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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"
  1. GRB 251014D: BOOTES-6/DPRT optical upper limit
  2. GRB 251014D: Swift-XRT afterglow detection
  3. GRB 251013C: MAO/AZT-22 optical observations
  4. GRB 251011B: SVOM/VT optical upper limit
  5. GRB 251013C: Swift ToO observations
  6. GRB 251013D: Fermi GBM Observation
  7. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations
  8. GRB 251014A: Swift-BAT refined analysis
  9. IceCube-251014A - IceCube observation of a high-energy neutrino candidate track-like event
  10. GRB 251013C: OHP/T193 further optical observations and possible color evolution
  11. GRB 251013C: Calapai Observatory, Massa S. Giorgio (Messina), optical observation
  12. GRB 251014D: Swift detection of a burst
  13. GRB 251014A: PRIME near-infrared upper limits
  14. GRB 251014C: Fermi GBM Final Localization
  15. GRB 251014A: Glowbug gamma-ray detection of a likely short burst
  16. GRB 251014A: VLT/FORS2 Optical Observation
  17. GRB 251013C: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an bright optical counterpart
  18. GRB 251012A: Glowbug gamma-ray detection of a likely short burst
  19. GRB 251013C: MarSEC, optical afterglow photometry
  20. GRB 251013C: OHP/T193 optical afterglow photometry and spectroscopy
  21. GRB 251014B: Swift ToO observations
  22. GRB 251013D: LAST optical upper limit on Swift/BAT-GUANO localization
  23. GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst
  24. GRB 251013C: Bassano Bresciano Observatory optical observations
  25. GRB 251013C: Early and late-time optical counterpart detection by LCO
  26. LIGO/Virgo/KAGRA S251014cn: NED Galaxies in the 3-Initial Localization Volume
  27. GRB 251013C: Fermi GBM Observation
  28. GRB 251013D: Swift ToO observations
  29. GRB 251014A: DDOTI Upper Limit
  30. GRB 251013C NUTTelA-TAO / BSTI Early Measurements
  31. LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
  32. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  33. GRB 251013C: Asiago optical observations
  34. GRB 251013A: CALET Gamma-Ray Burst Monitor detection
  35. GRB 251013C: ABObservatory optical observations
  36. GRB 251014A: SAO RAS optical upper limit
  37. GRB 251014A: Fermi GBM Observation
  38. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  39. GRB 251013C: EP-FXT counterpart detection
  40. GRB 251013C: AstroSat CZTI detection
  41. GRB 251011A: Swift/BAT-GUANO arcminute localization of a burst
  42. GRB 251013D: Swift/BAT-GUANO arcminute localization of a burst
  43. GRB 251013C: ALMA detection
  44. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) detection of the optical counterpart
  45. GRB 251013C: DDOTI detection of the optical afterglow
  46. GRB 251013C: SLKT optical afterglow photometry
  47. Swift GRB 251014A: Global MASTER-Net observations report
  48. GRB 251014A: Swift detection of a possibly-short burst
  49. GRB 251014A: Fermi GBM Final Real-time Localization
  50. Fermi trigger No 782044789: Global MASTER-Net observations report
  51. Fermi GRB 251013C: Global MASTER-Net observations report
  52. Fermi GRB 251013B: Global MASTER-Net observations report
  53. Fermi GRB 251013D: Global MASTER-Net observations report
  54. GRB 251013C: Swift-XRT counterpart detection
  55. GRB 251013C: GOTO optical afterglow detection
  56. GRB 251013C: SAO RAS optical observations
  57. GRB 251013C: LCO optical afterglow detection
  58. GRB 251013C: Optical Observations via Virtual Telescope Project, Italy
  59. GRB 251013C: NOT spectroscopic redshift z = 0.572
  60. GRB 251013C: LAST detection of optical counterpart
  61. GRB 251013C: BOOTES-6 early optical detection
  62. GRB 251013D: Fermi GBM Final Real-time Localization
  63. GRB 251013C: SVOM/VT optical observation
  64. GRB 251013C: SVOM detection of a burst
  65. GRB 251013C: Fermi GBM Final Real-time Localization
  66. LIGO/Virgo/KAGRA S251013x: Updated Sky localization and Source Classification
  67. GRB 251013B: SVOM/GRM observation
  68. GRB 251013A: SVOM/GRM observation
  69. GRB 251003A: Mondy optical upper limit
  70. MASTER OT J011025.98-583210.6 : SVOM/VT optical observation
  71. GRB 251013B: Fermi GBM Final Real-time Localization
  72. Fermi GRB 251013A: Global MASTER-Net observations report
  73. GRB 251013A: Fermi GBM Final Real-time Localization
  74. LIGO/Virgo/KAGRA S251013x: Identification of a GW compact binary merger candidate
  75. GRB 251011B inspection: MASTER orphan GRB detection
  76. GRB 251011A: Insight-HXMT detection
  77. GRB 251011B: Swift/UVOT Upper Limits
  78. Fermi GRB 251011A: Global MASTER-Net observations report
  79. GRB 251012A: Fermi GBM Final Real-time Localization
  80. GRB 251011B: SVOM/GRM observation
  81. GRB 251011B: Swift-XRT refined Analysis
  82. GRB 251011B: Fermi GBM Observation
  83. GRB 251011B : MASTER optical observations
  84. GRB 251011C: Fermi GBM Final Real-time Localization
  85. GRB 251011B: Enhanced Swift-XRT position
  86. GRB 251010A: AstroSat CZTI detection
  87. GRB 251011A: AstroSat CZTI detection
  88. GRB 251009B: SVOM/GRM observation of short GRB
  89. GRB 251011B: Swift detection of a burst
  90. GRB 251011B: Fermi GBM Final Real-time Localization
  91. GRB 251011A: Fermi GBM Final Real-time Localization
  92. Fermi Gamma-ray Burst Monitor trigger 781824269/251010892 is not a GRB
  93. GRB 251007B: Swift/UVOT Upper Limits
  94. GRB 251010A: Fermi GBM Final Real-time Localization
  95. GRB251007A: Swift/UVOT Detection
  96. GRB 251009A: GECAM-B detection of a short burst
  97. GRB 251009A: Insight-HXMT detection of a short burst
  98. GRB 251009B (short): Glowbug gamma-ray detection
  99. GRB 251009B: Insight-HXMT detection of a short burst
  100. GRB 251007A: Swift-BAT refined analysis

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