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"

23151 results found.

  1. GRB 251013C: LCO optical afterglow detection
  2. GRB 251013C: LAST detection of optical counterpart
  3. GRB 251013C: BOOTES-6 early optical detection
  4. GRB 251013C: SVOM/VT optical observation
  5. LIGO/Virgo/KAGRA S251013x: Identification of a GW compact binary merger candidate
  6. GRB 251011B inspection: MASTER orphan GRB detection
  7. GRB 251011A: Insight-HXMT detection
  8. GRB 251011B: Swift/UVOT Upper Limits
  9. GRB 251011B: Swift-XRT refined Analysis
  10. GRB 251010A: AstroSat CZTI detection
  11. GRB 251011A: AstroSat CZTI detection
  12. GRB 251011B: Swift detection of a burst
  13. GRB 251007B: Swift/UVOT Upper Limits
  14. GRB251007A: Swift/UVOT Detection
  15. GRB 251009B (short): Glowbug gamma-ray detection
  16. GRB 251007A: Swift-BAT refined analysis
  17. GRB 251006A: CALET Gamma-Ray Burst Monitor detection
  18. GRB 251007B - SVOM/ECLAIRs refined analysis
  19. GRB 250916A: TERI Gamma-ray detection
  20. GRB 250919A: TERI gamma-ray detection
  21. GRB 251006A: Fermi GBM Observation
  22. GRB 251007A: 1.5m OSN and 2.2m CAHA optical follow-up
  23. GRB 251002A - SVOM/ECLAIRs refined analysis
  24. GRB 251007B: COLIBRÍ optical upper limit
  25. GRB 251007A: AstroSat CZTI detection
  26. GRB 251006B/EP251006a: EP-FXT afterglow detection
  27. GRB 250917B: iTelescope T-26 upper limit
  28. GRB 251007B: SVOM/VT optical candidate
  29. GRB 251007B: Swift-XRT refined Analysis
  30. GRB 251007A: CALET Gamma-Ray Burst Monitor detection
  31. GRB 251005C: PRIME J-band upper limit
  32. GRB 251007A: Glowbug gamma-ray detection
  33. GRB 251007B: SVOM/C-GFT upper limit
  34. GRB 251007B: Swift detection of a burst
  35. GRB 251007A: Swift detection of a burst with an optical counterpart
  36. GRB 250702B/EP250702a: JWST/NIRCam Observations
  37. GRB 251005B: Glowbug gamma-ray detection
  38. EP251003a: LCO and VST fading optical counterpart
  39. GRB 251006B/EP251006a: EP-FXT follow-up observation
  40. GRB 251006B: COLIBRÍ optical upper limit
  41. GRB 251006B/EP251006a: EP-WXT detection
  42. LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate
  43. GRB 251006B: Fermi GBM Final Real-time Localization
  44. GRB 251006A (short): Glowbug gamma-ray detection
  45. GRB 251005C: COLIBRÍ optical observations
  46. GRB 251003A: LAST optical observations
  47. GRB 251002A: LAST optical observations
  48. GRB 251006A: Fermi GBM Final Real-time Localization
  49. GRB 251005C: AstroSat CZTI detection
  50. GRB 251005C: Swift/UVOT Upper Limits
  51. GRB 250902A: MSU cubesats detection
  52. GRB 251005C: Swift-XRT refined Analysis
  53. GRB 251005C: Fermi GBM Observation
  54. GRB 251005C: GOTO optical upper limits
  55. GRB 251005C: Swift detection of a burst
  56. GRB 251003A: J-band detection with WINTER
  57. GRB 251002A: NIR observations with WINTER
  58. GRB 251003A: Swift-BAT refined analysis
  59. GRB 251001B: NIR observations with WINTER
  60. GRB 251003A: Swift/UVOT Upper Limits
  61. GRB 251001A: AstroSat CZTI detection
  62. GRB 251001B: COLIBRÍ further observations and evidence of a multi-wavelength shallow decay
  63. GRB 251003A: Swift-XRT refined Analysis
  64. GRB 251003A: COLIBRÍ photometric redshift
  65. GRB 251003A: GOTO detection of the optical counterpart
  66. GRB 251002A: GOTO detection of optical counterpart
  67. EP250821a: iTelescope T-59 possible detection of the optical counterpart
  68. GRB 251003A: GTC/OSIRIS+ spectroscopic redshift z = 4.412
  69. GRB 251003A: Kilonova-Catcher optical afterglow detection
  70. GRB 251002A: Kilonova-Catcher optical afterglow detection
  71. GRB 251002A: SVOM/COLIBRÍ (FM-GFT) optical observations
  72. GRB 251001C: CALET Gamma-Ray Burst Monitor detection
  73. GRB 251003A: COLIBRÍ optical detection of the fading afterglow
  74. GRB 251003A: Swift detection of a burst
  75. Swift GRB251003A: Global MASTER-Net observations report
  76. GRB 251002A: BOOTES-6 early optical detection
  77. GRB 251002A: SAO RAS optical observations
  78. GRB 251002A: ULL-ASTRO-MASTER early detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  79. GRB 251002A: SVOM detection of a burst
  80. GRB 251001B: Swift-BAT refined analysis
  81. GRB 251001B: COLIBRÍ optical observations
  82. GRB 251001B: GTC/OSIRIS+ spectroscopic redshift z = 2.162
  83. GRB 251001B: NOT optical observations
  84. GRB 251001C: Glowbug gamma-ray detection
  85. GRB 251001B: Further GOTO observations of optical counterpart.
  86. GRB 250930A: SVOM/GRM observation
  87. GRB 251001B: TRT optical afterglow detection and potential host galaxy
  88. GRB 251001B: GOTO optical counterpart detection
  89. GRB 251001B: Swift detection of a burst
  90. GRB 251001A: Fermi GBM Detection
  91. GRB 250926A: CALET Gamma-Ray Burst Monitor detection
  92. LIGO/Virgo/KAGRA S250929c: Identification of a GW compact binary merger candidate
  93. GRB 250924A: SVOM/GRM observation
  94. GRB 250920C: ULL-ASTRO-MASTER early detection of the optical afterglow with LCO 40-cm telescope at Siding Spring Observatory
  95. GRB 250926A: AstroSat CZTI detection
  96. GRB 250925A: Swift-BAT refined analysis
  97. GRB 250925A: COLIBRÍ photometric redshift
  98. GRB 250925A: SVOM/GWAC-F60A upper limit
  99. GRB 250926A: DDOTI Optical Observations and Spatial Coincidence with the Orion Nebula
  100. GRB 250925A : MITSuME Akeno optical upper limits

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