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"

28122 results found.

  1. Fermi GRB 250918A: Global MASTER-Net observations report
  2. GRB 250919A / EP250919a: NuSTAR detection of bright prompt emission
  3. GRB 250918A: SVOM/GRM observation
  4. GRB 250919A: Swift-XRT afterglow detection
  5. GRB 250919A: SVOM/GRM observation of a very bright GRB
  6. GRB 250919A: BALROG localization (Fermi Trigger 779934537 / GRB 250919020)
  7. EP250919a: Einstein Probe detection of an X-ray transient
  8. GRB 250916A: Fermi GBM Observation
  9. GRB 250916A: KAIT optical observations
  10. GRB 250917B: VLT/HAWK-I near-infrared observations
  11. GRB 250916A: NuSTAR detection of the prompt emission
  12. GRB 250916A: further SAO RAS optical observations
  13. GRB 250917B: Swift-BAT refined analysis
  14. LIGO/Virgo/KAGRA S250918aw: 1 counterpart neutrino candidate event from an IceCube neutrino search
  15. GRB 250918A: BALROG localization (Fermi Trigger 779891543 / GRB 250918522)
  16. GRB 250917B: Swift/UVOT Upper Limits
  17. GRB 250916A: OSIRIS+/GTC redshift z = 2.015
  18. GRB 250916A: Swift-XRT observations
  19. GRB 250916A: MAO/AZT-22 optical observations
  20. GRB 250916A: SAO RAS optical observations
  21. GRB 250916A : GIT optical observations
  22. LIGO/Virgo/KAGRA S250917aq: Three counterpart neutrino candidates from IceCube neutrino searches
  23. LIGO/Virgo/KAGRA S250917aq: Updated Sky localization
  24. GRB 250916A: Glowbug gamma-ray detection
  25. GRB250917B: WFST optical observations
  26. GRB 250917B: Fermi GBM Observation
  27. GRB 250917B: Swift-XRT observations
  28. LIGO/Virgo/KAGRA S250917aq: Identification of a GW compact binary merger candidate
  29. GRB 250917B: Swift detection of a short burst
  30. GRB 250916A: AstroSat CZTI detection of a bright long burst
  31. EP250916a: Einstein Probe detection of an X-ray transient
  32. SVOM/sb25091517: SVOM detection of an X-ray transient
  33. GRB 250912A: Swift/BAT-GUANO localization skymap of a possibly short burst
  34. GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
  35. GRB 250912A: Swift-XRT observations
  36. GRB250912A: VLT/HAWK-I follow-up observations
  37. GRB 250912A: Fermi GBM Observation
  38. GRB 250912A: SVOM/GRM analysis suggests a possible short GRB with extended emission
  39. GRB 250912A:SVOM/VT optical upper limit
  40. GRB 250912A: LCO optical upper limit
  41. EP250911a: Global MASTER-Net observations report
  42. GRB 250912A: SVOM detection of a burst
  43. IceCube-Cascade 250911A: Upper limits from a search for additional neutrino events in IceCube
  44. LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search
  45. EP250911a: Upper limit from Fermi-GBM Observations
  46. LIGO/Virgo/KAGRA S250912f: Updated Sky localization
  47. GRB 250911A: GECAM-B detection
  48. GRB 250911A: Swift-BAT refined analysis
  49. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  50. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  51. GRB 250910B: SVOM/GRM observation
  52. EP250911a: SVOM/VT optical observation
  53. GRB 250911A: MASTER optical counterpart observations
  54. EP250911a: SAO RAS optical observations
  55. GRB 250911A: Swift-XRT refined Analysis
  56. EP250911a: Swift-XRT observations
  57. EP250911a: Optical detection with Kinder observations
  58. GRB 250911A: Swift/UVOT Detection
  59. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  60. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  61. LIGO/Virgo/KAGRA S250911ac: Updated Sky localization and Source Classification
  62. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  63. EP250911a: COLIBRÍ optical observations
  64. LIGO/Virgo/KAGRA S250908y: Updated Sky localization
  65. EP250911a: LCO optical counterpart discovery
  66. EP250911a: Einstein Probe detection of an X-ray transient
  67. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  68. GRB 250903A: SVOM/ECLAIRs refined analysis
  69. GRB 250911A: Enhanced Swift-XRT position
  70. GRB 250911A: Swift-XRT observations
  71. GRB 250911A: COLIBRÍ optical counterpart candidate
  72. LIGO/Virgo/KAGRA S250906ca: Updated Sky localization
  73. GRB 250910B: BALROG localization (Fermi Trigger 779223130 / GRB 250910786)
  74. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  75. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  76. GRB 250910A: SVOM/VT optical upper limit
  77. GRB 250910A: LCO optical upper limit
  78. EP250908b/EP#01709240653: Swift/UVOT Detection
  79. EP#01709240653: Swift-XRT observations
  80. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  81. EP250908c: SVOM/VT optical observation
  82. EP250908c: VLT/FORS2 optical counterpart identification
  83. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  84. EP250908b: SVOM/VT optical candidate
  85. Fermi GRB 250909A: Global MASTER-Net observations report
  86. EP250908c: Einstein Probe detection of an X-ray transient
  87. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  88. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  89. GRB 250907A: GECAM-B detection
  90. GRB 250905A: Swift-BAT refined analysis
  91. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  92. GRB 250903A: Swift-XRT afterglow detection
  93. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  94. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  95. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  96. EP250905a: Liverpool Telescope i-band upper limits
  97. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  98. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  99. EP250905a: Liverpool Telescope observations
  100. EP250905a: refined analysis of the EP-WXT and EP-FXT observations

Advanced

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