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"

22031 results found.

  1. GRB 251203B: Swift-XRT observations
  2. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  3. GRB 251203C: LCO optical upper limits
  4. GRB 251203B: LCO optical upper limits
  5. GRB 251203B: SVOM/VT optical observation
  6. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  7. GRB 251203B: SVOM detection of a burst
  8. EP251130a: MAO/AZT-22 optical observations
  9. EP251202a/GRB 251202A: KAIT optical observations
  10. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  11. IPN triangulation of GRB 251129B (short/hard)
  12. GRB251129A/EP251129a: Swift UVOT detection
  13. GRB 251202A: Swift/UVOT Detection
  14. GRB 251201B: Kilonova-Catcher optical afterglow detection
  15. GRB 251201B: Swift/UVOT Detection
  16. GRB 251130B: Glowbug gamma-ray detection
  17. EP251130a: continued NOT optical observations indicate steep fading phase
  18. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  19. GRB 251126A: SAO RAS optical marginal detection
  20. GRB 251202A: Swift-XRT afterglow detection
  21. EP251129a/GRB 251129A: NOWT Detection
  22. GRB 251126A: SVOM/VT optical observation
  23. EP251130a: SVOM/VT optical observation
  24. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  25. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  26. GRB 251201B: Swift-XRT refined Analysis
  27. GRB 251201A: SVOM/GRM observation of a burst
  28. GRB 251201B: SVOM/VT optical fading
  29. Swift GRB 251201B : MASTER optical counterpart detection
  30. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  31. GRB 251201B: Enhanced Swift-XRT position
  32. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  33. GRB 251130B: AstroSat CZTI detection
  34. GRB 251201B: Swift detection of a burst with an optical counterpart
  35. EP251130a: Mondy optical observations
  36. EP251130a: Optical detections with Kinder observations
  37. EP251130a: SAO RAS optical observations
  38. EP251130A: Optical observation from 1.3m DFOT
  39. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  40. EP251130a: JinShan optical observations
  41. GRB 251127A: SVOM/GRM observation
  42. EP251130a: Swift-XRT counterpart detection
  43. EP251130a: COLIBRÍ optical counterpart candidate
  44. EP251130a: Einstein Probe detection of an X-ray transient
  45. GRB 251129A / EP251129a: SAO RAS optical observations
  46. GRB 251126A: SAO RAS optical observations
  47. GRB 251128A: SVOM/GRM observation of a long burst
  48. SVOM GRB 251129A : MASTER optical counterpart detection
  49. GRB 251129A: Swift-XRT afterglow detection
  50. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  51. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  52. GRB 251129A: SVOM detection of a burst
  53. GRB 251129A: SVOM detection of a burst
  54. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  55. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  56. GRB 251127A: Glowbug gamma-ray detection
  57. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  58. GRB 251126A: further SAO RAS optical observations
  59. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  60. GRB251126A: MAO/AZT-22 optical observations
  61. GRB251126A: Continued optical observation from 1.3m DFOT
  62. GRB 251126A: Swift/UVOT Detection
  63. EP251124a: Pan-STARRS ri-band imaging and photometry
  64. GRB 251126A: Mondy and SAO RAS optical observations
  65. GRB 251126A: Swift-XRT refined Analysis
  66. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  67. GRB 251126A: 1.3m DFOT optical afterglow detection
  68. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  69. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  70. GRB 251126A: Enhanced Swift-XRT position
  71. GRB 251126A: Kilonova-Catcher optical afterglow detection
  72. GRB 251126A: Nanshan/HMT optical afterglow detection
  73. GRB 251126A: GIT discovery of the likely optical afterglow
  74. GRB 251126A: Swift detection of a burst
  75. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  76. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  77. EP251124b: NOT r- and z-band optical upper limits
  78. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  79. EP251124b: EP-WXT detection of a fast X-ray transient
  80. EP251124a: Xinglong GWAC-F60A optical observation
  81. EP251124a: NOT r- and z-band optical upper limits
  82. EP251124a: Swift-XRT observations
  83. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  84. EP251124a: Optical upper limit with Kinder observations
  85. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  86. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  87. EP251124a: GROWTH-India Telescope optical upper limits
  88. EP251124a: Einstein Probe detection of an X-ray transient
  89. GRB 251116C: Swift-XRT confirmation of fading
  90. GRB 251122A/EP251122a: FTW optical and NIR observations
  91. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  92. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  93. EP251118A: 3.6m DOT optical afterglow detection
  94. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  95. GRB 251122A / EP251122a: WFST optical observations
  96. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  97. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  98. GRB 251122A / EP251122a: LCO optical upper limits
  99. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  100. GRB 251122A/EP251122a: SVOM/C-GFT upper limit

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