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"
  1. IceCube-Cascade 240626A: Upper limits from a search for additional neutrino events in IceCube
  2. GRB 240628A: BALROG localization (Fermi Trigger 741288821 / GRB 240628732)
  3. GRB 240627A: NuSTAR Detection of the long GRB
  4. GRB 240615A: SAI CMO J- band observations
  5. GRB 240627A: AstroSat CZTI detection
  6. Fermi trigger No 741211696: Global MASTER-Net observations report
  7. EP240626a: Montarrenti Observatory optical upper limit
  8. EP240626a: KAIT optical upper limit
  9. LIGO/Virgo/KAGRA S240627by: Identification of a GW compact binary merger candidate
  10. EP240625a: GRANDMA Optical Upper Limits
  11. EP240626a: EP-FXT detection of the X-ray emission
  12. GRB 240624A: Swift-BAT refined analysis
  13. Konus-Wind detection of GRB 240619A
  14. EP240626a: BOOTES-7 optical upper limit
  15. EP240626a: EP-WXT detection of a fast X-ray transient
  16. Fermi GRB 240625B: Global MASTER-Net observations report
  17. GRB 240624B: CALET Gamma-Ray Burst Monitor detection
  18. GRB 240625B: Fermi GBM Final Real-time Localization
  19. GRB 240625A: Fermi GBM Observation
  20. EP240625a: NOT optical counterpart candidate
  21. EP240625a: EP-FXT detection of the X-ray emission
  22. GRB 240624B: GRBAlpha detection
  23. GRB 240625A: Fermi GBM Final Real-time Localization
  24. EP240625a: EP-WXT detection of a fast X-ray transient
  25. GRB240624A: Fermi GBM Observation
  26. LIGO/Virgo/KAGRA S240622h: Upper limits from Swift/BAT-GUANO
  27. LIGO/Virgo/KAGRA S240621dy: Upper limits from Swift/BAT-GUANO
  28. LIGO/Virgo/KAGRA S240618ah: Upper limits from Swift/BAT-GUANO
  29. Swift GRB 240624A: Global MASTER-Net observations report
  30. GRB240615A: Gemini-North observations of the BAT and XRT positions
  31. Fermi GRB 240624A: Global MASTER-Net observations report
  32. GRB 240624B: Fermi GBM Final Real-time Localization
  33. Fermi trigger No 740949590: Global MASTER-Net observations report
  34. LIGO/Virgo/KAGRA S240624cd: Retraction of GW unmodeled transient candidate
  35. GRB240615A: Gemini-North observations of the BAT and XRT positions
  36. GRB 240624A: Fermi GBM Final Real-time Localization
  37. GRB 240619A: detection of a radio counterpart with AMI-LA
  38. GRB 240624A: Swift detection of a burst
  39. LIGO/Virgo/KAGRA S240623dg: Retraction of GW compact binary merger candidate
  40. EP240618a: NOT further optical observations
  41. GRB 240619A: J-band detection with WINTER (duplicate submission of GCN 36739)
  42. GRB 240619A: J-band detection with WINTER
  43. LIGO/Virgo/KAGRA S240622h: Updated Sky localization and Source Classification
  44. Fermi trigger No 740744838: Global MASTER-Net observations report
  45. EP240618a: NOT optical counterpart candidate
  46. LIGO/Virgo/KAGRA S240621em: Updated Sky localization and Source Classification
  47. GRB 240529A: JinShan optical observations
  48. LIGO/Virgo/KAGRA S240621dy: Updated Sky localization and Source Classification
  49. LIGO/Virgo/KAGRA S240621eb: Updated Sky localization and Source Classification
  50. EP240618a: GSP optical upper limit
  51. LIGO/Virgo/KAGRA S240622h: Identification of a GW compact binary merger candidate
  52. LIGO/Virgo/KAGRA S240621em: Identification of a GW compact binary merger candidate
  53. LIGO/Virgo/KAGRA S240621eb: Identification of a GW compact binary merger candidate
  54. LIGO/Virgo/KAGRA S240621dy: Identification of a GW compact binary merger candidate
  55. IPN triangulation of GRB 240615A (short)
  56. X-ray transient EP240618a: Fermi/GBM non-detection
  57. GRB 240619A: GRBAlpha detection
  58. EP240618a: Swift/XRT upper limit
  59. EP240617a: tentative Swift/XRT detection of the afterglow
  60. GRB 240619A: Swift-XRT probable afterglow detection
  61. GRB 240619A: Swift ToO observations
  62. GRB 240619A: CALET Gamma-Ray Burst Monitor detection
  63. GRB 240619C: NuSTAR automated detection of the GRB
  64. GRB 240619A: Fermi GBM Observation
  65. Fermi GBM Sub-Threshold Detection of GRB 240619C
  66. GRB 240619A: GOTO candidate optical afterglow
  67. EP240618a: Abastumani optical observationsEP240618a
  68. GRB 240615A: NOT optical observations
  69. EP240618a: GRANDMA Optical Upper Limits
  70. GRB 240619C: AstroSat CZTI detection
  71. EP240618a: TRT optical upper limit
  72. Fermi trigger No 740474239: Global MASTER-Net observations report
  73. Fermi GRB 240619A: Global MASTER-Net observations report
  74. EP240617a: STEP/T80S optical limits
  75. GRB 240615A: possible transient detection from Wendelstein observations
  76. LIGO/Virgo S240615dg: GRANDMA/FRAM-CTA-N Observations
  77. LIGO/Virgo/KAGRA S240615dg: Updated Sky localization
  78. LIGO/Virgo/KAGRA S240618ah: Updated Sky localization
  79. EP240618a: OHP/T193 MISTRAL i' and Y band upper limits
  80. EP240618a: BOOTES-6/DPRT optical upper limit
  81. Fermi Gamma-ray Burst Monitor trigger 740474239/240619304 is not a GRB
  82. GRB 240619B: Fermi GBM Final Real-time Localization
  83. LIGO/Virgo S240615dg: Swift XRT observations, 39 X-ray sources
  84. Fermi trigger No 740430582: Global MASTER-Net observations report
  85. GRB240615A: 1.3m DFOT optical upper limit
  86. GRB 240619A: BALROG localization (Fermi Trigger 740461416 / GRB 240619155)
  87. GRB 240619A: Fermi GBM Final Real-time Localization
  88. EP240617a: BOOTES-6/DPRT optical upper limit
  89. EP240617a is likely a GRB event
  90. EP240617a: EP-WXT detection of a fast X-ray transient
  91. EP240618a: EP-WXT detection of a fast X-ray transient and EP-FXT quick follow-up
  92. LIGO/Virgo/KAGRA S240618ah: Identification of a GW compact binary merger candidate
  93. LIGO/Virgo/KAGRA S240615ea: Upper limits from Swift/BAT-GUANO
  94. LIGO/Virgo/KAGRA S240615dg: Upper limits from Swift/BAT-GUANO
  95. GRB 240615A: J-band upper limits from WINTER
  96. GRB 240615A: Fermi GBM Observation
  97. LIGO/Virgo/KAGRA S240615ea: Updated Sky localization
  98. GRB 240615A: Swift-XRT observations
  99. GRB 240615A: GECAM detection
  100. X-ray transient EP240414a: Chandra late time observation

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