Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

28260 results found.

  1. EP250610a: COLIBRÍ optical upper limit
  2. EP250610a: Einstein Probe detection of an X-ray transient
  3. Fermi trigger No 771072240: Global MASTER-Net observations report
  4. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  5. GRB 250605A: Swift/UVOT Upper Limits
  6. GRB 250527C: CrAO Optical Upper Limit
  7. GRB 250607A: SVOM/GRM observation of a long burst
  8. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  9. GRB 250605A: Swift-XRT refined Analysis
  10. GRB 250605A: Enhanced Swift-XRT position
  11. GRB 250605A: Swift detection of a burst
  12. IPN triangulation of GRB 250404B
  13. IPN triangulation of GRB 250529A
  14. GRB 250601A: PRIME H band upper limit.
  15. GRB 250601A: PRIME J band upper limit.
  16. GRB 250601A: VLT/FORS2 Optical Observation
  17. GRB 250601A: Fermi GBM Observation
  18. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  19. GRB 250603A: Swift/UVOT Upper Limits
  20. GRB 250603A: Swift-XRT refined Analysis
  21. GRB 250603A: Enhanced Swift-XRT position
  22. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  23. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  24. GRB 250602A: Fermi GBM Observation
  25. GRB 250602A: DDOTI Optical Upper Limit
  26. GRB 250530C: Swift-BAT refined analysis
  27. GRB 250601A: Swift/XRT candidate afterglow
  28. GRB 250601A: Swift-XRT observations
  29. GRB 250601A: Swift/BAT-GUANO arcminute localization of a likely short burst
  30. GRB 250601A: Fermi GBM Final Real-time Localization
  31. EP#01709177494: SVOM/VT optical observations
  32. EP#01709177494: Swift-XRT counterpart detection of known source
  33. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  34. GRB 250530C: Swift-XRT refined Analysis
  35. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  36. GRB 250530C: Enhanced Swift-XRT position
  37. GRB 250530C: Swift detection of a burst
  38. GRB 250530A: EP-FXT counterpart detection
  39. GRB 250530A: SVOM/VT optical upper limit
  40. GRB 250530A: Swift-XRT counterpart detection
  41. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  42. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  43. GRB 250530A: SVOM detection of a burst
  44. GRB 250527C: Swift/UVOT Upper Limits
  45. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  46. GRB 250527B: Swift-XRT observations
  47. GRB 250520A: Swift-BAT refined analysis
  48. GRB 250527C: Swift/BAT-GUANO arcminute localization of a burst
  49. GRB 250521D: SVOM/GRM analysis suggests a possible “long” duration type I burst
  50. GRB 250527B / MAXI J1450-527 : MAXI/GSC detection
  51. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  52. GRB 250314A: CIDER NB1008 upper limit
  53. EP250526a: COLIBRÍ optical upper limits
  54. EP250526a: Einstein Probe detection of a fast X-ray transient
  55. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  56. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  57. GRB 250523A: BALROG localization (Fermi Trigger 769703188 / GRB 250523602)
  58. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  59. EP#01709176612: Swift-XRT counterpart detection of flaring star
  60. GRB 250521D: DDOTI Optical Upper Limit
  61. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  62. GRB 250521D: LAST tentative optical counterpart candidate
  63. GRB 250521A: DDOTI Optical Upper Limit
  64. GRB 250520A: VLT/FORS2 Optical Observation
  65. GRB 250502A: Tautenburg observations
  66. GRB 250520A: Swift/UVOT Upper Limits
  67. IPN triangulation of GRB 250516B
  68. GRB 250520A: J-band observations with WINTER
  69. GRB 250520A: Gemini-South optical observations
  70. GRB 250520A: Swift-XRT refined Analysis
  71. GRB 250520A: REM optical/NIR early observations
  72. GRB 250520A：SVOM/VT optical candidate
  73. GRB 250520A: COLIBRÍ optical upper limit
  74. GRB 250520A: DDOTI Optical Upper Limit
  75. GRB 250520A: AstroSat CZTI detection of a short burst
  76. GRB 250520A: Enhanced Swift-XRT position
  77. GRB 250520A: Swift detection of a burst
  78. GRB 250516A: Swift-BAT refined analysis
  79. GRB 250516A: COLIBRÍ optical upper limit
  80. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  81. GRB 250515A: Swift-XRT observations
  82. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  83. GRB 250515A: 1.6m Mephisto optical detection
  84. GRB 250516A: Fermi GBM Observation
  85. GRB 250516A: Swift-XRT refined Analysis
  86. GRB 250516A: Swift/UVOT Detection
  87. GRB 250516B: GECAM-B detection of a bright long burst
  88. GRB 250516A: Enhanced Swift-XRT position
  89. GRB 250516A: Swift detection of a burst
  90. MAXI GRB250515.65: Global MASTER-Net observations report
  91. GRB 250424A: COLIBRÍ detection of the associated supernova
  92. GRB 250502A: TESS observations
  93. GRB 250509A: Swift-BAT refined analysis
  94. Fermi GRB 250512A: Global MASTER-Net observations report
  95. EP250512a/GRB 250512B: REM optical/NIR observations
  96. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  97. GRB 250507B: AstroSat CZTI detection
  98. EP250511a: Gemini optical counterpart observation
  99. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  100. EP250511a: Mephisto optical upper limits

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