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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"

6791 results found.

  1. GRB 240606B: Fermi GBM Observation
  2. GRB 240607A: Fermi GBM detection of a very bright burst
  3. GRB 240606B: Swift-XRT afterglow detection
  4. Swift Trigger 1235109: a possible GRB 240606A
  5. Swift Trigger 1232755: likely consistent with noise and not astrophysical
  6. Swift Trigger 1232465: consistent with noise
  7. GRB 240529A: continued SAO RAS optical observations
  8. GRB 240529A: OSN optical detection
  9. The EP-WXT source triggered on June 1st is likely a flaring star
  10. GRB 240529A: further SAO RAS optical observations
  11. GRB 240529A: 1.3m DFOT Optical observations
  12. Konus-Wind detection of GRB 240529A
  13. IPN triangulation of the initial episode of GRB 240529A
  14. GRB 240529A: SAO RAS optical observations
  15. GRB 240529A: optical photometry from Konkoly
  16. GRB 240529A: Swift-XRT refined Analysis
  17. GRB 240527B: Swift-XRT afterglow detection
  18. GRB 240527B: Fermi GBM Observation
  19. GRB 240527B: Fermi-LAT detection
  20. GRB 240523A: Swift-XRT refined Analysis
  21. GRB 240521B: Fermi GBM Observation
  22. Fermi GBM Sub-Threshold Detection of GRB 240516B
  23. EP240518a: possibly identified with a flare star by EP-FXT
  24. GRB 240516A: Swift-XRT refined Analysis
  25. GRB 240516A: Fermi GBM Observation
  26. GRB 240514B: Fermi GBM Detection
  27. GRB 240513A: Fermi GBM observation
  28. GRB 240513A: Swift-XRT observations
  29. LAT GRB240513.31: Global MASTER-Net observations report
  30. GRB 240513A: Fermi-LAT detection
  31. GRB 240511A: Fermi GBM Observation
  32. GRB 240511A: Swift-XRT refined Analysis
  33. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  34. GRB 240504A: Fermi GBM Observation
  35. EP240506a: TRT optical upper limit
  36. EP240506a: Optical upper limit with Kinder observations
  37. GRB 240502A: 1.3m DFOT Optical upper limit
  38. GRB 240502A: Fermi GBM Observation
  39. GRB 240415A 1.3m DFOT Optical upper limit
  40. Fermi-LAT gamma-ray observations of IceCube-240424A
  41. LIGO/Virgo/KAGRA S240422ed: A transient discovered from Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  42. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  43. EP240426b: EP-WXT detection of a new fast X-ray transient
  44. EP240426a: YAHPT optical upper limit
  45. XMM-Newton observation of EP240426a
  46. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  47. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  48. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  49. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  50. LXT240402A/GRB240402B: Chandra X-ray detection
  51. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  52. Fermi-LAT gamma-ray observations of IceCube-240419A
  53. GRB 240415B: Swift-XRT observations
  54. GRB 240415A: Swift-XRT refined Analysis
  55. GRB 240421B: Fermi GBM Observation
  56. GRB 240421B: Swift-XRT refined Analysis
  57. EP240420a: Nanshan optical counterpart observations
  58. EP240420a: detection of fading X-ray emission with refined position by EP-FXT
  59. GRB240418A - Candidate afterglow from NIRES
  60. GRB 240419B: Swift-XRT refined Analysis
  61. GRB 240419A: Swift-XRT refined Analysis
  62. GRB 240418A: Swift-XRT refined Analysis
  63. EP 240416a: Xinglong and NOT decaying optical counterpart
  64. EP240416a: Kinder optical counterpart candidate
  65. GRB 240415A: Fermi GBM Observation
  66. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  67. GRB 240415A: Earliest optical followup with the Kinder observations
  68. EP240414a: EP-FXT follow-up observation
  69. GRB 240414A: Fermi GBM Observation
  70. LXT 240402A/GRB 240402B: Swift follow-up observations
  71. EP240413a: Upper limits from GECAM-B Observation
  72. EP 240414a: NOT optical counterpart confirmation
  73. GRB 240414A: Swift-XRT refined Analysis
  74. GRB 240414A: Skynet Optical Afterglow Observations
  75. EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
  76. EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
  77. Fermi-LAT gamma-ray observations of IceCube-240412A
  78. GRB 240411B: Kinder observations with Lulin observatory
  79. GRB 240411B: Swift-XRT refined Analysis
  80. GRB 240411B: 1.3m DFOT Optical observations
  81. EP240408a: Upper limits from GECAM-B Observation
  82. Swift Trigger 1220736: detection of 4U 1543-62.
  83. Fermi-LAT gamma-ray observations of IceCube-240327B
  84. Fermi-LAT gamma-ray observations of IceCube-240327A
  85. LXT 240402A/GRB 240402B: rest-frame energetics from Konus-Wind observation
  86. GRB/FXT 240402B: Kinder optical counterpart candidate
  87. GRB 240403A: Fermi GBM Detection
  88. LXT 240402A: EP-FXT detection of the X-ray afterglow
  89. X-ray transient EP240331a: Kinder optical upper limits
  90. X-ray transient EP 240315a: Second epoch Chandra observations
  91. GRB 240318A: Fermi GBM Observation
  92. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  93. X-ray transient EP 240315a: Chandra observations
  94. GRB 240317B: Fermi GBM Observation
  95. X-ray transient EP240315a: Kinder follow-up observations for AT 2024eju with Lulin observatory
  96. Changes to the Fermi-GBM Triggering Thresholds
  97. Fermi-LAT gamma-ray observations of IceCube-240307A
  98. GRB 240306A: Fermi GBM observation
  99. Konus-Wind detection of GRB 231118A
  100. GRB 240305A: Fermi GBM observation

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