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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"

45423 results found.

  1. LIGO/Virgo/KAGRA S240919bn: Updated Sky localization
  2. GRB 240918B: Fermi GBM Detection
  3. LIGO/Virgo/KAGRA S240917cb: Updated Sky localization and EM Bright Classification
  4. LIGO/Virgo/KAGRA S240916ar: Updated Sky localization and EM Bright Classification
  5. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  6. EP240918a: EP observation update
  7. GRB 240910A: further Swift observations and confirmation of afterglow
  8. LIGO/Virgo/KAGRA S240919bn: Identification of a GW compact binary merger candidate
  9. EP240918a: Swift-XRT observation
  10. Fermi GRB 240918A: Global MASTER-Net observations report
  11. GRB 240918A: Fermi GBM Final Real-time Localization
  12. EP EP240918a: Global MASTER-Net observations report
  13. EP240918a: JinShan optical upper limits
  14. EP240918a: YAHPT Optical Upper Limit
  15. EP240918a: Optical upper limits with Kinder observations
  16. EP240918a: GMG Optical Upper Limit
  17. GRB 240916A: GRBAlpha detection
  18. GRB 240914B: GRBAlpha detection
  19. EP240918a: an X-ray transient detected by Einstein Probe
  20. GRB 240916A: NOT optical observation
  21. GRB 240912A: Swift-BAT refined analysis
  22. IPN triangulation of GRB 240913C / EP 240913a
  23. GRB 240825A: INTEGRAL SPI ACS LIGHT CURVE
  24. GRB 240825A: The nature of the afterglow motivates the search of the associated supernova
  25. GRB 240916A: Fermi GBM Observation
  26. LIGO/Virgo/KAGRA S240917cb: Identification of a GW compact binary merger candidate
  27. GRB 240821A: radio observation with the VLA
  28. GRB 240916A (AT 2024vlp / GOTO24fzn): VLT/X-shooter redshift
  29. GRB 240916A: Swift-XRT afterglow detection
  30. LIGO/Virgo/KAGRA S240916ar: Identification of a GW compact binary merger candidate
  31. GRB 240916A: Swift ToO observations
  32. LIGO/Virgo/KAGRA S240915b: NED Galaxies in the Localization Volume
  33. LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources
  34. GRB 240916A: JinShan optical decay in one of the two GOTO candidates
  35. GRB 240916B: Fermi GBM Final Real-time Localization
  36. GRB 240914B: Fermi GBM Final Localization
  37. The EP-WXT triggers 01709047257 and 01709047278 are not real sources
  38. GRB 240916A: GOTO identification of two new optical sources within the GBM localisation region
  39. EP EP240913a: Global MASTER-Net observations report
  40. LIGO/Virgo/KAGRA S240915b: Coverage and upper limits from MAXI/GSC observations
  41. GRB 240916A INTEGRAL SPI ACS LIGHT CURVE
  42. GRB 240916A: Fermi GBM Final Real-time Localization
  43. Fermi Gamma-ray Burst Monitor trigger 748124309/240915846 is not a GRB
  44. LIGO/Virgo/KAGRA S240915bd: Updated Sky localization
  45. EP240913a: VLT/HAWK-I near-infrared upper limits
  46. LIGO/Virgo/KAGRA S240915bd: Identification of a GW compact binary merger candidate
  47. LIGO/Virgo/KAGRA S240915b: Updated Sky localization and EM Bright Classification
  48. LIGO/Virgo/KAGRA S240915b: Identification of a GW compact binary merger candidate
  49. EP240913a/GRB 240913C: KAIT optical upper limit
  50. EP240913a / GRB 240913C INTEGRAL SPI ACS LIGHT CURVE
  51. GRB 240913C: Fermi GBM detection
  52. GRB 240914A: Swift-XRT observations
  53. GRB 240913C: Joint location by ETJASMIN
  54. GRB 240914B: AstroSat CZTI detection
  55. EP240913A / GRB 240913C: AstroSat CZTI detection
  56. GRB 240914A: SVOM/GRM observation
  57. GRB 240910A: SVOM/VT optical observations
  58. GRB 240914A: Swift ToO observations
  59. EP240913a: NOT optical upper limits
  60. EP240913a: JinShan optical upper limits
  61. EP240913a: ESO-NTT optical observations
  62. GRB 240914A: ESO-NTT optical observations
  63. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  64. GRB 240914B: BALROG localization (Fermi Trigger 747990592 / GRB 240914298)
  65. GRB 240914A : An intermediate duration GRB located on-board by SVOM/ECLAIRs.
  66. GRB 240905E: further NOT optical observations
  67. EP240913a: A GRB Event
  68. EP240913a: EP-WXT detection of a fast X-ray transient
  69. GRB 240913B: Fermi GBM Final Real-time Localization
  70. GRB 240911A: LCO optical observations
  71. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  72. Fermi Gamma-ray Burst Monitor trigger 747837485/240912526 is not a GRB
  73. GRB 240912A: Swift/UVOT Detection
  74. GRB 240911A: GOTO optical limits on Swift/XRT candidates
  75. Fermi trigger No 747920561: Global MASTER-Net observations report
  76. GRB 240912A: SVOM/GRM observation
  77. GRB 240911A: Swift-XRT observations
  78. Fermi GRB 240913A: Global MASTER-Net observations report
  79. GRB 240913A: Fermi GBM Final Real-time Localization
  80. GRB 240912A: J-band observations with WINTER
  81. GRB 240912A: Swift-XRT refined Analysis
  82. GRB 240912A: Fermi GBM Observation
  83. Swift GRB 240912A: Global MASTER-Net observations report
  84. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  85. GRB 240911A: Tiled Swift observations
  86. Fermi Gamma-ray Burst Monitor trigger 747839931/240912555 is not a GRB
  87. GRB 240912A : INTEGRAL SPI ACS LIGHT CURVE
  88. GRB 240912B: Fermi GBM Final Real-time Localization
  89. GRB 240912A: NOT optical spectroscopy
  90. GRB 240912A: Enhanced Swift-XRT position
  91. GRB 240912A: Redshift from OSIRIS+/GTC
  92. Fast X-ray Transient EP240801a: GMRT radio observations
  93. GRB 240910A: Redshift from OSIRIS+/GTC
  94. GRB 240912A: Swift detection of a burst with an optical counterpart
  95. GRB 240912A: Fermi GBM Final Real-time Localization
  96. GRB 240910A: Fermi GBM Observation
  97. GRB 240910A: NOT optical observations
  98. GRB 240911A : a likely weak GRB detected by SVOM/ECLAIRs
  99. GRB 240910A: Swift-XRT detection of GOTO24fvl/AT2024vfp
  100. GRB 240910A: JinShan optical observations

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