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"

849 results found.

  1. IPN triangulation of GRB 260512A
  2. EP260507a: Kinder optical counterpart candidate
  3. Konus-Wind detection of GRB 260415C
  4. Konus-Wind detection of GRB 260411C
  5. IPN triangulation of GRB 260429A
  6. IPN triangulation of GRB 260428A
  7. IPN triangulation of GRB 260424B (short)
  8. EP260416a: Optical follow-up observations with Kinder
  9. IPN triangulation of GRB 260411B
  10. EP260405a: SVOM/VT optical upper limits
  11. EP260329b: Optical follow-up with Kinder observations
  12. IPN triangulation of GRB 260320A
  13. IPN triangulation of GRB 260316B
  14. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  15. EP260321a: further Kinder optical observations
  16. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  17. EP260316a: optical upper limit with Kinder observations
  18. EP260314a: optical upper limit with Kinder observations
  19. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  20. IceCube Alert 260315A: Global MASTER-Net observations report
  21. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  22. EP260221a: Optical upper limit with Kinder observations
  23. IPN triangulation of GRB 260212A
  24. EP260213a: Optical upper limits with Kinder observations
  25. EP260209a: Global MASTER-Net observations report
  26. EP260210a: Optical upper limits with Kinder observations
  27. IPN triangulation of GRB 260207B (short/hard with EE)
  28. GRB 260208B: SVOM/GRM observation of a bright burst
  29. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  30. GRB 260101A: COLIBRÍ optical observations
  31. GRB 251222A/EP251222b: Optical detection with Kinder observations
  32. EP251222a: Optical upper limit with Kinder observations
  33. IPN triangulation of GRB 251220B (short)
  34. GRB 251209A: Fermi GBM observation
  35. IPN triangulation of GRB 251129B (short/hard)
  36. EP251130a: Optical detections with Kinder observations
  37. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  38. EP251124a: Optical upper limit with Kinder observations
  39. EP251118a: Continued Optical Detection with Kinder observations
  40. EP251118a: Optical detection with Kinder observations
  41. LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
  42. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  43. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  44. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  45. IPN triangulation of GRB 251108C
  46. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  47. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  48. IPN triangulation of GRB 251105B (possible sGRB with EE)
  49. LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
  50. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  51. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  52. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  53. IPN triangulation of GRB 251016B
  54. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  55. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  56. Swift GRB 251018A: Global MASTER-Net observations report
  57. IceCube Alert 251014.77: Global MASTER-Net observations report
  58. LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
  59. LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate
  60. GRB 251002A: FRAM-ORM afterglow detection
  61. LIGO/Virgo/KAGRA S250929c: Identification of a GW compact binary merger candidate
  62. LIGO/Virgo/KAGRA S250927ck: Identification of a GW compact binary merger candidate
  63. IPN triangulation of GRB 250920A (long/bright)
  64. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  65. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  66. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  67. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  68. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  69. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  70. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  71. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  72. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  73. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  74. IPN triangulation of GRB 250821B (long/bright)
  75. IPN triangulation of GRB 250814C (short)
  76. IPN triangulation of GRB 250804B (short)
  77. LIGO/Virgo/KAGRA S250813k: Identification of a GW compact binary merger candidate
  78. Konus-Wind detection of GRB 250807A
  79. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  80. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  81. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  82. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  83. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  84. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  85. IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
  86. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  87. IPN triangulation of GRB 250703A
  88. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  89. IPN triangulation of GRB 250627A (short)
  90. LIGO/Virgo/KAGRA S250702n: Identification of a GW compact binary merger candidate
  91. LIGO/Virgo/KAGRA S250629bs: Identification of a GW compact binary merger candidate
  92. LIGO/Virgo/KAGRA S250629ae: Identification of a GW compact binary merger candidate
  93. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate
  94. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  95. IPN triangulation of GRB 250404B
  96. IPN triangulation of GRB 250529A
  97. GRB 250603A: Swift/UVOT Upper Limits
  98. GRB 250421A: AstroSat CZTI detection
  99. IPN triangulation of GRB 250406B (short/hard)
  100. Konus-Wind detection of GRB 250404A / EP250404a

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