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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').
  1. LIGO/Virgo/KAGRA S240917cb: Identification of a GW compact binary merger candidate
  2. GRB 240821A: radio observation with the VLA
  3. GRB 240916A (AT 2024vlp / GOTO24fzn): VLT/X-shooter redshift
  4. GRB 240916A: Swift-XRT afterglow detection
  5. LIGO/Virgo/KAGRA S240916ar: Identification of a GW compact binary merger candidate
  6. GRB 240916A: Swift ToO observations
  7. LIGO/Virgo/KAGRA S240915b: NED Galaxies in the Localization Volume
  8. LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources
  9. GRB 240916A: JinShan optical decay in one of the two GOTO candidates
  10. GRB 240916B: Fermi GBM Final Real-time Localization
  11. GRB 240914B: Fermi GBM Final Localization
  12. The EP-WXT triggers 01709047257 and 01709047278 are not real sources
  13. GRB 240916A: GOTO identification of two new optical sources within the GBM localisation region
  14. EP EP240913a: Global MASTER-Net observations report
  15. LIGO/Virgo/KAGRA S240915b: Coverage and upper limits from MAXI/GSC observations
  16. GRB 240916A INTEGRAL SPI ACS LIGHT CURVE
  17. GRB 240916A: Fermi GBM Final Real-time Localization
  18. Fermi Gamma-ray Burst Monitor trigger 748124309/240915846 is not a GRB
  19. LIGO/Virgo/KAGRA S240915bd: Updated Sky localization
  20. EP240913a: VLT/HAWK-I near-infrared upper limits
  21. LIGO/Virgo/KAGRA S240915bd: Identification of a GW compact binary merger candidate
  22. LIGO/Virgo/KAGRA S240915b: Updated Sky localization and EM Bright Classification
  23. LIGO/Virgo/KAGRA S240915b: Identification of a GW compact binary merger candidate
  24. EP240913a/GRB 240913C: KAIT optical upper limit
  25. EP240913a / GRB 240913C INTEGRAL SPI ACS LIGHT CURVE
  26. GRB 240913C: Fermi GBM detection
  27. GRB 240914A: Swift-XRT observations
  28. GRB 240913C: Joint location by ETJASMIN
  29. GRB 240914B: AstroSat CZTI detection
  30. EP240913A / GRB 240913C: AstroSat CZTI detection
  31. GRB 240914A: SVOM/GRM observation
  32. GRB 240910A: SVOM/VT optical observations
  33. GRB 240914A: Swift ToO observations
  34. EP240913a: NOT optical upper limits
  35. EP240913a: JinShan optical upper limits
  36. EP240913a: ESO-NTT optical observations
  37. GRB 240914A: ESO-NTT optical observations
  38. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  39. GRB 240914B: BALROG localization (Fermi Trigger 747990592 / GRB 240914298)
  40. GRB 240914A : An intermediate duration GRB located on-board by SVOM/ECLAIRs.
  41. GRB 240905E: further NOT optical observations
  42. EP240913a: A GRB Event
  43. EP240913a: EP-WXT detection of a fast X-ray transient
  44. GRB 240913B: Fermi GBM Final Real-time Localization
  45. GRB 240911A: LCO optical observations
  46. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  47. Fermi Gamma-ray Burst Monitor trigger 747837485/240912526 is not a GRB
  48. GRB 240912A: Swift/UVOT Detection
  49. GRB 240911A: GOTO optical limits on Swift/XRT candidates
  50. Fermi trigger No 747920561: Global MASTER-Net observations report
  51. GRB 240912A: SVOM/GRM observation
  52. GRB 240911A: Swift-XRT observations
  53. Fermi GRB 240913A: Global MASTER-Net observations report
  54. GRB 240913A: Fermi GBM Final Real-time Localization
  55. GRB 240912A: J-band observations with WINTER
  56. GRB 240912A: Swift-XRT refined Analysis
  57. GRB 240912A: Fermi GBM Observation
  58. Swift GRB 240912A: Global MASTER-Net observations report
  59. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  60. GRB 240911A: Tiled Swift observations
  61. Fermi Gamma-ray Burst Monitor trigger 747839931/240912555 is not a GRB
  62. GRB 240912A : INTEGRAL SPI ACS LIGHT CURVE
  63. GRB 240912B: Fermi GBM Final Real-time Localization
  64. GRB 240912A: NOT optical spectroscopy
  65. GRB 240912A: Enhanced Swift-XRT position
  66. GRB 240912A: Redshift from OSIRIS+/GTC
  67. Fast X-ray Transient EP240801a: GMRT radio observations
  68. GRB 240910A: Redshift from OSIRIS+/GTC
  69. GRB 240912A: Swift detection of a burst with an optical counterpart
  70. GRB 240912A: Fermi GBM Final Real-time Localization
  71. GRB 240910A: Fermi GBM Observation
  72. GRB 240910A: NOT optical observations
  73. GRB 240911A : a likely weak GRB detected by SVOM/ECLAIRs
  74. GRB 240910A: Swift-XRT detection of GOTO24fvl/AT2024vfp
  75. GRB 240910A: JinShan optical observations
  76. GRB 240910A: GOTO candidate optical counterpart
  77. EP240908a: Optical afterglow confirmation
  78. GRB 240710A: SVOM/GRM observation
  79. GRB 240910A: Swift ToO observations
  80. IPN triangulation of GRB 240905B (short)
  81. GRB 240825A: 7DT Optical Upper Limit
  82. GRB 240905E: SVOM/VT optical observations
  83. GRB 240905E: SVOM/VT optical observations (duplicate submission of GCN 37453)
  84. LIGO/Virgo/KAGRA S240910ci: NED Galaxies in the Localization Volume
  85. GRB 240910A: GRBAlpha detection
  86. GRB 240910B: Fermi GBM Final Real-time Localization
  87. LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
  88. LIGO/Virgo/KAGRA S240910ci: Updated Sky localization and EM Bright Classification
  89. LIGO/Virgo/KAGRA S240910ci: Identification of a GW compact binary merger candidate
  90. GRB 240910A: SVOM/GRM observation
  91. EP240908a: Mondy and AbAO follow-up observations
  92. EP240908a: Updates on the WXT detection result around the trigger time
  93. Fermi GRB 240910A: Global MASTER-Net observations report
  94. GRB 240910A: Fermi GBM Final Real-time Localization
  95. LIGO/Virgo/KAGRA S240908bs: Upper limits from Swift/BAT-GUANO
  96. LIGO/Virgo/KAGRA S240907cg: Upper limits from Swift/BAT-GUANO
  97. EP240908a: optical afterglow candidate
  98. EP EP240908a: Global MASTER-Net observations report
  99. GRB 240905B: Fermi GBM Observation
  100. Fermi trigger No 747553301: Global MASTER-Net observations report

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