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"

28058 results found.

  1. GRB 250205A / EP250205A: further radio observations with the VLA
  2. EP250225a: NOT optical candidate counterpart
  3. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  4. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  5. EP250225a: TRT optical upper limits
  6. EP250226a/GRB 250226A: 1.6m Mephisto observations
  7. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  8. EP250226a/GRB 250226A: Kinder optical follow-up observations
  9. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  10. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  11. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  12. GRB 250225B: Fermi GBM Observation
  13. GRB 250225B: REM NIR upper limits
  14. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  15. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  16. EP250223a: CrAO ZTSH optical observation
  17. GRB 250225B: VLT optical and near-infrared candidate counterpart
  18. GRB 250225B: SVOM/GRM observation of a long burst
  19. EP250226a/GRB 250226A: GSP detects optical counterpart
  20. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  21. EP250226a / GRB 250226A: TRT optical counterpart observation
  22. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  23. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  24. EP250225a: GSP optical upper limit
  25. EP250223a: GMG Optical Observation
  26. EP250225a: Einstein Probe detected of a fast X-ray transient
  27. GRB 250225B: Swift detection of a burst
  28. EP250223a: GROWTH-India Telescope optical observations
  29. GRB 250221A: Swift-BAT refined analysis
  30. EP250215A: J band upper limit by SYSU 80cm telescope
  31. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  32. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  33. EP250223a: Kinder optical follow-up observations
  34. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  35. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  36. GRB 250119B: VZLUSAT-2 detection
  37. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  38. GRB 250202B: VZLUSAT-2 detection
  39. GRB 250222A: SVOM/GRM observation of a burst
  40. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  41. GRB 250206A: VZLUSAT-2 detection
  42. EP250223a: REM NIR upper limit
  43. EP250223a: TRT optical afterglow observation
  44. EP250223a: refined analysis of the EP-WXT and FXT observations
  45. EP250223a: 1.6m Mephisto and 50cm array observations
  46. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  47. 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
  48. EP250223a: OASDG optical observations
  49. EP250223a: LCO detection of the afterglow
  50. EP250223a: Swift/XRT localization
  51. EP250223a: NOT optical afterglow candidate
  52. EP250223a: Einstein Probe detection of an X-ray transient
  53. LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
  54. GRB 250221A: Optical counterpart detection by LCO.
  55. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  56. GRB 250221A: GRANDMA/TAROT Detection
  57. GRB 250221A: Swift-XRT refined Analysis
  58. GRB 250221A: NOT optical observations
  59. GRB 250221A: 1.6m Mephisto optical detection
  60. GRB 250221A: AKO Optical Upper Limit
  61. GRB 250221A: Swift/UVOT Detection
  62. EP250220a: Liverpool Telescope upper limits
  63. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  64. GRB 250221A: REM optical/NIR afterglow detection
  65. IceCube-250207A: MASTER flaring blazar QSOJ0854+2006 with Zhirkov effect
  66. GRB 250221A: Enhanced Swift-XRT position
  67. EP250220a: 1.6m Mephisto observations
  68. EP250220a: Liverpool Telescope optical upper limits
  69. EP250220a: Optical upper limit with Kinder observations
  70. SVOM trigger sb25022102 is not an astrophysical event
  71. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  72. GRB 250221A: Swift detection of a burst with an optical counterpart
  73. Swift GRB250221.15: Global MASTER-Net OT detection
  74. EP250220a: Xinglong optical upper limit
  75. GRB 250219A: Swift/UVOT Upper Limits
  76. GRB 250219A: OHP/T193 optical upper limit
  77. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  78. GRB 250219A: 1.6m Mephisto optical upper limits
  79. GRB 250219A: Swift-XRT observations
  80. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  81. Konus-Wind detection of GRB 250215A / EP250215a
  82. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  83. GRB 250217C: Swift-XRT observations
  84. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  85. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  86. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  87. GRB 250217C: SVOM/GRM observation
  88. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  89. SVOM/sb25021804: SVOM detection of a long X-ray transient
  90. GRB 250213A: Swift-XRT observations
  91. GRB 250216A: AstroSat CZTI detection
  92. GRB 250217C: AstroSat CZTI detection of a short burst
  93. IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
  94. GRANDMA/OPD observations of GRB250215A
  95. GRB 250215A / EP250215a: LCO detection of the afterglow
  96. GRB 250215A: Swift/UVOT Upper Limits
  97. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  98. GRB 250215A: Fermi GBM Observation
  99. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  100. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow

Advanced

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