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"

26053 results found.

  1. GRB 250221A: ATCA Detections and Upper Limits
  2. GRB 250225B: REM NIR upper limits
  3. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  4. Konus-Wind detection of GRB 250225B
  5. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  6. GRB 250225B: VLT optical and near-infrared candidate counterpart
  7. GRB 250225B: VLT/FORS2 candidate optical afterglow
  8. GRB 250225B: SVOM/GRM observation of a long burst
  9. GRB 250221A: EP-FXT detection of the X-ray afterglow
  10. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  11. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  12. Swift GRB 250225B: Global MASTER-Net observations report
  13. GRB 250225B: Swift detection of a burst
  14. EP250223a: GROWTH-India Telescope optical observations
  15. GRB 250221A: Swift-BAT refined analysis
  16. EP250215A: J band upper limit by SYSU 80cm telescope
  17. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  18. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  19. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  20. GRB 250207a: ATCA Radio Upper Limits
  21. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  22. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  23. GRB 250119B: VZLUSAT-2 detection
  24. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  25. GRB 250219A: EP-FXT afterglow detection
  26. EP250223a: GOTO optical afterglow detections
  27. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  28. EP250223a: REM NIR upper limit
  29. EP250223a: TRT optical afterglow observation
  30. EP250223a: refined analysis of the EP-WXT and FXT observations
  31. EP250223a: 1.6m Mephisto and 50cm array observations
  32. GRB 250221A: TNOT detection of the optical counterpart
  33. EP250223a: SVOM/VT optical observation
  34. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  35. 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
  36. EP250223a: OASDG optical observations
  37. EP250223a: LCO detection of the afterglow
  38. EP250223a: early optical detection by BOOTES-4
  39. EP250223a: NOT redshift z = 2.756
  40. EP250223a: Swift/XRT localization
  41. EP250223a: NOT optical afterglow candidate
  42. GRB 250221A: VLA radio detection
  43. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  44. GRB 250221A: continued Mondy optical observations, brightening afterglow
  45. GRB 250221A: Optical counterpart detection by LCO.
  46. GRB 250221A: Mondy optical observations
  47. Konus-Wind detection of GRB 250221A
  48. GRB 250221A: Assy optical observations
  49. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  50. GRB 250221A: VLT/X-shooter redshift z = 0.768
  51. GRB 250221A: GRANDMA/TAROT Detection
  52. GRB 250221A: Swift-XRT refined Analysis
  53. GRB 250221A: NOT optical observations
  54. GRB 250221A: 1.6m Mephisto optical detection
  55. GRB 250221A: AKO Optical Upper Limit
  56. GRB 250221A: Swift/UVOT Detection
  57. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  58. GRB 250221A: REM optical/NIR afterglow detection
  59. GRB 250221A: Enhanced Swift-XRT position
  60. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  61. GRB 250221A: Swift detection of a burst with an optical counterpart
  62. Swift GRB250221.15: Global MASTER-Net OT detection
  63. Swift GRB250221.15: Global MASTER-Net observations report
  64. GRB 250219A: Swift/UVOT Upper Limits
  65. GRB 250219A: OHP/T193 optical upper limit
  66. GRB 250219A: NOT optical observations
  67. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  68. GRB 250219A: 1.6m Mephisto optical upper limits
  69. GRB 250219A: SVOM/VT optical counterpart
  70. GRB 250219A: Swift-XRT observations
  71. GRB 250219A: Swift ToO observations
  72. GRB 250217C: Swift-XRT observations
  73. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  74. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  75. GRB 250217C: Tiled Swift observations
  76. GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
  77. IPN triangulation of GRB 250217C (short)
  78. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  79. SVOM/sb25021804: SVOM detection of a long X-ray transient
  80. GRB 250213A: Swift-XRT observations
  81. GRB 250215A / EP250215a: LCO detection of the afterglow
  82. GRB 250215A: Swift/UVOT Upper Limits
  83. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  84. EP250215a / GRB 250215A : GTC redshift z = 4.61
  85. GRB 250215A: Fermi GBM Observation
  86. EP250215a / GRB 250215A : NOT optical observations
  87. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  88. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  89. GRB 250215A: Swift-XRT refined Analysis
  90. GRB 250213A: Swift ToO observations
  91. GRB 250205A: VIRT Optical Upper Limit
  92. EP250207B: Chandra localization of the X-ray counterpart
  93. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  94. GRB 250211A: Swift ToO observations
  95. GRB 250207A: Fermi GBM Observation
  96. Konus-Wind detection of GRB 250207A
  97. GRB 250207A: Skynet optical afterglow observations
  98. GRB 241128A: VIRT Optical Upper Limit
  99. GRB 250207A: 1.3m DFOT Optical observations
  100. GRB 250206A: Swift-XRT observations

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