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"

15268 results found.

  1. GRB260114A: STEP/T80S optical limits
  2. Konus-Wind detection of GRB 260114A
  3. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  4. GRB 260114A: COLIBRÍ optical upper limits
  5. GRB 260114A: TNG NIR upper limit
  6. GRB 260114A: NOT optical observations
  7. Konus-Wind detection of GRB 251230A / EP251230a
  8. GRB 260114A: SVOM/GRM observation of a short burst
  9. GRB 260114A: GECAM-B observation of a short burst
  10. GRB 260114A: Fermi GBM observation
  11. GRB 260112B: GECAM-B observation
  12. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  13. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  14. EP260110a: TRT optical upper limits
  15. Konus-Wind detection of GRB 260101A
  16. GRB 260111A: Swift-XRT observations
  17. Swift Trigger 1439093: is probably not GRB 260113A
  18. GRB 260111A: GECAM-B observation of a burst
  19. GRB 260111A: Fermi GBM Observation
  20. GRB 260111A: Swift ToO observations
  21. GRB 251230A: Mondy Optical Observations
  22. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  23. EP260110a: SVOM/VT optical upper limits
  24. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  25. EP260110a: KAIT optical upper limit
  26. EP 260110a: COLIBRÍ optical observations
  27. EP260110a: BOOTES-5/JGU optical upper limit
  28. GRB 260102A: Swift-XRT afterglow detection
  29. GRB 260105B: Fermi GBM Detection
  30. GRB 260105A: SVOM/GRM observation
  31. GRB 260105B: SVOM/GRM observation
  32. EP260105a: SVOM/VT optical upperlimit
  33. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  34. EP260105a: LCO Optical Upper limit
  35. EP260104a: Einstein Probe detection of a fast X-ray transient
  36. GRB 260103A: Insight-HXMT/HE detection
  37. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  38. GRB 260103A: GECAM-B observation of a burst
  39. GRB 260103A: SVOM/GRM observation of a possible GRB
  40. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  41. GRB 260102A: EP-FXT follow-up observation
  42. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  43. GRB 251230A / EP251230a: GECAM-B detection
  44. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  45. GRB 260102A: Swift ToO observations
  46. GRB 260101A: Fermi GBM Observation
  47. GRB 260102A: SVOM detection of a burst
  48. GRB 260101A: GECAM-B detection
  49. GRB 260101A: NOT spectroscopic observations
  50. GRB 260101A: SVOM/GRM observation
  51. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  52. GRB 251230A: GRANDMA/TAROT Early Detection
  53. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  54. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  55. EP251229a: BOOTES-2 early optical upper limit
  56. GRB 251230A: Early optical counterpart detection by LCO.
  57. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  58. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  59. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  60. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  61. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  62. GRB 251226A: SVOM/GRM observation
  63. GRB 251226A: GECAM-B detection
  64. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  65. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  66. GRB 251222A: NUTTelA-TAO Early Measurements
  67. GRB 251222A/EP251222b: Optical detection with Kinder observations
  68. GRB 251205A: Kilonova-Catcher optical afterglow detection
  69. GRB 251222A: AbAO optical observations
  70. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  71. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  72. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  73. GRB 251222A: Fermi GBM Observation
  74. EP251220a: CrAO ZTSh optical observations
  75. GRB 251222A / EP251222b: GECAM-B observation
  76. Konus-Wind detection of GRB 251222A / EP251222b
  77. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  78. EP251222a: NTT/ULTRACAM optical observations
  79. GRB 251222A / EP251222b: LCO optical observations
  80. EP251222b/GRB 251222A: SVOM/GRM observation
  81. GRB 251222A: PRIME near-infrared detection
  82. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  83. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  84. GRB 251222A: Swift ToO observations
  85. GRB 251222A: SVOM detection of a long burst
  86. EP251220a: PRIME upper limit
  87. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  88. GRB 251221A: PRIME near-infrared observation
  89. GRB 251221A: UAFO and Mondy optical upper limit
  90. GRB 251221A: Fermi GBM Observation
  91. GRB 251220B: SVOM/GRM observation of a short burst
  92. GRB 251221A: COLIBRÍ detection of the optical counterpart
  93. GRB 251219A: SVOM/GRM observation of a short burst
  94. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  95. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  96. GRB 251215A: Swift-XRT afterglow detection
  97. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  98. IceCube-251218A - IceCube observation of a high-energy neutrino candidate track-like event
  99. GRB 251214B: VIRT Optical Upper Limit
  100. GRB 251202A/EP251202a: Koshka optical upper limit

Advanced

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