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"

36229 results found.

  1. EP250311a/GRB 250311A: EP-FXT follow-up observation
  2. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  3. GRB 250312A: Swift-XRT refined Analysis
  4. Fermi Gamma-ray Burst Monitor trigger 763509110/250312911 is not a GRB
  5. Fermi GRB 250312B: Global MASTER-Net observations report
  6. GRB 250312A: Enhanced Swift-XRT position
  7. GRB 250312B: Fermi GBM Final Localization
  8. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  9. GRB 250226B: Fermi GBM Observation
  10. Swift GRB 250312A: Global MASTER-Net observations report
  11. GRB 250302A: Fermi GBM Observation
  12. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  13. GRB 250312A: Swift detection of a burst
  14. GRB 241213A: VIRT Optical Upper Limit
  15. GRB 241228A: VIRT Optical Upper Limit
  16. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  17. GRB 250223B: Fermi GBM Observation
  18. GRB 250311A: Swift-XRT observations
  19. GRB 250228A: Fermi GBM Observation
  20. GRB 250309B: 1.3m DFOT Optical observations
  21. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  22. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  23. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  24. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  25. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  26. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  27. GRB 250309B: PRIME near-infrared detection
  28. GRB 250225B: Swift-BAT refined analysis
  29. GRB 250311A/EP250311a: TRT optical upper limit
  30. GRB 250311A: Tiled Swift observations
  31. EP250311a/GRB 250311A: EP-WXT detection
  32. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  33. GRB 250311B: SVOM detection of a burst
  34. GRB 250309B: SVOM/VT optical observation
  35. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  36. GRB 250309B / AT2025dws: further SAO RAS optical observations
  37. IceCube-250309A: Upper limits from Fermi-GBM Observations
  38. Konus-Wind detection of GRB 250309B
  39. GRB 250309B / AT2025dws: KMTNet-CTIO optical observations
  40. IPN triangulation of GRB 250308A (short)
  41. IPN triangulation of GRB 250309B
  42. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  43. GRB 250309B: Swift-XRT refined Analysis
  44. GRB 250309B / IceCube-250309A: GECAM-B observations
  45. GRB 250309B / AT2025dws: OSIRIS+/GTC spectroscopy z=1.898
  46. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  47. GRB 250309B / AT2025dws: SAO RAS optical observations
  48. GRB 250309B / AT2025dws: Swift-UVOT detection
  49. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  50. GRB 250309B: Fermi GBM Observation
  51. Fermi GRB 250309B: Global MASTER-Net observations report
  52. Fermi GRB 250309A: Global MASTER-Net observations report
  53. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  54. Fermi-LAT gamma-ray observations of IceCube-250309A
  55. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  56. GRB 250309B: Fermi GBM Final Localization
  57. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  58. GRB 230509B: Tiled Swift observations
  59. GRB 250308A: SVOM/GRM observation of a bright short burst
  60. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  61. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  62. GRB 250309A: Fermi GBM Final Real-time Localization
  63. GRB 250306A: EIRSAT-1 GMOD detection
  64. Fermi GRB 250307A: Global MASTER-Net observations report
  65. Konus-Wind detection of GRB 250306A
  66. GRB 250307A: Fermi GBM Final Real-time Localization
  67. GRB 250306A: Swift-BAT refined analysis
  68. GRB 250306A: NuSTAR detection of the prompt emission
  69. GRB 250305A: AstroSat CZTI detection
  70. GRB 250306A: AstroSat CZTI detection
  71. Fermi Gamma-ray Burst Monitor trigger 762963055/250306591 is not a GRB
  72. Swift GRB 250306A: Global MASTER-Net observations report
  73. GRB 250306A: Swift detection of a burst
  74. GRB 250305A: SVOM/GRM observation of a burst
  75. EP250304A: Upper limits from Fermi-GBM Observations
  76. Fermi GRB 250305A: Global MASTER-Net observations report
  77. GRB 250305A: Fermi GBM Final Real-time Localization
  78. EP250302a: Optical Observations at CrAO and SAO RAS
  79. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  80. EP 250304A: Optical counterpart detection by LCO
  81. Konus-Wind detection of GRB 250222A
  82. IPN triangulation of GRB 250222A
  83. EP250302a: Mondy Continued Optical Observations
  84. EP250304a: VLT/X-shooter redshift z = 0.200
  85. EP250302a: Mondy Observations and Optical Light Curve
  86. EP250302a: OHP/T193 optical and spectroscopic observations
  87. GRB 250226A: GRANDMA Optical Observations
  88. EP250302a: Montarrenti Observatory optical detection
  89. Fermi GRB 250302A: Global MASTER-Net observations report
  90. GRB 250302A: Fermi GBM Final Real-time Localization
  91. GRB 250228A: Fermi GBM Final Localization
  92. GRB 250225B: VLT near-infrared afterglow confirmation
  93. Konus-Wind detection of GRB 250226A
  94. GRB 250225B: EIRSAT-1 GMOD Detection
  95. GRB 250226A: KAO Optical Upper Limit
  96. GRB 250226A: AbAO AS-32 Optical Upper Limit
  97. EP250223A: Upper limits from Fermi-GBM Observations
  98. GRB 250225B: VLT/HAWKI near-infrared observations
  99. GRB 250226A: Fermi GBM Observation
  100. GRB 250226A / EP250226a: LCO detection of 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