Skip to main content
New! BOOM Notices and Schema v7.0.0. 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"

27324 results found.

  1. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  2. GRB 251126A: SAO RAS optical marginal detection
  3. GRB 251202A: Swift-XRT afterglow detection
  4. EP251129a/GRB 251129A: NOWT Detection
  5. GRB 251126A: SVOM/VT optical observation
  6. EP251130a: SVOM/VT optical observation
  7. Fermi GRB 251202A: Global MASTER-Net observations report
  8. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  9. GRB 251201B: Swift-XRT refined Analysis
  10. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  11. GRB 251201A: SVOM/GRM observation of a burst
  12. GRB 251201B: SVOM/VT optical fading
  13. Swift GRB 251201B : MASTER optical counterpart detection
  14. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  15. Swift GRB 251201B: Global MASTER-Net observations report
  16. GRB 251201B: Enhanced Swift-XRT position
  17. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  18. GRB 251201B: Swift detection of a burst with an optical counterpart
  19. GRB 251201B: Fermi GBM Final Real-time Localization
  20. EP251130a: Mondy optical observations
  21. EP251130a: Optical detections with Kinder observations
  22. SVOM GRB251201.19: Global MASTER-Net observations report
  23. EP251130a: SAO RAS optical observations
  24. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  25. EP251130A: Optical observation from 1.3m DFOT
  26. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  27. EP251130a: JinShan optical observations
  28. GRB 251201A: MAXI/GSC detection
  29. Fermi GRB 251130B: Global MASTER-Net observations report
  30. GRB 251127A: SVOM/GRM observation
  31. IceCube Alert 251130.75: Global MASTER-Net observations report
  32. EP251130a: Swift-XRT counterpart detection
  33. EP251130a: Global MASTER-Net observations report
  34. EP251130a: COLIBRÍ optical counterpart candidate
  35. EP251130a: Einstein Probe detection of an X-ray transient
  36. GRB 251129A / EP251129a: SAO RAS optical observations
  37. GRB 251126A: SAO RAS optical observations
  38. GRB 251128A: SVOM/GRM observation of a long burst
  39. SVOM GRB 251129A : MASTER optical counterpart detection
  40. GRB 251129A: Swift-XRT afterglow detection
  41. EP251129a: Global MASTER-Net observations report
  42. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  43. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  44. GRB 251128A: Fermi GBM Observation
  45. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  46. GRB 251129A: SVOM detection of a burst
  47. SVOM GRB251129A: Global MASTER-Net observations report
  48. GRB 251129A: SVOM detection of a burst
  49. GRB 251126A: Swift-BAT refined analysis
  50. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  51. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  52. Fermi GRB 251128A: Global MASTER-Net observations report
  53. GRB 251127A: Glowbug gamma-ray detection
  54. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  55. GRB 251126A: further SAO RAS optical observations
  56. GRB 251126A NUTTelA-TAO Early Measurements
  57. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  58. GRB251126A: MAO/AZT-22 optical observations
  59. GRB251126A: Continued optical observation from 1.3m DFOT
  60. GRB 251126A: Swift/UVOT Detection
  61. GRB 251126A: Mondy and SAO RAS optical observations
  62. GRB 251126A: Swift-XRT refined Analysis
  63. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  64. GRB 251126A: NOT optical observations
  65. GRB 251126A: 1.3m DFOT optical afterglow detection
  66. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  67. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  68. Fermi GRB 251127A: Global MASTER-Net observations report
  69. GRB 251126A: Enhanced Swift-XRT position
  70. GRB 251126A: Kilonova-Catcher optical afterglow detection
  71. GRB 251126A: Nanshan/HMT optical afterglow detection
  72. Swift GRB 251126A: Global MASTER-Net observations report
  73. GRB 251121A: Fermi GBM Observation
  74. GRB 251126A: GIT discovery of the likely optical afterglow
  75. GRB 251126A: Swift detection of a burst
  76. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  77. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  78. EP251124b: NOT r- and z-band optical upper limits
  79. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  80. Fermi GRB 251125B: Global MASTER-Net observations report
  81. EP251124b: Global MASTER-Net observations report
  82. EP251124b: EP-WXT detection of a fast X-ray transient
  83. EP251124a: Xinglong GWAC-F60A optical observation
  84. Fermi GRB 251125A: Global MASTER-Net observations report
  85. EP251124a: NOT r- and z-band optical upper limits
  86. EP251124a: Global MASTER-Net observations report
  87. EP251124a: Swift-XRT observations
  88. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  89. EP251124a: Optical upper limit with Kinder observations
  90. Fermi GRB 251124a: Global MASTER-Net observations report
  91. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  92. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  93. EP251124a: GROWTH-India Telescope optical upper limits
  94. EP251124a: Einstein Probe detection of an X-ray transient
  95. GRB 251116C: Swift-XRT confirmation of fading
  96. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  97. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  98. EP251118A: 3.6m DOT optical afterglow detection
  99. GRB 251122A / EP251122a: EP-FXT counterpart detection
  100. EP251122a: refined analysis of the EP-WXT and EP-FXT observations

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