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"

27768 results found.

  1. GRB 241025A: Swift-XRT refined Analysis
  2. GRB 241025C: Fermi GBM Detection
  3. GRB 241025A: Fermi GBM Observation
  4. IPN triangulation of GRB 241022A (short/hard)
  5. LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
  6. GRB 241025C: Fermi GBM Final Localization
  7. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  8. GRB 241025B: Fermi GBM Final Localization
  9. EP 241021a: Swift-XRT observations
  10. Swift GRB 241025A: Global MASTER-Net observations report
  11. EP241025a (GRB 241025A): EP observations update
  12. EP 241021A: Swift ToO observations
  13. EP241021a: Liverpool Telescope optical follow-up observations
  14. GRB 241025A: Enhanced Swift-XRT position
  15. GRB 241025A: NOT spectroscopic redshift of z = 4.20
  16. GRB 241025A: DDOTI Afterglow detection
  17. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  18. GRB 241025A: SVOM/GRM observation
  19. GRB 241025A: TRT optical afterglow observation
  20. GRB 241025A: Fermi GBM Final Real-time Localization
  21. GRB 241025A: Swift detection of a burst with an optical counterpart
  22. GRB 241001A: ATCA radio observations
  23. GRB 241024B: Fermi GBM Final Localization
  24. EP241021a: No Detection in Fermi-GBM Observation
  25. GRB 241010A: VIRT Optical Upper Limit
  26. GRB 241024A: Fermi GBM Final Localisation
  27. EP241021a: VLT/FORS2 redshift z = 0.75
  28. EP241021a: EP-FXT follow-up observation update
  29. EP241021a: Optical counterpart observations with the Liverpool Telescope
  30. EP241021a: 1.3m DFOT Optical observations
  31. EP241021a: NOT likely optical counterpart
  32. GRB241017A: 1.3m DFOT optical upper limit
  33. GRB 241018A: 1.3m DFOT Optical upper limit
  34. GRB 241018A: EP-FXT afterglow detection
  35. EP241021a: EP detection of a fast X-ray transient
  36. Konus-Wind detection of GRB 241018A
  37. GRB 241018A: BOOTES-4/MET optical upper limit
  38. GRB 241018A: Mondy optical upper limit
  39. GRB 241018A: SVOM/VT further analysis and counterpart confirmed
  40. GRB 241018A: GROWTH-India telescope optical upper limit
  41. GRB 241018A: Swift-XRT observations
  42. GRB 241018A: NOT optical observations
  43. GRB 241018A: Swift ToO observations
  44. GRB 241006A: VIRT Optical Upper Limit
  45. GRB 240727A: VIRT Optical Upper Limit
  46. GRB 241018A: X-ray afterglow candidate observed by MXT
  47. GRB 241016B: Fermi GBM Observations
  48. GRB 241018A: Detection of a bright long GRB by SVOM
  49. GRB 241017A: Swift-XRT observations
  50. GRB241017a: Liverpool Telescope observations of XRT uncatalogued sources
  51. GRB 241001A: EP-FXT afterglow detection
  52. GRB 241017A: GROWTH-India Telescope optical upper limit
  53. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  54. GRB241016C: Fermi GBM Final Localization
  55. GRB 241017A: Swift ToO observations
  56. GRB 241017A : Detection of a weak and soft long duration GRB by SVOM/ECLAIRs
  57. GRB 241016B: Fermi GBM Final Localization
  58. GRB 241016A: Fermi GBM Final Real-time Localization
  59. IceCube alert 139977_2910365 retraction
  60. GRB 241010A: Swift-BAT refined analysis
  61. GRB 241013B: Fermi GBM Observation
  62. GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
  63. GRB 240916A: radio detection with the VLA
  64. GRB 241009A: LCO optical upper limits
  65. GRB 241013B: Fermi GBM Final Real-time Localization
  66. GRB 241013A: Fermi GBM Final Real-time Localization
  67. GRB 241011A: Fermi GBM Final Real-time Localization
  68. GRB 241009A: GRANDMA optical upper limits
  69. GRB 241009A: Swift-XRT afterglow detection
  70. GRB 241010A: JinShan optical observations and potential host galaxy
  71. GRB 241006A: ATCA Radio Upper Limits
  72. GRB 241010A: Swift-XRT refined Analysis
  73. Swift GRB 241010A: Global MASTER-Net observations report
  74. GRB 241010A: J-band observations with WINTER
  75. GRB 241010B: Fermi GBM Final Real-time Localization
  76. GRB 241010A: Enhanced Swift-XRT position
  77. GRB 241010A: LCO optical observations
  78. GRB 241010A: Swift detection of a burst with an optical counterpart
  79. GRB 241006A: Swift-BAT refined analysis
  80. GRB 241009A: Swift ToO observations
  81. GRB 241009A : Detection of a long duration GRB by SVOM/ECLAIRs
  82. GRB 241008A: Fermi-LAT detection
  83. GRB 241002B: Swift-XRT afterglow detection
  84. GRB 241002A: NOT optical upper limits
  85. GRB 241008A: Fermi GBM Final Real-time Localization
  86. IceCube-241006A: No candidates from the Zwicky Transient Facility
  87. GRB 241006A: GRANDMA optical upper limits
  88. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  89. GRB 241006A: Swift-XRT refined Analysis
  90. GRB 241006A: PRIME near-infrared upper limits
  91. GRB 241006A: Swift/UVOT Upper Limits
  92. GRB 241006A: SVOM/VT follow-up and optical upper limit
  93. GRB 241001A: Swift-XRT afterglow detection
  94. GRB 241006A: Enhanced Swift-XRT position
  95. IceCube-241006A - IceCube observation of a high-energy neutrino candidate track-like event
  96. GRB 241006A: Swift detection of a burst
  97. Swift GRB241006.91: Global MASTER-Net observations report
  98. GRB 240930B: SVOM/C-GFT optical upper limit
  99. LIGO/Virgo/KAGRA S241005bo: Retraction of GW compact binary merger candidate
  100. GRB 240930B / EP 240930a: SVOM/GRM observation

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