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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"

21392 results found.

  1. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
  2. LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
  3. LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
  4. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  5. EP241125a: EP detection of an X-ray transient
  6. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
  7. LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations
  8. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  9. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  10. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  11. LIGO/Virgo/KAGRA S241125n: No counterpart candidates in INTEGRAL SPI-ACS prompt observation, comparisong with Swift/BAT counterpart
  12. LIGO/Virgo/KAGRA S241125n: Updated Sky localization and Coincidence with External Event
  13. LIGO/Virgo/KAGRA S241125n: Swift/BAT-GUANO candidate counterpart
  14. Konus-Wind detection of GRB 241117A
  15. IPN triangulation of GRB 241117A
  16. GRB 241026A: VIRT Optical Upper Limit
  17. GRB 241025A: VIRT Optical Upper Limit
  18. GRB 241115A: CALET Gamma-Ray Burst Monitor detection
  19. GRB 241115a: PRIME near-infrared upper limits
  20. GRB 241117A: Swift/BAT-GUANO localization skymap of a burst
  21. LIGO/Virgo/KAGRA S241116cq: Upper limits from Swift/BAT-GUANO
  22. GRB 241115B: Fermi GBM Observation
  23. GRB 241115B: Swift/BAT-GUANO localization skymap of a long burst
  24. GRB 241115C: Fermi GBM Observation
  25. GRB 241115A: Swift-XRT afterglow detection
  26. EP241115a/GRB 241115D: Optical upper limits with Kinder observations
  27. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  28. EP241113a: Swift XRT weak detection
  29. GRB 241115A: Fermi GBM Observation
  30. GRB 241115A: LCOGT Optical Upper Limits
  31. GRB 241115C: Swift/BAT-GUANO localization skymap of a burst
  32. Swift GRB 241115A: Global MASTER-Net observations report
  33. GRB 241115A: Swift detection of a burst
  34. GRB 241113A: Swift-BAT refined analysis
  35. GRB 241113A: PRIME near-infrared upper limits
  36. GRB 241113A: J-band observations with WINTER
  37. GRB 241113B: Swift-XRT observations
  38. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  39. GRB 241113A: KAIT optical observations
  40. GRB 241113A: Swift-XRT refined Analysis
  41. GRB 241113A: Swift/UVOT Detection
  42. GRB 241113A: REM detection of the optical/NIR afterglow
  43. Konus-Wind detection of GRB 241107A (short/hard)
  44. GRB 241113B: Swift ToO observations
  45. GRB 241113A: LCO optical observations
  46. GRB 241113A: Enhanced Swift-XRT position
  47. GRB241113A: LCOGT (40-cm) optical counterpart detection
  48. GRB 241113A: MASTER010615.66-224018.2 optical counterpart detection
  49. GRB 241113A: Swift detection of a burst with an optical counterpart
  50. Swift GRB241113.33: Global MASTER-Net observations report
  51. GRB 241107A: GROWTH-India telescope optical upper limit
  52. GRB 241112B: Swift-XRT afterglow detection
  53. GRB 241107A: Swift/BAT candidate arcminute localization of a short burst
  54. GRB 241112B: Swift ToO observations
  55. GRB 241107A: INTEGRAL IBIS localization
  56. IPN triangulation of GRB 241107A (short/hard)
  57. GRB 241025A: VZLUSAT-2 detection
  58. GRB 241108A: Further COLIBRÍ Upper Limits on the Optical Counterpart
  59. GRB 241108A: Swift-XRT observations
  60. GRB 241108A: Swift ToO observations
  61. GRB 241030A: TESS observations
  62. GRB 241105A: EP-FXT follow-up observations
  63. GRB 241105A: SVOM/GRM observation
  64. GRB 241105a: PRIME near-infrared upper limits
  65. GRB 241105A: Swift/UVOT Detection
  66. GRB 241105A: Swift/BAT-GUANO refined analysis of short burst with extended emission
  67. GRB 241030A: optical afterglow detection from the INAF Asiago Observatory
  68. GRB 241105A: BOOTES-7 optical detection
  69. GRB 241105A: Fermi GBM Observation of a Short Burst with Extended Emission
  70. GRB 241105A: Swift-XRT afterglow detection
  71. GRB 241104A: Swift-XRT observations
  72. GRB 240511A: LCO upper limits
  73. GRB 241105A: Swift ToO observations
  74. GRB 241105A: Swift/BAT-GUANO arcminute localization of a short burst
  75. GRB 241104A: Swift ToO observations
  76. GRB 241030A: GRBAlpha detection
  77. EP241103a: GIT optical upper limit
  78. EP241103a: GOTO optical upper limit
  79. EP241103a: Swift XRT detection and improved X-ray position
  80. GRB 241030A: Swift-UVOT observations of the optical prompt flare
  81. GRB 241030A: Rapid release of TESS data.
  82. Swift GRB 241101A: Global MASTER-Net observations report
  83. GRB 241101A: FRAM-ORM optical limit
  84. GRB 241101A: Swift-BAT refined analysis
  85. GRB 241030B: Swift-XRT refined Analysis
  86. GRB 241030A / EP241030a: GMG possible spectroscopic redshift at z ~ 1.4
  87. GRB 241101A: Swift detection of a burst
  88. GRB 241030B: NUTTelA-TAO / BSTI Optical Limits
  89. GRB 241030B: Montarrenti Observatory optical upper limit
  90. GRB 241030A / EP241030a: FTW Optical and NIR observations of the optical counterpart
  91. GRB 241030A: Fermi GBM Observation
  92. GRB 241030B: LCOGT Optical Upper Limits
  93. GRB 241030B: Swift-BAT refined analysis
  94. GRB 241030A: Swift-BAT refined analysis
  95. GRB 241030B: Swift/UVOT Detection
  96. GRB 241029A: LCO optical detection
  97. Swift GRB241030.77: Global MASTER-Net observations report
  98. GRB 241030B: SVOM/GRM observation
  99. GRB 241030B : MITSuME Akeno optical upper limits
  100. GRB 241030A: COLIBRI Continuing Detection of the Afterglow

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