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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

19327 results found.

  1. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  2. GRB 251027A: Swift-XRT observations
  3. GRB 251017A: Mondy AZT-33IK and Koshka Zeiss-1000 optical observations
  4. GRB 251027A: SVOM detection of a faint burst
  5. LIGO/Virgo/KAGRA S251026bn: Updated Sky localization
  6. Fermi GRB 251025C: Global MASTER-Net observations report
  7. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  8. GRB 251026A: Swift-XRT observations
  9. GRB 251025B: OHP/T193 optical detection
  10. GRB 251025B: J-band detection with WINTER
  11. GRB 251026A: SVOM/C-GFT upper limit
  12. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  13. GRB 251025B: Swift-XRT afterglow detection
  14. GRB 251024A: Swift-BAT refined analysis
  15. GRB 251024A: Swift-XRT refined Analysis
  16. GRB 251025A (sb25102501): stellar flare confirmed
  17. GRB 251025B: MASTER OT detection
  18. GRB 251025B: SVOM/C-GFT optical counterpart detection
  19. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  20. GRB 251025A: SVOM/VT VHF optical upper limit
  21. GRB 251003A: VLA Detection
  22. GRB 251023C: Glowbug gamma-ray detection
  23. GRB 251024A: LCOGT Optical Afterglow Detection
  24. GRB 251023C: AstroSat CZTI detection
  25. GRB 251022A: Swift-XRT detection of GOTO25iym
  26. GRB 251023C: Swift/BAT-GUANO localization skymap of a burst
  27. GRB 251022A: Fermi GBM Observation
  28. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  29. GRB 251023A: Glowbug gamma-ray detection
  30. GRB 251023B: Glowbug gamma-ray detection
  31. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  32. GRB 251023B: CALET Gamma-Ray Burst Monitor detection
  33. EP#01709247298: Swift-XRT counterpart detection
  34. GRB 251013C: further SAO RAS optical observations
  35. GRB 251022A: MASTER OT detection
  36. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  37. EP251023a: GSP Optical Counterpart Detection
  38. GRB 251016B: Fermi GBM Detection
  39. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  40. EP251021b: BOOTES-7 optical upper limit
  41. LIGO/Virgo/KAGRA S251021u: Updated Sky localization
  42. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo/KAGRA S251018bi: Updated Sky localization
  44. Fermi-LAT gamma-ray observations of IceCube-251018A
  45. GRB 251017A : RAPAS follow-up observations
  46. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  47. GRB 251017A: Swift-BAT refined analysis
  48. GRB 251018A: Fermi GBM Observation
  49. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  50. GRB 251018A: Swift-XRT refined Analysis
  51. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  52. GRB 251016A: Swift-XRT afterglow detection
  53. GRB 251016A: Swift/UVOT Detection
  54. GRB 251016A: VLT/FORS2 Optical Observation
  55. GRB 251017A: COLIBRÍ photometric redshift
  56. GRB 251017A: Swift-XRT refined Analysis
  57. GRB 251018A: MASTER OT detection
  58. GRB 251018A: Swift detection of a burst with an optical counterpart
  59. GRB 251011A: Fermi GBM Observation
  60. GRB 251017A: J-band detection with WINTER
  61. GRB 251017A: Glowbug gamma-ray detection
  62. GRB 251016A: AstroSat CZTI detection of a short burst
  63. GRB 251017A: COLIBRÍ Early Afterglow Detection
  64. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  65. GRB 251017A: Swift detection of a burst with an optical counterpart
  66. GRB 251007B: Swift-BAT refined analysis
  67. GRB 251014D: Swift-BAT refined analysis
  68. GRB 251016A: BOOTES-6/DPRT optical upper limit
  69. GRB 251016A: Glowbug gamma-ray detection of a short burst
  70. sb25101602: Swift-XRT counterpart detection
  71. GRB 251014A: Swift-XRT observations
  72. LIGO/Virgo/KAGRA S251014cn: Updated Sky localization
  73. Upper limits from a search for additional neutrino events in IceCube
  74. IceCube Alert 251014.77: Global MASTER-Net observations report
  75. Fermi-LAT Gamma-ray Observations of IceCube-251014A
  76. GRB 251013D: Swift-XRT observations
  77. GRB 251014B: Swift-XRT observations
  78. GRB 251014D: Swift-XRT afterglow detection
  79. GRB 251013D: Fermi GBM Observation
  80. GRB 251014A: Swift-BAT refined analysis
  81. GRB 251013C: OHP/T193 further optical observations and possible color evolution
  82. GRB 251014A: PRIME near-infrared upper limits
  83. GRB 251014A: Glowbug gamma-ray detection of a likely short burst
  84. GRB 251012A: Glowbug gamma-ray detection of a likely short burst
  85. GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst
  86. GRB 251013C: Early and late-time optical counterpart detection by LCO
  87. LIGO/Virgo/KAGRA S251014cn: NED Galaxies in the 3-Initial Localization Volume
  88. GRB 251013C: Fermi GBM Observation
  89. LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
  90. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  91. GRB 251014A: SAO RAS optical upper limit
  92. GRB 251014A: Fermi GBM Observation
  93. GRB 251013C: EP-FXT counterpart detection
  94. GRB 251011A: Swift/BAT-GUANO arcminute localization of a burst
  95. GRB 251013D: Swift/BAT-GUANO arcminute localization of a burst
  96. GRB 251013C: Swift-XRT counterpart detection
  97. GRB 251013C: SAO RAS optical observations
  98. GRB 251013C: Optical Observations via Virtual Telescope Project, Italy
  99. GRB 251013C: SVOM/VT optical observation
  100. LIGO/Virgo/KAGRA S251013x: Updated Sky localization and Source Classification

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