Skip to main content
New! Browse Circulars by Event, Advanced Search, Sample Codes, Schema Release. 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"

18506 results found.

  1. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  2. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  3. GRB 250119B: VZLUSAT-2 detection
  4. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  5. GRB 250219A: EP-FXT afterglow detection
  6. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  7. EP250223a: REM NIR upper limit
  8. EP250223a: TRT optical afterglow observation
  9. EP250223a: refined analysis of the EP-WXT and FXT observations
  10. EP250223a: SVOM/VT optical observation
  11. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  12. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO trigger with ID 762004910: Identification of a GW compact binary merger candidate possibly associated with a sub-threshold Swift/BAT-GUANO trigger
  13. EP250223a: OASDG optical observations
  14. EP250223a: LCO detection of the afterglow
  15. EP250223a: early optical detection by BOOTES-4
  16. EP250223a: NOT redshift z = 2.756
  17. EP250223a: Swift/XRT localization
  18. GRB 250221A: VLA radio detection
  19. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  20. GRB 250221A: continued Mondy optical observations, brightening afterglow
  21. GRB 250221A: Optical counterpart detection by LCO.
  22. GRB 250221A: Mondy optical observations
  23. Konus-Wind detection of GRB 250221A
  24. GRB 250221A: Assy optical observations
  25. GRB 250221A: GRANDMA/TAROT Detection
  26. GRB 250221A: Swift-XRT refined Analysis
  27. GRB 250221A: NOT optical observations
  28. GRB 250221A: 1.6m Mephisto optical detection
  29. GRB 250221A: AKO Optical Upper Limit
  30. GRB 250221A: Swift/UVOT Detection
  31. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  32. GRB 250221A: REM optical/NIR afterglow detection
  33. GRB 250221A: Enhanced Swift-XRT position
  34. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  35. GRB 250221A: Swift detection of a burst with an optical counterpart
  36. Swift GRB250221.15: Global MASTER-Net OT detection
  37. Swift GRB250221.15: Global MASTER-Net observations report
  38. GRB 250219A: Swift/UVOT Upper Limits
  39. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  40. GRB 250219A: 1.6m Mephisto optical upper limits
  41. GRB 250219A: SVOM/VT optical counterpart
  42. GRB 250219A: Swift-XRT observations
  43. GRB 250219A: Swift ToO observations
  44. GRB 250217C: Swift-XRT observations
  45. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  46. GRB 250217C: Tiled Swift observations
  47. IPN triangulation of GRB 250217C (short)
  48. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  49. SVOM/sb25021804: SVOM detection of a long X-ray transient
  50. GRB 250213A: Swift-XRT observations
  51. GRB 250215A / EP250215a: LCO detection of the afterglow
  52. GRB 250215A: Swift/UVOT Upper Limits
  53. GRB 250215A: Fermi GBM Observation
  54. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  55. GRB 250215A: Swift-XRT refined Analysis
  56. GRB 250213A: Swift ToO observations
  57. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  58. GRB 250211A: Swift ToO observations
  59. GRB 250207A: Fermi GBM Observation
  60. Konus-Wind detection of GRB 250207A
  61. GRB 250207A: Skynet optical afterglow observations
  62. GRB 250207A: 1.3m DFOT Optical observations
  63. GRB 250206A: Swift-XRT observations
  64. GRB 250129A: GRANDMA Continued Afterglow Detection
  65. GRB 250207A: Swift-BAT refined analysis
  66. GRB 250205A: 1.3m DFOT optical upper limit
  67. GRB 250206A: Tiled Swift observations
  68. GRB 250206A: Fermi-LAT detection
  69. GRB 250207B: Swift-XRT observations
  70. EP250207a: EP-WXT detection and XRT follow-up observation
  71. GRB 250207A: Swift-XRT refined Analysis
  72. GRB 250207A: Enhanced Swift-XRT position
  73. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  74. GRB 250207A: REM IR afterglow detection
  75. GRB 250207A: FRAM-Auger optical detection
  76. GRB 250207B: Tiled Swift observations
  77. GRB 250207A: REM optical afterglow detection
  78. GRB 250207A: Swift/UVOT Detection
  79. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  80. GRB 250207A: Swift detection of a burst with optical counterpart
  81. GRB 250205A: Fermi GBM Observation
  82. GRB 250205A: Swift/UVOT Upper Limits
  83. GRB 250205A: Swift/XRT detection
  84. IPN triangulation of GRB 250201A
  85. GRB 250129A: Swift-BAT refined analysis
  86. IPN triangulation of GRB 250204B (short/hard)
  87. IPN triangulation of GRB 250202B
  88. GRB 250129A: LCO late afterglow detection
  89. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  90. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  91. GRB 250129A: SVOM/C-GFT optical observations
  92. Swift GRB250129A: MASTER 4 days observations report
  93. Konus-Wind detection of GRB 250129A
  94. GRB 250129A: 1.3m DFOT Optical observations
  95. GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
  96. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  97. GRB 250129A: COLIBRÍ Optical Observations
  98. GRB 250129A: TNG NIR afterglow detection
  99. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  100. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading

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