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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').

23737 results found.

  1. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  2. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  3. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  4. LIGO/Virgo/KAGRA S250119ag: Updated Sky localization
  5. GRB 250117A: GECAM observation of a short burst
  6. LIGO/Virgo/KAGRA S250118dp: Updated Sky localization
  7. GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)
  8. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  9. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  10. LIGO/Virgo/KAGRA S250118t: Updated Sky localization
  11. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  12. EP250108a / AT2025kg: GMG Optical Observations
  13. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  14. GRB 241217A / EP241217B: radio detection with the VLA
  15. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  16. GRB 250114B: Swift-XRT afterglow detection
  17. EP250108a: MeerKAT radio upper limit
  18. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  19. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  20. LIGO/Virgo/KAGRA S250114ax: Updated Sky localization
  21. IPN triangulation of GRB 250113A
  22. GRB 250114B: Liverpool Telescope optical upper limit
  23. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  24. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  25. GRB 250114B: Swift-XRT observations
  26. GRB 250114A: LCO optical counterpart detection.
  27. GRB 250114B: OHP/T193 optical upper limit
  28. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  29. GRB 250114A: Swift-XRT refined Analysis
  30. GRB 250114A: LCOGT optical afterglow i-band detection
  31. GRB 250114B : GIT optical upper limit
  32. EP250111a: SAO RAS optical upper limit
  33. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  34. GRB 250114B: a short GRB detected with INTEGRAL
  35. GRB 250114A: Enhanced Swift-XRT position
  36. GRB 250114A: REM detection of the optical and NIR counterpart
  37. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  38. Swift GRB250114A: Global MASTER-Net OT detection
  39. GRB 250114A: LCO optical observations
  40. GRB 250114A: TRT optical observations
  41. GRB 250114A: Swift detection of a burst with an optical counterpart
  42. GRB 250101A: Terskol Zeiss-2000 optical observations
  43. EP250108a / AT 2025kg: SAO RAS optical observations
  44. EP241021a: SMA radio observation
  45. GRB 250113A: SVOM/GRM observation of a long burst
  46. GRB 250107A: VZLUSAT-2 detection
  47. EP250109b: optical upper limits with the Liverpool Telescope
  48. GRB 250106A: Swift-XRT afterglow detection
  49. EP250111a: KAIT optical observations
  50. GRB 250109A / EP250109a: Mephisto optical upper limits
  51. EP250108a: Mephisto detection
  52. EP250111a: Mondy optical observation
  53. EP250108a / AT 2025kg: LCO optical observations
  54. EP250108a / AT 2025kg: Swift UVOT detections
  55. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  56. EP250111a: NOT likely optical counterpart
  57. GRB 250101B: Fermi GBM Observation
  58. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  59. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  60. GRB 250108A: Swift/XRT afterglow fading
  61. LIGO/Virgo/KAGRA S250109bi: Updated Sky localization
  62. LIGO/Virgo/KAGRA S250109f: Updated Sky localization
  63. LIGO/Virgo/KAGRA S250108eo: Updated Sky localization
  64. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  65. GRB 250101A: CMO RC-500 optical observations
  66. GRB 250109A: Fermi GBM Observation
  67. EP250108a: NOT optical observations
  68. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  69. GRB 250109a: GMG Optical Upper Limit
  70. EP250109a: Swift/UVOT non-detection
  71. IPN triangulation of GRB 250107D (short/hard)
  72. EP250108a: Liverpool Telescope likely optical counterpart
  73. GRB 250108B: Swift-BAT refined analysis
  74. GRB 250108B: 1.3m DFOT upper limit
  75. GRB 250108B: REM optical/NIR upper limits
  76. GRB 250101A: Terskol K-800 optical observations
  77. EP250109a: Swift/XRT non-detection
  78. GRB 250108A: Swift/UVOT Upper Limits
  79. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  80. GRB 250108A: NOT optical upper limit
  81. EP250108a: EP-WXT detection of an X-ray transient
  82. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  83. GRB 250108B: Swift-XRT refined Analysis
  84. GRB 250103A: 1.6m Mephisto optical observations
  85. GRB 250108A: Swift-XRT afterglow detection
  86. GRB 250108A:SVOM/VT optical candidate
  87. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  88. GRB 250108B: Swift/UVOT Upper Limits
  89. GRB 250103A: Swift-XRT afterglow detection
  90. GRB 250108B: Enhanced Swift-XRT position
  91. GRB 250108B: Swift detection of a burst
  92. GRB 250107A: Fermi GBM Observation
  93. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  94. GRB 250106A: SVOM/VT 2nd optical deep observation
  95. GRB 250101A: J band upper limit by SYSU 80cm telescope
  96. EPWXT01709129925: Xinglong optical observations
  97. GRB 250106A: NOT optical observations
  98. LIGO/Virgo/KAGRA S250104v: Updated Sky localization
  99. GRB 250103B: REM optical/NIR upper limits
  100. GRB 250101A: REM optical/NIR counterpart detection

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