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"

7406 results found.

  1. GRB 251006B/EP251006a: EP-FXT afterglow detection
  2. GRB 251007B: SVOM/VT optical candidate
  3. GRB 251007B: SVOM/C-GFT upper limit
  4. GRB 251007B: Swift detection of a burst
  5. GRB 251007A: Swift detection of a burst with an optical counterpart
  6. GRB 251006B/EP251006a: SVOM/VT optical candidate
  7. GRB 251005C: SVOM/VT optical fading
  8. LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate
  9. GRB 251005C: VLT/X-shooter Imaging
  10. GRB 251005C: SVOM/VT optical candidate
  11. GRB 251005C: Swift detection of a burst
  12. LIGO/Virgo/KAGRA S251003at: Retraction of GW compact binary merger candidate
  13. GRB 251002A: Swift-XRT afterglow detection
  14. GRB 251003A: 1.5m OSN afterglow candidate
  15. GRB 251003A: Swift detection of a burst
  16. GRB 251002A: SVOM/VT optical observation
  17. GRB 251001B: Swift detection of a burst
  18. LIGO/Virgo/KAGRA S250830bp: SOAR spectroscopy of two DESGW candidates
  19. LIGO/Virgo/KAGRA S250929c: Updated Sky localization
  20. LIGO/Virgo/KAGRA S250929c: Identification of a GW compact binary merger candidate
  21. LIGO/Virgo/KAGRA S250927cy: Updated Sky localization
  22. LIGO/Virgo/KAGRA S250927ck: Updated Sky localization
  23. LIGO/Virgo/KAGRA S250927cy: Identification of a GW compact binary merger candidate
  24. LIGO/Virgo/KAGRA S250927ck: Identification of a GW compact binary merger candidate
  25. IceCube-250926A - IceCube observation of a high-energy neutrino candidate track-like event
  26. GRB250925A: Liverpool Telescope optical observations
  27. GRB 250925A: NOT optical afterglow candidate
  28. GRB 250925A: Leavitt Observatory optical upper limit
  29. GRB 250924A: 1.6m Mephisto optical upper limits
  30. GRB 250924A: Swift detection of a burst with an optical counterpart
  31. GRB 250920C: COLIBRÍ optical observations
  32. GRB 250920B: NIR observations with WINTER
  33. GRB 250917B: Mondy and Zeiss-1000 SAO RAS optical observations, optical observations, afterglow candidate
  34. GRB250920C: LCOGT Optical Detection
  35. GRB 250920C: GOTO optical counterpart candidate
  36. LIGO/Virgo/KAGRA S250920bq: Coverage and upper limits from MAXI/GSC observations
  37. GRB 250920B: Swift detection of a burst with a bright optical counterpart.
  38. GRB 250919A / EP250919a: NuSTAR detection of bright prompt emission
  39. GRB 250916A: NuSTAR detection of the prompt emission
  40. LIGO/Virgo/KAGRA S250918aw: 1 counterpart neutrino candidate event from an IceCube neutrino search
  41. LIGO/Virgo/KAGRA S250917aq: Three counterpart neutrino candidates from IceCube neutrino searches
  42. LIGO/Virgo/KAGRA S250917aq: Updated Sky localization
  43. GRB 250916A: Swift ToO observations
  44. LIGO/Virgo/KAGRA S250917aq: Identification of a GW compact binary merger candidate
  45. GRB 250917B: Swift detection of a short burst
  46. GRB 250916A: GOTO optical counterpart candidate
  47. LIGO/Virgo/KAGRA S250818k: HCT optical follow-up
  48. GRB 250912A: VLT observations
  49. GRB 250912A: SVOM/GRM analysis suggests a possible short GRB with extended emission
  50. LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search
  51. EP250908c: tentative VLT/FORS2 redshift z = 2.87
  52. LIGO/Virgo/KAGRA S250912f: Updated Sky localization
  53. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  54. EP250911a: Optical detection with Kinder observations
  55. LIGO/Virgo/KAGRA S250911ac: Updated Sky localization and Source Classification
  56. LIGO/Virgo/KAGRA S250908y: Updated Sky localization
  57. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  58. GRB 250911A: COLIBRÍ optical counterpart candidate
  59. LIGO/Virgo/KAGRA S250906ca: Updated Sky localization
  60. GRB 250910A: SVOM/VT optical upper limit
  61. EP250908C: GROND observation of the fading optical counterpart
  62. LIGO/Virgo/KAGRA S250910b: Retraction of GW compact binary merger candidate
  63. EP#01709240653: Swift-XRT observations
  64. The EP-WXT trigger 01709240674 is triggered by the known source SS Cyg
  65. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  66. EP250908b: SVOM/VT optical candidate
  67. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  68. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  69. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  70. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  71. IceCube-250905A - IceCube observation of a high-energy neutrino candidate track-like event
  72. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  73. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  74. EP detected a brightening of LMXB 1ES 1735-26.9
  75. GRB 250905A: KAIT optical upper limit
  76. GRB 250905A: Swift detection of a burst
  77. GRB 250904A: Swift detection of a burst
  78. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  79. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  80. GRB 250903A: Swift-XRT observations
  81. EP250903a: Swift-XRT observations
  82. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  83. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  84. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  85. EP250903a: LCO candidate counterpart discovery
  86. EP/WXT01709201159: GOTO optical follow-up
  87. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  88. LIGO/Virgo/KAGRA S250901cb: Updated Sky localization
  89. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  90. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  91. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  92. EP250831a: NOT optical observations and tentative afterglow candidate
  93. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  94. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  95. IceCube-250831A - IceCube observation of a high-energy neutrino candidate track-like event
  96. GRB 250831A: Swift-XRT counterpart detection
  97. GRB 250831A: SVOM/VT upper limit with VHF data
  98. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  99. LIGO/Virgo/KAGRA S250830bp: NED Galaxies in the 4-Update Localization Volume
  100. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification

Advanced

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