Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

45418 results found.

  1. EP250812a: Nickel optical upper limit
  2. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  3. GRB 250812A: NTT spectroscopic redshift z = 2.57
  4. GRB250812a: STEP/T80S Indication of slow decay of afterglow
  5. EP250812a: NOT, NTT, and GS observations
  6. GRB 250812A: Swift/UVOT Detection
  7. GRB 250813A: Fermi GBM Final Localization
  8. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  9. EP250812a: Liverpool Telescope upper limits
  10. EP250812a: SVOM/VT optical counterpart
  11. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  12. IceCube-250813A - IceCube observation of a high-energy neutrino candidate track-like event
  13. IceCube Alert 250813.14: Global MASTER-Net observations report
  14. LIGO/Virgo/KAGRA S250813k: Identification of a GW compact binary merger candidate
  15. GRB 250812A: EP-FXT counterpart detection
  16. GRB 250812A: Swift ToO observations
  17. GRB 250807B: Swift-BAT refined analysis
  18. EP 250812a: GOTO optical upper limit
  19. GRB 250812A: Kilonova-Catcher optical afterglow detection
  20. EP250812a: Swift-XRT counterpart detection
  21. Fermi Gamma-ray Burst Monitor trigger 776705265/250812644 is not a GRB
  22. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  23. EP250812a: Einstein Probe detection of an X-ray transient
  24. GRB 250812A: SVOM/VT optical afterglow confirmation
  25. GRB 250812A: Swift-XRT afterglow detection
  26. GRB 250812A: TRT likely optical counterpart detection
  27. IceCube-Cascade 250809A: Upper limits from a search for additional neutrino events in IceCube
  28. GRB 250812A: SVOM detection of a faint long burst
  29. GRB 250809A: Swift-BAT refined analysis
  30. Fermi Gamma-ray Burst Monitor trigger 776620220/250811660 is not a GRB
  31. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  32. GRB 250807A: Swift-BAT refined analysis
  33. LIGO/Virgo/KAGRA S250810ck: Updated Sky localization and EM Bright Classification
  34. GRB 250809A: Swift/UVOT Detection
  35. LIGO/Virgo/KAGRA S250810ck: Identification of a GW compact binary merger candidate
  36. Corrected Swift-XRT Refined Analysis of GRB 250809A
  37. GRB 250809A: Swift-XRT refined Analysis
  38. GRB 250807B: SVOM/VT optical observation
  39. EP250807a: EP-FXT follow-up observation upper limit
  40. GRB 250809A: LCOGT Optical Upper Limits
  41. GRB 250702B: Chandra X-ray Detection
  42. EP250807a: Global MASTER-Net observations report
  43. Fermi GRB 250808A: Global MASTER-Net observations report
  44. Fermi Gamma-ray Burst Monitor trigger 776449964/250809689 is not a GRB
  45. GRB 250808A: VLT X-shooter candidate counterpart
  46. GRB 250809A: Prompt enhanced Swift-XRT position
  47. GRB 250809A: Swift detection of a gamma ray burst
  48. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  49. GRB 250808A: Fermi GBM Observation
  50. GRB 250808A: Swift-XRT candidate counterpart detection
  51. GRB 250807A: SVOM/VT optical continued observation
  52. EP-WXT trigger 01709195487: KAIT confirmation of the stellar flare
  53. GRB 250808A: SVOM detection of a long burst
  54. GRB 250808A: Fermi GBM Final Real-time Localization
  55. Konus-Wind detection of GRB 250807A
  56. GRB 250807B: Swift/UVOT Detection
  57. GRB 250807B: Kilonova-Catcher optical afterglow detection
  58. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  59. GRB 250807A: Swift/UVOT Detection
  60. GRB 250807A: Swift-XRT refined Analysis
  61. GRB 250807B: VLT/X-Shooter spectroscopic redshift z = 1.522
  62. GRB 250806A: SVOM/MXT refined analysis
  63. GRB 250806A: SVOM/ECLAIRs refined analysis
  64. EP250807a: NTT z-band optical upper limit
  65. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  66. GRB 250804B: Insight-HXMT detection
  67. GRB 250807A: SVOM/GRM observation
  68. Swift GRB250807.45: Global MASTER-Net observations report
  69. GRB 250807A: AstroSat CZTI detection of bright long burst
  70. GRB 250807B: Swift-XRT refined Analysis
  71. GRB 250806A: NOT z-band upper limit and host galaxy candidate
  72. GRB 250807B: NTT optical observations
  73. EP250807a: EP-WXT detection of a fast X-ray transient
  74. EP 250807.979: GOTO optical upper limit
  75. EP250807a: COLIBRÍ optical upper limit
  76. GRB 250807A: SVOM/VT optical observation
  77. EP250806a: Upper limit from Fermi-GBM Observations
  78. GRB 250807B: Enhanced Swift-XRT position
  79. Swift GRB250807.65: Global MASTER-Net observations report
  80. GRB 250807A: Enhanced Swift-XRT position
  81. IceCube-Cascade 250804A: Upper limits from a search for additional neutrino events in IceCube
  82. GRB 250807B: Swift detection of a burst with an optical counterpart.
  83. GRB 250805A: Kilonova-Catcher optical upper limits
  84. EP250806a:SVOM/VT refined analysis
  85. GRB 250805A: Swift/UVOT Upper Limits
  86. GRB 250806A: Swift/UVOT U-band detection
  87. EP250806a: Liverpool telescope optical upper limit
  88. GRB 250807A: Swift detection of a burst with an optical counterpart
  89. IceCube Alert 250804.84: Global MASTER-Net observations report
  90. GRB 250806A: EP-FXT observation
  91. EP#01709198415/EP250806a: Swift-XRT observations
  92. EP250806a: Global MASTER-Net observations report
  93. EP250802a: EP-FXT follow-up observation
  94. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  95. EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS
  96. EP250806a: SVOM /VT optical candidate
  97. GRB 250806A: J-band upper limit from WINTER
  98. GRB 250805A: Swift-BAT refined analysis
  99. GRB 250806A: KAIT optical upper limit
  100. GRB 250806A: SVOM/VT refined analysis

Advanced

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