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"
  1. GRB 240825A: Swift-XRT refined Analysis
  2. GRB 240825A: VLT/X-shooter redshift
  3. GRB 240825A: SVOM/C-GFT optical observations
  4. GRB 240825A: Montarrenti Observatory optical observations
  5. GRB 240825A: Enhanced Swift-XRT position
  6. GRB 240825A: MASTER optical counterpart observation
  7. GRB 240825A: Fermi-LAT detection
  8. GRB 240825A: LCO optical observations
  9. GRB 240824B: KAIT optical upper limit
  10. SGR 1E 1841-045 / Kes 73 (Trigger 1249878): Osservatorio Atronomico Nastro Verde optical upper limit
  11. GRB 240824B: Fermi GBM Observation
  12. Fermi GRB 240825A: Global MASTER-Net observations report
  13. SGR 1E 1841-045 / Kes 73 (Trigger 1249653) - Osservatorio Astronomico Nastro Verde upper limit
  14. GRB 240824B: NOT optical upper limit
  15. GRB 240825A: GMG Optical Observation
  16. Swift GRB 240825A: Global MASTER-Net observations report
  17. GRB 240825A: 1.6m Mephisto multi-band detection
  18. GRB 240825A: AKO Optical Afterglow Detection
  19. GRB 240825A: Skynet Optical Afterglow observations
  20. GRB 240825A: Nanshan/HMT optical afterglow observations
  21. GRB 240825A: Swift detection of a burst with a bright optical counterpart
  22. GRB 240825A: Fermi GBM Final Real-time Localization
  23. GRB 240824A: Swift-BAT refined analysis
  24. GRB 240824A: SVOM/C-GFT optical upper limit
  25. GRB 240824B: Swift-XRT afterglow detection
  26. GRB 240824A: Swift-XRT observations
  27. LIGO/Virgo/KAGRA S240825ar: Identification of a GW compact binary merger candidate
  28. GRB 240824B: Swift/BAT arcminute localization of a burst
  29. GRB 240824B: Swift ToO observations
  30. Fermi GRB 240824C: Global MASTER-Net observations report
  31. GRB 240824C: Fermi GBM Final Localization
  32. GRB 240824A: Swift/UVOT Upper Limits
  33. GRB 240821A: Swift/UVOT observations of the XRT sources.
  34. GRB 240824B: MAXI/GSC detection
  35. GRB 240824B: Fermi GBM Final Real-time Localization
  36. GRB 240824A: Retraction of GCN 37255
  37. GRB240824A: GRANDMA/TAROT-TCA Upper Limit
  38. SGR 1E 1841-045 / Kes 73: Leavitt Observatory optical upper limit
  39. GRB 240824A: KAIT optical upper limit
  40. GRB 240824A: Skynet Optical Afterglow Discovery
  41. GRB 240824A: Swift detection of a burst
  42. Swift GRB240824.04: Global MASTER-Net observations report
  43. SGR 1E 1841-045 / Kes 73: Montarrenti Observatory optical upper limits
  44. GRB 240821A: Colibri Optical Upper Limit
  45. EP240820a: PRIME J-band Observations
  46. GRB 240821A: Swift-XRT observations
  47. GRB 240822A: AstroSat CZTI detection of a short burst
  48. GRB 240821A: REM optical/NIR upper limits
  49. GRB 240821A: LCO optical observations
  50. GRB 240821A: JinShan optical upper limits
  51. GRB 240809A: Mondy and AbAO Optical Observations
  52. GRB 240821A: SVOM/VT follow-up and optical upper limit
  53. GRB 240821A: GMG Optical Upper Limit
  54. Fermi GRB 240821A: Global MASTER-Net observations report
  55. GECAM-B observation of a short burst from SGR 1E 1841-045 / Kes 73
  56. GRB 240821A: Fermi GBM Observation
  57. Fermi trigger No 745964969: Global MASTER-Net observations report
  58. Fermi trigger No 745925274: Global MASTER-Net observations report
  59. GRB 240821A: Swift ToO observations
  60. Fermi trigger No 746019401: Global MASTER-Net observations report
  61. Fermi-GBM Observations of the reactivation of SGR 1E 1841-045 / Kes 73
  62. Fermi trigger No 745935375: Global MASTER-Net observations report
  63. GRB240821A: EIRSAT-1 GMOD Detection
  64. GRB240821B: First GRB Detected by EIRSAT-1 GMOD
  65. GRB 240821A: EP-FXT follow-up observation and afterglow candidates
  66. Fermi GRB 240821B: Global MASTER-Net observations report
  67. EP240801a: Keck/LRIS spectroscopic redshift confirmation
  68. GRB 240821A: SVOM/GRM observation
  69. GRB 240821A: SVOM/GRM observation
  70. GRB 240821A: GRANDMA/LesMakes-T60 Upper Limit
  71. GRB 240821B: Fermi GBM Final Localization
  72. Fermi trigger No 745866488: Global MASTER-Net observations report
  73. Trigger 1249878: Swift detection of another burst from SGR 1E 1841-045 / Kes 73
  74. GRB 240821A: BALROG localization (Fermi Trigger 745958167 / GRB 240821775)
  75. GRB 240821A : a likely short GRB detected by SVOM/ECLAIRs
  76. GRB 240821A: Fermi GBM Final Real-time Localization
  77. GRB 240819A: Swift-XRT observations
  78. GRB 240819A: JinShan optical upper limits on one Swift/XRT source
  79. GRB 240820B: SVOM/GRM observation
  80. EP240820a: TRT optical upper limit
  81. EP240820a: EP detection of a fast X-ray transient
  82. GRB 240819A: KAIT optical upper limit
  83. EP240816a: PRIME upper limits
  84. Trigger 1249653: Swift detection of SGR 1E 1841-045 / Kes 73
  85. Fermi trigger No 745873283: Global MASTER-Net observations report
  86. Fermi trigger No 745871958: Global MASTER-Net observations report
  87. GRB 240819A : an X-ray transient detected by SVOM/ECLAIRs
  88. GRB 240819A: TRT optical upper limits on the Swift/XRT and EP/FXT sources
  89. GRB 240819A: X-ray follow-up observation with EP-FXT
  90. Fermi Gamma-ray Burst Monitor trigger 745811685 / 240820080 is not a GRB
  91. GRB 240820A: Fermi GBM Final Real-time Localization
  92. GRB 240819A: Swift ToO observations
  93. GRB 240814A: SVOM/GRM observation
  94. EP240816b: Liverpool Telescope optical follow-up observations
  95. GRB 240814C: SVOM/GRM observation
  96. EP240816a: BOOTES-6/DPRT optical upper limit
  97. GRB 240815A: SVOM/GRM observation
  98. GRB 240817A: Fermi GBM Final Real-time Localization
  99. Integral GRB240816.79: Global MASTER-Net observations report
  100. IceCube-240721A: AT2023qqp and AT2024pge likely unrelated

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