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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"

3311 results found.

  1. Konus-Wind detection of GRB 240606B
  2. Konus-Wind detection of GRB 240603A
  3. The EP-WXT source triggered on June 1st is likely a flaring star
  4. Konus-Wind detection of GRB 240529A
  5. LXT 240528A: LEIA detection of a fast X-ray transient
  6. EP240518a: GSP optical upper limit
  7. EP240518a: possibly identified with a flare star by EP-FXT
  8. EP240518a: EP-WXT detection of a new X-ray transient
  9. Konus-Wind detection of GRB 240513A
  10. EP240506a: Xinglong optical upper limit
  11. EP240506a: CrAO ZTSH optical upper limit
  12. EP240506a: Archival radio searching
  13. EP240506a: TRT optical upper limit
  14. EP240506a: BOOTES Network optical upper limit
  15. EP240506a: Optical upper limit with Kinder observations
  16. EP240506a: EP-WXT detection of a new fast X-ray transient
  17. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  18. EP240426b: AST3-2 optical upper limit
  19. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  20. EP240426b: EP-WXT detection of a new fast X-ray transient
  21. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  22. LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
  23. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  24. LIGO/Virgo/KAGRA S240422ed: BOOTES-4/MET Optical Upper Limits for EP240426a
  25. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  26. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  27. EP240426a: GMG optical upper limit
  28. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  29. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  30. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  31. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  32. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  33. LXT240402A/GRB240402B: Chandra X-ray detection
  34. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  35. EP240420a: TNT upper limit to its optical counterpart
  36. EP240420a: Xinglong decaying optical counterpart
  37. EP240420a: Nanshan optical counterpart observations
  38. EP240420a: GWAC-F50A optical upper limit
  39. EP240420a: detection of fading X-ray emission with refined position by EP-FXT
  40. EP240420a: NOT optical counterpart candidate and potential host
  41. EP240420a: EP-WXT detection of a fast X-ray transient
  42. EP240416a: J-band observations with WINTER
  43. EP240417a: EP-WXT detection of a fast X-ray transient
  44. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  45. EP240416a: BOOTES-2/TELMA Optical Upper Limit
  46. EP 240416a: Xinglong and NOT decaying optical counterpart
  47. EP240416A: MASTER optical observations
  48. EP240416a: Kinder optical counterpart candidate
  49. EP240416a: EP-WXT detection of a fast X-ray transient
  50. EP240413a: BOOTES-2/TELMA Optical Upper Limit
  51. EP 240414a: BOOTES-4/MET Optical Upper Limits
  52. EP240414a: EP-FXT follow-up observation
  53. LXT 240402A/GRB 240402B: Swift follow-up observations
  54. X-ray transient EP 240414a - GTC spectroscopic observations
  55. EP240413a: Upper limits from GECAM-B Observation
  56. EP 240414a: NOT optical counterpart confirmation
  57. EP240413A: GOTO optical upper limits
  58. EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
  59. EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
  60. EP240414a: EP-WXT detection of a fast X-ray transient
  61. EP240413a: EP-WXT detection of a fast X-ray transient
  62. EP240408a: GSP optical upper limit
  63. EP240408A: MASTER optical observations
  64. EP240408a: Upper limits from GECAM-B Observation
  65. EP240408a: Swift follow-up observation
  66. EP240408a: BOOTES-6/DPRT optical upper limit
  67. EP240408a: EP-WXT detection of a fast X-ray transient
  68. LXT 240402A/GRB 240402B: rest-frame energetics from Konus-Wind observation
  69. X-ray transient LXT 240402A: WFST optical upper limits​
  70. Konus-Wind detection of LXT 240402A/GRB 240402B
  71. GRB/FXT 240402B: Kinder optical counterpart candidate
  72. GRB/FXT 240402B: VLT/FORS2 optical afterglow candidate
  73. X-ray transient LXT240402A: AST3-3 optical upper limits
  74. LXT 240402A: EP-FXT detection of the X-ray afterglow
  75. GRB 240402B: GECAM-C detection
  76. X-ray transient LXT 240402A: LEIA detection
  77. X-ray transient EP240331A: GRANDMA-Kilonova catcher optical upper limit
  78. EP240331A: MASTER optical observations
  79. X-ray transient EP 240315a: Second epoch Chandra observations
  80. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  81. X-ray transient EP 240315a: Chandra observations
  82. X-ray transient EP240315a: MeerKAT radio detection
  83. X-ray transient EP240315a: GTC/OSIRIS spectroscopic redshift confirmation
  84. X-ray transient EP240315a: EP-FXT detection of the X-ray afterglow
  85. X-ray transient EP240315a: Montarrenti Observatory optical upper limit
  86. X-ray transient EP240315a: orphan FXT?
  87. X-ray transient EP240315a: Nanshan/HMT optical upper limit
  88. Einstein Probe detected of a fast X-ray transient EP240315a
  89. Konus-Wind detection of GRB 231118A
  90. Konus-Wind detection of GRB 240227A (short/hard)
  91. Konus-Wind detection of GRB 240303B
  92. Konus-Wind detection of GRB 240225B (long)
  93. Transient EPW20240219aa: REM optical/NIR upper limits
  94. Transient EPW20240219aa: Xinglong-2.16m optical upper limit
  95. Transient EPW20240219aa: GECKO: LOAO Optical Upper Limits
  96. Transient EPW20240219aa: 7DT Optical Upper Limits
  97. Insight-HXMT/HE Sub-Threshold Detection of Transient EPW20240219aa
  98. Konus-Wind detection of GRB 240218A
  99. Konus-Wind detection of GRB 240204A
  100. Konus-Wind detection of GRB 240205A (short)

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