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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"

28052 results found.

  1. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  2. EP251023a: NOT optical counterpart detection
  3. EP251023a: GSP Optical Counterpart Detection
  4. EP251023a: Einstein Probe detection of an X-ray transient
  5. GRB 251016B: Fermi GBM Detection
  6. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  7. EP251021b: Einstein Probe detection of a fast X-ray transient
  8. LIGO/Virgo/KAGRA S251021u: Updated Sky localization
  9. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  10. LIGO/Virgo/KAGRA S251018bi: Updated Sky localization
  11. Fermi-LAT gamma-ray observations of IceCube-251018A
  12. GRB 251017A : RAPAS follow-up observations
  13. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  14. GRB 251017A: COLIBRÍ optical observations of a late plateau
  15. IceCube-251018A: DDOTI Optical Upper Limit
  16. GRB 251017A: Swift-BAT refined analysis
  17. GRB 251018A: Fermi GBM Observation
  18. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  19. GRB 251018A: Swift-XRT refined Analysis
  20. GRB 251018A: Enhanced Swift-XRT position
  21. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  22. GRB 251016A: Swift-XRT afterglow detection
  23. GRB 251017A: Swift/UVOT Detection
  24. GRB 251016A: Swift/UVOT Detection
  25. GRB 251018A: Swift/UVOT Detection
  26. GRB 251016A: VLT/FORS2 Optical Observation
  27. GRB 251017A: COLIBRÍ photometric redshift
  28. GRB 251017A: Swift-XRT refined Analysis
  29. GRB 251018A: MASTER OT detection
  30. GRB 251018A: TRT optical afterglow detection
  31. GRB 251018A: Swift detection of a burst with an optical counterpart
  32. GRB 251011A: Fermi GBM Observation
  33. GRB 251017A: J-band detection with WINTER
  34. GRB 251017A: Glowbug gamma-ray detection
  35. GRB 251013C: Liverpool Telescope observations
  36. GRB 251013C: Leavitt Observatory optical photometry
  37. GRB 251017A: JinShan observations of the optical afterglow
  38. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  39. GRB 251016A: AstroSat CZTI detection of a short burst
  40. GRB 251017A: Enhanced Swift-XRT position
  41. GRB 251017A: COLIBRÍ Early Afterglow Detection
  42. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  43. GRB 251017A: Swift detection of a burst with an optical counterpart
  44. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  45. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  46. GRB 251007B: Swift-BAT refined analysis
  47. GRB 251014D: Swift-BAT refined analysis
  48. GRB 251016A: BOOTES-6/DPRT optical upper limit
  49. GRB 251016A: Glowbug gamma-ray detection of a short burst
  50. sb25101602: Swift-XRT counterpart detection
  51. GRB 251014A: Swift-XRT observations
  52. LIGO/Virgo/KAGRA S251014cn: Updated Sky localization
  53. GRB 251014B: PRIME J-band upper limit
  54. Upper limits from a search for additional neutrino events in IceCube
  55. IceCube Alert 251014.77: Global MASTER-Net observations report
  56. GRB 251013C: Kilonova-Catcher optical afterglow detection
  57. Fermi-LAT Gamma-ray Observations of IceCube-251014A
  58. GRB 251013D: Swift/UVOT Observations
  59. GRB 251013C: Swift/UVOT Detection
  60. GRB 251013C: detection of a radio counterpart at 15.5GHz
  61. GRB 251013D: Swift-XRT observations
  62. Swift Trigger 1404295: possible GRB 251015A
  63. GRB 251014B: Swift-XRT observations
  64. GRB 251014B: Swift/UVOT Upper Limits
  65. GRB 251014B: VLT/FORS2 Optical Observation
  66. GRB 251014D: Swift/UVOT Upper Limits
  67. GRB 251014D: Swift-XRT afterglow detection
  68. GRB 251013C: MAO/AZT-22 optical observations
  69. GRB 251011B: SVOM/VT optical upper limit
  70. GRB 251013D: Fermi GBM Observation
  71. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations
  72. GRB 251014A: Swift-BAT refined analysis
  73. GRB 251013C: OHP/T193 further optical observations and possible color evolution
  74. GRB 251013C: Calapai Observatory, Massa S. Giorgio (Messina), optical observation
  75. GRB 251014D: Swift detection of a burst
  76. GRB 251014A: PRIME near-infrared upper limits
  77. GRB 251014A: Glowbug gamma-ray detection of a likely short burst
  78. GRB 251014A: VLT/FORS2 Optical Observation
  79. GRB 251012A: Glowbug gamma-ray detection of a likely short burst
  80. GRB 251013C: MarSEC, optical afterglow photometry
  81. GRB 251013C: OHP/T193 optical afterglow photometry and spectroscopy
  82. GRB 251013D: LAST optical upper limit on Swift/BAT-GUANO localization
  83. GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst
  84. GRB 251013C: Bassano Bresciano Observatory optical observations
  85. GRB 251013C: Early and late-time optical counterpart detection by LCO
  86. LIGO/Virgo/KAGRA S251014cn: NED Galaxies in the 3-Initial Localization Volume
  87. GRB 251013C: Fermi GBM Observation
  88. GRB 251014A: DDOTI Upper Limit
  89. GRB 251013C NUTTelA-TAO / BSTI Early Measurements
  90. LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
  91. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  92. GRB 251013C: Asiago optical observations
  93. GRB 251013C: ABObservatory optical observations
  94. GRB 251014A: SAO RAS optical upper limit
  95. GRB 251014A: Fermi GBM Observation
  96. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  97. GRB 251013C: EP-FXT counterpart detection
  98. GRB 251011A: Swift/BAT-GUANO arcminute localization of a burst
  99. GRB 251013D: Swift/BAT-GUANO arcminute localization of a burst
  100. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) detection of the optical counterpart

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