Skip to main content
New! Super-Kamiokande JSON Notices and Schema v4.5.0. 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"
  1. GRB251221A: 7DT optical upper limits
  2. EP251222a: GSP Optical Counterpart Detection
  3. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  4. GRB 251222A / EP251222b: SVOM/VT optical rebrightening
  5. EP251222b/GRB 251222A: SVOM/GRM observation
  6. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  7. EP251222a: Einstein Probe detection of an X-ray transient
  8. The EP-WXT trigger 01709250397 is likely a flaring star
  9. EP251221a: Global MASTER-Net observations report
  10. GRB 251222A: PRIME near-infrared detection
  11. EP251221a: NOT optical upper limit
  12. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  13. GRB 251222A: NOT optical observations
  14. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  15. IPN triangulation of GRB 251220B (short)
  16. GRB 251222A: Swift ToO observations
  17. GRB 251222A: BALROG localization (Fermi Trigger / GRB 251222712)
  18. GRB 251222A: SVOM/VT optical candidate
  19. GRB 251222A: SVOM detection of a long burst
  20. SVOM GRB251222A: Global MASTER-Net observations report
  21. GRB 251222A: Fermi GBM Final Real-time Localization
  22. EP251220a: PRIME upper limit
  23. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  24. GRB 251221A: PRIME near-infrared observation
  25. EP251220a: NOT optical observations
  26. EP251220a: FTW optical and NIR observations
  27. GRB 251221A: UAFO and Mondy optical upper limit
  28. GRB 251221A: Swift-XRT refined Analysis
  29. EP251221a: Einstein Probe detection of a fast X-ray transient
  30. GRB 251221A: Swift/UVOT Upper Limits
  31. Fermi Gamma-ray Burst Monitor trigger 788028118/251221696 is not a GRB
  32. GRB 251221A: Enhanced Swift-XRT position
  33. GRB 251221A: Fermi GBM Observation
  34. GRB 251221B: Fermi GBM Final Real-time Localization
  35. EP251220a: EP-FXT follow-up observation
  36. GRB 251220B: SVOM/GRM observation of a short burst
  37. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  38. EP 251220a: GOTO optical counterpart detection
  39. GRB 251221A: COLIBRÍ detection of the optical counterpart
  40. EP 251220a: COLIBRÍ detection of the optical counterpart
  41. GRB 251221A: Swift detection of a burst
  42. Swift GRB251221A: Global MASTER-Net observations report
  43. GRB 251221A: Fermi GBM Final Real-time Localization
  44. EP251220a: Global MASTER-Net observations report
  45. EP251220a: EP detection of a fast X-ray transient
  46. SVOM GRB251220.98: Global MASTER-Net observations report
  47. GRB 251220B: Fermi GBM Final Real-time Localization
  48. GRB 251219A: SVOM/GRM observation of a short burst
  49. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  50. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  51. GRB 251220A: MAXI/GSC detection
  52. GRB 251215A: Swift-XRT afterglow detection
  53. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  54. IceCube-251218A: COLIBRÍ optical upper limits
  55. SVOM GRB251219.11: Global MASTER-Net observations report
  56. IceCube-251218A - IceCube observation of a high-energy neutrino candidate track-like event
  57. IceCube Alert 251218.85: Global MASTER-Net observations report
  58. GRB 251214B: VIRT Optical Upper Limit
  59. Fermi trigger No 787736968: Global MASTER-Net observations report
  60. Fermi GRB 251217A: Global MASTER-Net observations report
  61. GRB 251217A: Fermi GBM Final Real-time Localization
  62. GRB 251215A: Swift/UVOT Upper LImits
  63. GRB 251215A: Fermi GBM Observation
  64. Fermi GRB 251216A: Global MASTER-Net observations report
  65. GRB 251202A/EP251202a: Koshka optical upper limit
  66. GRB 251214B: Mondy optical upper limit
  67. GRB 251215A: COLIBRÍ optical upper limit
  68. GRB 251216A: Fermi GBM Final Real-time Localization
  69. EP251214b: KAIT optical upper limit
  70. GRB 251215A: Swift-XRT observations
  71. Fermi GRB 251215A: Global MASTER-Net observations report
  72. EP251214a: Optical upper limit with Kinder observations
  73. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  74. GRB 251215A: Glowbug gamma-ray detection
  75. GRB 251214B: UAFO optical upper limit
  76. GRB 251214B: VLT/X-shooter observations
  77. GRB 251213A: GRID-10B observation
  78. GRB 251214B: Swift-BAT refined analysis
  79. GRB 251202A: radio detection with the VLA
  80. EP251214b: Global MASTER-Net observations report
  81. EP251214b : Einstein Probe detection of a fast X-ray transient
  82. EP251214b : Einstein Probe detection of a fast X-ray transient
  83. GRB 251214B: AbAO optical observations
  84. GRB 251214B: LCO detection of the optical counterpart
  85. GRB 251209A: GECAM-B observation of a long burst
  86. GRB 251214D: GECAM-B observation of a long burst
  87. GRB 251214B: Fermi GBM Observation
  88. GRB 251209A: Insight-HXMT/HE detection
  89. GRB 251215A: Swift ToO observations
  90. EP251214b (EP trigger 01709250023): LCO optical limits
  91. GRID detection of GRB 251213A
  92. GRB 251203B: AbAO optical observations
  93. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  94. GRB 251214B: GECAM-B observation of a long burst
  95. GRB 251214B: Swift-XRT refined Analysis
  96. GRB 251213A: SVOM/GRM observation
  97. EP251214a: KAIT optical upper limit
  98. GRB 251214D: AstroSat CZTI detection of a long burst
  99. GRB 251213A: AstroSat CZTI detection
  100. GRB 251214A: AstroSat CZTI detection

Advanced

Download all Circulars as a .tar.gz archive:
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov