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"

21921 results found.

  1. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  2. EP250223a: CrAO ZTSH optical observation
  3. GRB 250225B: VLT optical and near-infrared candidate counterpart
  4. GRB 250225B: VLT/FORS2 candidate optical afterglow
  5. GRB 250225B: SVOM/GRM observation of a long burst
  6. GRB 250226A: GECAM-B detection
  7. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  8. EP250226a / GRB 250226A: TRT optical counterpart observation
  9. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  10. EP250223a: GMG Optical Observation
  11. EP250225a: Einstein Probe detected of a fast X-ray transient
  12. EP250223a: GROWTH-India Telescope optical observations
  13. EP250215A: J band upper limit by SYSU 80cm telescope
  14. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  15. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  16. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  17. EP250223a: Kinder optical follow-up observations
  18. GRB 250119B: VZLUSAT-2 detection
  19. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  20. GRB 250202B: VZLUSAT-2 detection
  21. GRB 250222A: SVOM/GRM observation of a burst
  22. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  23. GRB 250210A: VZLUSAT-2 detection
  24. GRB 250206A: VZLUSAT-2 detection
  25. EP250223a: REM NIR upper limit
  26. EP250223a: TRT optical afterglow observation
  27. EP250223a: refined analysis of the EP-WXT and FXT observations
  28. EP250223a: 1.6m Mephisto and 50cm array observations
  29. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  30. 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
  31. EP250223a: OASDG optical observations
  32. EP250223a: NOT optical afterglow candidate
  33. EP250223a: Einstein Probe detection of an X-ray transient
  34. GRB 250221A: Optical counterpart detection by LCO.
  35. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  36. GRB 250221A: GRANDMA/TAROT Detection
  37. GRB 250221A: 1.6m Mephisto optical detection
  38. GRB 250221A: AKO Optical Upper Limit
  39. GRB 250221A: Swift/UVOT Detection
  40. EP250220a: Liverpool Telescope upper limits
  41. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  42. GRB 250221A: REM optical/NIR afterglow detection
  43. GRB 250221A: Enhanced Swift-XRT position
  44. EP250220a: 1.6m Mephisto observations
  45. EP250220a: Liverpool Telescope optical upper limits
  46. EP250220a: Optical upper limit with Kinder observations
  47. SVOM trigger sb25022102 is not an astrophysical event
  48. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  49. GRB 250221A: Swift detection of a burst with an optical counterpart
  50. Swift GRB250221.15: Global MASTER-Net OT detection
  51. EP250220a: Xinglong optical upper limit
  52. Konus-Wind detection of GRB 250217C (short)
  53. GRB 250219A: Swift/UVOT Upper Limits
  54. GRB 250219A: OHP/T193 optical upper limit
  55. GRB 250219A: NOT optical observations
  56. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  57. GRB 250219A: 1.6m Mephisto optical upper limits
  58. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  59. GRB 250219A: SVOM detection of a burst
  60. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  61. GRB 250217C: Swift-XRT observations
  62. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  63. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  64. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  65. GRB 250217C: SVOM/GRM observation
  66. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  67. SVOM/sb25021804: SVOM detection of a long X-ray transient
  68. GRANDMA/OPD observations of GRB250215A
  69. GRB 250215A / EP250215a: LCO detection of the afterglow
  70. GRB 250215A: Swift/UVOT Upper Limits
  71. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  72. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  73. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  74. GRB 250215A: SVOM/GRM observation
  75. EP250215a / GRB 250215A: AstroSat CZTI detection
  76. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  77. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  78. EP250207b: Xinglong optical upper limit
  79. EP250212a: Xinglong optical upper limit
  80. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  81. GRB 250205A: VIRT Optical Upper Limit
  82. GRB 250205A: Leavitt Observatory optical upper limit
  83. GRB 250210A: GRBAlpha detection
  84. EP250207B: Chandra localization of the X-ray counterpart
  85. EP250212a: Liverpool Telescope optical upper limits
  86. GRB250101A: Radio upper limits from GMRT observations
  87. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  88. EP250207B: GTC z-band Observations
  89. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  90. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  91. EP250207b: NOT optical counterpart candidate
  92. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  93. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  94. GRB 250205A / EP250205A: radio detection with the VLA
  95. EP250207b: Tentative z-band brightening source
  96. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  97. Konus-Wind detection of GRB 250207A
  98. Konus-Wind detection of GRB 250206A
  99. GRB 250210A: SVOM/GRM observation of a long burst
  100. EP250207b: Liverpool Telescope possible optical counterpart

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