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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"

19362 results found.

  1. IPN triangulation of GRB 241022A (short/hard)
  2. LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
  3. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  4. EP 241021a: Swift-XRT observations
  5. Swift GRB 241025A: Global MASTER-Net observations report
  6. EP241025a (GRB 241025A): EP observations update
  7. EP 241021A: Swift ToO observations
  8. GRB 241025A: Enhanced Swift-XRT position
  9. GRB 241025A: NOT spectroscopic redshift of z = 4.20
  10. GRB 241025A: DDOTI Afterglow detection
  11. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  12. GRB 241025A: SVOM/GRM observation
  13. GRB 241025A: TRT optical afterglow observation
  14. GRB 241025A: Swift detection of a burst with an optical counterpart
  15. GRB 241018A: EP-FXT afterglow detection
  16. GRB 241018A: Mondy optical upper limit
  17. GRB 241018A: SVOM/VT further analysis and counterpart confirmed
  18. GRB 241018A: GROWTH-India telescope optical upper limit
  19. GRB 241018A: Swift-XRT observations
  20. GRB 241018A: NOT optical observations
  21. GRB 241018A: Swift ToO observations
  22. GRB 241006A: VIRT Optical Upper Limit
  23. GRB 240727A: VIRT Optical Upper Limit
  24. GRB 241016B: Fermi GBM Observations
  25. GRB 241017A: Swift-XRT observations
  26. GRB241017a: Liverpool Telescope observations of XRT uncatalogued sources
  27. GRB 241001A: EP-FXT afterglow detection
  28. GRB 241017A: GROWTH-India Telescope optical upper limit
  29. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  30. GRB 241017A: Swift ToO observations
  31. GRB 241010A: Swift-BAT refined analysis
  32. GRB 241013B: Fermi GBM Observation
  33. GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
  34. GRB 241009A: LCO optical upper limits
  35. GRB 241009A: GRANDMA optical upper limits
  36. GRB 241009A: Swift-XRT afterglow detection
  37. GRB 241010A: JinShan optical observations and potential host galaxy
  38. GRB 241006A: ATCA Radio Upper Limits
  39. GRB 241010A: Swift-XRT refined Analysis
  40. Swift GRB 241010A: Global MASTER-Net observations report
  41. GRB 241010A: J-band observations with WINTER
  42. GRB 241010A: Enhanced Swift-XRT position
  43. GRB 241010A: LCO optical observations
  44. GRB 241010A: Swift detection of a burst with an optical counterpart
  45. GRB 241006A: Swift-BAT refined analysis
  46. GRB 241009A: Swift ToO observations
  47. GRB 241002B: Swift-XRT afterglow detection
  48. GRB 241002A: NOT optical upper limits
  49. GRB 241006A: GRANDMA optical upper limits
  50. GRB 241006A: Swift-XRT refined Analysis
  51. GRB 241006A: PRIME near-infrared upper limits
  52. GRB 241006A: Swift/UVOT Upper Limits
  53. GRB 241006A: SVOM/VT follow-up and optical upper limit
  54. GRB 241001A: Swift-XRT afterglow detection
  55. GRB 241006A: Enhanced Swift-XRT position
  56. GRB 241006A: Swift detection of a burst
  57. Swift GRB241006.91: Global MASTER-Net observations report
  58. GRB 240930B: SVOM/C-GFT optical upper limit
  59. GRB 240930B / EP 240930a: SVOM/GRM observation
  60. GRB 241002B: Fermi GBM Observation
  61. GRB 241002B: Swift-XRT observations
  62. GRB 241002A: Swift-BAT refined analysis
  63. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  64. GRB 241002B: Swift ToO observations
  65. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  66. GRB 241002C: Swift ToO observations
  67. IPN triangulation of GRB 240930B / EP 240930a
  68. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  69. GRB 241002A: Swift/UVOT Upper Limits
  70. GRB 241002A: Swift-XRT refined Analysis
  71. GRB 241002A: LCOGT Optical Upper Limits
  72. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  73. GRB 241001A: Swift/UVOT Detection
  74. GRB 241001A: Swift-XRT observations
  75. GRB241001A: optical afterglow candidate
  76. GRB 241002A: 1.5m OSN optical upper limit
  77. GRB 241002A: Enhanced Swift-XRT position
  78. LIGO/Virgo/KAGRA S241002e: Identification of a GW compact binary merger candidate
  79. GRB 241002A: Swift detection of a burst
  80. GRB 240930B: Fermi GBM Observation
  81. GRB 241001A: Swift ToO observations
  82. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  83. SVOM/GRM detection of a burst from SGR Swift J1818.0-1607
  84. AMON NuEM 240926A: Swift XRT Follow-up
  85. Konus-Wind detection of GRB 240912A
  86. Swift Trigger 1256950 is probably not a GRB
  87. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  88. LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO
  89. LIGO/Virgo/KAGRA S240919bn: Upper limits from Swift/BAT-GUANO
  90. GRB 240529A: FRAM-ORM early optical afterglow observations reveal plateau and rebrightening
  91. GW S240915b and S240919bn : Swift UVOT follow-up
  92. Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
  93. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  94. LIGO/Virgo S240919bn: GOTO optical upper limits
  95. LIGO/Virgo S240919bn: Swift XRT observations, 10 X-ray sources
  96. EP240913A/GRB 240913C: AbAO optical upper limit
  97. GRB 240910A: further Swift observations and confirmation of afterglow
  98. EP240918a: Swift-XRT observation
  99. GRB 240912A: Swift-BAT refined analysis
  100. IPN triangulation of GRB 240913C / EP 240913a

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