Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

32569 results found.

  1. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  2. EP250730a: Global MASTER-Net observations report
  3. EP250730a: COLIBRÍ optical upper limit
  4. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  5. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  6. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  7. GRB 250725A: AstroSat CZTI detection
  8. GRB 250727A: EP-FXT follow-up observation
  9. GRB 250725A: PRIME near-infrared observations
  10. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  11. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  12. GRB: Clarification on Gamma-Ray Burst Naming Convention
  13. GRB 250727A: SVOM/ECLAIRs refined analysis
  14. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  15. GRB 250728A: COLIBRÍ optical upper limit
  16. GRB 250728A: Fermi GBM Observation
  17. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  18. GRB 250728A: Swift ToO observations
  19. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  20. GRB 250727A: AST3-2 Upper limit
  21. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  22. GRB 250727A: EP-FXT counterpart detection
  23. GRB250727A: SVOM/VT optical upper limit
  24. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  25. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  26. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  27. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  28. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  29. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  30. GRB 250725A: Fermi GBM Observation
  31. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  32. GRB 250725A: Swift-BAT refined analysis
  33. Konus-Wind detection of GRB 250725A
  34. GRB 250725A: SVOM/GRM observation
  35. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  36. GRB 250725A: Swift/UVOT Upper Limits
  37. GRB 250725A: Fermi-LAT detection
  38. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  39. GRB 250725A: BOOTES-7 early optical detection
  40. GRB 250725A: SVOM/VT optical candidate
  41. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate (duplicate submission)
  42. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  44. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  45. SVOM J195836+32283 is not a real source
  46. SVOM J195836+32283/sb25072103: Second VT observation
  47. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  48. GRB 250721A: Fermi GBM Observation
  49. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  50. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  51. GRB 250713A : SVOM/ECLAIRs refined analysis
  52. GRB 250717B: SVOM/GRM observation
  53. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  54. GRB 250721A: Tiled Swift observations
  55. GRB 250721A: MAXI/GSC detection
  56. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  57. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  58. GRB 250717B: COLIBRÍ optical upper limit
  59. GRB 250718B: Fermi GBM Final Localization Correction
  60. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  61. GRB 250717B: Swift ToO observations
  62. GRB 270713A: Kitab and AbAO Optical Observations
  63. GRB 250717B: Fermi GBM Observation
  64. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  65. Konus-Wind detection of GRB 250716A
  66. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  67. GRB 250716A: Swift ToO observations
  68. GRB 250714A: SVOM/GRM observation
  69. Fermi GRB 250716A: Global MASTER-Net observations report
  70. Fermi GRB 250715A: Global MASTER-Net observations report
  71. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  72. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  73. GRB 250713A: Mephisto optical upper limits
  74. Fermi GRB 250714A: Global MASTER-Net observations report
  75. GRB 250713A: SVOM/VT optical upper limit
  76. GRB 250713A: NOT optical upper limits
  77. GRB 250713A: OHP/T193 upper limit
  78. GRB 250713A: SVOM/C-GFT upper limit
  79. GRB 250706B/C: 7DT Follow-up Observations
  80. GRB 250713A: EP-FXT counterpart detection
  81. EP250711a: COLIBRÍ continuous optical observations
  82. GRB 250706A: Swift-BAT refined analysis
  83. GRB 250702F: Swift-BAT refined analysis
  84. GRB 250628A: Swift-BAT refined analysis
  85. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  86. GRB 250713A: JinShan optical upper limits
  87. EP250711a: Global MASTER-Net observations report
  88. GRB 250711A: DDOTI Optical Upper Limit
  89. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  90. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate (duplicate submission)
  91. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  92. GRB 250711A: SVOM/GRM observation
  93. EP250711a: NOT optical counterpart candidate
  94. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  95. Fermi GRB 250711A: Global MASTER-Net observations report
  96. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  97. GRB 250704A: GRANDMA observations
  98. GRB 250704A: SVOM/ECLAIRs refined analysis
  99. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  100. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov