Skip to main content
New! BOOM Notices and Schema v7.0.0. 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"

22917 results found.

  1. GRB250912A: VLT/HAWK-I follow-up observations
  2. GRB 250912A:SVOM/VT optical upper limit
  3. GRB 250912A: LCO optical upper limit
  4. GRB 250912A: SVOM detection of a burst
  5. LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search
  6. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  7. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  8. GRB 250910B: SVOM/GRM observation
  9. EP250911a: SVOM/VT optical observation
  10. EP250911a: SAO RAS optical observations
  11. EP250911a: Swift-XRT observations
  12. EP250911a: Optical detection with Kinder observations
  13. GRB 250911A: Swift/UVOT Detection
  14. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  15. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  16. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  17. EP250911a: COLIBRÍ optical observations
  18. EP250911a: Einstein Probe detection of an X-ray transient
  19. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  20. GRB 250903A: SVOM/ECLAIRs refined analysis
  21. GRB 250911A: Enhanced Swift-XRT position
  22. GRB 250911A: Swift-XRT observations
  23. GRB 250911A: COLIBRÍ optical counterpart candidate
  24. GRB 250911A: Swift detection of a burst
  25. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  26. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  27. GRB 250910A: SVOM/VT optical upper limit
  28. GRB 250910A: LCO optical upper limit
  29. EP250908b/EP#01709240653: Swift/UVOT Detection
  30. EP#01709240653: Swift-XRT observations
  31. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  32. EP250908c: SVOM/VT optical observation
  33. EP250908c: VLT/FORS2 optical counterpart identification
  34. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  35. EP250908b: SVOM/VT optical candidate
  36. EP250908c: Einstein Probe detection of an X-ray transient
  37. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  38. EP#01709240652 (possibly EP250908a): FTW optical and NIR observations
  39. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  40. GRB 250903A: Swift-XRT afterglow detection
  41. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  42. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  43. EP250905a: Liverpool Telescope i-band upper limits
  44. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  45. EP250905a: Liverpool Telescope observations
  46. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  47. EP250905b: EP-WXT detection of a fast X-ray transient
  48. EP250905a: JinShan likely optical counterpart detection
  49. GRB 250905A: Swift/UVOT Upper Limits
  50. GRB 250901A - SVOM/ECLAIRs refined analysis
  51. EP250905a: Einstein Probe detection of an X-ray transient
  52. GRB250904A: Liverpool Telescope upper limits
  53. GRB 250905A: Enhanced Swift-XRT position
  54. GRB 250904A: Swift/UVOT Detection
  55. GRB 250903A: Swift/UVOT detection
  56. GRB 250904A: Swift-XRT refined Analysis
  57. EP detected a brightening of LMXB 1ES 1735-26.9
  58. GRB 250905A: KAIT optical upper limit
  59. GRB 250905A: Swift detection of a burst
  60. GRB 250904A: Enhanced Swift-XRT position
  61. GRB 250904A: TRT optical counterpart detection
  62. GRB 250904A: Swift detection of a burst
  63. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  64. GRB 250903A: Swift-XRT observations
  65. EP250903a: Swift-XRT observations
  66. EP#01709201209: Swift-XRT observations
  67. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  68. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  69. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  70. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  71. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  72. GRB 250903A: LCO optical observation
  73. GRB 250903A: LCO optical afterglow detection
  74. GRB 250903A: SVOM/VT optical confirmation with VHF data
  75. EP250901a: Mondy, Assy and SAO RAS optical limits
  76. Subject GRB 250903A: SVOM/MXT afterglow detection
  77. EP250903a: LCO candidate counterpart discovery
  78. GRB 250903A: TRT optical counterpart detection
  79. EP250903a: TRT optical observations
  80. EP250903a: Einstein Probe detection of an X-ray transient
  81. EP 250827B: Detection of supernova counterpart by LCO.
  82. EP/WXT01709201159: GOTO optical follow-up
  83. GRB 250902B: SVOM/GRM observation
  84. EP250827b: SVOM/VT observation of AT 2025wkm
  85. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  86. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  87. GRB 250901A: Swift/UVOT Upper Limit
  88. GRB 250830B: Swift-XRT afterglow detection
  89. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  90. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  91. GRB 250902A: SVOM/GRM observation
  92. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  93. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  94. GRB 250901A: SVOM/VT optical afterglow with VHF data
  95. GRB 250901A: Swift-XRT afterglow detection
  96. EP250901a: Swift-XRT observations
  97. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  98. GRB 250901A: LCO optical upper limit
  99. EP250827b: Swift observations of AT 2025wkm
  100. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate

Advanced

Download all Circulars as a .tar.gz archive:
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov