. GRB 250806A: Kilonova-Catcher optical upper limits
  59. EP250806a: Einstein Probe detection of an X-ray transient
  60. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  61. GRB 250806A: SVOM/VT optical upper limit
  62. GRB 250806A: SVOM detection of a soft burst
  63. GRB 250805A: SVOM/VT optical counterpart
  64. GRB 250805A: ESO/VLT observations
  65. GRB 250805A: Swift-XRT refined Analysis
  66. GRB 250804B: Swift-XRT observations
  67. GRB 250805A: Enhanced Swift-XRT position
  68. GRB 250804C: AstroSat CZTI detection of a long burst
  69. GRB 250805A: TRT optical upper limits
  70. IceCube-250804A - IceCube observation of a high-energy neutrino candidate track-like event
  71. GRB 250805A: Swift-XRT observations
  72. GRB 250805A: Swift detection of a burst
  73. Swift GRB250805.26: Global MASTER-Net observations report
  74. GRB 250804B: Tiled Swift observations
  75. Fermi trigger No 776041355: Global MASTER-Net observations report
  76. GRB 250804B: SVOM/GRM observation of a short burst
  77. GRB 250804A: Fermi GBM Final Localization
  78. EP250802a: additional Liverpool Telescope upper limits
  79. EP250730a: SVOM/VT optical upper limit
  80. Fermi Gamma-ray Burst Monitor trigger 775945985/250803856 is not a GRB
  81. EP250802a: Liverpool Telescope optical upper limits
  82. EP250802a: Global MASTER-Net observations report
  83. EP250802a: GROWTH-India Telescope optical upper limit
  84. EP250802a: Einstein Probe detection of an X-ray transient
  85. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  86. The EP-WXT trigger 01709198251 is likely a flaring star
  87. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  88. The EP-WXT trigger 01709198202 is likely a flaring star
  89. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  90. GRB 250702B: SMA observations
  91. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  92. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  93. EP250711a: CrAO and Assy optical observations
  94. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  95. EP250730a: Global MASTER-Net observations report
  96. EP250730a: COLIBRÍ optical upper limit
  97. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  98. EP250730a: Einstein Probe detection of an X-ray transient
  99. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  100. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT follow up of AT 2025smm

Advanced

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