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"

24376 results found.

  1. EP250911a: SVOM/VT optical observation
  2. GRB 250910C: Fermi GBM Final Localization Correction
  3. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  4. GRB 250909B: SVOM/GRM observation
  5. LIGO/Virgo/KAGRA S250911ac: Updated Sky localization and Source Classification
  6. LIGO/Virgo/KAGRA S250908y: Updated Sky localization
  7. Fermi GRB 250910B: Global MASTER-Net observations report
  8. EP250911a: LCO optical counterpart discovery
  9. EP250910a: Global MASTER-Net observations report
  10. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  11. GRB 250903A: SVOM/ECLAIRs refined analysis
  12. GRB 250911A: Swift detection of a burst
  13. LIGO/Virgo/KAGRA S250906ca: Updated Sky localization
  14. GRB 250910B: BALROG localization (Fermi Trigger 779223130 / GRB 250910786)
  15. GRB 250910B: Fermi GBM Final Real-time Localization
  16. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  17. GRB 250910A: SVOM/VT optical upper limit
  18. GRB 250910A: SVOM/MXT possible afterglow detection
  19. GRB 250910A: SVOM detection of a faint burst
  20. LIGO/Virgo/KAGRA S250910b: Retraction of GW compact binary merger candidate
  21. GRB 250702B: Late time Chandra observations
  22. The EP-WXT trigger 01709240674 is triggered by the known source SS Cyg
  23. EP250908c: SVOM/VT optical observation
  24. EP250908c: VLT/FORS2 optical counterpart identification
  25. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  26. EP250908b: SVOM/VT optical candidate
  27. The EP-WXT trigger EP250908a/01709240652 is not a real source
  28. EP250908c: Global MASTER-Net observations report
  29. Fermi GRB 250909A: Global MASTER-Net observations report
  30. GRB 250909A: Fermi GBM Final Real-time Localization
  31. EP#01709240652 (possibly EP250908a): FTW optical and NIR observations
  32. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  33. GRB 250907A: GECAM-B detection
  34. GRB 250905A: Swift-BAT refined analysis
  35. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  36. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  37. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  38. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  39. EP250905b: EP-FXT follow-up observation
  40. EP250905b: Global MASTER-Net observations report
  41. EP250905a: FTW one optical and multiple NIR counterpart candidates
  42. IceCube-250905A - IceCube observation of a high-energy neutrino candidate track-like event
  43. GRB 250904A: Swift-BAT refined analysis
  44. IceCube Alert 250905.84: Global MASTER-Net observations report
  45. EP250905a: Global MASTER-Net observations report
  46. GRB 250901A - SVOM/ECLAIRs refined analysis
  47. GRB 250905B: Fermi GBM Final Localization
  48. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  49. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  50. EP detected a brightening of LMXB 1ES 1735-26.9
  51. GRB 250905A: KAIT optical upper limit
  52. GRB 250905A: Swift detection of a burst
  53. Swift GRB250905.09: Global MASTER-Net observations report
  54. Swift GRB 250904A: Global MASTER-Net observations report
  55. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  56. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  57. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  58. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  59. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  60. GRB 250902A: VZLUSAT-2 detection
  61. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  62. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  63. GRB 250830C: VZLUSAT-2 detection
  64. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  65. The EP-WXT trigger 01709201209 is likely a flaring star
  66. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  67. GRB 250903A: EP-FXT counterpart detection
  68. GRB 250902A: GECAM-B detection
  69. EP250903a: SVOM/VT optical confirmation
  70. EP250901a: Mondy, Assy and SAO RAS optical limits
  71. EP250903a: LCO candidate counterpart discovery
  72. GRB 250903A: SVOM detection of a burst
  73. EP250903a: Global MASTER-Net observations report
  74. EP250903a: Einstein Probe detection of an X-ray transient
  75. EP/WXT01709201159: GOTO optical follow-up
  76. GRB 250902B: SVOM/GRM observation
  77. EP250827b: SVOM/VT observation of AT 2025wkm
  78. Fermi GRB 250902B: Global MASTER-Net observations report
  79. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  80. GRB 250902A: Fermi GBM Detection
  81. GRB 250902B: Fermi GBM Final Real-time Localization
  82. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  83. GRB 250830B: Swift-XRT afterglow detection
  84. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  85. LIGO/Virgo/KAGRA S250901cb: Updated Sky localization
  86. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  87. GRB 250902A: SVOM/GRM observation
  88. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  89. GRB 250901A: EP-FXT follow-up observation
  90. GRB 250902A: Fermi GBM Final Real-time Localization
  91. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  92. EP250827b: Swift observations of AT 2025wkm
  93. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  94. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  95. EP250827b: FTW Observations of AT 2025wkm
  96. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  97. GRB 250901A: SVOM detection of a burst
  98. GRB 250831B: SVOM/GRM observation
  99. EP250901a: Mephisto optical upper limits
  100. GRB 250830C: GECAM-B detection

Advanced

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