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"

1094 results found.

  1. EP240703b: EP-WXT detection of a fast X-ray transient
  2. EP240702a: Swift/XRT upper limit
  3. EP240703a: EP-WXT detection of a fast X-ray transient
  4. EP240702a: GSP optical upper limit
  5. EP240702a: EP-WXT detection of a fast X-ray transient
  6. EP240626a: Montarrenti Observatory optical upper limit
  7. EP240626a: KAIT optical upper limit
  8. EP240625a: GRANDMA Optical Upper Limits
  9. EP240626a: EP-FXT detection of the X-ray emission
  10. EP240626a: BOOTES-7 optical upper limit
  11. EP240626a: EP-WXT detection of a fast X-ray transient
  12. EP240625a: EP-FXT detection of the X-ray emission
  13. EP240625a: EP-WXT detection of a fast X-ray transient
  14. EP240618a: GSP optical upper limit
  15. X-ray transient EP240618a: Fermi/GBM non-detection
  16. EP240618a: Swift/XRT upper limit
  17. EP240617a: tentative Swift/XRT detection of the afterglow
  18. EP240618a: GRANDMA Optical Upper Limits
  19. EP240617a: STEP/T80S optical limits
  20. EP240618a: BOOTES-6/DPRT optical upper limit
  21. EP240617a: BOOTES-6/DPRT optical upper limit
  22. EP240617a: EP-WXT detection of a fast X-ray transient
  23. EP240618a: EP-WXT detection of a fast X-ray transient and EP-FXT quick follow-up
  24. X-ray transient EP240414a: Chandra late time observation
  25. The EP-WXT source triggered on June 1st is likely a flaring star
  26. LXT 240528A: LEIA detection of a fast X-ray transient
  27. EP240518a: GSP optical upper limit
  28. EP240518a: possibly identified with a flare star by EP-FXT
  29. EP240518a: EP-WXT detection of a new X-ray transient
  30. EP240506a: Archival radio searching
  31. EP240506a: EP-WXT detection of a new fast X-ray transient
  32. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  33. EP240426b: AST3-2 optical upper limit
  34. EP240426b: EP-WXT detection of a new fast X-ray transient
  35. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  36. EP240426a: YAHPT optical upper limit
  37. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  38. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  39. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  40. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  41. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  42. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  43. EP240417a: no counterpart detection by SOAR
  44. EP240420a: GWAC-F50A optical upper limit
  45. EP240420a: detection of fading X-ray emission with refined position by EP-FXT
  46. EP240420a: EP-WXT detection of a fast X-ray transient
  47. EP240417a: YAHPT Optical Upper Limits
  48. EP240417a: EP-WXT detection of a fast X-ray transient
  49. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  50. EP240416a: EP-WXT detection of a fast X-ray transient
  51. EP240414a: EP-FXT follow-up observation
  52. EP 240414a: NOT optical counterpart confirmation
  53. EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
  54. EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
  55. EP240414a: EP-WXT detection of a fast X-ray transient
  56. EP240413a: EP-WXT detection of a fast X-ray transient
  57. EP240408a: GSP optical upper limit
  58. EP240408a: Swift follow-up observation
  59. EP240408a: BOOTES-6/DPRT optical upper limit
  60. EP240408a: EP-WXT detection of a fast X-ray transient
  61. X-ray transient LXT 240402A: WFST optical upper limits​
  62. GRB/FXT 240402B: Kinder optical counterpart candidate
  63. GRB/FXT 240402B: VLT/FORS2 optical afterglow candidate
  64. X-ray transient LXT240402A: AST3-3 optical upper limits
  65. LXT 240402A: EP-FXT detection of the X-ray afterglow
  66. X-ray transient LXT 240402A: LEIA detection
  67. X-ray transient EP240331a: Kinder optical upper limits
  68. X-ray transient EP240331A: GRANDMA-Kilonova catcher optical upper limit
  69. X-ray transient EP20240331a: MeerLICHT optical upper limits
  70. X-ray transient EP240315a: Ondrejov D50 optical limit
  71. Transient EPW20240219aa: REM optical/NIR further observations
  72. X-ray transient EP240315a: GTC/HiPERCAM photometry
  73. X-ray transient EP240315a: GTC/OSIRIS spectroscopic redshift confirmation
  74. X-ray transient EP240315a: PRIME near infrared detection
  75. X-ray transient EP240315a: 3.6 m TNG NIR detection
  76. X-ray transient EP240315a/AT2024eju: TShAO (Zeiss-1000) observatory optical upper limit
  77. X-ray transient EP240315a: EP-FXT detection of the X-ray afterglow
  78. X-ray transient EP240315a: Kitab observatory optical upper limitns
  79. X-ray transient EP240315a: Montarrenti Observatory optical upper limit
  80. X-ray transient EP240315a: orphan FXT?
  81. X-ray transient EP240315a: GROND J-band detection
  82. X-ray transient EP240315a: VLT/X-shooter spectroscopic redshift of z = 4.859
  83. X-ray transient EP240315a: Nanshan/HMT optical upper limit
  84. X-ray transient EP240315a: ATLAS detection of a possible optical counterpart AT2024eju
  85. Einstein Probe detected of a fast X-ray transient EP240315a
  86. Transient EPW20240219aa: REM optical/NIR upper limits
  87. Transient EPW20240219aa: GECKO: LOAO Optical Upper Limits
  88. Transient EPW20240219aa: 7DT Optical Upper Limits
  89. VLA X-band observation of EPW20240219aa
  90. Transient EPW20240219aa: upper limit in gamma-ray range from SPI-ACS/INTEGRAL observations
  91. Insight-HXMT/HE Sub-Threshold Detection of Transient EPW20240219aa
  92. Fermi GBM Sub-Threshold Detection of EPW20240219aa as a likely GRB
  93. GRB 230307A: soft X-ray detection with LEIA
  94. GRB 221009A: LEIA X-ray Afterglow Detection

Advanced

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