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"

20967 results found.

  1. EP251214a: Optical upper limit with Kinder observations
  2. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  3. GRB 251214B: UAFO optical upper limit
  4. GRB 251214B: VLT/X-shooter observations
  5. GRB 251202A: radio detection with the VLA
  6. EP251214b: Global MASTER-Net observations report
  7. GRB 251214B: AbAO optical observations
  8. GRB 251214B: LCO detection of the optical counterpart
  9. GRB 251215A: Swift ToO observations
  10. EP251214b (EP trigger 01709250023): LCO optical limits
  11. GRB 251203B: AbAO optical observations
  12. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  13. GRB 251214B: Swift/UVOT Detection
  14. GRB 251214B: COLIBRÍ observations of the afterglow
  15. GRB 251214B: 1.3m DFOT optical detection
  16. EP251214a: Global MASTER-Net observations report
  17. GRB 251214B: Xinglong-2.16m optical observation
  18. GRB 251214B : MASTER optical afterglow detection
  19. Fermi trigger No 787396657: Global MASTER-Net observations report
  20. GRB 251214B: SVOM/C-GFT optical observations
  21. Swift GRB 251214B: Global MASTER-Net observations report
  22. Fermi GRB 251214A: Global MASTER-Net observations report
  23. EP251212a: Global MASTER-Net observations report
  24. EP251212a: KAIT optical upper limit
  25. IceCube-251210A: No Candidate Transients from the Zwicky Transient Facility
  26. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  27. Fermi GRB 251211B: Global MASTER-Net observations report
  28. IceCube-251210A: DDOTI Optical Upper Limit
  29. SVOM GRB251211.12: Global MASTER-Net observations report
  30. GRB 251205A: 1.3m DFOT optical upper limit
  31. IceCube Alert 251210.46: Global MASTER-Net observations report
  32. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  33. EP251130a: Mondy and AbAO optical observations
  34. Fermi GRB 251209A: Global MASTER-Net observations report
  35. Fermi GRB 251208C: Global MASTER-Net observations report
  36. GRB 251208B: Swift-XRT afterglow detection
  37. GRB 251208D: LAST optical upper limit
  38. GRB 251208D: LCO analysis of the XRT sources
  39. GRB 251208B: GROWTH-India Telescope optical upper limits
  40. GRB 251205A: J-band detection with WINTER
  41. GRB 251208D: Swift-XRT observations
  42. GRB 251129A: e-MERLIN C-band observations
  43. LAT GRB251208.43: Global MASTER-Net observations report
  44. GRB 251205A: Liverpool Telescope further optical follow-up observations
  45. SVOM GRB251208D: Global MASTER-Net observations report
  46. GRB 251208B: Swift ToO observations
  47. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  48. GRB 251205A: FTW optical and NIR observations
  49. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  50. GRB 251205A: Liverpool Telescope further optical follow-up observations
  51. SVOM GRB251206.86: Global MASTER-Net observations report
  52. GRB 251205A: ZTF and ATLAS optical afterglow detections
  53. GRB 251205A: GROWTH-India Telescope optical observations
  54. GRB 251205A: Swift/UVOT Detection
  55. GRB 251205A: Liverpool Telescope optical follow-up observations
  56. GRB 251203C: Swift/UVOT Upper Limit
  57. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  58. GRB 251205A: COLIBRÍ optical observations
  59. GRB 251205A: GOTO optical afterglow detection
  60. GRB 251205A: NOT optical observations
  61. Swift GRB 251205A : MASTER OT detection with host galaxy
  62. Swift GRB251205A: Global MASTER-Net observations report
  63. GRB 251203C: SVOM/ECLAIRs refined analysis
  64. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  65. GRB 251203C: J-band observations with WINTER
  66. EP251130a: JinShan near-infrared observations
  67. GRB 251203C: SVOM/VT optical counterpart
  68. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  69. GRB 251203B: Swift-XRT observations
  70. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  71. GRB 251203B: LCO optical upper limits
  72. GRB 251203B: SVOM/VT optical observation
  73. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  74. SVOM GRB251203.77: Global MASTER-Net observations report
  75. SVOM GRB251203B: Global MASTER-Net observations report
  76. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  77. EP251130a: MAO/AZT-22 optical observations
  78. GRB 251202A / EP251202a: SVOM/VT optical observation
  79. EP251202a/GRB 251202A: KAIT optical observations
  80. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  81. Fermi GRB 251202B: Global MASTER-Net observations report
  82. GRB251129A/EP251129a: Swift UVOT detection
  83. GRB 251202A: Swift/UVOT Detection
  84. GRB 251201B: Kilonova-Catcher optical afterglow detection
  85. GRB 251201B: Swift/UVOT Detection
  86. EP251130a: continued NOT optical observations indicate steep fading phase
  87. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  88. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  89. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  90. GRB 251202A: GOTO optical afterglow detection
  91. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  92. GRB 251202A: Swift-XRT afterglow detection
  93. Fermi GRB 251202A: Global MASTER-Net observations report
  94. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  95. Swift GRB 251201B: Global MASTER-Net observations report
  96. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  97. EP251130a: Mondy optical observations
  98. EP251130a: Optical detections with Kinder observations
  99. SVOM GRB251201.19: Global MASTER-Net observations report
  100. EP251130a: SAO RAS optical observations

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
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