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"

41696 results found.

  1. GRB 260603A: SVOM/VT optical observations
  2. EP260602a: NOT NIR J-band observations
  3. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  4. EP260602d: Einstein Probe detection of a fast X-ray transient
  5. Fermi trigger No 802141998: Global MASTER-Net observations report
  6. EP260602a: SVOM/VT optical magnitudes correction
  7. GRB 260601A: SVOM/GRM observation of a short burst
  8. EP260602c: Einstein Probe detection of a fast X-ray transient
  9. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  10. EP260602a: COLIBRÍ optical observations
  11. GRB260601B/EP260601a: NOT near-infrared observations
  12. SVOM GRB260603.23: Global MASTER-Net observations report
  13. GRB 260603A: SVOM detection of a burst
  14. EP260602b: Einstein Probe detection of a fast X-ray transient
  15. GRB 260601B/EP260601a: Insight-HXMT detection
  16. Fermi GRB 260602B: Global MASTER-Net observations report
  17. Fermi GRB 260602B: Global MASTER-Net observations report
  18. EP260602a: SVOM/VT optical candidate
  19. GRB 260601A: GECAM-B observation of a short burst
  20. GRB 260601B/EP260601a: J-band upper limit with WINTER
  21. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  22. EP260530a/AT 2026nwl: KAIT optical observations
  23. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  24. EP260602a: Optical upper limits with Kinder observations
  25. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  26. EP260602a: Einstein Probe detection of a fast X-ray transient
  27. GRB 260601B/EP260601a: SVOM/VT optical observations
  28. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  29. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  30. EP260601a: Einstein Probe detection of an X-ray transient
  31. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  32. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  33. GRB 260601A: Glowbug gamma-ray detection of a short burst
  34. GRB 260531B: Glowbug gamma-ray detection
  35. GRB 260516D: VLA radio detection
  36. GRB 260601A: Fermi GBM Observation
  37. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  38. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  39. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  40. Fermi GRB 260601A: Global MASTER-Net observations report
  41. GRB 260531B: GECAM-B observation
  42. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  43. The EP-WXT trigger 01709266272 is likely a flaring star
  44. GRB 260531C: Fermi GBM Final Localization Correction
  45. Fermi Gamma-ray Burst Monitor trigger 801900520/260531256 is not a GRB
  46. AT2026nik: EP-FXT X-ray counterpart
  47. Fermi trigger No 801900520: Global MASTER-Net observations report
  48. GRB 260531A: MAXI/GSC detection
  49. AT 2026nuz: COLIBRÍ optical observations
  50. IPN triangulation of GRB 260527A / EP260527a
  51. EP260527a/GRB 260527A: further FTW optical and NIR observations
  52. GRB 260530B: SVOM/GRM detection of a possible bright short GRB
  53. GRB 260527A / EP260527a: VLA radio detection
  54. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  55. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  56. GRB 260529A: GOTO tentative optical afterglow candidate
  57. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  58. GRB 260527A/EP260527a: Insight-HXMT detection
  59. Fermi GRB 260529A: Global MASTER-Net observations report
  60. EP260526a: SVOM/VT optical upper limits
  61. GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
  62. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  63. EP260527a / GRB 260527A: NOT optical observations
  64. GRB 260527A/EP260527a: FTW optical and NIR observations
  65. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  66. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  67. EP260527a/GRB 260527A: EP-FXT follow-up observation
  68. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  69. GRB 260526A: GECAM-B observation
  70. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  71. EP260526a: EP-FXT follow-up observation
  72. EP260527a: SVOM/VT optical observation
  73. EP260527a: COLIBRÍ optical detection
  74. EP260527a: Einstein Probe detection of a fast X-ray transient
  75. The EP-WXT trigger 01709266172 is likely a flaring star
  76. The EP-WXT trigger 01709266147 is likely a flaring star
  77. Fermi trigger No 801580882: Global MASTER-Net observations report
  78. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  79. EP260526a: LCO optical upper limits
  80. EP260526a: Einstein Probe detection of a fast X-ray transient
  81. GRB 260525A: AstroSat CZTI detection
  82. EP260526.405: COLIBRÍ optical upper limits
  83. The EP-WXT trigger 01709266106 is not a real source
  84. Fermi GRB 260526A: Global MASTER-Net observations report
  85. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  86. EP-WXT 01709266106: NOT optical upper limits
  87. Fermi GRB 260525A: Global MASTER-Net observations report
  88. GRB 260523B: AstroSat CZTI detection
  89. GRB 260523B: GECAM-B observation
  90. Fermi GRB 260523A: Global MASTER-Net observations report
  91. GRB 260522A: Fermi GBM Observation
  92. GRB 260522B: NuSTAR detection of prompt emission
  93. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  94. GRB 260522A: GOTO optical upper limit
  95. Fermi trigger No 801135305: Global MASTER-Net observations report
  96. Fermi GRB 260522A: Global MASTER-Net observations report
  97. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  98. GRB 260522A: Fermi-LAT detection
  99. GRB 260519C: SVOM/GRM observation
  100. GRB 260511A: iTelescope T-75 optical detection

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
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