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"

36339 results found.

  1. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  2. GRB 250309B / AT2025dws: further SAO RAS optical observations
  3. IceCube-250309A: Upper limits from Fermi-GBM Observations
  4. Konus-Wind detection of GRB 250309B
  5. GRB 250309B / AT2025dws: KMTNet-CTIO optical observations
  6. IPN triangulation of GRB 250308A (short)
  7. IPN triangulation of GRB 250309B
  8. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  9. GRB 250309B: Swift-XRT refined Analysis
  10. GRB 250309B / IceCube-250309A: GECAM-B observations
  11. GRB 250309B / AT2025dws: OSIRIS+/GTC spectroscopy z=1.898
  12. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  13. GRB 250309B / AT2025dws: SAO RAS optical observations
  14. GRB 250309B / AT2025dws: Swift-UVOT detection
  15. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  16. GRB 250309B: Fermi GBM Observation
  17. Fermi GRB 250309B: Global MASTER-Net observations report
  18. Fermi GRB 250309A: Global MASTER-Net observations report
  19. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  20. Fermi-LAT gamma-ray observations of IceCube-250309A
  21. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  22. GRB 250309B: Fermi GBM Final Localization
  23. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  24. GRB 230509B: Tiled Swift observations
  25. GRB 250308A: SVOM/GRM observation of a bright short burst
  26. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  27. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  28. GRB 250309A: Fermi GBM Final Real-time Localization
  29. GRB 250306A: EIRSAT-1 GMOD detection
  30. Fermi GRB 250307A: Global MASTER-Net observations report
  31. Konus-Wind detection of GRB 250306A
  32. GRB 250307A: Fermi GBM Final Real-time Localization
  33. GRB 250306A: Swift-BAT refined analysis
  34. GRB 250306A: NuSTAR detection of the prompt emission
  35. GRB 250305A: AstroSat CZTI detection
  36. GRB 250306A: AstroSat CZTI detection
  37. Fermi Gamma-ray Burst Monitor trigger 762963055/250306591 is not a GRB
  38. Swift GRB 250306A: Global MASTER-Net observations report
  39. GRB 250306A: Swift detection of a burst
  40. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  41. GRB 250305A: SVOM/GRM observation of a burst
  42. EP250304A: Upper limits from Fermi-GBM Observations
  43. Fermi GRB 250305A: Global MASTER-Net observations report
  44. GRB 250305A: Fermi GBM Final Real-time Localization
  45. EP250302a: Optical Observations at CrAO and SAO RAS
  46. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  47. EP 250304A: Optical counterpart detection by LCO
  48. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  49. Konus-Wind detection of GRB 250222A
  50. IPN triangulation of GRB 250222A
  51. EP250302a: Mondy Continued Optical Observations
  52. EP250304a: VLT/X-shooter redshift z = 0.200
  53. EP250302a: NUTTelA-TAO Early Measurments
  54. EP250302a: Mondy Observations and Optical Light Curve
  55. EP250302a: OHP/T193 optical and spectroscopic observations
  56. GRB 250226A: GRANDMA Optical Observations
  57. EP250302a: Montarrenti Observatory optical detection
  58. Fermi GRB 250302A: Global MASTER-Net observations report
  59. GRB 250302A: Fermi GBM Final Real-time Localization
  60. GRB 250228A: Fermi GBM Final Localization
  61. GRB 250225B: VLT near-infrared afterglow confirmation
  62. Konus-Wind detection of GRB 250226A
  63. GRB 250225B: EIRSAT-1 GMOD Detection
  64. GRB 250226A: KAO Optical Upper Limit
  65. GRB 250226A: AbAO AS-32 Optical Upper Limit
  66. EP250223A: Upper limits from Fermi-GBM Observations
  67. GRB 250225B: VLT/HAWKI near-infrared observations
  68. GRB 250226A: Fermi GBM Observation
  69. GRB 250226A / EP250226a: LCO detection of the afterglow
  70. GRB 250225B: VLT/Xshooter imaging
  71. GRB 250205A / EP250205A: further radio observations with the VLA
  72. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  73. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  74. GRB 250225B: INTEGRAL SPI-ACS detection
  75. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  76. EP250226a / GRB 250226A: SVOM/VT optical observations
  77. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  78. EP250226a/GRB 250226A: 1.6m Mephisto observations
  79. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  80. EP250226a/GRB 250226A: Kinder optical follow-up observations
  81. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  82. Fermi GRB 250226B: Global MASTER-Net observations report
  83. GRB 250226B: Fermi GBM Final Real-time Localization
  84. GRB 250225B: Fermi GBM Observation
  85. GRB 250221A: ATCA Detections and Upper Limits
  86. GRB 250225B: REM NIR upper limits
  87. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  88. Konus-Wind detection of GRB 250225B
  89. EP250223a: CrAO ZTSH optical observation
  90. GRB 250225B: VLT optical and near-infrared candidate counterpart
  91. GRB 250225B: VLT/FORS2 candidate optical afterglow
  92. GRB 250225B: SVOM/GRM observation of a long burst
  93. GRB 250226A: GECAM-B detection
  94. GRB 250221A: EP-FXT detection of the X-ray afterglow
  95. GRB 250214A: SVOM/GRM observation
  96. EP250226a/GRB 250226A: GSP detects optical counterpart
  97. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  98. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  99. EP250226a / GRB 250226A: TRT optical counterpart observation
  100. Swift GRB 250225B: Global MASTER-Net observations report

Advanced

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