Skip to main content
New! Browse Circulars by Event, Advanced Search, Sample Codes, Schema Release. 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"
  1. GRB 240824A: KAIT optical upper limit
  2. GRB 240824A: Skynet Optical Afterglow Discovery
  3. GRB 240824A: Swift detection of a burst
  4. Swift GRB240824.04: Global MASTER-Net observations report
  5. SGR 1E 1841-045 / Kes 73: Montarrenti Observatory optical upper limits
  6. GRB 240821A: Colibri Optical Upper Limit
  7. EP240820a: PRIME J-band Observations
  8. GRB 240821A: Swift-XRT observations
  9. GRB 240822A: AstroSat CZTI detection of a short burst
  10. GRB 240821A: REM optical/NIR upper limits
  11. GRB 240821A: LCO optical observations
  12. GRB 240821A: JinShan optical upper limits
  13. GRB 240809A: Mondy and AbAO Optical Observations
  14. GRB 240821A: SVOM/VT follow-up and optical upper limit
  15. GRB 240821A: GMG Optical Upper Limit
  16. Fermi GRB 240821A: Global MASTER-Net observations report
  17. GECAM-B observation of a short burst from SGR 1E 1841-045 / Kes 73
  18. GRB 240821A: Fermi GBM Observation
  19. Fermi trigger No 745964969: Global MASTER-Net observations report
  20. Fermi trigger No 745925274: Global MASTER-Net observations report
  21. GRB 240821A: Swift ToO observations
  22. Fermi trigger No 746019401: Global MASTER-Net observations report
  23. Fermi-GBM Observations of the reactivation of SGR 1E 1841-045 / Kes 73
  24. Fermi trigger No 745935375: Global MASTER-Net observations report
  25. GRB240821A: EIRSAT-1 GMOD Detection
  26. GRB240821B: First GRB Detected by EIRSAT-1 GMOD
  27. GRB 240821A: EP-FXT follow-up observation and afterglow candidates
  28. Fermi GRB 240821B: Global MASTER-Net observations report
  29. EP240801a: Keck/LRIS spectroscopic redshift confirmation
  30. GRB 240821A: SVOM/GRM observation
  31. GRB 240821A: SVOM/GRM observation
  32. GRB 240821A: GRANDMA/LesMakes-T60 Upper Limit
  33. GRB 240821B: Fermi GBM Final Localization
  34. Fermi trigger No 745866488: Global MASTER-Net observations report
  35. Trigger 1249878: Swift detection of another burst from SGR 1E 1841-045 / Kes 73
  36. GRB 240821A: BALROG localization (Fermi Trigger 745958167 / GRB 240821775)
  37. GRB 240821A : a likely short GRB detected by SVOM/ECLAIRs
  38. GRB 240821A: Fermi GBM Final Real-time Localization
  39. GRB 240819A: Swift-XRT observations
  40. GRB 240819A: JinShan optical upper limits on one Swift/XRT source
  41. GRB 240820B: SVOM/GRM observation
  42. EP240820a: TRT optical upper limit
  43. EP240820a: EP detection of a fast X-ray transient
  44. GRB 240819A: KAIT optical upper limit
  45. EP240816a: PRIME upper limits
  46. Trigger 1249653: Swift detection of SGR 1E 1841-045 / Kes 73
  47. Fermi trigger No 745873283: Global MASTER-Net observations report
  48. Fermi trigger No 745871958: Global MASTER-Net observations report
  49. GRB 240819A : an X-ray transient detected by SVOM/ECLAIRs
  50. GRB 240819A: TRT optical upper limits on the Swift/XRT and EP/FXT sources
  51. GRB 240819A: X-ray follow-up observation with EP-FXT
  52. Fermi Gamma-ray Burst Monitor trigger 745811685 / 240820080 is not a GRB
  53. GRB 240820A: Fermi GBM Final Real-time Localization
  54. GRB 240819A: Swift ToO observations
  55. GRB 240814A: SVOM/GRM observation
  56. EP240816b: Liverpool Telescope optical follow-up observations
  57. GRB 240814C: SVOM/GRM observation
  58. EP240816a: BOOTES-6/DPRT optical upper limit
  59. GRB 240815A: SVOM/GRM observation
  60. GRB 240817A: Fermi GBM Final Real-time Localization
  61. Integral GRB240816.79: Global MASTER-Net observations report
  62. IceCube-240721A: AT2023qqp and AT2024pge likely unrelated
  63. GRB GRB 240809A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  64. IBAS Alert n.10856: not a GRB
  65. GRB 240805B: Osservatorio Astronomico Nastro Verde upper limit
  66. EP240816b: KAIT optical upper limit
  67. GRB 240814B: GRBAlpha detection
  68. Fermi trigger No 745501396: Global MASTER-Net observations report
  69. EP240816a: EP detection of a fast X-ray transient and follow-up observation
  70. EP EP240816b: Global MASTER-Net observations report
  71. EP240816b: TRT optical upper limit
  72. EP240816b: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  73. Fermi GRB 240814A: Global MASTER-Net observations report
  74. Fermi GRB 240814C: Global MASTER-Net observations report
  75. Fermi trigger No 745306088: Global MASTER-Net observations report
  76. GRB 240814C: Fermi GBM Final Real-time Localization
  77. Fermi GRB 240814B: Global MASTER-Net observations report
  78. GRB 240812B: SVOM/GRM observation
  79. EP240802a: Kinder optical, SWIFT-UVOT, and SWIFT-XRT upper limits 6 days after the WXT detection
  80. GRB 240814B: Fermi GBM Final Real-time Localization
  81. GRB 240814A: Fermi GBM Final Real-time Localization
  82. LIGO/Virgo/KAGRA S240813d: Updated Sky localization
  83. Fermi trigger No 745220784: Global MASTER-Net observations report
  84. Konus-Wind detection of GRB 240811A
  85. Konus-Wind detection of GRB 240810A
  86. Fermi Gamma-ray Burst Monitor trigger 745220784/240813240 is not a GRB
  87. LIGO/Virgo/KAGRA S240813d: Identification of a GW compact binary merger candidate
  88. LIGO/Virgo/KAGRA S240813c: Updated Sky localization
  89. LIGO/Virgo/KAGRA S240813c: Identification of a GW compact binary merger candidate
  90. GRB 240809A: Correction to the VLA source position in GCN 37158
  91. GRB 240810A: SVOM/GRM observation
  92. Fermi Gamma-ray Burst Monitor trigger 240812940/745194848 is not a GRB
  93. Fermi Gamma-ray Burst Monitor trigger 240812917/745192855 is not a GRB
  94. Fermi Gamma-ray Burst Monitor trigger 240812917/745192855 is not a GRB
  95. GRB 240809A: ATA radio non-detection
  96. GRB 240812D: Fermi GBM Final Real-time Localization
  97. GRB 240812C: Fermi GBM Final Real-time Localization
  98. GRB 240809A : RAPAS follow-up observations
  99. GRB 240809A: VLA detection
  100. GRB 240809A: ALMA detection

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