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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"

6403 results found.

  1. EP240618a: Swift/XRT upper limit
  2. EP240617a: tentative Swift/XRT detection of the afterglow
  3. GRB 240619A: Swift-XRT probable afterglow detection
  4. GRB 240619A: Fermi GBM Observation
  5. LIGO/Virgo S240615dg: Swift XRT observations, 39 X-ray sources
  6. Fermi trigger No 740430582: Global MASTER-Net observations report
  7. GRB240615A: 1.3m DFOT optical upper limit
  8. EP240617a: EP-WXT detection of a fast X-ray transient
  9. GRB 240615A: Fermi GBM Observation
  10. GRB 240615A: Swift-XRT observations
  11. GRB 240615A: FLWO-1.2m optical upper limits
  12. GRB 240607A: Fermi GBM Observation
  13. GRB 240606B: Fermi GBM Observation
  14. GRB 240607A: Fermi GBM detection of a very bright burst
  15. GRB 240606B: Swift-XRT afterglow detection
  16. Swift Trigger 1235109: a possible GRB 240606A
  17. Swift Trigger 1232755: likely consistent with noise and not astrophysical
  18. Swift Trigger 1232465: consistent with noise
  19. GRB 240529A: continued SAO RAS optical observations
  20. GRB 240529A: OSN optical detection
  21. The EP-WXT source triggered on June 1st is likely a flaring star
  22. GRB 240529A: further SAO RAS optical observations
  23. GRB 240529A: 1.3m DFOT Optical observations
  24. Konus-Wind detection of GRB 240529A
  25. IPN triangulation of the initial episode of GRB 240529A
  26. GRB 240529A: SAO RAS optical observations
  27. GRB 240529A: optical photometry from Konkoly
  28. GRB 240529A: Swift-XRT refined Analysis
  29. GRB 240527B: Swift-XRT afterglow detection
  30. GRB 240527B: Fermi GBM Observation
  31. GRB 240527B: Fermi-LAT detection
  32. GRB 240523A: Swift-XRT refined Analysis
  33. GRB 240521B: Fermi GBM Observation
  34. Fermi GBM Sub-Threshold Detection of GRB 240516B
  35. EP240518a: possibly identified with a flare star by EP-FXT
  36. GRB 240516A: Swift-XRT refined Analysis
  37. GRB 240516A: Fermi GBM Observation
  38. GRB 240514B: Fermi GBM Detection
  39. GRB 240513A: Fermi GBM observation
  40. GRB 240513A: Swift-XRT observations
  41. LAT GRB240513.31: Global MASTER-Net observations report
  42. GRB 240513A: Fermi-LAT detection
  43. GRB 240511A: Fermi GBM Observation
  44. GRB 240511A: Swift-XRT refined Analysis
  45. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  46. GRB 240504A: Fermi GBM Observation
  47. EP240506a: TRT optical upper limit
  48. EP240506a: Optical upper limit with Kinder observations
  49. GRB 240502A: 1.3m DFOT Optical upper limit
  50. GRB 240502A: Fermi GBM Observation
  51. GRB 240415A 1.3m DFOT Optical upper limit
  52. Fermi-LAT gamma-ray observations of IceCube-240424A
  53. LIGO/Virgo/KAGRA S240422ed: A transient discovered from Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  54. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  55. EP240426b: EP-WXT detection of a new fast X-ray transient
  56. EP240426a: YAHPT optical upper limit
  57. XMM-Newton observation of EP240426a
  58. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  59. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  60. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  61. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  62. LXT240402A/GRB240402B: Chandra X-ray detection
  63. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  64. Fermi-LAT gamma-ray observations of IceCube-240419A
  65. GRB 240415B: Swift-XRT observations
  66. GRB 240415A: Swift-XRT refined Analysis
  67. GRB 240421B: Fermi GBM Observation
  68. GRB 240421B: Swift-XRT refined Analysis
  69. EP240420a: Nanshan optical counterpart observations
  70. EP240420a: detection of fading X-ray emission with refined position by EP-FXT
  71. GRB240418A - Candidate afterglow from NIRES
  72. GRB 240419B: Swift-XRT refined Analysis
  73. GRB 240419A: Swift-XRT refined Analysis
  74. GRB 240418A: Swift-XRT refined Analysis
  75. EP 240416a: Xinglong and NOT decaying optical counterpart
  76. EP240416a: Kinder optical counterpart candidate
  77. GRB 240415A: Fermi GBM Observation
  78. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  79. GRB 240415A: Earliest optical followup with the Kinder observations
  80. EP240414a: EP-FXT follow-up observation
  81. GRB 240414A: Fermi GBM Observation
  82. LXT 240402A/GRB 240402B: Swift follow-up observations
  83. EP240413a: Upper limits from GECAM-B Observation
  84. EP 240414a: NOT optical counterpart confirmation
  85. GRB 240414A: Swift-XRT refined Analysis
  86. GRB 240414A: Skynet Optical Afterglow Observations
  87. EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
  88. EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
  89. Fermi-LAT gamma-ray observations of IceCube-240412A
  90. GRB 240411B: Kinder observations with Lulin observatory
  91. GRB 240411B: Swift-XRT refined Analysis
  92. GRB 240411B: 1.3m DFOT Optical observations
  93. EP240408a: Upper limits from GECAM-B Observation
  94. Swift Trigger 1220736: detection of 4U 1543-62.
  95. Fermi-LAT gamma-ray observations of IceCube-240327B
  96. Fermi-LAT gamma-ray observations of IceCube-240327A
  97. LXT 240402A/GRB 240402B: rest-frame energetics from Konus-Wind observation
  98. GRB/FXT 240402B: Kinder optical counterpart candidate
  99. GRB 240403A: Fermi GBM Detection
  100. LXT 240402A: EP-FXT detection of the X-ray afterglow

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