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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"

18524 results found.

  1. GRB 241127A: Enhanced Swift-XRT position
  2. GRB 241127A: LCOGT (40-cm) optical counterpart detection
  3. Swift GRB241127.91: Global MASTER-Net OT detection
  4. LIGO/Virgo/KAGRA S241125n: Update on Coincidence False Alarm Method
  5. GRB 241127A: Swift detection of a burst with an optical counterpart
  6. Swift GRB241127.91: Global MASTER-Net observations report
  7. Swift GRB241127.91: Global MASTER-Net OT detection
  8. LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
  9. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  10. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  11. IPN triangulation of GRB 241114B
  12. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  13. LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
  14. Trigger_18947: Swift ToO observations (retracted)
  15. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
  16. LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
  17. LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
  18. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  19. EP241125a: EP detection of an X-ray transient
  20. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
  21. LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations
  22. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  23. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  24. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  25. LIGO/Virgo/KAGRA S241125n: No counterpart candidates in INTEGRAL SPI-ACS prompt observation, comparisong with Swift/BAT counterpart
  26. LIGO/Virgo/KAGRA S241125n: Updated Sky localization and Coincidence with External Event
  27. LIGO/Virgo/KAGRA S241125n: Swift/BAT-GUANO candidate counterpart
  28. Konus-Wind detection of GRB 241117A
  29. IPN triangulation of GRB 241117A
  30. GRB 241025A: VIRT Optical Upper Limit
  31. GRB 241115A: CALET Gamma-Ray Burst Monitor detection
  32. GRB 241115a: PRIME near-infrared upper limits
  33. GRB 241117A: Swift/BAT-GUANO localization skymap of a burst
  34. LIGO/Virgo/KAGRA S241116cq: Upper limits from Swift/BAT-GUANO
  35. GRB 241115B: Fermi GBM Observation
  36. GRB 241115B: Swift/BAT-GUANO localization skymap of a long burst
  37. GRB 241115C: Fermi GBM Observation
  38. GRB 241115A: Swift-XRT afterglow detection
  39. EP241115a/GRB 241115D: Optical upper limits with Kinder observations
  40. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  41. EP241113a: Swift XRT weak detection
  42. GRB 241115A: Fermi GBM Observation
  43. GRB 241115A: LCOGT Optical Upper Limits
  44. GRB 241115C: Swift/BAT-GUANO localization skymap of a burst
  45. Swift GRB 241115A: Global MASTER-Net observations report
  46. GRB 241115A: Swift detection of a burst
  47. GRB 241113A: Swift-BAT refined analysis
  48. GRB 241113A: PRIME near-infrared upper limits
  49. GRB 241113A: J-band observations with WINTER
  50. GRB 241113B: Swift-XRT observations
  51. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  52. GRB 241113A: KAIT optical observations
  53. GRB 241113A: Swift-XRT refined Analysis
  54. GRB 241113A: Swift/UVOT Detection
  55. GRB 241113A: REM detection of the optical/NIR afterglow
  56. Konus-Wind detection of GRB 241107A (short/hard)
  57. GRB 241113B: Swift ToO observations
  58. GRB 241113A: LCO optical observations
  59. GRB 241113A: Enhanced Swift-XRT position
  60. GRB241113A: LCOGT (40-cm) optical counterpart detection
  61. GRB 241113A: MASTER010615.66-224018.2 optical counterpart detection
  62. GRB 241113A: Swift detection of a burst with an optical counterpart
  63. Swift GRB241113.33: Global MASTER-Net observations report
  64. GRB 241107A: GROWTH-India telescope optical upper limit
  65. GRB 241112B: Swift-XRT afterglow detection
  66. GRB 241107A: Swift/BAT candidate arcminute localization of a short burst
  67. GRB 241112B: Swift ToO observations
  68. GRB 241107A: INTEGRAL IBIS localization
  69. IPN triangulation of GRB 241107A (short/hard)
  70. GRB 241025A: VZLUSAT-2 detection
  71. GRB 241108A: Swift-XRT observations
  72. GRB 241108A: Swift ToO observations
  73. GRB 241030A: TESS observations
  74. GRB 241105A: EP-FXT follow-up observations
  75. GRB 241105A: SVOM/GRM observation
  76. GRB 241105a: PRIME near-infrared upper limits
  77. GRB 241105A: Swift/UVOT Detection
  78. GRB 241105A: Swift/BAT-GUANO refined analysis of short burst with extended emission
  79. GRB 241030A: optical afterglow detection from the INAF Asiago Observatory
  80. GRB 241105A: BOOTES-7 optical detection
  81. GRB 241105A: Fermi GBM Observation of a Short Burst with Extended Emission
  82. GRB 241105A: Swift-XRT afterglow detection
  83. GRB 241104A: Swift-XRT observations
  84. GRB 241105A: Swift ToO observations
  85. GRB 241105A: Swift/BAT-GUANO arcminute localization of a short burst
  86. GRB 241104A: Swift ToO observations
  87. GRB 241030A: GRBAlpha detection
  88. EP241103a: GIT optical upper limit
  89. EP241103a: GOTO optical upper limit
  90. EP241103a: Swift XRT detection and improved X-ray position
  91. GRB 241030A: Swift-UVOT observations of the optical prompt flare
  92. GRB 241030A: Rapid release of TESS data.
  93. Swift GRB 241101A: Global MASTER-Net observations report
  94. GRB 241101A: FRAM-ORM optical limit
  95. GRB 241101A: Swift-BAT refined analysis
  96. GRB 241030B: Swift-XRT refined Analysis
  97. GRB 241030A / EP241030a: GMG possible spectroscopic redshift at z ~ 1.4
  98. GRB 241101A: Swift detection of a burst
  99. GRB 241030B: Montarrenti Observatory optical upper limit
  100. GRB 241030A / EP241030a: FTW Optical and NIR observations of the optical counterpart

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