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"

39163 results found.

  1. GRB 241026A: SVOM/GRM observation
  2. EP241026B: GROWTH-India Telescope optical upper limit
  3. GRB 241025A: Swift/UVOT Detection
  4. GRB 241026A: GROWTH-India Telescope optical observations
  5. GRB 241026A Fermi GBM Analysis
  6. GRB 241026A: BTA redshift identification of z = 2.79
  7. GRB 241026A: J-band observations with WINTER
  8. GRB 241025A: SAO RAS optical observations
  9. GRB 241026A: Las Cumbres optical detection
  10. GRB 241025A: Mondy optical observations
  11. EP241021a: further SAO RAS optical observations
  12. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  13. GRB 241026A: Swift-XRT refined Analysis
  14. EP 241026b: LBT optical observations
  15. EP EP241026b: Global MASTER-Net observations report
  16. GRB 241026A: Enhanced Swift-XRT position
  17. GRB 241026A: KAIT optical observations
  18. Fermi trigger No 751616906: Global MASTER-Net observations report
  19. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  20. GRB 241026A: SAO RAS observations of possible optical afterglow
  21. Fermi GRB 241026A: Global MASTER-Net observations report
  22. GRB 241026A: Prompt enhanced Swift-XRT position
  23. GRB 241026A: Swift detection of a burst
  24. Swift GRB241026.95: Global MASTER-Net observations report
  25. GRB 241026A: Fermi GBM Final Real-time Localization
  26. GRB241025A: 1.3m DFOT optical afterglow detection
  27. ​GRB 241025A: optical photometry from Konkoly
  28. GRB 241025A: GROWTH-India Telescope optical observations
  29. GRB 241025A: COLIBRÍ Detection of the Afterglow
  30. GRB 241025A: Swift-XRT refined Analysis
  31. GRB 241025C: Fermi GBM Detection
  32. GRB 241025A: Fermi GBM Observation
  33. IPN triangulation of GRB 241022A (short/hard)
  34. LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
  35. GRB 241025C: Fermi GBM Final Localization
  36. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  37. GRB 241025B: Fermi GBM Final Localization
  38. Fermi trigger No 751563375: Global MASTER-Net observations report
  39. Fermi trigger No 751554401: Global MASTER-Net observations report
  40. EP 241021a: Swift-XRT observations
  41. Fermi GRB 241025A: Global MASTER-Net observations report
  42. Swift GRB 241025A: Global MASTER-Net observations report
  43. EP241025a (GRB 241025A): EP observations update
  44. GRB 241025A : SVOM/VT optical afterglow observations
  45. EP 241021A: Swift ToO observations
  46. GRB 241025A: Enhanced Swift-XRT position
  47. GRB 241001A: JWST spectroscopic identification of a supernova counterpart
  48. GRB 241025A: NOT spectroscopic redshift of z = 4.20
  49. GRB 241025A: DDOTI Afterglow detection
  50. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  51. GRB 241025A: SVOM/GRM observation
  52. GRB 241025A: TRT optical afterglow observation
  53. Fermi GRB 241024B: Global MASTER-Net observations report
  54. GRB 241025A: Fermi GBM Final Real-time Localization
  55. GRB 241025A: Swift detection of a burst with an optical counterpart
  56. GRB 241001A: ATCA radio observations
  57. GRB 241024B: Fermi GBM Final Localization
  58. EP241021a: No Detection in Fermi-GBM Observation
  59. GRB 241010A: VIRT Optical Upper Limit
  60. GRB 241024A: Fermi GBM Final Localisation
  61. EP241021a: VLT/FORS2 redshift z = 0.75
  62. Fermi trigger No 751449953: Global MASTER-Net observations report
  63. EP241021a: SAO RAS optical observations
  64. EP241021a: KAIT optical observations
  65. IPN triangulation of GRB 241021A (long)
  66. EP241021a: 1.3m DFOT Optical observations
  67. EP241021a: GSP detects optical candidate counterpart
  68. EP241021a: TRT optical observations
  69. GRB 241018A: SVOM/C-GFT optical observations
  70. EP EP241021a: Global MASTER-Net observations report
  71. GRB241017A: 1.3m DFOT optical upper limit
  72. GRB 241018A: 1.3m DFOT Optical upper limit
  73. GRB 241018A: EP-FXT afterglow detection
  74. Konus-Wind detection of GRB 241018A
  75. GRB 241018A: SVOM/GRM observation
  76. GRB 241018A/sb24101802: Mephisto optical upper limit
  77. GRB 241017A/sb24101702: Mephisto optical upper limit
  78. GRB 241018A: BOOTES-4/MET optical upper limit
  79. GRB 241018A: Mondy optical upper limit
  80. GRB 241018A: SVOM/VT further analysis and counterpart confirmed
  81. GRB 241018A: GROWTH-India telescope optical upper limit
  82. GRB 241018A: Swift-XRT observations
  83. GRB 241018A: REM optical/NIR upper limits
  84. GRB 241018A: NOT optical observations
  85. GRB 241017A: SVOM/VT follow-up and optical upper limit
  86. GRB 241018A: SVOM/VT follow-up and optical candidate
  87. GRB 241018A: LCO/0.4m optical upper limits
  88. GRB 241018A: Swift ToO observations
  89. GRB 241006A: VIRT Optical Upper Limit
  90. GRB 240727A: VIRT Optical Upper Limit
  91. GRB 241018A: X-ray afterglow candidate observed by MXT
  92. GRB 241016B: Fermi GBM Observations
  93. GRB 241018A: Detection of a bright long GRB by SVOM
  94. GRB 241017A: Swift-XRT observations
  95. GRB 241001A: EP-FXT afterglow detection
  96. GRB 241017A: GROWTH-India Telescope optical upper limit
  97. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  98. GRB 241017A: J-band upper limit from WINTER
  99. Fermi trigger No 750788395: Global MASTER-Net observations report
  100. GRB 241016B: 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