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"

3300 results found.

  1. EP240506a: Archival radio searching
  2. EP240506a: TRT optical upper limit
  3. EP240506a: BOOTES Network optical upper limit
  4. EP240506a: Optical upper limit with Kinder observations
  5. EP240506a: EP-WXT detection of a new fast X-ray transient
  6. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  7. EP240426b: AST3-2 optical upper limit
  8. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  9. EP240426b: EP-WXT detection of a new fast X-ray transient
  10. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  11. LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
  12. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  13. LIGO/Virgo/KAGRA S240422ed: BOOTES-4/MET Optical Upper Limits for EP240426a
  14. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  15. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  16. EP240426a: GMG optical upper limit
  17. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  18. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  19. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  20. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  21. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  22. LXT240402A/GRB240402B: Chandra X-ray detection
  23. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  24. EP240420a: TNT upper limit to its optical counterpart
  25. EP240420a: Xinglong decaying optical counterpart
  26. EP240420a: Nanshan optical counterpart observations
  27. EP240420a: GWAC-F50A optical upper limit
  28. EP240420a: detection of fading X-ray emission with refined position by EP-FXT
  29. EP240420a: NOT optical counterpart candidate and potential host
  30. EP240420a: EP-WXT detection of a fast X-ray transient
  31. EP240416a: J-band observations with WINTER
  32. EP240417a: EP-WXT detection of a fast X-ray transient
  33. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  34. EP240416a: BOOTES-2/TELMA Optical Upper Limit
  35. EP 240416a: Xinglong and NOT decaying optical counterpart
  36. EP240416A: MASTER optical observations
  37. EP240416a: Kinder optical counterpart candidate
  38. EP240416a: EP-WXT detection of a fast X-ray transient
  39. EP240413a: BOOTES-2/TELMA Optical Upper Limit
  40. EP 240414a: BOOTES-4/MET Optical Upper Limits
  41. EP240414a: EP-FXT follow-up observation
  42. LXT 240402A/GRB 240402B: Swift follow-up observations
  43. X-ray transient EP 240414a - GTC spectroscopic observations
  44. EP240413a: Upper limits from GECAM-B Observation
  45. EP 240414a: NOT optical counterpart confirmation
  46. EP240413A: GOTO optical upper limits
  47. EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
  48. EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
  49. EP240414a: EP-WXT detection of a fast X-ray transient
  50. EP240413a: EP-WXT detection of a fast X-ray transient
  51. EP240408a: GSP optical upper limit
  52. EP240408A: MASTER optical observations
  53. EP240408a: Upper limits from GECAM-B Observation
  54. EP240408a: Swift follow-up observation
  55. EP240408a: BOOTES-6/DPRT optical upper limit
  56. EP240408a: EP-WXT detection of a fast X-ray transient
  57. LXT 240402A/GRB 240402B: rest-frame energetics from Konus-Wind observation
  58. X-ray transient LXT 240402A: WFST optical upper limits​
  59. Konus-Wind detection of LXT 240402A/GRB 240402B
  60. GRB/FXT 240402B: Kinder optical counterpart candidate
  61. GRB/FXT 240402B: VLT/FORS2 optical afterglow candidate
  62. X-ray transient LXT240402A: AST3-3 optical upper limits
  63. LXT 240402A: EP-FXT detection of the X-ray afterglow
  64. GRB 240402B: GECAM-C detection
  65. X-ray transient LXT 240402A: LEIA detection
  66. X-ray transient EP240331A: GRANDMA-Kilonova catcher optical upper limit
  67. EP240331A: MASTER optical observations
  68. X-ray transient EP 240315a: Second epoch Chandra observations
  69. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  70. X-ray transient EP 240315a: Chandra observations
  71. X-ray transient EP240315a: MeerKAT radio detection
  72. X-ray transient EP240315a: GTC/OSIRIS spectroscopic redshift confirmation
  73. X-ray transient EP240315a: EP-FXT detection of the X-ray afterglow
  74. X-ray transient EP240315a: Montarrenti Observatory optical upper limit
  75. X-ray transient EP240315a: orphan FXT?
  76. X-ray transient EP240315a: Nanshan/HMT optical upper limit
  77. Einstein Probe detected of a fast X-ray transient EP240315a
  78. Konus-Wind detection of GRB 231118A
  79. Konus-Wind detection of GRB 240227A (short/hard)
  80. Konus-Wind detection of GRB 240303B
  81. Konus-Wind detection of GRB 240225B (long)
  82. Transient EPW20240219aa: REM optical/NIR upper limits
  83. Transient EPW20240219aa: Xinglong-2.16m optical upper limit
  84. Transient EPW20240219aa: GECKO: LOAO Optical Upper Limits
  85. Transient EPW20240219aa: 7DT Optical Upper Limits
  86. Insight-HXMT/HE Sub-Threshold Detection of Transient EPW20240219aa
  87. Konus-Wind detection of GRB 240218A
  88. Konus-Wind detection of GRB 240204A
  89. Konus-Wind detection of GRB 240205A (short)
  90. Konus-Wind detection of GRB 240205B (long / very soft)
  91. Konus-Wind detection of GRB 240125A
  92. Konus-Wind detection of GRB 240124B
  93. Konus-Wind detection of GRB 240123C
  94. Konus-Wind detection of GRB 240112A
  95. Konus-Wind detection of GRB 240119A (short/hard)
  96. Konus-Wind detection of GRB 240118A
  97. Konus-Wind detection of GRB 240112C
  98. Konus-Wind detection of GRB 240101C
  99. Konus-Wind detection of GRB 231215A
  100. Konus-Wind detection of GRB 231210B

Advanced

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