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"

21526 results found.

  1. GRB 250225B: REM NIR upper limits
  2. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  3. Konus-Wind detection of GRB 250225B
  4. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  5. GRB 250225B: VLT/FORS2 candidate optical afterglow
  6. GRB 250225B: SVOM/GRM observation of a long burst
  7. GRB 250221A: EP-FXT detection of the X-ray afterglow
  8. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  9. Swift GRB 250225B: Global MASTER-Net observations report
  10. GRB 250225B: Swift detection of a burst
  11. GRB 250221A: Swift-BAT refined analysis
  12. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  13. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  14. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  15. GRB 250207a: ATCA Radio Upper Limits
  16. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  17. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  18. GRB 250119B: VZLUSAT-2 detection
  19. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  20. GRB 250219A: EP-FXT afterglow detection
  21. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  22. EP250223a: REM NIR upper limit
  23. EP250223a: TRT optical afterglow observation
  24. EP250223a: refined analysis of the EP-WXT and FXT observations
  25. EP250223a: SVOM/VT optical observation
  26. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  27. 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
  28. EP250223a: OASDG optical observations
  29. EP250223a: LCO detection of the afterglow
  30. EP250223a: early optical detection by BOOTES-4
  31. EP250223a: NOT redshift z = 2.756
  32. EP250223a: Swift/XRT localization
  33. GRB 250221A: VLA radio detection
  34. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  35. GRB 250221A: continued Mondy optical observations, brightening afterglow
  36. GRB 250221A: Optical counterpart detection by LCO.
  37. GRB 250221A: Mondy optical observations
  38. Konus-Wind detection of GRB 250221A
  39. GRB 250221A: Assy optical observations
  40. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  41. GRB 250221A: GRANDMA/TAROT Detection
  42. GRB 250221A: Swift-XRT refined Analysis
  43. GRB 250221A: NOT optical observations
  44. GRB 250221A: 1.6m Mephisto optical detection
  45. GRB 250221A: AKO Optical Upper Limit
  46. GRB 250221A: Swift/UVOT Detection
  47. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  48. GRB 250221A: REM optical/NIR afterglow detection
  49. GRB 250221A: Enhanced Swift-XRT position
  50. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  51. GRB 250221A: Swift detection of a burst with an optical counterpart
  52. Swift GRB250221.15: Global MASTER-Net OT detection
  53. Swift GRB250221.15: Global MASTER-Net observations report
  54. GRB 250219A: Swift/UVOT Upper Limits
  55. GRB 250219A: OHP/T193 optical upper limit
  56. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  57. GRB 250219A: 1.6m Mephisto optical upper limits
  58. GRB 250219A: SVOM/VT optical counterpart
  59. GRB 250219A: Swift-XRT observations
  60. GRB 250219A: Swift ToO observations
  61. GRB 250217C: Swift-XRT observations
  62. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  63. GRB 250217C: Tiled Swift observations
  64. IPN triangulation of GRB 250217C (short)
  65. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  66. SVOM/sb25021804: SVOM detection of a long X-ray transient
  67. GRB 250213A: Swift-XRT observations
  68. GRB 250215A / EP250215a: LCO detection of the afterglow
  69. GRB 250215A: Swift/UVOT Upper Limits
  70. GRB 250215A: Fermi GBM Observation
  71. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  72. GRB 250215A: Swift-XRT refined Analysis
  73. GRB 250213A: Swift ToO observations
  74. GRB 250205A: VIRT Optical Upper Limit
  75. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  76. GRB 250211A: Swift ToO observations
  77. GRB 250207A: Fermi GBM Observation
  78. Konus-Wind detection of GRB 250207A
  79. GRB 250207A: Skynet optical afterglow observations
  80. GRB 241128A: VIRT Optical Upper Limit
  81. GRB 250207A: 1.3m DFOT Optical observations
  82. GRB 250206A: Swift-XRT observations
  83. GRB 250129A: GRANDMA Continued Afterglow Detection
  84. GRB 250207A: Swift-BAT refined analysis
  85. GRB 250205A: 1.3m DFOT optical upper limit
  86. GRB 250206A: Tiled Swift observations
  87. GRB 250206A: Fermi-LAT detection
  88. GRB 250207B: Swift-XRT observations
  89. EP250207a: EP-WXT detection and XRT follow-up observation
  90. GRB 250207A: Swift-XRT refined Analysis
  91. GRB 250207A: Enhanced Swift-XRT position
  92. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  93. GRB 250207A: REM IR afterglow detection
  94. GRB 250207A: FRAM-Auger optical detection
  95. GRB 250207B: Tiled Swift observations
  96. GRB 250207A: REM optical afterglow detection
  97. GRB 250207A: Swift/UVOT Detection
  98. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  99. GRB 250207A: Swift detection of a burst with optical counterpart
  100. GRB 250205A: Fermi GBM Observation

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov