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"

32578 results found.

  1. EP250802a: Liverpool Telescope optical upper limits
  2. EP250802a: Global MASTER-Net observations report
  3. EP250802a: GROWTH-India Telescope optical upper limit
  4. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  5. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  6. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  7. GRB 250702B: SMA observations
  8. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  9. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  10. EP250711a: CrAO and Assy optical observations
  11. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  12. EP250730a: Global MASTER-Net observations report
  13. EP250730a: COLIBRÍ optical upper limit
  14. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  15. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  16. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  17. GRB 250725A: AstroSat CZTI detection
  18. GRB 250727A: EP-FXT follow-up observation
  19. GRB 250725A: PRIME near-infrared observations
  20. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  21. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  22. GRB: Clarification on Gamma-Ray Burst Naming Convention
  23. GRB 250727A: SVOM/ECLAIRs refined analysis
  24. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  25. GRB 250728A: COLIBRÍ optical upper limit
  26. GRB 250728A: Fermi GBM Observation
  27. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  28. GRB 250728A: Swift ToO observations
  29. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  30. GRB 250727A: AST3-2 Upper limit
  31. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  32. GRB 250727A: EP-FXT counterpart detection
  33. GRB250727A: SVOM/VT optical upper limit
  34. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  35. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  36. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  37. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  38. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  39. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  40. GRB 250725A: Fermi GBM Observation
  41. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  42. GRB 250725A: Swift-BAT refined analysis
  43. Konus-Wind detection of GRB 250725A
  44. GRB 250725A: SVOM/GRM observation
  45. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  46. GRB 250725A: Swift/UVOT Upper Limits
  47. GRB 250725A: Fermi-LAT detection
  48. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  49. GRB 250725A: BOOTES-7 early optical detection
  50. GRB 250725A: SVOM/VT optical candidate
  51. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate (duplicate submission)
  52. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  53. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  54. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  55. SVOM J195836+32283 is not a real source
  56. SVOM J195836+32283/sb25072103: Second VT observation
  57. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  58. GRB 250721A: Fermi GBM Observation
  59. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  60. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  61. GRB 250713A : SVOM/ECLAIRs refined analysis
  62. GRB 250717B: SVOM/GRM observation
  63. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  64. GRB 250721A: Tiled Swift observations
  65. GRB 250721A: MAXI/GSC detection
  66. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  67. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  68. GRB 250717B: COLIBRÍ optical upper limit
  69. GRB 250718B: Fermi GBM Final Localization Correction
  70. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  71. GRB 250717B: Swift ToO observations
  72. GRB 270713A: Kitab and AbAO Optical Observations
  73. GRB 250717B: Fermi GBM Observation
  74. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  75. Konus-Wind detection of GRB 250716A
  76. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  77. GRB 250716A: Swift ToO observations
  78. GRB 250714A: SVOM/GRM observation
  79. Fermi GRB 250716A: Global MASTER-Net observations report
  80. Fermi GRB 250715A: Global MASTER-Net observations report
  81. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  82. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  83. GRB 250713A: Mephisto optical upper limits
  84. Fermi GRB 250714A: Global MASTER-Net observations report
  85. GRB 250713A: SVOM/VT optical upper limit
  86. GRB 250713A: NOT optical upper limits
  87. GRB 250713A: OHP/T193 upper limit
  88. GRB 250713A: SVOM/C-GFT upper limit
  89. GRB 250706B/C: 7DT Follow-up Observations
  90. GRB 250713A: EP-FXT counterpart detection
  91. EP250711a: COLIBRÍ continuous optical observations
  92. GRB 250706A: Swift-BAT refined analysis
  93. GRB 250702F: Swift-BAT refined analysis
  94. GRB 250628A: Swift-BAT refined analysis
  95. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  96. GRB 250713A: JinShan optical upper limits
  97. EP250711a: Global MASTER-Net observations report
  98. GRB 250711A: DDOTI Optical Upper Limit
  99. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  100. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate (duplicate submission)

Advanced

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