Skip to main content
Due to the lapse in federal government funding, NASA is not updating this website. See the Operations FAQ for GCN impacts.
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"

25952 results found.

  1. GRB 251013C: Swift-XRT counterpart detection
  2. GRB 251013C: SAO RAS optical observations
  3. GRB 251013C: LCO optical afterglow detection
  4. GRB 251013C: Optical Observations via Virtual Telescope Project, Italy
  5. GRB 251013C: LAST detection of optical counterpart
  6. GRB 251013C: SVOM/VT optical observation
  7. GRB 251013C: SVOM detection of a burst
  8. LIGO/Virgo/KAGRA S251013x: Updated Sky localization and Source Classification
  9. GRB 251013B: SVOM/GRM observation
  10. GRB 251013A: SVOM/GRM observation
  11. GRB 251003A: Mondy optical upper limit
  12. MASTER OT J011025.98-583210.6 : SVOM/VT optical observation
  13. LIGO/Virgo/KAGRA S251013x: Identification of a GW compact binary merger candidate
  14. GRB 251011B inspection: MASTER orphan GRB detection
  15. GRB 251011B: Swift/UVOT Upper Limits
  16. Fermi GRB 251011A: Global MASTER-Net observations report
  17. GRB 251011B: SVOM/GRM observation
  18. GRB 251011B: Swift-XRT refined Analysis
  19. GRB 251011B: Fermi GBM Observation
  20. GRB 251011B : MASTER optical observations
  21. GRB 251011B: Enhanced Swift-XRT position
  22. GRB 251011B: Swift detection of a burst
  23. GRB 251007B: Swift/UVOT Upper Limits
  24. GRB251007A: Swift/UVOT Detection
  25. GRB 251009A: GECAM-B detection of a short burst
  26. GRB 251009B (short): Glowbug gamma-ray detection
  27. GRB 251007A: Swift-BAT refined analysis
  28. GRB 251007A: SVOM/GRM observation
  29. SVOM/sb25101004: SVOM detection of a stellar flare
  30. GRB 250916A: TERI Gamma-ray detection
  31. GRB 250919A: TERI gamma-ray detection
  32. EP251006a: Global MASTER-Net observations report
  33. GRB 251006A: Fermi GBM Observation
  34. GRB 251003A: Fermi GBM Observation
  35. GRB 251006B: Fermi GBM Observation
  36. GRB 251007B: COLIBRÍ optical upper limit
  37. GRB 251007A: AstroSat CZTI detection
  38. GRB 250917B: iTelescope T-26 upper limit
  39. EP250911a: Koshka Zeiss-1000 Optical Upper Limit
  40. GRB 251007A: Swift-XRT refined Analysis
  41. GRB 251007A: Enhanced Swift-XRT position
  42. GRB 251007B: Swift-XRT refined Analysis
  43. GRB 251007B: Enhanced Swift-XRT position
  44. GRB 251007A: AKO Optical Upper Limit
  45. GRB 251007A: SVOM/C-GFT optical observations
  46. GRB 251005C: PRIME J-band upper limit
  47. GRB 251007A: Glowbug gamma-ray detection
  48. GRB 251007B: SVOM/C-GFT upper limit
  49. GRB 251007B: Swift detection of a burst
  50. GRB 251007A: Swift detection of a burst with an optical counterpart
  51. GRB 250702B/EP250702a: JWST/NIRCam Observations
  52. GRB 251006A: Swift/BAT-GUANO subthreshold detection of a short burst
  53. GRB 251005B: Glowbug gamma-ray detection
  54. EP251003a: LCO and VST fading optical counterpart
  55. GRB 251006B/EP251006a: EP-FXT follow-up observation
  56. GRB 251006B: SVOM/GRM observation
  57. GRB 251006B: COLIBRÍ optical upper limit
  58. GRB 251006B/EP251006a: EP-WXT detection
  59. GRB 251005C: SVOM/VT optical fading
  60. GRB 251005C: SVOM/GRM observation of a likely short GRB
  61. LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate
  62. GRB 251006B: BALROG localization (Fermi Trigger 781473909 / GRB 251006837)
  63. GRB 251006A (short): Glowbug gamma-ray detection
  64. GRB 251005C: COLIBRÍ optical observations
  65. GRB 251005C: VLT/X-shooter Imaging
  66. GRB 251003A: LAST optical observations
  67. GRB 251002A: LAST optical observations
  68. GRB 251005​C: Swift/UVOT Upper Limits
  69. GRB 250902A: MSU cubesats detection
  70. GRB 251005C: Swift-XRT refined Analysis
  71. GRB 251005C: Enhanced Swift-XRT position
  72. GRB 251005C: Swift detection of a burst
  73. GRB 251002A: Mondy/AZT-33IK optical observations
  74. EP251003a: Einstein Probe detection of an X-ray transient
  75. GRB 251003A: J-band detection with WINTER
  76. GRB 251002A: NIR observations with WINTER
  77. Fermi GBM Sub-Threshold Detection of GRB 250910A
  78. GRB 251003A: Swift-BAT refined analysis
  79. GRB 251001B: NIR observations with WINTER
  80. GRB 251002A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  81. GRB 251003A: Swift/UVOT Upper Limits
  82. GRB 251002A: Swift/UVOT detection
  83. GRB 251001A: AstroSat CZTI detection
  84. GRB 251001B: COLIBRÍ further observations and evidence of a multi-wavelength shallow decay
  85. GRB 251003A: Swift-XRT refined Analysis
  86. GRB 251003A: COLIBRÍ photometric redshift
  87. GRB 251002A: Fermi GBM Observation
  88. GRB 251002A: GOTO detection of optical counterpart
  89. GRB 251001C: SVOM/GRM observation
  90. EP250821a: iTelescope T-59 possible detection of the optical counterpart
  91. GRB 251003A: Enhanced Swift-XRT position
  92. GRB 251002A: AKO Early Optical Afterglow Detection
  93. GRB 251003A: Kilonova-Catcher optical afterglow detection
  94. GRB 251002A: Swift-XRT afterglow detection
  95. GRB 251001B: AbAO optical upper limit
  96. GRB 251002A: Kilonova-Catcher optical afterglow detection
  97. GRB 251002A: AbAO optical observations
  98. GRB 251002A: SVOM/COLIBRÍ (FM-GFT) optical observations
  99. GRB 251001C: CALET Gamma-Ray Burst Monitor detection
  100. GRB 251002A: J band observations by SYSU 80cm infrared telescope

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