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"

23409 results found.

  1. EP250911a: SVOM/VT optical observation
  2. EP250911a: SAO RAS optical observations
  3. EP250911a: Swift-XRT observations
  4. EP250911a: Optical detection with Kinder observations
  5. GRB 250911A: Swift/UVOT Detection
  6. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  7. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  8. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  9. EP250911a: COLIBRÍ optical observations
  10. EP250911a: Einstein Probe detection of an X-ray transient
  11. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  12. GRB 250903A: SVOM/ECLAIRs refined analysis
  13. GRB 250911A: Enhanced Swift-XRT position
  14. GRB 250911A: Swift-XRT observations
  15. GRB 250911A: COLIBRÍ optical counterpart candidate
  16. GRB 250911A: Swift detection of a burst
  17. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  18. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  19. GRB 250910A: SVOM/VT optical upper limit
  20. GRB 250910A: LCO optical upper limit
  21. EP250908b/EP#01709240653: Swift/UVOT Detection
  22. EP#01709240653: Swift-XRT observations
  23. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  24. EP250908c: SVOM/VT optical observation
  25. EP250908c: VLT/FORS2 optical counterpart identification
  26. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  27. EP250908b: SVOM/VT optical candidate
  28. EP250908c: Einstein Probe detection of an X-ray transient
  29. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  30. EP#01709240652 (possibly EP250908a): FTW optical and NIR observations
  31. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  32. GRB 250903A: Swift-XRT afterglow detection
  33. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  34. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  35. EP250905a: Liverpool Telescope i-band upper limits
  36. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  37. EP250905a: Liverpool Telescope observations
  38. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  39. EP250905b: EP-WXT detection of a fast X-ray transient
  40. EP250905a: JinShan likely optical counterpart detection
  41. GRB 250905A: Swift/UVOT Upper Limits
  42. GRB 250901A - SVOM/ECLAIRs refined analysis
  43. EP250905a: Einstein Probe detection of an X-ray transient
  44. GRB250904A: Liverpool Telescope upper limits
  45. GRB 250905A: Enhanced Swift-XRT position
  46. GRB 250904A: Swift/UVOT Detection
  47. GRB 250903A: Swift/UVOT detection
  48. GRB 250904A: Swift-XRT refined Analysis
  49. EP detected a brightening of LMXB 1ES 1735-26.9
  50. GRB 250905A: KAIT optical upper limit
  51. GRB 250905A: Swift detection of a burst
  52. GRB 250904A: Enhanced Swift-XRT position
  53. GRB 250904A: TRT optical counterpart detection
  54. GRB 250904A: Swift detection of a burst
  55. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  56. GRB 250903A: Swift-XRT observations
  57. EP250903a: Swift-XRT observations
  58. EP#01709201209: Swift-XRT observations
  59. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  60. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  61. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  62. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  63. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  64. GRB 250903A: LCO optical observation
  65. GRB 250903A: LCO optical afterglow detection
  66. GRB 250903A: SVOM/VT optical confirmation with VHF data
  67. EP250901a: Mondy, Assy and SAO RAS optical limits
  68. Subject GRB 250903A: SVOM/MXT afterglow detection
  69. EP250903a: LCO candidate counterpart discovery
  70. GRB 250903A: TRT optical counterpart detection
  71. EP250903a: TRT optical observations
  72. EP250903a: Einstein Probe detection of an X-ray transient
  73. EP 250827B: Detection of supernova counterpart by LCO.
  74. EP/WXT01709201159: GOTO optical follow-up
  75. GRB 250902B: SVOM/GRM observation
  76. EP250827b: SVOM/VT observation of AT 2025wkm
  77. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  78. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  79. GRB 250901A: Swift/UVOT Upper Limit
  80. GRB 250830B: Swift-XRT afterglow detection
  81. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  82. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  83. GRB 250902A: SVOM/GRM observation
  84. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  85. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  86. GRB 250901A: SVOM/VT optical afterglow with VHF data
  87. GRB 250901A: Swift-XRT afterglow detection
  88. EP250901a: Swift-XRT observations
  89. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  90. GRB 250901A: LCO optical upper limit
  91. EP250827b: Swift observations of AT 2025wkm
  92. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  93. EP250831a: NOT optical observations and tentative afterglow candidate
  94. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  95. GRB 250901A: SVOM detection of a burst
  96. EP250901a: Mephisto optical upper limits
  97. EP250901a: Einstein Probe detection of an X-ray transient
  98. EP250831a: Swift-XRT observations
  99. EP250831a: EP-WXT detection of a fast X-ray transient
  100. GRB 250831A: Swift-XRT counterpart 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