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"

11100 results found.

  1. GRB 250816A: SVOM/GRM observation of a short burst
  2. Fermi GRB 250814B: Global MASTER-Net observations report
  3. GRB 250816A: Fermi GBM Final Real-time Localization
  4. GRB 250815A: Fermi GBM Final Localization
  5. GRB 250813B: Liverpool Telescope optical upper limits
  6. GRB 250814A: Further COLIBRÍ optical upper limit
  7. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  8. GRB 250814A: GRAWITA TNG NIR observations
  9. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  10. GRB250814A: TRT optical upper limits
  11. GRB 250814B: SVOM/GRM observation
  12. GRB 250813B: SVOM/GRM observation
  13. GRB 250814A: P200/WIRC observations of the afterglow candidate
  14. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  15. GRB 250814A: KAIT optical upper limit
  16. GRB 240814A: Fermi GBM Observation
  17. GRB 250814A: Possible afterglow candidate from P200/WIRC
  18. GRB 250813B: Fermi GBM Observation
  19. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  20. Fermi trigger No 776818276: Global MASTER-Net observations report
  21. GRB 250814A: J-band upper limit from WINTER
  22. GRB 250814A: COLIBRÍ optical upper limit
  23. GRB 250814B: Fermi GBM Final Real-time Localization
  24. GRB 250813A: AstroSat CZTI detection
  25. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  26. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  27. GRB 250814A: Fermi GBM Final Real-time Localization
  28. GRB 250813A: Fermi GBM Final Localization
  29. IceCube-250813A - IceCube observation of a high-energy neutrino candidate track-like event
  30. Fermi Gamma-ray Burst Monitor trigger 776705265/250812644 is not a GRB
  31. Fermi Gamma-ray Burst Monitor trigger 776620220/250811660 is not a GRB
  32. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  33. GRB 250702B: Chandra X-ray Detection
  34. Fermi GRB 250808A: Global MASTER-Net observations report
  35. Fermi Gamma-ray Burst Monitor trigger 776449964/250809689 is not a GRB
  36. GRB 250808A: Fermi GBM Observation
  37. GRB 250808A: SVOM detection of a long burst
  38. GRB 250808A: Fermi GBM Final Real-time Localization
  39. EP250806a: Upper limit from Fermi-GBM Observations
  40. GRB 250804C: AstroSat CZTI detection of a long burst
  41. IceCube-250804A - IceCube observation of a high-energy neutrino candidate track-like event
  42. Fermi trigger No 776041355: Global MASTER-Net observations report
  43. GRB 250804A: Fermi GBM Final Localization
  44. Fermi Gamma-ray Burst Monitor trigger 775945985/250803856 is not a GRB
  45. GRB 250725A: AstroSat CZTI detection
  46. GRB 250725A: PRIME near-infrared observations
  47. GRB 250728A: Swift-XRT observations
  48. GRB 250728A: COLIBRÍ optical upper limit
  49. GRB 250728A: Fermi GBM Observation
  50. Fermi trigger No 775387550: Global MASTER-Net observations report
  51. GRB 250728A: Swift ToO observations
  52. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  53. GRB 250725A: Fermi GBM Observation
  54. Konus-Wind detection of GRB 250725A
  55. GRB 250725A: SVOM/GRM observation
  56. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  57. GRB 250725A: Fermi-LAT detection
  58. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  59. GRB 250725A: SVOM/VT optical candidate
  60. GRB 250725A: Fermi GBM Final Real-time Localization
  61. Fermi GRB 250725A: Global MASTER-Net observations report
  62. GRB 250723B: Fermi GBM Final Real-time Localization
  63. GRB 250721A: Fermi GBM Observation
  64. GRB 250723A: Fermi GBM Final Real-time Localization
  65. GRB 250722A: Fermi GBM Final Real-time Localization
  66. GRB 250717B: SVOM/GRM observation
  67. GRB 250721A: MAXI/GSC detection
  68. GRB 250721A: Fermi GBM Final Localization
  69. GRB 250720B: Fermi GBM Final Localization Correction
  70. GRB 250720A: Fermi GBM Final Localization
  71. Fermi trigger No 774730635: Global MASTER-Net observations report
  72. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  73. Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB
  74. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  75. GRB 250717B: COLIBRÍ optical upper limit
  76. GRB 250717B: Swift-XRT observations
  77. GRB 250718B: Fermi GBM Final Localization Correction
  78. GRB 250718B: Fermi GBM Final Real-time Localization
  79. GRB 250717B: Swift ToO observations
  80. GRB 250717B: Fermi GBM Observation
  81. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  82. Konus-Wind detection of GRB 250716A
  83. GRB 250716A: Swift-XRT afterglow detection
  84. GRB 250717B: Fermi GBM Final Real-time Localization
  85. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  86. GRB 250717A: Fermi GBM Final Real-time Localization
  87. GRB 250716A: Swift ToO observations
  88. GRB 250716A: GOTO tentative optical counterpart candidate
  89. GRB 250716A: Fermi GBM Observation
  90. GRB 250714A: SVOM/GRM observation
  91. Fermi GRB 250716A: Global MASTER-Net observations report
  92. GRB 250716A: Fermi GBM Final Real-time Localization
  93. Fermi GRB 250715A: Global MASTER-Net observations report
  94. GRB 250715A: Fermi GBM Final Real-time Localization
  95. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  96. Fermi GRB 250714A: Global MASTER-Net observations report
  97. GRB 250714A: Fermi GBM Final Real-time Localization
  98. GRB 250711A: DDOTI Optical Upper Limit
  99. GRB 250711A: SVOM/GRM observation
  100. Fermi GRB 250711A: Global MASTER-Net observations report

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