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"

25980 results found.

  1. GRB 251013C: Calapai Observatory, Massa S. Giorgio (Messina), optical observation
  2. GRB 251014D: Swift detection of a burst
  3. GRB 251014A: PRIME near-infrared upper limits
  4. GRB 251014A: Glowbug gamma-ray detection of a likely short burst
  5. GRB 251014A: VLT/FORS2 Optical Observation
  6. GRB 251012A: Glowbug gamma-ray detection of a likely short burst
  7. GRB 251013C: MarSEC, optical afterglow photometry
  8. GRB 251013C: OHP/T193 optical afterglow photometry and spectroscopy
  9. GRB 251013D: LAST optical upper limit on Swift/BAT-GUANO localization
  10. GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst
  11. GRB 251013C: Bassano Bresciano Observatory optical observations
  12. GRB 251013C: Early and late-time optical counterpart detection by LCO
  13. LIGO/Virgo/KAGRA S251014cn: NED Galaxies in the 3-Initial Localization Volume
  14. GRB 251013C: Fermi GBM Observation
  15. GRB 251014A: DDOTI Upper Limit
  16. GRB 251013C NUTTelA-TAO / BSTI Early Measurements
  17. LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
  18. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  19. GRB 251013C: Asiago optical observations
  20. GRB 251013C: ABObservatory optical observations
  21. GRB 251014A: SAO RAS optical upper limit
  22. GRB 251014A: Fermi GBM Observation
  23. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  24. GRB 251013C: EP-FXT counterpart detection
  25. GRB 251011A: Swift/BAT-GUANO arcminute localization of a burst
  26. GRB 251013D: Swift/BAT-GUANO arcminute localization of a burst
  27. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) detection of the optical counterpart
  28. GRB 251013C: DDOTI detection of the optical afterglow
  29. GRB 251013C: Swift-XRT counterpart detection
  30. GRB 251013C: SAO RAS optical observations
  31. GRB 251013C: LCO optical afterglow detection
  32. GRB 251013C: Optical Observations via Virtual Telescope Project, Italy
  33. GRB 251013C: LAST detection of optical counterpart
  34. GRB 251013C: SVOM/VT optical observation
  35. GRB 251013C: SVOM detection of a burst
  36. LIGO/Virgo/KAGRA S251013x: Updated Sky localization and Source Classification
  37. GRB 251013B: SVOM/GRM observation
  38. GRB 251013A: SVOM/GRM observation
  39. GRB 251003A: Mondy optical upper limit
  40. MASTER OT J011025.98-583210.6 : SVOM/VT optical observation
  41. LIGO/Virgo/KAGRA S251013x: Identification of a GW compact binary merger candidate
  42. GRB 251011B inspection: MASTER orphan GRB detection
  43. GRB 251011B: Swift/UVOT Upper Limits
  44. Fermi GRB 251011A: Global MASTER-Net observations report
  45. GRB 251011B: SVOM/GRM observation
  46. GRB 251011B: Swift-XRT refined Analysis
  47. GRB 251011B: Fermi GBM Observation
  48. GRB 251011B : MASTER optical observations
  49. GRB 251011B: Enhanced Swift-XRT position
  50. GRB 251011B: Swift detection of a burst
  51. GRB 251007B: Swift/UVOT Upper Limits
  52. GRB251007A: Swift/UVOT Detection
  53. GRB 251009A: GECAM-B detection of a short burst
  54. GRB 251009B (short): Glowbug gamma-ray detection
  55. GRB 251007A: Swift-BAT refined analysis
  56. GRB 251007A: SVOM/GRM observation
  57. SVOM/sb25101004: SVOM detection of a stellar flare
  58. GRB 250916A: TERI Gamma-ray detection
  59. GRB 250919A: TERI gamma-ray detection
  60. EP251006a: Global MASTER-Net observations report
  61. GRB 251006A: Fermi GBM Observation
  62. GRB 251003A: Fermi GBM Observation
  63. GRB 251006B: Fermi GBM Observation
  64. GRB 251007B: COLIBRÍ optical upper limit
  65. GRB 251007A: AstroSat CZTI detection
  66. GRB 250917B: iTelescope T-26 upper limit
  67. EP250911a: Koshka Zeiss-1000 Optical Upper Limit
  68. GRB 251007A: Swift-XRT refined Analysis
  69. GRB 251007A: Enhanced Swift-XRT position
  70. GRB 251007B: Swift-XRT refined Analysis
  71. GRB 251007B: Enhanced Swift-XRT position
  72. GRB 251007A: AKO Optical Upper Limit
  73. GRB 251007A: SVOM/C-GFT optical observations
  74. GRB 251005C: PRIME J-band upper limit
  75. GRB 251007A: Glowbug gamma-ray detection
  76. GRB 251007B: SVOM/C-GFT upper limit
  77. GRB 251007B: Swift detection of a burst
  78. GRB 251007A: Swift detection of a burst with an optical counterpart
  79. GRB 250702B/EP250702a: JWST/NIRCam Observations
  80. GRB 251006A: Swift/BAT-GUANO subthreshold detection of a short burst
  81. GRB 251005B: Glowbug gamma-ray detection
  82. EP251003a: LCO and VST fading optical counterpart
  83. GRB 251006B/EP251006a: EP-FXT follow-up observation
  84. GRB 251006B: SVOM/GRM observation
  85. GRB 251006B: COLIBRÍ optical upper limit
  86. GRB 251006B/EP251006a: EP-WXT detection
  87. GRB 251005C: SVOM/VT optical fading
  88. GRB 251005C: SVOM/GRM observation of a likely short GRB
  89. LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate
  90. GRB 251006B: BALROG localization (Fermi Trigger 781473909 / GRB 251006837)
  91. GRB 251006A (short): Glowbug gamma-ray detection
  92. GRB 251005C: COLIBRÍ optical observations
  93. GRB 251005C: VLT/X-shooter Imaging
  94. GRB 251003A: LAST optical observations
  95. GRB 251002A: LAST optical observations
  96. GRB 251005​C: Swift/UVOT Upper Limits
  97. GRB 250902A: MSU cubesats detection
  98. GRB 251005C: Swift-XRT refined Analysis
  99. GRB 251005C: Enhanced Swift-XRT position
  100. GRB 251005C: Swift detection of a burst

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