Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! 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"

868 results found.

  1. GRB 260924A: Optical follow-up observations with Kinder
  2. GRB 260925A: FRAM-Auger optical limit
  3. IPN triangulation of GRB 260916B (short)
  4. IPN triangulation of GRB 260810A
  5. GRB 260917B: FRAM-Auger optical limits
  6. GRB 260827A: SVOM/GRM observation
  7. IPN triangulation of GRB 260829A
  8. GRB 260810A: SVOM/GRM observation
  9. GRB 260727A: AstroSat CZTI detection
  10. IPN triangulation of GRB 260706B
  11. GRB 260704A: SVOM/ECLAIRs refined analysis
  12. IPN triangulation of GRB 260627A
  13. IPN triangulation of GRB 260605A
  14. EP260623a: Optical follow-up observations with Kinder
  15. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  16. IPN triangulation of GRB 260617A (short)
  17. GRB 260604C: AstroSat CZTI detection
  18. EP260602d: Optical Upper limits with kinder observations
  19. IPN triangulation of GRB 260527A / EP260527a
  20. IPN triangulation of GRB 260512A
  21. EP260507a: Kinder optical counterpart candidate
  22. Konus-Wind detection of GRB 260415C
  23. Konus-Wind detection of GRB 260411C
  24. IPN triangulation of GRB 260429A
  25. IPN triangulation of GRB 260428A
  26. IPN triangulation of GRB 260424B (short)
  27. EP260416a: Optical follow-up observations with Kinder
  28. IPN triangulation of GRB 260411B
  29. EP260405a: SVOM/VT optical upper limits
  30. EP260329b: Optical follow-up with Kinder observations
  31. IPN triangulation of GRB 260320A
  32. IPN triangulation of GRB 260316B
  33. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  34. EP260321a: further Kinder optical observations
  35. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  36. EP260316a: optical upper limit with Kinder observations
  37. EP260314a: optical upper limit with Kinder observations
  38. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  39. IceCube Alert 260315A: Global MASTER-Net observations report
  40. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  41. EP260221a: Optical upper limit with Kinder observations
  42. IPN triangulation of GRB 260212A
  43. EP260213a: Optical upper limits with Kinder observations
  44. EP260209a: Global MASTER-Net observations report
  45. EP260210a: Optical upper limits with Kinder observations
  46. IPN triangulation of GRB 260207B (short/hard with EE)
  47. GRB 260208B: SVOM/GRM observation of a bright burst
  48. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  49. GRB 260101A: COLIBRÍ optical observations
  50. GRB 251222A/EP251222b: Optical detection with Kinder observations
  51. EP251222a: Optical upper limit with Kinder observations
  52. IPN triangulation of GRB 251220B (short)
  53. GRB 251209A: Fermi GBM observation
  54. IPN triangulation of GRB 251129B (short/hard)
  55. EP251130a: Optical detections with Kinder observations
  56. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  57. EP251124a: Optical upper limit with Kinder observations
  58. EP251118a: Continued Optical Detection with Kinder observations
  59. EP251118a: Optical detection with Kinder observations
  60. LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
  61. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  62. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  63. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  64. IPN triangulation of GRB 251108C
  65. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  66. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  67. IPN triangulation of GRB 251105B (possible sGRB with EE)
  68. LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
  69. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  70. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  71. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  72. IPN triangulation of GRB 251016B
  73. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  74. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  75. Swift GRB 251018A: Global MASTER-Net observations report
  76. IceCube Alert 251014.77: Global MASTER-Net observations report
  77. LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
  78. LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate
  79. GRB 251002A: FRAM-ORM afterglow detection
  80. LIGO/Virgo/KAGRA S250929c: Identification of a GW compact binary merger candidate
  81. LIGO/Virgo/KAGRA S250927ck: Identification of a GW compact binary merger candidate
  82. IPN triangulation of GRB 250920A (long/bright)
  83. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  84. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  86. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  87. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  88. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  89. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  90. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  91. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  92. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  93. IPN triangulation of GRB 250821B (long/bright)
  94. IPN triangulation of GRB 250814C (short)
  95. IPN triangulation of GRB 250804B (short)
  96. LIGO/Virgo/KAGRA S250813k: Identification of a GW compact binary merger candidate
  97. Konus-Wind detection of GRB 250807A
  98. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  99. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  100. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
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